Theme 6. Environmental monitoring and assessment

doi:10.4103/0972-0464.368745

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Year : 2023 | Volume : 46 | Issue : 5 | Page : 300-404

Theme 6. Environmental monitoring and assessment

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07-Feb-2023

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DOI: 10.4103/0972-0464.368745

How to cite this article:
. Theme 6. Environmental monitoring and assessment. Radiat Prot Environ 2023;46, Suppl S1:300-404

How to cite this URL:
. Theme 6. Environmental monitoring and assessment. Radiat Prot Environ [serial online] 2023 [cited 2023 Mar 23];46, Suppl S1:300-404. Available from: https://www.rpe.org.in/text.asp?2023/46/5/300/368745

Abstract - 61120: Natural radioactivity and the associated hazards in different depths of sediment samples of the northeast coastal area of Tamil Nadu

V. Sathish, A. Chandrasekaran

Department of Physics, Sri Sivasubramaniya Nadar College of Engineering, Chennai, Tamil Nadu, India

E-mail: [email protected]

Introduction: Natural radionuclides contribute 87% of the radiation exposure to human beings, as they are dependent on the mineralogical qualities of soil, rocks, and sediments, while anthropogenic activities contribute the remainder. The measurement of natural radionuclides raises the question of background radiation data, which can be used to provide a reference level for radioactive material emitted into the environment (UNSCEAR, 2000). Several natural radioactivity studies in surrounding areas to assess long-term external exposure have been carried out by Sivakumar et al., Harikrishnan et al, and Thangam et al.^[1],[2],[3]

Objectives: To assess the distributions of natural radionuclides (²³⁸U, ²³²Th, and ⁴⁰K) in three different depth profiles of the beach sediments from the northeast coast of Tamil Nadu.

To calculate different radiological parameters to assess the radiations which are associated with the different depths of sediment samples.

Abstract Review: The activity concentration of natural ²³⁸U, ²³²Th, and ⁴⁰K radionuclides was investigated along the northeast coast of Tamil Nadu. Sediment samples were collected from 21 locations at depths ranging from 0 to 20 cm (top), 20 to 40 cm (middle), and 40 to 60 cm (bottom) and evaluated for radionuclides activity concentration using a NaI(Tl) γ-ray detector. The gamma-ray photo peaks corresponding to 1460 keV for ⁴⁰K, 1764 keV for ²¹⁴Bi, and 2614 keV for ²⁰⁸Tl were used for determining the activity concentrations of ⁴⁰K, ²³⁸U, and ²³²Th respectively. The measured values of ²³⁸U, ⁴⁰K, and ²³²Th were above the global average values reported by UNSCEAR 2000. The concentration appears to be decreasing with depth, though it may not be statistically significant and has to be verified with more samples and analysis. Ra_eq calculated using equation (Ra_eq = A_U+1.43A_Th+0.077A_K) was below the recommended level of 370 Bq kg⁻¹. All radiological parameters except the top surface are results in lower than the recommended safety limits.

Figure 1: Depth-wise distributions of absorbed dose rate

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Table 1: Average activity concentration and radiological parameters for the sediment samples in depth-wise profile

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Keywords: Beach sediment, dose assessment, NaI(Tl) γ-ray detector, natural radioactivity

References

Harikrishnan N, Ravisankar R, Chandrasekaran A, Gandhi MS, Vijayagopal P, Mehra R. Ecotoxicol Environ Saf 2018;162:521-8.
Sivakumar S, Chandrasekaran A, Senthilkumar G, Suresh Gandhi M, Ravisankar R. Iran J Sci Technol Trans A Sci 2018;42:601-14.
Thangam V, Rajalakshmi A, Chandrasekaran A, Arun B, Viswanathan S, Venkatraman B. J Radioanal Nucl Chem 2022;331:1207-23.
UNSCEAR. United Nations Scientific Committee on the Effect of Atomic Radiation. Sources and Effects of Ionizing Radiation. Report to General Assembly, with Scientific Annexures. New York: United Nations; 2000.

Abstract - 61137: Environmental radiation monitoring after the Fukushima Nuclear Power Plant accident (5) database for radioactive substance monitoring data

F. Nagao, H. Kurikami, K. Ochi¹, K. Yoshimura¹, Y. Sanada¹

Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Miharu Town, ¹Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Minamisoma City, Japan

E-mail: [email protected]

In March 2011, the great earthquake and tsunami hit the Fukushima-Daiichi Nuclear Power Plant (FDNPP) and radioactive substance had been scattered over east Japan, especially in Fukushima Prefecture. After the accident, various organizations including the Secretariat of the Nuclear Regulation Authority, Fukushima Prefecture, research organizations, and so on had been environmental radiation monitoring data. These data were monitored, arranged and published by each manner. It is important to integrate these 10 years of environmental monitoring data and present them to domestic and international researchers in order to clarify the behavior of radioactive materials in Fukushima and to reconstruct the exposure assessment. The easy-to-understand publication of these data will also help improve the literacy of residents. Japan Atomic Energy Agency (JAEA) regularly collects and publishes via an online database environmental monitoring data related to the FDNPP accident, published by various organizations.^[1] Gathered data are converted into a common file format (CSV format) suitable for analyzing the spatial distributions and temporal changes of radioactive materials. JAEA has provided collected data in our website (https://emdb.jaea.go.jp/emdb/). The website was largely used over 100,000 access per month in average, but it had small functions because it was stable website. In addition, the registration of new data was laborious, which means the manual work was large, not only data conversion, but also preparing map images and graphic data. JAEA upgraded the website to have dynamic system based on web application and background relational database system. The collected data covered were largely segregated into dose rate and radioactivity, with radioactivity segregated into 12 categories. These categories are (1) soil depth distribution, (2) sea water, (3) marine soil, (4) deposition soil & environment samples, (5) airborne particles, (6) fallout, (7) river water, (8) river soil, (9) drinking water, (10) wild animals & aquatic organisms, (11) ship towing monitoring and (12) food. These sorting was taken into consideration to be able to display the same units on the same map. These data are 59,322,151 as of May 2022. These csv data were registered in a database and a web-based application was built to control search and display functions using SQL. The map display of data is automatically averaged within a predefined mesh according to the scale you wish to display. Various maps and graphs showing distributions of radioactive materials are also available on the website to promote intuitive understanding for users [Figure 1]. In addition to the map visualization function, this database has trend display, search, and download functions. Download files can be selected from csv, text, and shp files, which are standard features of ArcGIS. For soil depth distribution, a special graph of vertical distribution can be displayed. Such big data can be used as machine learning supervisory data for more complex analysis. In addition, standardizing the characteristics of data from different measurement methods and creating an integrated map will enable a more accurate understanding of the current situation. For more advanced analysis, we plan to register the integrated map data which are statistically integrated from different survey data such as air-borne survey, car-borne survey, walk-borne survey and monitoring post.^[2]

Figure 1: Database for Radioactive Substance Monitoring Data https://emdb.jaea.go.jp/emdb/ (The map displayed above is air dose rate by air-borne monitoring, Oct. 2021)

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Keywords: Database, fukushima, monitoring data, open data

References

Seki A, Saito K, Takemiya H. J Radiol Prot 2021;41:S89-98.
Wainwright HM, Seki A, Chen J, Saito K. J Environ Radioact 2017;167:62-9.

Abstract - 61150: Determination of internal and external hazard index of natural radioactivity in Ponnai river sand sample Tamil Nadu, India using a statistical approach

C. K. Senthil Kumar, A. Chandrasekaran¹, C. Gurumoorthy

Centre for Applied Nuclear Research, Bharath Institute of Higher Education and Research, ¹Department of Physics, SSN College of Engineering, Chennai, Tamil Nadu, India

E-mail: [email protected]

River sand is an environmental component that is always used as a building material in India and hence in the present study, the activity concentrations such as ²²⁶Ra, ²³²Th, and ⁴⁰K have been measured in sand samples collected from Ponnai River, Tamil Nadu using a high-resolution gamma-ray spectrometer consisting of an HPGe detector. The gamma-ray photo peaks corresponding to 1460 keV for ⁴⁰K, 1764 keV for ²¹⁴Bi, and 2614 keV for ²⁰⁸Tl were used for determining the activity concentrations of ⁴⁰K, ²³⁸U, and ²³²Th respectively. The measured activity concentrations vary from 13.30 to 54.83 Bq kg^-1 with a mean value of 31.07 Bq kg^-1 for ²²⁶Ra, from 26.15 to 245.33 Bq kg^-1 with a mean value of 83.61 Bq kg^-1 for ²³²Th, from 218.76 to 581.88 Bq kg^-1 with a mean value of 416.36 Bq kg^-1 for ⁴⁰K. The mean activity concentration of natural radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K of the present work has been compared with other similar studies. Radium equivalent activity (Ra_eq) ranges from 96.95 to 421.54 Bq kg^-1 with a mean value of 179.77 Bq kg^-1. The results of the studied samples have values of less than the maximum limit of 370 Bq kg^-1.^[1] In order to assess the radiation associated with sand radiological parameters such as activity utilization index and external and internal radiation hazards, alpha and gamma indexes were calculated. This mean value is almost equal to the world average absorbed dose rate value of 84 nGy h^-1.^[2] Hence the river sand is significant in terms of radiological hazards and required continuous monitoring in the study area. The results show that calculated external radiation hazards (H_ex) values are ranges from 0.27 to 1.14 with a mean value of 0.49. This mean value is less than the recommended limit of unity. The mean value of the internal hazard indexfor sand samples is 0.58 which is less than one only. These results indicate that sand samples do not pose radiation hazards in the study area the mean value of the internal hazard indexfor sand samples is 0.58 which is less than one only. These indicate that sand samples do not pose radiation hazards in the study area. Finally, statistical parameters in [Table 1] (mean, minimum, maximum, standard deviation, variance, skewness, and kurtosis) of ²²⁶Ra, ²³²Th, and ⁴⁰K were obtained for river sand samples in the study area.

Figure 1: The variation of indoor and outdoor absorbed gamma dose rate with sample ID

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Table 1: Basic statistical parameters of radionuclides

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Keywords: Effective dose rate, hazard index, HPGe detector, radionuclides, river sand

References

UNSCEAR. United National Scientific Committee on the Effects of Atomic Radiation. Sources and Risks of Ionizing Radiation. Report to the General Assembly with Annexes. New York: United Nations; 2000.
ICRP 60. Recommendations of the International Commission on Radiological Protection, in ICRP Publication 60. Oxford, UK: Pergamon Press Annals of the ICRP; 1990.

Abstract - 61159: Environmental radiation monitoring after the Fukushima NPP accident (4) development of external exposure dose simulators for individuals

R. Sato, K. Yoshimura, T. Abe, H. Funaki, A. Mori, Y. Sanada, T. Mori¹, T. Sato¹

Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Minamisoma, ¹Social Infrastructure Solution Div., Hitachi Solutions East Japan, Sendai, 980-0021, Japan

E-mail: [email protected]

After the Fukushima Daiichi Nuclear Power Plant accident, external exposure from radionuclides deposited on the ground is by far dominant pathway contributing effective dose in the most affected regions. In 2013, the Nuclear Regulation Authority of Japan stated the importance of residents understanding their own exposure doses. Personal dosimeters are generally used to measure individual exposure doses; however, they cannot be used for predictive or retrospective evaluations and it can be burdensome to wear personal dosimeters at all times. Therefore, a model was developed to estimate exposure doses on the basis of air dose rates and personal behavior.^[1] The model can predictively and retrospectively estimate realistic individual effective doses without burden by changing the air dose rate data used for estimation. The accuracy of the model was confirmed in previous studies,^[2] Sato et al. (in press)^[3] and in this study. We have developed three types of external exposure dose simulators based on the model to meet the need for residents to more easily estimate their own doses. In all three simulators, the server side database stores air dose rate data obtained from environmental radiation monitoring, dose reduction factors according to the type of place and transportation, and conversion factors from air dose to effective dose. The server side calculates exposure doses based on behavior data (place, type of place and transportation, and time) set by the client side, and displays the results on the client side. The features of each simulator are shown below. The first is a web-based simulator that can estimate exposure doses by selecting places on a map and manually inputting behavior data. Routes between places are automatically searched. Since the simulator is used on a browser, it can be used on a variety of devices, such as PCs, smartphones, and digital signage with touch screen. Therefore, it is a basic simulator suitable for various situations. The second is a smartphone application that records the place and time using GPS information and estimate exposure doses along the route of one's own activities. The smartphone application can continuously acquire location information in background operation, allowing for easy route making. As with the web-based simulator, it also has a function that create behavior data manually. Currently, only Android OS is supported, and Internet access is required for estimation. This smartphone application is suitable for easy estimation of exposure doses along recorded route. The third is a combined system consisting of a smartphone application that uses GPS information to create behavior data and a PC application that reads the behavior data and calculates exposure doses. By limiting the function of the smartphone application to creating behavior data only, the application can be used even in mountainous areas where reception is bad, as long as GPS signal can be received. The smartphone application is available for Android OS and iOS. A two-dimensional barcode was adopted for transmitting behavior data from smartphone to PC, considering user convenience. The PCs are intended to be located at public facility, thus simulation completes on the local network. The PC application also has a function to manage statistical information, allowing management of the exposure doses of people entering the target area. This combined system is suitable for simple estimation and management of exposure doses in the areas evacuation orders are lifted. By utilizing these simulators according to the purpose, residents can easily grasp their own exposure doses. Currently, we are lending the devices on which developed simulators are installed to municipalities with specified reconstruction and revitalization base in Fukushima Prefecture, and the simulators are used as one of risk communication tools. The web-based simulator is being prepared to be available as open source software from Japan Atomic Energy Agency. In addition, we are considering linking our simulators with the database for radioactive substance monitoring data (https://emdb.jaea.go.jp/emdb/) for greater convenience in the future. The developed simulators can be used in case of future nuclear disaster by adjusting the calculation parameters.

Keywords: Air dose rate, external exposure, fukushima, life pattern, simulator

References

Sato T, Andoh M, Sato M, Saito K. J Environ Radioact 2019;210:105973.
Sanada Y, Kurikami H, Funaki H, Yoshimura K, Abe T, Ishida M, et al. Trans Atomic Energy Soc Jpn 2021;20:62-73.
Sato R, Yoshimura K, Sanada Y, Sato T. J Radiat Prot Res. [In press].

Abstract - 61161: Environmental radiation monitoring after the Fukushima NPP accident (3) Sediment discharge from river to coastal area

T. Misonou, H. Funaki, T. Nakanishi¹, T. Tsuruta, T. Shiribiki, Y. Sanada

Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Minamisoma, ¹Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Miharu, 975-0036, Japan

E-mail: [email protected]

Typhoon Hagibis (on 11-12 October 2019) and the subsequent typhoon Bualoi (on 24-25 October 2019) caused considerable flood damage in Fukushima region. Nakanishi et al.^[1] reported that approximately 90% of annual sediment (681 t km^–2 y^–1) and ¹³⁷Cs discharges from the Ukedo River catchment in 2019 occurred during typhoons Hagibis and Bualoi. The Ukedo River has a catchment with a high ¹³⁷Cs inventory due to the FDNPP accident. This sediment discharge was almost twice that related to the largest ever flood event since the FDNPP accident, which was caused by the typhoon Etau in September 2015. Thus, there was concern about re-contamination of the seabed sediment in the coastal area due to the deposition of particulate ¹³⁷Cs discharged from river. The aim of this study is to specifically assess the extent and duration of the impact of re-contamination and to understand the behavior of radiocesium entering the coastal area. The study was conducted the Ukedo River mouth located approximately 5–10 km north of the FDNPP. The seabed sediment cores were collected using multiple coring and vibracoring techniques at seven locations in 2019 (before typhoon events), 2020 and 2021 to avoid bedrock [Figure 1]. The sediment samples were dried at 105 °C for approximately 1 day, homogenized and transferred into plastic containers for gamma ray measurement. The activity concentration of ¹³⁷Cs in each sample was determined via gamma ray spectrometry using high-purity germanium detectors coupled with multi-channel analysers. Then, the ¹³⁷Cs activity concentrations in the samples were decay corrected to the sampling date. [Figure 2] shows the total ¹³⁷Cs inventory (kBq m^–2) of the core surface layer (0–10 cm depth) from 2019 to 2021. Overall, the ¹³⁷Cs inventory increased from an average of 21.4 kBq m^–2 (range: 11.1–30.6 kBq m^–2) in 2019 to an average of 38.9 kBq m^–2 (range: 19.9–78.4 kBq m^–2) in 2020. In particular, the ¹³⁷Cs inventory at No.19 in 2020 was three times higher than that in 2019. These results indicate that sediments with high ¹³⁷Cs activity concentrations supplied from the river catchment by two extreme typhoon events in 2019 were widely deposited an extent of about 5 km from the river mouth. On the other hand, the ¹³⁷Cs inventory decreased to an average of 27.9 kBq m^–2 (range: 18.2–36.6 kBq m^–2) in 2021. Tsuruta et al.^[2] indicated that resuspension and offshore transport of particulate ¹³⁷Cs are the main factors causing the ¹³⁷Cs inventory in surface coastal seabed sediments to decline faster than the offshore seabed sediment and river suspended solids environmental half-life (about 3 years). However, the fact that the ¹³⁷Cs inventory in 2021, two years after the huge typhoons passed, is still higher than that in 2019 shows that the impact of sediment discharge from river caused by Hagibis and Bualoi were enormous. We plan to clarify the details of the mechanism through continuous monitoring.

Figure 1: Distribution of seabed sampling locations. Seabed sediments and bedrock were classified based on the paper of Tsuruta ^{et al}.[2]

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Figure 2: ¹³⁷Cs inventory (kBq m^–2) of the surface layer (0–10 cm depth) from 2019 to 2021. Three sites with high ¹³⁷Cs concentrations (excluding depressions) were compared

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Keywords: Coastal area, Fukushima, monitoring, radiocesium, seabed sediment

References

Nakanishi T, Ohyama T, Hagiwara H, Sakuma K. J Coast Res 2021;114:310-4.
Tsuruta T, Shiribiki T, Misonou T, Nakanishi T, Sanada Y, Urabe Y. J Coast Res 2021;114:320-4.

Abstract - 61189: Environmental radiation monitoring after the Fukushima NPP ACCIDENT Characteristics of soil penetration of deposited radiocesium

K. Ochi^1,2, T. Abe¹, M. Sasaki¹, R. Sato¹, K. Yoshimura¹ and Y. Sanada¹

¹Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Minamisoma, ²Graduate School of Frontier Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan

E-mail: [email protected]

The degree of radiocesium (¹³⁴Cs and ¹³⁷Cs) penetration into the soil is expressed in terms of “relaxation mass depth (bs“, which is the numerical value of the slope of the vertical distribution of radiocesium concentration approximated by an exponential function. The b is an important parameter for determining the inventory of radiocesium in soil from air dose rates, and a Table of “recommended values” for simplified assessment is provided by international organizations.^[1] We have been regularly monitored the vertical distribution of radiocesium in soil in urban areas as part of a national project. Previous studies have used these monitoring results to evaluate the adequacy of the conversion factors from air dose rates to inventories and ICRU recommendations value for each b.^[2] Ten years after the accident, the degree of soil penetration of radiocesium is complicated by differences in soil types and human activities, and long-term reliable monitoring is needed. In addition, information on b in forested areas, which account for 60% of Fukushima Prefecture, is limited, making inventory assessments of radiocesium in contaminated areas difficult. In this study, we present the results of regular β monitoring and compare detailed β measurements in a small area of forest and virgin land, and discuss the characteristics of these measurements. Air dose rates, β, radiocesium inventories were obtained at the same location. Air dose rates were measured at 1 m above the ground level with a NaI(Tl) scintillation detector. Soil samples were collected at different intervals to a depth of 10 cm using a scraper plate. The radiocesium concentration in soil was determined by gamma-ray spectrometry using a high-purity Ge semiconductor detector. By the vertical distribution of radiocesium in the soil, the b was evaluated. The radiocesium inventory in soil (MI) is the sum of the product of soil weight and radiocesium concentration in each layer. The relationship between radiocesium inventory and air dose rate was evaluated using the ambient dose equivalent conversion coefficients for radiocesium (ADC_Rcs) based on b based on esium inventory in ADC_Rcs, the radiocesium inventory (CI) calculated from the air dose rates and ADC_Rcs was compared with MI. The deviation of the CI from the MI was evaluated by relative deviation. For evaluating the evolution of the vertical distribution of radiocesium in a wide range of soils, about 70 sites were surveyed during 2011-2021. As a result, b has gradually increased with time and appears to have saturate in recent years [Figure 1]. For confirming the adaptability of ADC_Rcs to forests, which are assumed to be adapted to plains, the three above-mentioned datasets (dose rates, β, MI) were obtained from 2017-2021 in virgin lands and forests. There was no significant difference in the relative deviation of CI to MI for the two land uses. To verify the validity of these results, a more detailed survey of a 25m×25m area was conducted in 2019 in the virgin lands and forests near the Fukushima Dai-ichi Nuclear Power station. Findings in the narrow area were not significantly different from these in the broad area. It was suggested that at the state sufficiently long after the accident, radiocesium inventories can be estimated from air dose rates using ADC_Rcs, even in forests. Differences in the geometry between the two lands uses will be discussed in detail in the future. Such long-term evaluation of β and consideration of land-use characteristics can be applied not only to the evaluation of the current inventory of radiocesium, but also to the evaluation during a post-accident situation.

Figure 1: Temporal variation of effective relaxation mass depth for ¹³⁷Cs

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Keywords: Fukushima NPP accident, radiocesium, soil, vertical distribution

References

ICRU. Gamm-Ray Spectrometry in the Environment, Report 53; 1994.
Ochi K, Funaki H, Yoshimura K, Iimoto T, Matsuda N, Sanada Y. Radiat Environ Biophys 2022;61:147-59.

Abstract - 61191: Environmental radiation monitoring after the Fukushima NPP accident (2) Long-term monitoring of atmospheric radiocesium concentrations

T. Abe, H. Funaki, K. Yoshimura, R. Sato, M. Sasaki, Y. Sanada

Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Minamisoma, Japan

E-mail: [email protected]

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 released large amount of radiocesium (¹³⁷Cs) into the atmosphere. Monitoring of air dose rates and ¹³⁷Cs in atmospheric aerosol in the Specified Reconstruction and Revitalization Base (SRRB) has been conducted. SRRB is an area where decontamination is underway in preparation for the lifting of entry restrictions. The atmospheric ¹³⁷Cs concentration and estimated internal exposure dose are important information for the lifting of entry restrictions, and exposure assessment based on continuous measurement data is required. While the results of long-term monitoring in the difficult-to-return zone have been reported by Abe et al.,^[1] long-term monitoring in the SRRB have not yet been studied in detail.In addition, the urban area where the study site is located consists of paved and unpaved surfaces, and the resuspension of soil particles on the ground surface may be affected by different pavement conditions. To assess the internal exposure dose in the SRRB, we performed continuous atmospheric aerosol monitoring and considered the effects of different pavement conditions. The atmospheric aerosol samples from Jun 2019 to March 2022 were collected on glass fiber filters using a high-volume air sampler placed approximately 1.25 m above the ground surface. Moreover, atmospheric aerosol was regularly collected for 2 weeks with a flow rate of 1000 L min^–1. The activity concentrations of ¹³⁷Cs in the aerosol samples were determined by a γ spectrometer equipped with a multi-channel analyser. Internal dose due to inhalation of atmospheric radiocesium was evaluated using a respiratory rate coefficient value of 1.93 m³ h^-1and an effective dose coefficient of 3.9 × 10^-5 mSv Bq^-1, assuming a situation in which people stay in the study site for 10 hours. Comparison of atmospheric ¹³⁷Cs concentrations between unpaved and paved surfaces, we could not find significant differences. In addition, it was found that the half-lives of the atmospheric ¹³⁷Cs concentrations on the unpaved and paved surfaces were 2.67 y^-1 and 2.61 y^-1 respectively. On the other hand, air dose rates differ approximately three times between paved and unpaved surfaces. Mikami et al.^[2] reported that Air dose rates depend on the deposition of radionuclides on the ground surface. It was considered that although the concentration in atmospheric particles was the same, the exposure air dose rates were three times different due to different attenuation in paved and unpaved surfaces. [Figure 1] shows the estimated inhalation dose rates. Inhalation doses showed a decreasing trend for all pavement conditions. The inhalation dose at the maximum ¹³⁷Cs concentration was estimated to be 1.1×10^-3μSv per day, which is 0.01 % of the external exposure, even under conservative conditions on the pavement surface. As a result of investigating the variation of radioactivity concentration in atmospheric aerosol at SRRB, we found that internal exposure dose has a lower impact compared to external exposure dose. Although some areas of the SRRB were lifted in 30 June 2022, decontamination work and restoration work are still in progress. Since the amount of traffic by residents is expected to increase in the future, it is important to continuously estimate internal exposure doses based on the measured atmospheric ¹³⁷Cs concentrations in the air and air dose rates.

Figure 1: Temporal changes in internal exposure dose which was calculated by monitoring of atmospheric radiocesium concentrations

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Keywords: Atmospheric aerosol, internal exposure dose rate, pavement condition, radiocesium, SRRB

References

Abe T, Yoshimura K, Sanada Y. Aerosol Air Qual Res 2021;21:200636.
Mikami S, Maeyama T, Hoshide Y, Sakamoto R, Sato S, Okuda N, et al. J Environ Radioact 2015;139:320-43.

Abstract - 61269: Effect of residence time of water on uranium mobilisation in alluvial and hard rock formations of Jaipur district, Rajasthan

Diksha Pant, Tirumalesh Keesari,Hemant Mohokar, Annadasankar Roy, U. K. Sinha, H. J. Pant

Isotope and Radiation Application Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

The availability of portable groundwater is the major problem faced by many northern and north western states of India both in terms of quality and quantity. Recent studies reports, presence of uranium in groundwater of some Indian states above the drinking water permissible limit (30 μg/L as per BIS 2021 and 60 μg/L as per AERB).^[1] Similar findings were reported in Rajasthan by Coyte et al.^[2] Subsequently some studies were conducted in this state to delineate the high and low uranium zones in few districts of Rajasthan but none of the studies has attempted to corelate the uranium prevalence with groundwater residence time. This article details the findings from the isotope study carried out in Jaipur with the objective to understand the role of groundwater residence time on uranium release mechanism. The study area, Jaipur district of Rajasthan, has two different types of geological formations, viz., i) alluvial and ii) hard rock. The study area extends from 26.436° to 27.865° N latitudes and 74.915° to 76.293° E longitudes is drained by ephemeral rivers. The groundwater exists under unconfined to confined condition. About 67% of the area is occupied by alluvial aquifer (38.9%: young and 28.1%: older alluvial) and the remaining 37% area is occupied by Schist, Quartzite, Granite, and Gneiss aquifers. Samples were collected for environmental tritium and total uranium from different aquifers and the depths of wells ranged from 45m to 130m below ground level (bgl). The total uranium was measured using LED fluorimeter i.e. UA1, Quantalase. For tritium measurement electrolytic enrichment followed by counting in Quantallus 1220 liquid scintillation counter. The uranium ranges from 5.33 to 142 μg/L and 19 to 145 μg/L in alluvial and hard rock formations respectively. Both the formations are equally affected by uranium contamination. From the depth plot, it is observed that the deeper samples have lower concentration compared to shallower depth in alluvial formation while for hard rock formation no such trend is observed. The tritium for alluvial formation ranges from 0.24 to 2.77 TU while 0.63 to 4.39 TU for hard rock formation. The depth profile of tritium indicates that the deeper aquifers belonging to both the formations possess tritium content suggesting that deeper groundwater in these aquifers are also receiving modern recharge. From tritium versus uranium plot, it is observed that higher uranium concentrations (75- 142 μg/L) are observed in samples having higher tritium values (2.3 to 2.8 TU) i.e. actively recharging systems of alluvial formation. From this trend it can be inferred that recharging water containing high carbonate and nitrate is facilitating mobilization of uranium from the minerals. The regions having higher residence time i.e. low tritium values (0.24 to 2 TU) show lower uranium concentrations (5 to 60 μg/L). In the contrary, the hard rock formations, show low tritium and high uranium content, i.e. groundwater with longer residence time containing higher uranium concentrations. This can be attributed to selective leaching or/and alpha recoil phenomenon promoting uranium release into groundwater. The inferences observations from this study suggest the importance of groundwater residence time in determining/suggesting the process responsible for uranium mobilisation into groundwater.

Figure 1: Depth profile of (a) tritium and (b) uranium concentration in alluvial and hard rock formations

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Figure 2: Correlation plot for tritium and uranium

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Keywords: Alluvial formations, hard rock formation, residence time, tritium, uranium

References

CGWB, Uranium Occurrences in Shallow Aquifer of India, Central Ground Water Board (CGWB), Ministry of Jal Shakti, Department of Water Resources, River Development and Ganga Rejuvenation Government of India; 2020. Available from: http://cgwb.gov.in/WQ/URANIUM_REPORT_2019-20.pdf.
Coyte RM, Singh A, Furst KE, Mitch WA, Vengosh A. Co-occurrence of geogenic and anthropogenic contaminants in groundwater from Rajasthan, India. Sci Total Environ 2019;688:1216-27.

Abstract - 61279: Distribution of radon activity in hard rock aquifers of Southern India

Annadasankar Roy, Tirumalesh Keesari, Diksha Pant, Hemant Mohokar, U. K. Sinha

Isotope and Radiation Application Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Radon (Rn) is a major “naturally occurring radioactive material (NORM)” having substantial impact on drinking water supplies worldwide. Inhalation and ingestion of Rn increase the risk to lung cancer. Groundwater contains comparatively higher levels of dissolved Rn as compared to rain, river and other surface waters. The US Environment Protection Agency (EPA) has suggested a maximum contaminant level (MCL) of 11000 Bq/m³ (11 Bq/L) for radon activity in water.^[1] This level leads to an estimated lifetime cancer risk of 2 in 10,000. This article summarises the findings from a groundwater study carried out in a hard rock aquifer of Southern India which is already suffering from elevated fluoride concentration in groundwater. A detailed account is given on the effective dose from Rn contamination in groundwater and its relation with the physico-chemical parameters of water samples in the study area. The study area belongs to the Nalgonda district of Telangana State (India) and lies between 17°06'48.2” and 17°16'39.33” North latitudes, and 78°52'00” and 78°08'30” East longitudes. It falls in Eastern Dharwar Craton of Deccan Plateau and is composed of the granite/gneissic rocks of the Peninsular Gneissic Complex. A total of 14 samples were collected from dug wells and bore wells with varying depth of 60 to 330 feet during November 2011. Dissolved radon (²²²Rn) in water was measured using a portable continuous activity monitor (SRM - SMART RnDuo Monitor). The radon activity in groundwater varies from 13.6 to 9662 Bq/L with a mean value of 1971±3286 Bq/L. The values suggested that all of the samples are having more than proposed MCL value by EPA (11 Bq/L) [Figure 1]. The effective dose values for ingestion were estimated using the Equation (1);

AED_ig = C_Rn× DWI × DCF × EF (1)

Where, AED_ig is annual effective dose from ingestion, C_Rnis radon concentration in Bq/L, DWI is the daily water intake (2 L/day) as per WHO, DCF is the ingesting dose conversion factor of ²²²Rn (10⁻⁸ Sv/Bq) as per UNSCEAR and EF is the exposure frequency (365 days/year). The radon dose was estimated to be 99-70533 μSv/y with a mean value of 14392±23991 μSv/y. Total 93% samples were found to have effective dose (ingestion) values more than recommended safe limit of 100 μSv/y [Figure 1]. The F^- vs. Rn (Bq/L) plot [Figure 2] suggests that except four samples other samples do not show any significant trend. The four samples show increasing trend in Fconcentration with decrease in Rn activity. Correlation analysis was performed in order to identify the dependency of the Rn release with other physico-chemical parameters of water samples. The correlation coefficients indicated poor correlation of Rn activity with electrical conductivity (EC, μS/cm) (R² = -0.35), pH (-0.14), temperature (°C) (-0.22) and alkalinity (mg/L) (-0.04) of groundwater. The inferences from this study suggest that apart from severe fluoride contamination, the hard rock aquifers of southern India are also facing issues due to elevated levels of Rn activity of groundwater. Proper large-scale study including regular monitoring and identifying the main sources of Rn in groundwater must be done in future to ensure healthy consumption of groundwater for the local people.

Figure 1: Box-Whisker plot showing Rn activity and dose estimated in the study

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Figure 2: Fluoride conc. versus Radon activity (Bq/L)

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Keywords: Groundwater, hard rock formation, radon contamination, radon release mechanism

Reference

USEPA. Review of RSC analysis, Report prepared by Wade Miller Associates, Inc. For the United States Environmental Protection Agency; 1991.

Abstract - 61289: Transfer factor of natural radionuclides in Sacharum spontaneum growing on uranium tailings pond

P. Lenka¹, V. K. Thakur¹, Sarjan Singh¹, C. G. Sumesh¹, A. C. Patra¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, BARC, ²Homi Bhabha National Institute, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Mining, milling and processing of uranium ore is an integral part of the first stage of Indian Nuclear Power Program. Jaduguda region of Singhbhum Shear Zone has been the core of uranium exploration and processing in India. Centralised ore processing unit of Jaduguda processes mined uraninite from Jaduguda, Bhatin and Narwapahar. The process produces large quantities of waste, mainly fine sand in slurry form, called mill tailings, which are discharged into open engineered impoundments called tailings pond (TP). The major portions of the activities of uranium series radionuclides are retained in the tailings.^[1] Once the TP reaches its designed capacity, it is covered with soil. The TP is densely populated with species like Saccharum spontaneum, Typha latifolia etc. These plants may sequester heavy metals and radionuclides from the ambient environment. A preliminary study was conducted to evaluate the uptake of natural radionuclides by Saccharum spontaneum (local name- Kans). These uptake studies are important for remediation of radioactive waste disposal sites. Kans samples and its root zone soil (RZS) (mixture of soil and uranium tailings) were collected from tailings ponds. Root and shoot parts were separated; mud and sand particles were removed by washing repeatedly in running water followed by EDTA solution and ultra-pure water. Root and shoot samples were then air dried followed by oven drying for 24 hours at 110°C and dry weight was recorded. The dried samples were kept at 350°C in a muffle furnace for ashing. The RZS samples were processed for gamma spectrometric analysis as per standard procedure.^[2] The RZS and ashed root and shoot samples were sealed hermetically for radon and its progeny to attain equilibrium with ²²⁶Ra. The samples were analysed using a 40% R.E. p-type HPGe gamma spectrometer with carbon fiber window and 1.7 keV resolution at 1332 keV gamma line of ⁶⁰Co peak. ²²⁶Ra, ²²⁸Ra, ²³⁵U, ²¹⁰Pb and ⁴⁰K activity concentrations in dry weight of RZS and Kans were estimated. The uncertainty of data were evaluated using error propagation of uncertainties of all major contributors. The transfer factors (TF) from soil to plant were evaluated for respective radionuclides using the formula:^[3]

The TFs for soil to Saccharum spontaneum for root and shoot part of the plant are presented in [Table 1]. Mean soil to root TFs for ²²⁶Ra and ²²⁸Ra were found to be of the same order validating the analysis methodology. The TFs for ²²⁶Ra, ²²⁸Ra, ²³⁵U and ²¹⁰Pb for root parts were found to be an order higher than that for shoots. This is due to the fact that root is the primary organ of plant anatomy that assimilates nutrients and minerals from soil, which it is in contact with. Similar orders of TFs for uranium and radium has been reported earlier.^[4] Only for ⁴⁰K the TFs for both root and shoot are of same order, due to the fact that potassium is an essential element for the growth of plant and ⁴⁰K is 0.012 % of natural potassium. The information on soil to plant TFs for the species growing on TPs will provide important data for future remedial actions for such sites. Further extensive studies are being carried out for evaluation of bioaccumulation of natural radionuclides by other plant species growing in the uranium tailings ponds.

Table 1: Transfer factor from soil to Kans

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Acknowledgement

Authors are thankful to Dr. D.K. Aswal, Director, Health Safety & Environment Group for his constant encouragement and support.

Keywords: Gamma spectrometry, transfer factor, uranium mill tailings

References

Khan AH, Jha VN, Jha S, Kumar R. International Sympoisum on Geoenvironmental Reclamation. Nagpur, India: 200. p. 20-2.
Lenka P, Jha SK, Gothankar SS, Tripathi RM, Puranik VD. J Environ Radioact 2009;100:509-14.
Strom M, Smodis B. Nucl Eng Design 2013;261:279-84.
Jha VN, Tripathi RM, Sethy NK, Sahoo SK. Sci Total Environ 2106;539:175-84.

Abstract - 61293: Natural radioactivity in soil samples and external radiation dose in and around Kota, Rajasthan

C. G. Sumesh¹, P. Lenka¹, A. K. Goyal¹, V. P. Singh¹, A. C. Patra¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, BARC, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

A significant part of the total dose contribution in the form of natural sources comes from terrestrial gamma radionuclides.^[1] Natural radioactivity in soil comes from ⁴⁰K, U and Th series radionuclides. Artificial radionuclides can also be present from global fallout. The intensity of terrestrial radiation is not homogenous around the world and depends on the geological formations in the region. Only nuclides with half-lives comparable with the age of the Earth or their corresponding decay products, existing in terrestrial materials, such as ⁴⁰K, ²³⁸U and ²³²Th radionuclides are of great interest in natural radioactivity. These radionuclides are used to assess external gamma radiation dose rate prevalent in an area. The principle objective of the present study is to establish the baseline radioactivity levels in surface soil samples around the upcoming Nuclear Fuel Complex at Kota, Rajasthan. This study provides the existing natural radioactivity levels in soils and estimates the background radiation dose received by public. Knowledge of the environmental conditions prevailing at a site before the start of operation is essential to compare with the conditions during and post-operational period. This helps in planning and development of appropriate monitoring and surveillance activities. The soil samples were collected from 20 locations following standard methodologies. The samples were collected and processed for gamma spectrometric analysis as per standard procedure.^[2] The homogenized sample was packed in a standard geometry 250ml airtight PVC plastic container. The container was sealed hermetically and kept for one month to ensure equilibrium between ²²⁶Ra and its daughters and ²²⁸Ra and its progeny before being analysed by gamma spectrometry. A coaxial HPGe detector of 40 % R.E. with resolution of 1.78 keV for 1332 keV ⁶⁰Co gamma energy was used for assay of the samples. Graded shielding of copper, tin and 100 mm lead was used to reduce background to optimum levels. The detector was calibrated for energy and efficiency using IAEA-RGU1 and RGTh sources with identical geometry as that of the sample. The background subtracted gamma spectra were analysed for ²³⁸U (63 keV-²³⁴Th; 1001 keV-^234mPa), ²³²Th (911 kev, ²²⁸Ac) and ⁴⁰K (1460 keV) using ORTEC Gammavision software. The total air absorbed gamma dose rate (nGy.h^-1) due to the mean activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K (Bq.kg^-1) in the samples were calculated using the equation below according to UNSCEAR, 2000.

D (nGy.h¹) = 0.463A_U+ 0.604A_Th + 0.0417A_K

The annual effective dose rate was calculated by using the conversion coefficient from absorbed dose in air to effective dose (0.7 Sv.Gy^-1) and outdoor occupancy factor (0.2). The effective dose rate in μSv.y^-1 was calculated by using the formula in the following equation.^[1]

Annual dose (μSv.y^-1) = D (nGy.h¹) x 8760 h.y^-1 x 0.2 x 0.7 Sv.Gy^-1 x 10^-3 μSv.Y^-1

The summary of results is presented in [Table 1] below. The mean concentration of radionuclides ²³⁸U, ²³²Th and ⁴⁰K were found to be 36.6, 57.3 and 456 Bq.kg^-1, respectively. The consequent external gamma exposure rates were 16.9, 34.6 and 19.0 nGy.h^-1from ²³⁸U, ²³²Th and ⁴⁰K, respectively. NORM levels in the surface soil samples around upcoming NFC, Kota, Rajasthan are found to be comparable to the reported values across the world.^[1] The estimated annual effective dose (external) due to terrestrial radioactivity is found to be 87 ± 15 μSv.y^-1, which is comparable to the national and global average levels.

Table 1: Soil radioactivity concentrations and associated dose in the study area

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Keywords: External radiation dose, gamma spectrometry, natural radioactivity, surface soils

References

UNSCEAR. Sources and Effects of Ionizing Radiation. Vol. 1. United Nations; 2000.
Lenka P, Jha SK, Gothankar SS, Tripathi RM, Puranik VD. J Environ Radioact 2009;100:509-14.

Abstract - 61315: Effect of beach sand mining on the exhalation rate of radon and thoron from the soil

Parthasarathi Prusty¹, A. Sahu¹, A. Rout¹, R. P. Patra¹, S. K. Jha^1,2, M S Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Every portion of soil contains a certain amount of radium isotopes that release radon (²²²Rn) and thoron (²²⁰Rn) in small or large quantities to the atmosphere through the processes like diffusion and advection. It is estimated that around 2.4 × 10⁹ Ci of radon is released from the soil annually on a global scale.^[1] The release rate is more where ores of uranium and thorium are found.^[2] The eastern coastal region of India is fully enriched with the various mineral of high specific gravity. Out of all available minerals, monazite is radioactive due to the presence of thorium and uranium. The placer depositions are being mined and processed for the extraction of uranium, thorium and rare earths. In the present study, an attempt was made to figure out the degree of reduction in exhalation of radon and thoron from soil due to the mining activity of heavy minerals. The measurement was carried out using RAD 7 which is having a solid state semiconductor-based detector. The radon isotopes were allowed to build up on the soil surface with the help of a container of specific volume. Then the radon and thoron activities were monitored for certain time period till it attains saturation. In case of radon, processes like back diffusion and leakage were also taken into consideration while doing the experiment and reflected in terms of time period to achieve the equilibrium. The set of radon activity data obtained from the field experiments were fitted [Figure 1] in the standard radon build up model to obtain the surface exhalation rate. In case of thoron the exhalation was evaluated using the experimental parameters and saturated thoron activity. The estimated exhalation rates of radon and thoron are listed in the [Table 1]. The results shows that there is a significant reduction in both radon and thoron exhalation rates from the soil after the extraction of heavy minerals. In the mineral deposition area, the exhalation of both radon and thoron are expected to be high because the layers of placer deposition. Since the mineral deposition is close to the surface the radon transport phenomena are also likely to be affected significantly which causes a higher exhalation rate of radon. The study indicates the thorium mining or the extraction of heavy minerals has positive radiological impact on the environment. It reduces the background radioactivity of the site.

Figure 1: Radon exhalation profile in mineral deposition and mined out areas as a function of time

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Table 1: Exhalation of radon and thoron from mineral deposition and mine out areas

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Keywords: Heavy minerals, placer deposits, Radon exhalation, thoron

References

Harley JH, Moghissi AA. Richard Edward Stanley. In: Noble Gases. US: Environmental Protection Agency; 1975. p. 111.
Jha SK, Prusty P, Sahu A, et al. Study on radon (²²²Rn) emanation coefficient and mass exhalation rate from heavy minerals of high specific gravity. J Radioanal Nucl Chem 2021;328:339-46.

Abstract - 61318: Distribution of ²²⁶Ra and ²¹⁰Po in groundwater around uranium mining, milling, and tailings management site at Turamdih, Jharkhand

Samim Molla¹, B. K. Rana^1,2, S. Jha³, Gopal Verma¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, ³Health Physics Unit, UCIL, Turamdih, Jharkhand, India

E-mail: [email protected]

²²⁶Ra is a naturally occurring radionuclide, originating from its parent ²³⁸U. ²²⁶Ra is the most important isotope among all radium isotopes because of its longest half-life (1600 y) and similar chemical behavior to Ca. The immediate decay product of ²²⁶Ra is the short-lived noble gas ²²²Rn (t_1/2= 3.8 days) which either may escape before its decay, or decay within the matrix to produce further daughter radionuclides like ²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi, ²¹⁴Po, ²¹⁰Pb,²¹⁰Bi, and ²¹⁰Po. ²¹⁰Po is an alpha-emitting (5.3 MeV) radionuclide and decays to stable ²⁰⁶Pb. ²¹⁰Po is the most important radionuclide among the natural polonium isotopes, because of their relatively long half-life and they can take part in environmental processes. Both ²²⁶Ra and ²¹⁰Po in water are well-reported for their health hazard and WHO^[1] has proposed a guidance level of 1000 and 100 mBqL^-1, respectively for drinking water to regulate the committed effective dose well within 0.1 mSvy^-1. As the Singhbhum thrust belt is known for uranium mineralization, thus an elevated level of ²²⁶Ra and ²¹⁰Po may be expected in the groundwater around the Turamdih region. In the present study, an attempt has been made to understand the actual level of ²²⁶Ra and ²¹⁰Po groundwater and their distribution around the Turamdih site in Jharkhand which can act as baseline data for other uranium mining sites. 107 nos. of groundwater samples were collected from borewells around 15 km of the mining, milling, and tailings management site at Turamdih, Jharkhand. ²²⁶Ra content was estimated by emanometric technique using the Eq.1 (BIS, 2003):

C is net counts, E is the efficiency of the cell, t is counting delay in minutes, T is counting duration in minutes, θ is build-up period in minutes, λ is the decay constant of ²²²Rn and V is the volume of the sample. The ²¹⁰Po concentration was estimated by deposition on a silver planchet and followed by alpha counting, using the Eq. (2):

where C is net counts in T seconds (counting time), E is counting efficiency (%), V is the volume (liter) of a sample, λ is the decay constant of ²¹⁰Po (s^-1), and t is the delay between sampling and analysis time (s). ²²⁶Ra concentration in groundwater was observed to be varied from 3–210 mBqL^-1with a mean of 20 mBqL^-1 which is well below the WHO recommended guidance level (1000 mBqL^-1). The ²²⁶Ra concentration was also comparable with other uranium mining regions of the country as well as other continents (Jaduguda, India: <3.5-208 mBqL^-1, France: 7-700 mBqL^-1, Germany: 1-1800 mBqL^-1.^[3] The frequency distribution of ²²⁶Ra concentration is presented in [Figure 1]. ²¹⁰Po concentration in groundwater was observed to be varied from 8–77 mBqL^-1with a mean of 34 mBqL^-1, which is well below the WHO recommended guidance level (100 mBqL^-1). The concentrations of ²²⁶Ra and ²¹⁰Po were observed to be heterogeneously distributed in the groundwater in this region, which may be attributed to the local geological condition, hydrogeochemistry, and different types of rock aquifer interaction. The occurrences of ²²⁶Ra and ²¹⁰Po in groundwater depend on several parameters such as the concentration of long-lived parent radionuclides (²³⁸U, ²³⁴U, ²³⁰Th, etc.) in the rock/soil, the solubility of parent radionuclides, solubility of ²²⁶Ra and ²¹⁰Po, rate of release of ²²⁶Ra and ²¹⁰Po by weathering and recoil process and contact time with groundwater.

Figure 1: Frequency distribution of ²²⁶Ra

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Keywords: ²¹⁰Po, ²²⁶Ra, radionuclides in groundwater, uranium mining

References

WHO (World Health Organization). Guidelines for Drinking Water Quality: Radiological Aspects; 2004.
IS 14194-4: Part 4: Radium [CHD 30: Nuclear Materials]; 2003.
Annex B. UNSCEAR Vol. 1; 2000.

Abstract - 61324: Uranium and manganese distribution in ground water sources around Uranium Corporation of India Limited complex at Jaduguda

Sarjan Singh^1,2, S. K. Jha^1,2, V. N. Jha², N. K. Sethy², M. S. Kulkarni^2,3

Departments of ¹Chemical Sciences and ³Physical Sciences, Homi Bhabha National Institute, ²Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Introduction: Mineralogical feature of an area has an important bearing on the abundance of elements into the associated hydrosphere. For favourable economics some of the minerals are extracted for beneficiation for desired products. The beneficiation units have a potential to modify the pre existing status of the environment, water sources in particular. Uranium Corporation of India Limited (UCIL) has been carrying out mining and processing of uranium ore in Jaduguda region for more than six decades. There is a laid down procedure of waste management with a number of control measures in place to avoid migration of contaminants towards water table. The industry is separating uranium compound (yellow cake) from the host minerals using acid leach technique with use of oxidant like pyrolusite. From environmental perspective, U and Mn assume significance due to the associated chemistry and physicochemical conditions. Apart from this, the elements U and Mn are potential health hazard at elevated levels associated with nephrology and neurotoxicity. Present investigation has been carried out in the uranium mineralized area of Jaduguda with an operating uranium mine, a mill, solid waste depository and the Effluent Treatment Plant for removal of these contaminants before discharge. The water sources were selected based on their uses for drinking purposes consisting of tube wells, bore wells and from dug wells.

Materials and Methods: Eighty Five (85) samples of ground water (GW) used for drinking purposes have been collected from the areas adjoining the UCIL complex at Jaduguda. The pH, temperature, electrical conductivities (E_c) and TDS measurements were carried out on site with HORIBA monitor (model no. U-53). After filtration (0.45 μm, membrane), samples were analyzed for total U content using the LED fluorimeter (Quantalase make, Indore). Samples were analyzed for Mn using ICP-OES (Horiba JY radial viewing Ultima 2).

Results and Discussion: pH of the samples varied from 6.6 to 7.8 with an average of 7.2. E_c and TDS varied from 242 to 869 μS cm^-1 and 160 to 540 mg L^-1 with an average of 460 μS cm^-1 and 320 mg L^-1. The concentration of nat. U in samples was in the range of 0.4 ± 0.05 μg L^-1 to 34 ± 2.7 μg L^-1 with a GM of 2.5 μg L^-1. Samples have been found to contain uranium less than the limit of 60 μg L^-1as prescribed by Atomic Energy Regulatory Board (AERB), India. The concentration of Mn in samples was in the range of 1.7± 0.6 μg L^-1to 1242 ± 35 μg L^-1with a GM of 84 μg L^-1.The acceptable limit of Mn in drinking water in India is 100 μg L^-1 with permissible limit in the absence of alternate source as 300 μg L^-1 (IS 10500:2012). Mineralization has an important bearing on the distribution of manganese in the ground water sources with more than 60 % exceeding the acceptable limit. The results are in agreement with reported level.^[1] Samples were classified into four groups based on distance from UCIL complex [Figure 1] and [Figure 2].

Conclusion: Results revealed that the distribution of U and Mn in ground water around Jaduguda is natural and related to the wide spread mineralization. The beneficiation operations at UCIL and state of art technology is able to retain the said contaminates within the designated waste depository.

Figure 1: Distribution of U (μg L^-1) in GW w.r.t distance from tailings management facilty, Jaduguda

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Figure 2: Distribution of Mn (μg L^-1) in GW w.r.t distance from tailings management facilty, Jaduguda

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Keywords: Drinking water, jaduguda, manganese, uranium

Reference

Giri S, Mahato MK, Singh G. Environ Monit Assess 2012;184:1351-8.

Abstract - 61338: Assessment of ²³²Th particulates released from the processing of monazite

Parthasarathi Prusty¹, A. Sahu¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

The Chatrapur beach placer deposition, part of the eastern coast of Odisha state, India is a high background radiation area due to the presence of radiogenic heavy minerals. The beach sands are mined and separated by the Indian Rare Earth Limited to get the individual minerals. Out of all the minerals, monazite is processed chemically in Rare Earth Extraction Plant (REEP) to get the desired products like uranium, thorium and rare earth chloride. During the monazite processing, the radioactive gaseous effluent are being discharged into the atmosphere through a central stack after scrubbing. Thorium and its progenies are the major radioactive element present the gaseous waste. In the present study, the assassment of ²³²Th particulates present in the gaseous effluent was carried out within an 4 km range from the effluent release point. The study was carried out based on a theoretical generic model.^[1] The activity discharged at the source point is taken as 3.5 Bq/s. The source strength is decided with 1 Bq/m³ activity discharge rate with 12500 m³/h volume discharge rate. A neutral atmospheric stability class (Pasquill-Gifford stability class D) is assumed for the screening calculation. The radioactive decay and the deposition mechanism of the radioactive particulates are also considered while doing the evaluation. The screening calculations were carried out for the displacement zone where it is taken the effluent release height (H) is 2.5 times bigger than the building height (H_B) of the plant. Also, calculations were performed for the wake zone where the effluent release height is smaller than 2.5 times the building height and the receptor point (x) is greater than 2.5 times square root of the nearby plant building area (A_B). The latter one is the actual scenario of the existing plant. The activity pattern of ²³²Th in the atmosphere is shown in [Figure 1] with respect to the distance from the source point. [Figure 1] clearly indicates that the activity is reduced effectively if we increase the release point of the effluent. The ground deposition of thorium particulates was also calculated using the recommended deposition coefficient of 1000 m/d. The range of the deposition rate for ²³²Th is shown in [Table 1]. The deposition rate is also found to be lesser if the effluent release occurs in the displacement zone. The study concluded that the ²³²Th activity is lesser to some degree in the surrounding environment if the release point is greater (displacement zone) than the building height. The activity pattern in that case is nearly same up to 800 m due to the identical value of diffusion factor and after that, it reduces effectively. If the stack height is less than the building height (wake zone) then the ²³²Th activity is on the higher side and a drastic activity reduction pattern is observed with distance from the source.

Figure 1: ^232+228Th activity in the air as a function of distance from the source point

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Table 1: Ground deposition rate of ²³²Th

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Keywords: ²³²Th activity, high background area, monazite, plume model placer deposit

Reference

IAEA. Generic Models for use in Assessing the Impact of Discharges of Radioactive Substances to the Environment. Safety Series No. 19. Vienna: IAEA; 2001.

Abstract - 61349: Application of Error Functions to Determine the Best Fitting of Regression Models tothe Experimental Data

Ajay Kumar

BRNS Secretariat, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

The experimental data are generally analysed by numerous regression models in their linear and nonlinear forms.^[1],[2] Over the past few decades, linear form of regression has been developed as a major option particularly in fitting the experimental data.^[1],[2] However, in the recent studies, nonlinear form of regression has been expanded representing a potentially viable and powerful tool in the area of analytical sciences. Furthermore, recent studies have also indicated the growing discrepancy between the theoretical predictions and experimental data resulting in different outcome of models. To avoid such discrepancies and to find the best fit model to the experimental data, a number of error functions are used, producing minimum error distribution between the experimental and theoretical data. It is assumed that, experimental data are similar to the calculated data, then the value of error function as χ² will be a small number. However, if both are significantly different, then χ² value will be a large number. Furthermore, the coefficient of determination (R²) value is also used to determine the best fitting of linear models and is considered perfect fit when its value is close to 1. However, the use of R²value in determining the best fitting of linear model, is not the suitable method as R²has a finite value. Linear fit calculates only the difference between theoretical and experimental data whereas non-linear fit is used to avoid errors affecting R² during linearity. In the present study, some common error functions [Table 1] are highlighted and discussed for the comparisons of linear and nonlinear regression models. Linear regression divulges an analytical solution, whereas non-linear needs the use of an iterative numerical method to minimize the least-squares function. The non-linear regression models usually provide better fits. In addition, transformations of non-linear to linear models implicitly change their error structure leading to violation of normality assumptions of experimental data.

Table 1: Common error functions

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References

Dogan K, Yunus K, Mustafa T, Mustafa O. J Hazard Mater 2007;144:432-7.
Shahmohammadi S, Babazadeh H. Int J Environ Sci Technol 2014;11:111-8.

Abstract - 61351: Assessment of gamma radiation levels in soil samples from Tanguar Haor area, Sunamganj, Bangladesh using γ-ray spectrometry and estimation of population exposure

Tasrina Rabia Choudhury, Jannatul Ferdous¹

Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, ¹Health Physics Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka, Bangladesh

E-mail: [email protected]

The knowledge of radionuclides distribution and radiation levels in the environment is important for assessing the effects of radiation exposure due to both terrestrial and extra-terrestrial sources.^[1] Tanguar Haor is one of the largest wetland systems located in the northeast region of Bangladesh and plays an important role in the economy of the country with its natural richness and biodiversity. A comprehensive study was planned and carried out to determine the level of gamma activity concentration in soil samples which were collected from Tanguar Haor area, Sunamganj, Bangladesh. The activity concentrations of radioactive materials ²²⁶Ra, ²³²Th and ⁴⁰K were determined by means of a gamma-ray spectrometry system using an HPGe detector with 30% relative efficiency in a low background configuration and the radiological hazard parameters in that region were estimated.

[Table 1]. The gamma activity concentrations in soil samples of Tanguar Haor area are tabulated along with their errors ± in [Table 1].

From this table it is observed that the measured gamma activity concentrations of naturally occurring radionuclides such as Ra-226, Ra-228 and K-40 ranging from 30.6±1.66 to 46. 5±7.09 Bq /kg, 23.4 ± 4.65 to 42.9±6.44 Bq /kg and 335.9 ± 11.8 to 479.4 ± 16.8 Bq /kg in wetland soil samples, respectively. In soil samples, the mean activity concentrations for ²²⁶Ra, ²²⁸Ra and ⁴⁰K were found to be 37.5 ± 5.32, 32.9± 5.91 and 402±55.9 Bq.kg⁻¹, respectively. The results obtained for the corresponding nuclides Ra-226, Ra-228 and K-40 in soil of the study area are higher than the world average values 35, 30 and 400 Bqkg^-1.^[2] The radiological hazard indices such as radium equivalent activity, external health hazard indices, absorbed dose rate and annual effective doses of the soil samples in this region were estimated and compared with the world averages. The average value of radium equivalent activity is less than the criterion limit of 370 Bq.k^-1.^[3] The average outdoor and indoor annual effective dose for soil samples is 0.069 mSv which is near about the world average value of 0.07 mSvy^-1 for outdoors and indoor annual effective dose 0.36 mSv which is lower than 0.41 mSvy^-1 for indoors.^[2] The obtained result in this work can be used as the regional base line data for estimation the future radioactivity contamination in the studied region.

Table 1

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Keywords: Gamma radiation, radiological hazards, soil

References

Ahmed NK. Measurement of natural radioactivity in building materials in Qena City, Upper Egypt. J Environ Radioact 2005;83:91-9.
UNSCEAR. Effects of Atomic Radiation to the General Assembly, in United Nations Scientific Committee on the Effect of Atomic Radiation. New York: United Nations; 2000.
UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). Exposure from Natural Sources of Radiation of Radiation. Report to the General Assembly, United Nations; 1993.

Abstract - 61360: Standardization of parameters for detection limit of gamma emitting radionuclides in air particulates

S. J. Sartandel, Rupali C. K. Kamat, V. B. Yadav, V. A. Pulhani, I. V. Saradhi, A. V. Kumar

Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Airborne radioactivity may be due to primordial, cosmogenic or anthropogenic radionuclides present in the dust particles of ambient air (APM). These are used as tracers for different processes in the atmosphere. Regular radiological surveillance of air particulate activity can serve as a background to detect any unforeseen event, releasing anthropogenic fission/activation products. The large uncertainty in measurement and detection of low level anthropogenic contribution in APM makes differentiating a true/false signal a challenge. Hence, there is a need to assess the sensitivity of the instrument and method suitability for desirable detection limits. Current manuscript gives the minimum detectable activity (MDA) for anthropogenic, cosmogenic and natural radionuclide's in APM in Mumbai. Air particulate samples were collected on glass fibre filters using high-volume air sampling system of flow rate 1.1 m³ min^-1. The sampled filters were compacted, into a circular pellet of 4.5 cm diameter using a hydraulic press to get an efficient counting geometry. A p-type carbon end contact HPGe spectrometer coupled to GAMMA PRO spectrum analysis software. Detector was calibrated for energy response and efficiency over an energy range of 46 to 2614 keV using IAEA RGU and RGTh pellet, and cross checked using IAEA-2020 and IAEA-2021 Filter paper in similar geometry as the samples. Generally a blank sample in similar matrix is used for the MDA estimation, but to understand impact of natural radionuclide's concentration in estimation of anthropogenic radionuclides, MDA for anthropogenic radionuclides has been estimated using both blank and actual air sampled filter pellet. Background estimation algorithm has been considered for two scenarios, peak seen and peak not seen in the spectrum.^[1] MDA estimation (Eq.1) by ISO11929, 2021 is similar to one defined by Curie, 1984 but with an additional uncertainty parameter.

K_S, K_W, K_C - Decay correction factors for sampling duration, between sampling and acquisition start and during acquisition time respectively.

w (weighting factor) = (1/t.ε_E.γi.V_o)

t=Acquisition time(s), ε_E=counting-efficiency, γ_i=gamma abundance, V_o= Sample volume.

As seen in [Figure 1], MDA decreases with increasing counting time and an optimum of 24 hours was found to be desirable for achieving required detection limit of 10 μBq m^-3 for ¹⁴⁰Ba as achieved in CTBTO stations (Miley et.al.,2019; CTBTO, 2007). MDA of natural/cosmogenic radionuclides were estimated using blank filter but for anthropogenic radionuclides both blank and sampled air filter were used [Figure 2]. Contribution of short lived radon-thoron progeny of natural U, Th series radionuclides, Compton from ⁴⁰K and ⁷Be leads to higher background mostly at the low energy gamma spectrum. MDA estimated using sampled filter for anthropogenic radionuclides [Figure 2] such as ^99mTc, ¹²⁹I, ¹⁴⁴Ce, ¹⁴³Ce, ¹³²Te with lower energy shows comparatively higher levels than blank filter. Thus the MDA determined using a filter paper with sampled APM may be recommended for identifying a true signal for anthropogenic activity.

Figure 1: Radionuclide MDA variation with counting time

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Figure 2: MDA of a blank and sampled air particulate

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Keywords: Anthropogenic, cosmogenic, minimum detectable activity, natural

References

Done L, Ioan MR. Appl Radiat Isot 2006;114:28-32.
BSI Standards Limited. ISO 11929 ; 2021.
Currie LA. NUREG/CR-4007; 1984. p. 40-55.
Miley, et al. J Environ Radiat 2019;208-09, 106037.
CTBTO. CTBT/PTS/INF.58/Rev.8; 2007.

Abstract - 61362: Tissue free and organically bound tritium in rice plant grown around Kakrapar NPP Site, India

Amol Chandrakar, C. P. Joshi, A. K. Patra, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory (ESS, EMAD, BARC), Surat, Gujarat, ¹Environmental Monitoring and Assessment Division (EMAD), BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Two Pressurized Heavy Water Reactor (PHWR) of capacity 220 MWe each are operational at Kakrapar Atomic Power Station (KAPS)-1&2, Gujarat. Small quantity of tritium (³H) is released to atmosphere from the operation of PHWR, much within the allowed regulatory limits. ³H as tritiated water (HTO) is incorporated into terrestrial biota through root uptake and foliar uptake process as tissue free water tritium (TFWT). A portion of TFWT is converted into organically bound tritium (OBT) through metabolic process. OBT exhibits longer residence time in organism than tritiated water. TFWT and OBT which are present in the biota samples may be transported to human through food chains. Rice is a major component of diet around this site. An attempt was made to study the migration of ³H through rice. Rice paddy were collected during harvesting season (October, 2020) from eight villages around 1.6-15 Km of Kakrapar Gujarat Site. Tissue free water were extracted using freeze drying technique and organically bound water were extracted by thermal batch combustion method using Pyrolyzer.^[1] ³H activity was analysed by using Liquid Scintillation Spectrometer (LSS) (Quantulus 1220). The background and efficiency of LSS is 1 cpm and 24%, respectively. TFWT and total OBT activity in different parts of the rice plant (rice and hay) are provided in [Table 1]. TFWT activity in rice and hay was found to be <4-17 (GM: 12; GSD:2) and <4-20 Bq l^-1 (GM: 13; GSD:2), respectively. Total OBT activity in rice and hay was found to be <9-18 (GM: 13; GSD:1) and <13-18 Bq l^-1 (GM: 14; GSD:1), respectively. TFWT and total OBT activity in rice and hay are comparable. Total OBT activity in rice was found to be <5-5.8 (GM: 5.2; GSD:1.1) Bq kg^-1 dry wt. For the computation of OBT activity (expressed as Bq l^-1of combustion water) in terrestrial plants, knowledge on water equivalent factor (WEQp) , defined as the volume of water produced from the combustion of 1 kg of the dry sample, is essential. Site specific WEQp in rice was found to be 0.5-0.7 (average: 0.55) L kg^-1. From the measured OBT activity, the ingestion dose to the inhabitants in the vicinity of NPP was calculated. The residence time of NE-OBT is about three times longer than that of TFWT, therefore, the dose due to NE-OBT is recognised to be significant when compared to TFWT. The effective dose coefficient for OBT ingestion of adult is 4.1 × 10^-11 Sv /Bq^-1(UNSCEAR, 2016).^[2] The annual ingestion dose to a person residing around Kakrapar Gujarat site due to OBT is calculated due to the consumption of rice and was found to be 0.04 μSv /y^-1. Nayak et al., 2020^[1] reported the ingestion dose due to OBT around Kaiga, Karnataka as 0.09-0.27 μSv y^-1. The annual effective dose due to ingestion of total OBT is a negligible fraction (0.004%) of the annual dose limit of 1000 μSv y^-1for the general public (other than natural sources) recommended by ICRP^[3] and the Atomic Energy Regulatory Board, India.

Table 1: Tissue free water tritium and organically bound tritium activity in different parts of rice

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Keywords: ³H, HTO, OBT, TFWT

References

Nayak RS, DSouza RS, Kamath SS, Mohan MP, Bharath S, Narayana B, et al. Appl Radiat Isot 2020;166:109390.
UNSCEAR, 2016. Available from: https://www.unscear.org/docs/publications/2016/UNSCEAR_2016_Report.pdf.
ICRP. Oxford: Pergamon Press; 1991. Available from: https://www.icrp.org/docs/ICRP_Publication_103-Annals_of_the_ICRP_37(2-4).

Abstract - 61367: Studies on dilution and dispersion pattern of tritium (³H) in Moticher Lake at Kakrapar Gujarat site using generic dispersion model

C. P. Joshi, A. K. Patra, Amol Chandrakar, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory (ESS, EMAD, BARC), Surat, Gujarat, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: c[email protected]

Low level radioactive liquid effluents are generated during the operation of nuclear power plant at Kakrapar, which contains mainly ³H, ^134+137Cs, ⁹⁰Sr and ⁶⁰Co. After proper treatment and dilution, it is discharged into Moticher lake through Blowdown point. Moticher lake is a small lake system having 8 sq km catchment area. This lake acts as a balancing reservoir between Kakrapar canal (up stream) and Ratania regulator (down stream) which is the first public utilization point. This dilution study was performed using ³H (T_1/2: 12.3 y) as a tracer. ³H has a high potential for migration into the aquatic, atmospheric and terrestrial environment. Water samples are collected from blowdown point and Ratania regulator (1.6 km) and analysed for ³H activity using Liquid Scintillation Spectrometer (LSS) (Quantulus 1220). Six set of experiments were carried out on six different aquatic releases with different time duration. During each experiment, water velocity, depth, incoming water flow and blowdown flow data was taken as input parameters for prediction model. The background and efficiency of LSS is about 1 cpm and 24%, respectively. Generic model, detailed inIAEA safety series,^[1] was used for predicting tritium activity in the lake water using the following Equation (1).

Cw_TOT= Q_i/Q_r× e^-(λ × x/U) (1)

Where Cw_TOT is the total radionuclide in water (Bq/m³), Q_i is the average discharge rate for radionuclide i (Bq/s), Q_r is the river flow rate ranged from 68-100 m³/s (Avg. 92 m³/s), U is the net fresh water velocity ranged from 0.4-1.0 m/s (Avg. 0.7 m/s), Lambda is the radioactive decay constant (1.79 E-09 per s) and X is the distance between the discharge point and the receptor (1600 m). The experiment was performed on different release occasions. The observed ³H activity at blowdown point was in the range of 308 to 3984 Bq/l. The predicted and observed ³H activity at Ratania regulator was 5-75 Bq/l and 12-48 Bq/l, respectively. In all the cases, predicted activity is more than the observed activity, except in one case. The reason may be the non-uniform weed growth through out the lake, disturbing the dilution pattern of the lake. The model prediction provides a conservative estimate, as many removal mechanisms are not considered in this generic model. The observed ³H activity at Ramghat (2.2 km downstream of lower Ganga canal) from main out fall Narora Atomic Power Station was varied 8.5-12 Bq/l.^[2] The predicted and observed dilution factors at Ratania regulator were 41-154 and 24-314, respectively. The factors affecting this dilution process are flow rate of incoming water, depth and width of water body, water velocity, weed growth within the lake etc. The site specific estimates will be useful for the preliminary dilution estimation, during accidental releases, if any.

Table 1: ³H activity along with dilution factors at Ratania regulator

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Keywords: Dilution, dispersion, IAEA SRS 19, LSS, tritium

References

IAEA. Technical Report Series No.19. IAEA; 2001. p. 47-52.
Gauatm YP, Kumar D, Sharma AK, Saradhi IV, Kumar AV. NUCAR-2021; 2021.

Abstract - 61369: Natural radioactivity in food grains and vegetables generated in eastern coast of India

Abinash Sahu¹, P. Prusty¹, A. Rout¹, R. P. Patra¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, Mumbai, ²Homi Bhabha National Institute, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

The beach sands of Indian coast is abundant with the heavy minerals (i.e. the minerals having specific gravity more than silica). The beach sands in the eastern coast of India contain majorly illeminite, silminite, rutile, zircon, garnet and monazite. Among all these heavy minerals monazite contains 8 – 10 % of ThO₂ and around 0.3 % U₃O₈. U & Th content trapped in the monazite are basically in the phosphate form and occur in equilibrium with their daughter products. Due to the abundant presence of U, Th and their daughter products in the beach sand of this area, the observed background radiation level is comparatively higher than other parts of the country. In this study an attempt was made to understand the migration of radioactivity to the locally grown food grains and vegetables as the radioactivity present in the consumable parts of the plant are very helpful in the dose assessment model. The study was carried out in the eastern coast of India between Gopalpur in the south and Rushikulya in the north. The area is stretched around 20 km. Two types of major grains i.e. rice and dal along with two vegetables i.e. brinjal and lady finger were selected as they are locally grown in this area and are a part of the everyday staple of the local population. The samples were collected and prepared as per the guidelines of IAEA TRS-295.^[1] The samples were dried in a hot air oven and turned to dry ashing as per the procedure. The samples were cooled down and stored in a desiccator. After sample preparation, the samples were then hermetically sealed in the containers for 30 days so that the daughter radio nuclides reach the secular equilibrium. The samples were then analysed in a p-type high purity Ge detector system with 40 % relative efficiency with respect to the 3” × 3” NaI(Tl) detector system. The HPGe detector system was calibrated using IAEA RGU & IAEA RGTh standards for estimation of the naturally occurring radionuclides of U & Th. The samples were analysed for 100000 s. A typical spectrum generated in the HPGe detector for rice is presented in the [Figure 1]. The graphical representation for counts is in log format where as the channel no. is in linear format. The activity of U²³⁸ and Th²³² are calculated from the activities of their daughter radionuclides. The results of the analysis are summarised in the [Table 1]. The results presented are in Bq kg^-1 of fresh weight of the food grain or vegetable. The activity due to thorium daughter products is higher than the activity due to uranium daughter products. The results clearly shows that the activity in the soil is transferred to the food grain and vegetables. These transfer factors are helpful in establishing the dose estimation model.^[2]

Table 1: Radioactivity in the food grains and vegetables

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The authors are grateful to Dr. D. K. Aswal, Director, Heath Safety & Environment Group for encouraging to carry out the study.

Figure 1: Graphical representation of the spectrum from HPGe detector

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Keywords: Gross alpha, gross beta, radioactivity, radium

References

IAEA. A Guide Book for Measurement of Radionuclides in Food and the Environment. Technical Reports Series No. 295, IAEA; 1989.
IAEA. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments. Technical Reports Series No. 472, IAEA; 2010.

Abstract - 61372: An experimental study of airborne iodine -131 collection in different activated charcoal adsorbing media

Jyotsna A. Sapkal, Pankaj Sorate, Pratap Singh, R. V. Kolekar

Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

It is essential to carry out monitoring of I-131 activity released during its radiochemical processing at Isotope Wing, RLG to demonstrate compliance with the authorized limits set by the regulatory authorities. Study related to the trapping of I-131 using different types of activated charcoal granules, released from the production plant, was carried out. Experiments were carried out at filter house using specially designed sampling setup at relative humidity ~ 75%, ambient temperature ~25⁰C & sampling period 1 week. Four different types of activated charcoal granules viz Activated, Silver (Ag), Triethylene Di-amine and Ag + Triethylene Di-amine impregnated granular activated charcoal media were used for estimation of Iodine -131 collection efficiency. It was observed that Ag+ Triethylene Di-amine charcoal granules have very high collection efficiency compared to only activated, Ag and Triethylene Di-amine impregnated charcoal granules. This paper describes in brief about the experiment related to study of collection efficiency of I-131 using activated charcoal impregnated with different types of the medium and comparison of the results obtained.

Where A_i^th is the activity of I-131 collected in i^thcartridge.

For activated charcoal granules mediums viz Activated, Ag charcoal, the collection efficiency in the first charcoal cartridge varies between 27 – 43% indicating that Ag activated charcoal has better collection efficiency over activated charcoal. For Triethylene Di-amine charcoal and Ag + Triethylene Di-amine the collection efficiency in the first cartridge is 68 - 99 % & indicates that the Ag + Triethylene Di-amine charcoal have very high adsorption as compared to activated charcoal, Ag activated charcoal & Triethylene Di-amine charcoal granules. It was found that the iodine collection efficiency in Ag + Triethylene Di-amine charcoal is found to be 99% in the 1 cartridge itself and in the remaining cartridges is less than 1%. The study indicates that Ag+ Triethylene Di-amine charcoal granules is the most appropriate medium for estimation of I-131 activity released through exhaust system. Further study related to adsorption efficiency is planned under various environmental conditions. However, the availability of an Ag+ Triethylene Di-amine activated charcoal and economics of its use needs to be reviewed.

Figure 1: % collection (adsorption) efficiency of different charcoal granular media

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Table 1: The percentage collection efficiency in each cartridge of different media

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Keywords: I-131, activated charcoal granules, authorized limit, collection efficiency, cartridges

References

Manucha SM. Porous Carbons, Department of Materials Science, Sardar Patel University.
Sapkal JA, Suresh M, Rath DP, Shreenivas V, Bairwa SM, Amruta CT, et al. Development of Multiple Cartridge System for Effective Estimation of I-131 Release From Stack. Mumbai: IARPNC, 19-21; 2014.

Abstract - 61374: Levels of tritium in various environmental compartments at Kalpakkam

J. Thulasi Brindha, K. R. Sreedevi, T. Jesan, K. S. Rao, C. Manonmani, A. Thilakavathi, Anitha Manu, S. Ramkumar, I. V. Saradhi1, A. Vinod Kumar¹

Environmental Survey Laboratory, Kalpakkam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Tritium, an activation product may get released as tritiated water (HTO) during the operation of PHWR type reactor, within the permissible limits, through both atmospheric and aquatic route. This released tritium follows the water cycle and gets partly incorporated in biota. As part of environmental monitoring, tritium is regularly monitored in different environmental matrices such as air moisture, fresh water, sea water and biota. This paper presents the summary of tritium monitoring at Kalpakkam during 2017 – 2021. Environmental samples are collected from various locations upto 30km radius from MAPS. Air moisture samples are collected using ice condensation method. Fresh water and sea water samples are subjected to distillation to remove interference from other radionuclides and to reduce quenching in Liquid Scintillation Analyser (LSA). MDA for 10 ml sample + 10 ml Ultima Gold LL scintillation cocktail and counting time of 200 min in LSA Hidex 300 SL is 0.06 Bq/m³ for air moisture sample and 3 Bq/L for freshwater samples. MDA for seawater samples is 9 Bq/L for a sample volume of 5ml and counting time of 100 min. In the case of biota samples, free water from the samples is extracted using Freeze dryer for Tissue Free Water Tritium (TFWT). Organically Bound Tritium (OBT) is extracted by subjecting the oven dried samples to oxidation using Pyrolyser Raddec 6 trio. TFWT and OBT are then measured in LSA. MDA is 3 Bq/L for TFWT and 60 Bq/L for OBT (2g dry sample) for a counting time of 200 min. Summary of tritium measurements in air moisture, fresh water and sea water samples for the period 2017 – 2021 are presented in [Table 1]. From the table it is observed that in all matrices 70 – 75 % of the samples are BDL. The higher air tritium activity during the years 2017 and 2021 was observed during release of tritium well within the Tech spec, but slightly high compared to day to day release. The locations matching with plume direction. Even though few samples are above BDL and comparatively higher, the mean values are less and the resulting dose very less inferring negligible impact of plant operations on environment. Tritium present in air moisture and ground water get partly exchanged with free water of the vegetation (TFWT) and also get incorporated with organic matter as OBT during photosynthesis.^[1] TFWT is exchangeable with water, hence it may get eliminated before consumption of the products whereas OBT will be available during consumption. Hence, vegetation samples like rice, ragi, brinjal, papaya, raw mango were analysed for TFWT and OBT and the results shown in [Table 2]. The observed levels are low. Environmental monitoring of tritium at Kalpakkam showed that the levels of tritium in all matrices are low in order and contribute negligible dose to members of public at Kalpakkam.

Table 1: Tritium activity levels

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Table 2: Tissue free water tritium and organically bound tritium in biota samples

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Keywords: Air, OBT, sea water, TFWT, tritium

Reference

IAEA-TECDOC-1616; 2009.

Abstract - 61375: Environmental impact of different forms of tritium (HTO, tissue free water tritium, and organically bound tritium) at Tarapur

A. Baburajan, R. H. Gaikwad, V. Sudheendran, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Tarapur, TAPP PO, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Tritium (E_max:18.6 keV, T_½: 12.3 y), a radioisotope of hydrogen released into the air from the Pressurised Heavy Water Reactor (PHWR) and Fuel Reprocessing Plant (to a small extent) at Tarapur, mostly in HTO form, undergoes environmental transport and gets converted into Tissue Free Water Tritium (TFWT) in plants and a fraction of it is converted into Organically Bound Tritium (OBT) during photosynthesis. It gets translocated into different parts of the plant and has a long (T_½: 40 days) residence period. Environmental Survey Laboratory (ESL) at Tarapur as well as other PHWR sites regularly monitors tritium in air and computes population dose due to inhalation and skin absorption. A limited work on the measurement of these forms of tritium (TFWT, OBT) is available for tropical countries and no study was conducted on the impact of these nuclides on the population dose at NPP sites in India. In view of this knowledge gap, a study has been undertaken to determine the concentration of these components of tritium in air and different food items (rice, vegetable, fruits, milk, and fish) and to evaluate the population dose at Tarapur. The air tritium, TFWT, and OBT in edible terrestrial and aquatic matrices were measured using the method specified by Baburajan 2021.^[1] The geometric mean concentration of tritium (HTO) in air, TFWT, and OBT in edible sample matrices at various receptor locations during the period 2014-2018 was estimated and is presented in [Figure 1]. The geometric standard deviation is provided above the graph. It is observed from the figure that among different food items, a higher OBT is found in rice, possibly due to its high organic content. The variation in TFWT and OBT concentration may be due to difference in partitioning mechanism of tritium (HTO) within the plant water and organic matter; also, the TFWT gets continuously exchange with the air tritium, tries to attain equilibrium within a few hours and hence an external factor influences its concentration. Whereas, the OBT retained in the organic compound exchanges very slowly into tissue free water. The mean population dose using site-specific dietary data^[2] was computed for different zonal distances and is presented in [Table 1]. From the table, it is seen that the total dose to the member of the public at 1.6-5 km is 0.082 μSv y^-1and reduces with distance. It is also evident from the table that the majority of the total dose (61.8% to 65.7%) is contributed by OBT in food items. Also, the OBT dose computed for different food items indicated that the rice is the major contributor to the ingestion dose may be due to its higher organic content and higher annual intake^[2] when compared to other food items. The study indicates that measurement of all components of tritium is important and the OBT dose is higher compared to others. However the total tritium dose is found to be negligible when compared to the population dose limit of 1000 μSv y^-1 for the public.

Table 1: Annual mean population dose due to different forms of tritium at Tarapur

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Figure 1: Mean TFWT and OBT concentration in edible samples at 1.6-5 km distance from NPP site. TFWT: Tissue free water tritium, OBT: Organically bound tritium

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Keywords: Tritium, tissue free water tritium, organically bound tritium, environment, impact

References

Baburajan A. Studies on the Environmental Radiological Impact of Tritium and Carbon-14 Including the Organically Bound Forms around the Nuclear Facility Site at Tarapur, Ph.D. Thesis, Mangalore University; 2021.
Patil SS, Sudheendran V, Baburajan A, Rao DD, Chandramouli S, Patel PV, et al. Re-evaluation of Dietary intake based on a New Demographic Survey and the Dose Due to Ingestion at Tarapur. NSE-13, June 5-7, North – Eastern Hill University, Shillong, India; 2004.

Abstract - 61376: Estimation of organically bound tritium in wheat sample and computation of ingestion dose around NAPS Narora site

Y. P. Gautam, Deepak Kumar, A. K. Sharma, A. R. Tripathi, Vineet Kumar, Sanjeev Kumar, J. Kumar, V. Kumar, B. Singh, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Narora Atomic Power Station, Narora, Uttar Pradesh, ¹EMAD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]n

Tritium (3H) is a radioactive isotope of hydrogen (T1/2 = 12.3 year), and it decays to ³He by emitting low energy beta radiation with an average energy of 5.7 keV and a maximum energy of 18.6 keV.^[1] Tritium in the environment exist in several forms, such as gaseous (HT, HTO, CH3T), liquid (HTO or organic molecules in solutions) or organically bound tritium (OBT) which can get incorporated into living organisms (vegetables, animals, humans). Tritium from air/water is incorporated into plant/animal biota as Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT).^[2]

In the present study, terrestrial food products such as wheat grain is collected from different off-site locations around the NAPS Narora site during March 2020 to May 2021 and analysed for OBT. Tritium released as HTO through atmospheric route is main pathway of tritium intake for above matrix.

Samples were dried to remove moisture and crushed into fine powder and combusted in Pyrolyser system (tube furnace) in the presence of oxygen and air mixture at 600-800 °C. The combusted water was collected in glass bubbler kept in cryo-cooler system. Later distillation has been carried out on collected water to reduce quenching effects.^[3] Treated water is mixed with scintillation solution and counted in Quantulus 1220C ultra low level Liquid Scintillation Counter (LSC) for determination of OBT activity in the samples, using site specific water equivalent factor (WEQp) evaluated earlier:

Where CW (volume of combustion water) & CE (Counting Efficiency %) Rec. (Recovery %) of Pyrolyser System, DW (Dry weight), C_OBT (OBT Concentration), H_p (Consumption rate, 164 kg/a), DF_ing (Dose conversion factor: 4.2E-11 Sv/Bq), f_d (correction fraction),E_ing(Ingestion dose due to wheat intake). The OBT levels observed in wheat are insignificant in terms of dose received in comparison with the natural radiation dose received by members of public. OBT formation and the accumulation as organic compounds depends on period of growing season of the matrices. Wheat crops is important because having more OBT concentration due to larger growing period. The OBT activity in wheat from the study will provide useful information to access the existence of tritium exposure conditions in the environment and input to the environmental transfer model. The levels obtained in the current study are comparable with the studies carried out at Kaiga site.^[4]

Table 1: Organically bound tritium in various wheat samples

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Keywords: Environmental sample, organically bound tritium, tritium, water equivalent factor

References

Publication, 38, Elsevier ICRP Radionuclide Transformations: Energy and Intensity of Emissions. International Commission of Radiological Protection; 1983.
IAEA Management of Waste Containing Tritium and Carbon-14, Report IAEA 421, Vienna; 2004.
Baglan, N., Alanic, G., Pointurier, F., 2005. Tritium determination at trace level: which strategy to determine accurately HTO and OBT in environmental samples? Fusion Sci. Technol. 48, 749e754.
Karunakara N, R Nayak, Srinivas S K, Ravi P M, Dileep B N and Narayan B(2020), Standardisation of methods for long term continuous sampling of air for H-3 measurement, and for the measurement of OBT and TFWT in the environmental matrices. BRNS project No.: 2013/36/19-BRNS/3339.

Abstract - 61379: Atmospheric ³H impact assessment (2011-2021) around Narora Atomic Power Station

A. K. Sharma, Y. P. Gautam, Deepak Kumar, Vineet Kumar, J. Kumar, A. R. Tripathi, Sanjeev Kumar, Vimal Kumar, B. Singh, I. V. Saradhi², A. Vinod Kumar¹

Environmental Survey Laboratory, Narora Atomic Power Station, Narora, ²EMAD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Tritium is radioactive isotope of hydrogen, is ubiquitous in nature and also it is produced by Pressurized Heavy Water Reactors (PHWRs).^[1] The nuclide ³H decays to form ³He by emission of a beta particle with a maximum energy of 18.6 keV and an average energy of 5.7 keV. Environmental Survey Laboratory located at Narora Atomic Power Station (NAPS) site regularly monitors the concentration of tritium in the environment to ensure the safety of the public since gaseous radioactive waste, which contains tritium, is being released through a 145 m high stack at NAPS site. This paper presents the result of analyses of tritium in atmospheric environment covering an area up to 30 km radius around NAPS site during 2011-2021. Large numbers of air moisture samples were collected around the NAPS site, for estimating tritium in atmospheric environment, which has been used in calculation of radiation dose to the public. Air moisture samples were collected at ground level from different villages up to a distance of 30 km around NAPS site using ice condensation method. The activity of tritium in the sample is counted using ultra low-level liquid scintillation spectrometer (LSS) (Model: Tricarb-3170 TR/SL). The system background count rate was 1–2 cpm and counting efficiency of LSS system for the detection of ³H was about 25%. The detection limit of the present system for ³H was estimated to be about 0.10 Bq.m^–3 in air. The committed effective dose (CED) to members of the public due to inhalation is derived using the mean ³H concentration in air and the breathing rate of an Indian adult, as per the standard guideline. The breathing rate of 23 m³.d^–1[2] and dose conversion factor of 1.8*10^–11 Sv.Bq^–1 was used for the dose computation. From [Table 1], it is observed that during 2011-2021 out of 6105 air moisture samples, the ³H activity in 2367 samples was below the detection level (BDL). The atmospheric ³H concentration around NAPS site was found to be in the range of ≤0.10–99.7 Bq.m^–3. The mean inhalation dose due to Tritium to the member of general public at different distances (1.6–30 km) from NAPS site was found to be ranged from 0.10 – 0.23 μSv.y^–1 as shown in [Figure 1]. The maximum inhalation dose due to ³H is about 0.2% of apportioned dose to the general public for NAPS 1&2 operation.^[3]

Figure 1: Mean inhalation dose at different distances (2011-2021)

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Table 1: Tritium concentration distribution around Narora Atomic Power Station (2011-2021)

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Keywords: Dose conversion factor, inhalation dose, pressurized heavy water reactor, tritium

References

Blaylock BG, Hoffman FO, Frank ML. Radiat Prot Dosim 1986;16:65.
Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment, IAEA,SRS-19; 2001.
Technical Specification for NAPS Operation (Part-A & Part-B), Narora Atomic Power Station. Narora, Bulandshahr, U.P: Nuclear Power Corporation of India, Ltd; 1999.

Abstract - 61380: Temporal distribution of uranium concentration in hand pump water around construction site Gorakhpur Haryana Anu Vidyut Pariyojana, Hisar, Haryana

Sanjeev Kumar, Y. P. Gautam, Vineet Kumar, Deepak Kumar, A. K. Sharma, A. R. Tripathi, J. Kumar,V. Kumar, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Narora Atomic Power Station, Narora, Uttar Pradesh, ¹EMAD, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India

E-mail: [email protected]

Uranium is a naturally occurring radioactive element. Small amounts of uranium are present in certain types of soils and rocks, especially granite. Natural uranium comprises isotopes of U-234, U-235 and U-238. More than 99 percent of uranium found in nature is uranium-238. Uranium occurs more often in bedrock and deep bedrock wells are more likely than shallow wells to have elevated levels of uranium^[1] which will vary greatly vary from place to place. The aim of the present work is to determine the base line data on uranium concentration in drinking water around upcoming nuclear site in Hisar, Haryana. Samples of hand pump water were collected from different locations around Gorakhpur Haryana Anu Vidyut Pariyojana (GHAVP). Sampling locations are shown in the [Figure 1]. The collected hand pump samples were filtered through the 0.45 μ whatmann filter paper to remove any suspended solids in the water, acidified with 0.1M nitric acid (AR Grade, Merck) and stored in, acid washed, 100 ml capacity polypropylene bottles. Samples were collected in air-tight lab grade polypropylene bottles of 100 ml capacity.^[2] Samples were analyzed for uranium content using “Fluorat-02-4M” liquid analyzer. Quality assurance of the data was made by the analysis of Inorganic Venture (USA) make CGU1 Uranium Standard of 1000ppm concentration of uranium and by replicate analysis. 5 ml of reagent water was taken into polypropylene vial, pipette 0.5 ml of a sample solution and 0.5 ml of sodium polysilicate solution into this vial. Mixed solution was placed into a cell of the analyzer and measurements were started by liquid analyzer. Percentage distribution of Uranium concentration in pre-monsoon, post-monsoon and monsoon are shown in [Figure 2], [Figure 3], [Figure 4]. U-concentration in Hand pump water ranged from ≤2 to 86 ppb with Geometric mean of 20 ppb in pre-monsoon , ≤2 to 107 ppb with Geometric mean of 12 ppb in post-monsoon, ≤2 to 65 ppb with Geometric mean of 20 ppb in monsoon season.Variation in concentration during monsoon season may be due to ground water recharge from rainfall. The overall geometric mean of Uranium concentration in study area was found to be 19.9 ppb and is well below the limit given by AERB(1). The mean concentration of Uranium in hand pump water is slightly higher than the reported value 14.6 ppb in Narora region.^[2]Variation in concentration during monsoon season may be due to ground water recharge from rainfall. No significant variation in GM values were observed during pre and post monsoon.

Figure 1: Location map of the study area

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Figure 2: % distribution of uranium concentration in pre-monsoon season

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Figure 3: % distribution of uranium concentration in post-monsoon season

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Figure 4: % distribution of uranium concentration in monsoon season

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Keywords: Drinking water, fluorometry system, uranium, WHO

References

AERB (Atomic Energy Regulatory Board), Directive for Limit on Uranium in Drinking Water, Mumbai, India; 2004.
Manbir Singh VK, Garg Y, Gautam P, Avinash Kumar. Ingestion Dose to General Public from Natural Uranium in Ground Water around NAPS, Narora EEMJ_496_Singh_12; 2013.

Abstract - 61386: Assessment of soil to wheat transfer factor and discrimination factor around NAPS Narora and GHAVP Haryana, two NPP site of Northern India

Deepak Kumar, Y. P. Gauatm, A. K. Sharma, Sanjeev Kumar, Vineet Kumar, A. R. Tripathi, J. Kumar, I. V. Saradhi¹,A. Vinod Kumar¹

Environmental Survey Laboratory, Narora Atomic Power Station, Narora, Uttar Pradesh, ¹EMAD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Radiation to which the human is exposed comes from many diverse sources. Some of these are natural and other are anthropogenic. The plant takes deposited radionuclides from soil and the radionuclide transfer is commonly expressed as soil to plant transfer factor (TF). The rates at which the various radionuclides will migrate through, different soil to plant systems depend upon soil type, pH, soil/liquid distribution coefficient, exchangeable K⁺, organic matter content etc. [1]. During the present study two inland NPP site i.e. operational site NAPS Narora and upcoming site GHAVP, Haryana were selected to estimate K-40 and Cs-137 content in soil and wheat (Triticum aestivum) grain, discrimination factor (DF) and their transfer factor (TF), as TF is regarded as one of the most important parameter, in environmental safety assessment for nuclear facilities, as well as for risk assessment to humans. Study area is an alluvial plain of Indo-Gangetic basin having sandy to loam and loam to sandy type soil. A total of 30 samples each (soil and wheat) from both the sites were collected at different locations around site as per standard protocols [2]. Wheat sample and corresponding soil from the field were collected simultaneously. The collected samples were dried at 100 °C for about 24 hours to remove moisture then grinded and sieved through a 500 μm mesh-size sieve. 1kg of samples were filled in airtight Marinelli beakers and sealed. The samples were subjected to gamma-ray spectrometric analysis using P-type HPGe (50% Relative Efficiency) spectrometric system. The radioactivity concentration of Cs-137 and K-40 were determined from γ-ray energies of 661.62keV and 1460.7 keV, respectively, by using Eq. (1):

Where E: Counting efficiency (%), I: Intensity (%) and W: Weight of sample

From observed activity concentrations of radionuclide in the wheat and in the corresponding soil, the TF values were calculated using the Eq. (2):

To check and compare the efficiency of absorption of Cs/K in wheat, discrimination factor (DF) was evaluated by Eq. (3)

The activity concentrations of K-40 and Cs-137 in soil and wheat grain of both sites are given in [Table 1]. K and Cs both are monovalent and being in same group in periodic table follows similar uptake pattern. Their radioactive counter parts namely Cs-137 and K-40 also follows as similar trend of transfer from soil to wheat grain as that of stable. In present study it is observed that concentration of Cs-137 in soil and in wheat grain is found to be 2 order of magnitude less than the concentrations of K-40 in soil and in wheat grain. High activity of K-40 in wheat grain might be attributed to its high mobility in soil and its subsequent uptake by the wheat plant due to biological requirement of plants for potassium, as it is a major essential nutrient element for the growth of plant. The study was conducted on wheat grain which is widely consumed by the population of north India.

Table 2 gives the DF and soil to wheat grain TF for Cs-137 and K-40. The higher mobility of K-40 in soil and its subsequent uptake by the plants depends on many factors such as pH, bioavailability, presence of organic matter, clay mineral etc. The estimated DF values are less than unity confirms that K⁺ is more efficiently absorbed then Cs⁺. The level of activity concentration of natural and anthropogenic radionuclide in the soils under investigation at both the NPP site are comparable and was below the world average.

Table 1: Cs-137 and K-40 activity in soil and wheat grain

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Table 2: Soil to wheat grain transfer factor and discrimination factor

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Keywords: Cs-137, discrimination factor, K-40, soil samples, transfer factor, wheat samples

References

Kumar A, Singhal RK, et al. Impact of tropical ecosystem on the migration behavior of K-40, Cs-137, Th-232, U-238 in perennial plants, water air soil pollutions. 2008;293-302.
International Atomic Energy Agency. Measurement of radionuclides in food and the environment, TRS-295. Vienna: International Atomic Energy Agency; 1989.

Abstract - 61387: Carbon-14 activity in the vicinity of different pressurised heavy water reactor sites using mango tree leaves

A. R. Tripathi, Deepak Kumar, Y. P. Gauatm, A. K. Sharma, Vineet Kumar, J. Kumar, Sanjeev Kumar, Vimal Kumar, B. Singh, S. N. Tiwary¹, A. K. Patra², A. Baburajan³, I. V. Saradhi⁴, A. Vinod Kumar⁴

Environmental Survey Laboratory, Narora Atomic Power Station, Narora, ¹ESL RAPS, ²ESL KAPS,³ESL TAPS, ⁴EMAD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected])

C (T_1/2=5730 y) is a pure beta emitter (with E_max=156 keV) occurs naturally due to its cosmogenic origin and is also produced in nuclear power plants through neutron activation of ¹⁴N, ¹⁵N, ¹⁷O, ¹⁶O, and ¹³C and partly released to the environment. ¹⁴C is released as ¹⁴CO₂ and ¹⁴CH₄form from the Nuclear Power Plants.^[1] During preliminary studies average ⁴CO₂release from all four NPP is around 0.29 TBq/GWe-a. The released ¹⁴CO₂ is quickly assimilated by plants through photosynthesis, which necessitates the ¹⁴C monitoring in the environment to evaluate the radiation dose to the general public through this route. Mango tree being most commonly fruit bearing tree available around different Pressurised Heavy water reactor (PHWR) sites of India i.e. NAPS, KAPS, RAPS and TAPS considered for study. Aim of the study is to estimate the impact on the environment around different PHWR sites due to release of ¹⁴C through gaseous route. Mango leaf samples from within 1.6km site and beyond site boundary were collected on monthly basis during 2020-22. Sampling locations were selected in downwind direction of the plant site and away from roads obviate the influence of fossil fuel combustion. ¹⁴C specific activity (Bq/kg of C) in mango leaves is an important primary indicator of ¹⁴C levels in the environment around the site. The samples were oven dried at 100 °C, crushed into fine powder and combusted by thermal oxidation^[2] using Pyrolyser Trio system for separation of carbon in the form of CO₂. Separated CO₂is collected as dry ice during combustion process and trapped in mixture of pre weighed carbon trap (CO₂absorbent) and Carbon count (Scintillation Solution). Post weighing the mixture amount of CO₂ trapped is quantified followed by counting in LSC (Quantulus 1220C Perkin Elmer, USA). The ¹⁴C specific activity (Bq/kg of C) of mango leafs samples is estimated using following equation.

Where C_g, C_b (gross and background count per min.), E (fractional Counting Efficiency) & C (Wt. of CO₂ kg). [Figure 1] shows the Geometric mean of ¹⁴C specific activity in the mango leaves samples collected at different PHWR sites. Soil samples also collected and analysed for ¹⁴C specific activity which was found below natural level of 226Bq/KgC. The geometric mean of ¹⁴C specific activity in mango leaves within and beyond 1.6km site boundary of all sites under study ranging from 269 to 311 Bq/kg C and 220 to 253 Bq/kgC, respectively. Maximum concentration of C-14 found due to purging of Moderator cover gas intermittently and sample collected in downwind direction. The ¹⁴C levels observed in beyond site boundary of all PHWR sites under study were insignificant in terms of dose received in comparison with the natural radiation dose received by members of public.^[3] The levels obtained in the current study are comparable with the studies carried out at Kaiga site.^[2]

Figure 1: Mean ¹⁴C activity in mango leaves samples collected within and beyond 1.6km site boundary at different PHWR sites. PHWR: Pressurised heavy water reactor

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Keywords: Carbon trap, carbon-14, environmental impact, pressurised heavy water reactor, pyrolyser

References

IAEA. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Fresh Water Environments Report IAEA 472, Vienna; 2010.
D'Souza RS, Nayak, et al. Optimisation of a batch thermal combustion method using a tube furnace oxidation system (pyrolyser) and LSC for carbon-14 determination in environmental matrices. J Environ Radioact 2020. [doi.org/10.1016/j.jenvrad.2020.106345].
Choppin GR, et al. Radiochem Nucl Chem 2002. (doi.org/10.1016/B978-0-7506-74638.X5000-6).

Abstract - 61392: Analysis of anions in environmental water samples around an upcoming nuclear facility

V. K. Thakur¹, A. C. Patra¹, S. K. Jha^1,2, P. Lenka¹, G. P. Verma¹, S. K. Sahoo¹, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

About 71% of the Earth's surface is water-covered and the oceans hold about 96.5% of all Earth's water. Less than 1% of the world's freshwater is readily accessible.The water supplied from surface sources is exposed to air pollution and other contaminating agents. Onthe other hand, groundwater is generally less prone to occasional contaminants and nearly tells about the nature of the detrital material of the aquifer. Surface water is used for drinking, in household activities, agricultural and feed water for industries. Concentration of anions, cations and other water quality parameters are important with respect to its usability for drinking or domestic purposes. In the present study, as a part of preoperational survey around an upcoming nuclear facility at Kota, Rajasthan, environmental water samples were collected around the site for determination of prevalent trace elements, cations, anions and radionuclides. This paper presents the anionic study of the groundwater and surface water samples collected from the site. Many natural factors can affect environmental water quality; primary factors being the source and chemical composition (cations and anions). By measuring the concentrations of these ions, the chemical quality of the water can be characterized. Sixteen water samples were collected around the study area and were analysed by Ion chromatographic (IC) system 840 professional Metrohm system using anion exchange column. The mobile phase used is a mixture of millimolar solutions of Sodium carbonate and Sodium bi-carbonate. 100 mmol solution of H₂SO₄ is used for regeneration of suppresser. The samples are diluted using Millipore ultra-purified water. IC system is calibrated with 0.5 ppm, 1.0 ppm and 5 ppm of mixed anion standards (Fluka). Calibration curve is obtained for each anion and routine instrument blank, standards and duplicate sample analyses were carried out for anions like fluoride (F^-), chloride (Cl^-), bromide (Br^-), nitrite (NO₂^-),nitrate (NO₃^-), sulphate (SO₄^2-) etc. for quality control and quality assurance. The level of nitrite,phosphate and bromide in most of the samples were found to be below detection limit i.e., 0.05 ppm, whereasthat of fluoride varied from <0.05 ppm to 3.36 ppm, with mean of 0.80 ppm.Concentrations of chloride, nitrate and sulphate varied from15.6-779 ppm, 0.64-398 ppm and 7.5-160 ppm with average concentrations of 169.2 ppm, 90.2 ppm and 45.4 ppm respectively. Phosphate ranges between 0.05-0.3 ppm with mean value of 0.06 ppm. Concentrations of these anions were found to be well within the BIS and WHO guideline values.^[1],[2] [Table 1] depicts the measured anion levels and their comparison with national and global guideline values. These anions were chosen for the study as these can serve as indicators for infiltration of contaminants and radionuclides into water sources. From the data obtained, positivecorrelations between concentrations of chloride and sulphate (0.51) and that of nitrate and sulphate (0.84) were observed confirming their natural origin.^[3]

Figure 1: Correlation between SO₄^2- with Cl^-& NO₃^-

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Table 1: Concentrations of anions measured in the water samples (n=16)

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Keywords: Anions, ion chromatography, water

References

WHO. Guidelines for Drinking Water Quality. WHO; 2011.
Drinking Water Specification IS 10500. 2012.
Martinez, et al. Water Res 2020;182:115962.

Abstract - 61407: Numerical study on the particle size evolution of SrO₂aerosols using discrete sectional method

Shikha Sivakumar, A. Jasmin Sudha, V. Subramanian, B. Venkatraman

Aerosol Transport and Biodiversity Section, Radiological and Environmental Safety Division, Safety, Quality and Resource Management Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Predicting nuclear aerosol behaviour during postulated accidents in nuclear power plants is integral to reactor safety evaluation. Nuclear aerosol properties are governed by the particle size evolution which is an indicator of aerosol behaviour. During an accident scenario in a reactor, a small fraction of radioactive fission products will be released into the containment, which is responsible for the environmental source term. Size growth of these aerosols with time governs their settling behaviour inside RCB. Hence, a numerical study of the evolution of size distribution of these aerosols with different generation rates is taken up in the present work. Experiments have already been reported in the literature on the settling behaviour of SrO₂ aerosols inside the ATF chamber at IGCAR.^[1] Strontium peroxide's size evolution and deposition are obtained through numerical simulations in the present study. An open source code from github, based on the discrete-sectional method is used to solve the General Dynamic Equation (GDE) governing the dynamics of SrO₂ aerosols. This method can model a wide range of sizes, using both discrete and sectional bins to increase the accuracy of the simulation. Hence, this method is ideal to incorporate particle generation models and chemical reactions. The effect of geometric factor on size distribution was studied using the code and the results indicated that κ = 1.0718(size doubles for every ten bins) provides optimum accuracy in the simulation. This κ value and 500 bins are sufficient to cover the entire size regime of the aerosol considered. Parametric study is carried out with different particle generation rates (R). In each case, R is held constant for two minutes after which there is no particle generation. Then particle size evolution upto an hour is studied. The particle size distribution of SrO₂ aerosol at different times, ignoring losses is presented in [Figure 1]. As the aerosols undergo coagulation, condensation and evaporation, the size distribution evolves and it shifts towards larger sizes. The change in count median diameter (CMD) [Figure 2] and mass median diameter (MMD) can be used as an indicator to show the change in size distribution, and the results are presented in [Table 1]. For the generation rates ranging from 10⁶ to 10¹³ no.cm^-3s^-1, CMD after an hour is found to vary between a nano meter and a micron as seen in [Table 1]. The evolution of the size distribution for different generation rates is presented in [Figure 2]. The effect of gravitational deposition on the total mass concentration is studied, for a particular case, in an effort to compare the code prediction with available experimental data.^[1] The gravitational deposition rate is calculated for the ATF chamber and fed into the code as size-dependent input. Considering R=10¹³no.cm^-3s^-1, the normalized mass concentration w.r.t. time is compared with experimental data in [Figure 3]. The discrepancy between the two is due to wall plating and other losses. In 1 hour, the mass concentration of SrO₂ aerosol has reduced to 36.53% of initial value due to gravitational settling alone. The applicability of the code to aerosol dynamics is demonstrated in this study. It is further planned to use the code for other nuclear aerosols.

Figure 1: Evolution of size distribution

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Figure 2: Growth of CMD at different R (no.cm^-3s^-1)

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Figure 3: Effect of gravitational deposition

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Table 1: Size evolution at the end of 1 h

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Keywords: Discrete sectional method, fission product aerosol, general dynamic equation, gravitational settling

Reference

Subramanian V, Baskaran R, Misra J, Indira R. Experimental study on the behavior of suspended aerosols of sodium and nonradioactive fission products (SrO₂and CeO₂) in a closed vessel. Nucl Technol 2011;176:83-92.

Abstract - 61432: Radiological characterization of natural radioactivity in coal, fly ash and bottom ash using HPGe gamma-ray spectrometry

S. V. Bara¹, S. Chinnaesakki¹, M. R. Dhumale¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, ²Homi Bhabha National Institute, BARC, Mumbai, Maharashtra, India

E-mail: [email protected], [email protected]

Combustion of coal contributes to more than 70% of the power generation. Coal being a fossil fuel contains traces of naturally occurring radionuclides due to ²³⁸U, ²³²Th and ⁴⁰K. Operation of thermal power plants generates huge amount of solid wastes i.e. fly ash and bottom ash. There is a significant enrichment of natural radioactivity in ashes produced by the combustion of coal. Enrichment ratio is the ratio of concentration of the nuclide in ash to its concentration in the feed coal. The enrichment ratio in ashes depends on the level of radioactivity present in coal. Fly ash from thermal power plants is being used as a substitute for conventional raw materials in construction and other industries. Hence, it is now mandatory to analyze these samples before its commercial deployment. This paper discusses the analysis of coal, fly ash and bottom ash received from various thermal power plants across India. Fifteen coal samples with their corresponding fly ash and bottom ash were sealed in 250 cc plastic containers and analyzed using gamma-ray spectrometry system having p-type HPGe with 50 %, coupled with 64 k DSP MCA module Standard reference materials have been used for the calibration of the system covering 46 keV to 2614 keV. Natural radioactivity due to the presence of ²³⁸U, ²³²Th their daughter products and ⁴⁰Kwere estimated. [Figure 1] shows the gamma spectra of coal, fly ash and bottom ash acquired for 10⁵ seconds. [Table 1] shows the activity concentrations due to ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, ²²⁸Th and ⁴⁰K. [Table 2] presents the radionuclide activity ratios in coal and ashes. The enrichment factors in fly ash and bottom ash samples is shown in [Figure 2]. In most cases, the enrichment factors in fly ash for all above listed radionuclides were 2 – 4 times higher than the parent coal. This has also been observed in other studies.^[1],[2] The enrichment factor observed for ²¹⁰Pb in fly ash is the highest among other radionuclides and its enrichment in in fly ash is also high as compaired to bottom ash.This enrichment of ²¹⁰Pb in fly ash is due to the combustion process in which coal is subjected to high temperatures which results in volatilization of Pb and its enrichment in fly ash.The activity ratio of ²²⁶Ra/²³⁸U in the ashes are consistant with their feed coal reflects that combustion process does not result in enrichment these of long lived radionuclides and secular eqilibrium is maintained in ash samples as well.^[3]

Figure 1: HPGe Gamma spectra of Coal, Fly and Bottom Ash

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Figure 2: Natural radioactivity enrichment from coal to ashes

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Table 1: Radionuclide activity concentrations in coal and ashes

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Table 2: Radionuclide isotopic ratios in coal and ashes

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Keywords: Gamma spectrometry, HPGe, Radioactivity, Coal

References

Sahu SK. Enrichment and particle size dependence of polonium and other naturally occurring radionuclides in coal ash. J Environ Radioact 2014;138:421-6.
Flues, et al. J Radioanal Nucl Chem 2006;270:597-602.
Lauer NE, et al. Environ Sci Technol 2015;49:11227-33.

Abstract - 61433: Accurate measurement of ¹³⁴Cs/¹³⁷Cs ratio in Japanese bamboo using HPGe gamma-ray spectrometry

M. R. Dhumale¹, S. Chinnaesakki¹, S. V. Bara¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, BARC, ²Homi Bhabha National Institute, BARC, Mumbai, Maharashtra, India

E-mail: [email protected], [email protected]

Cesium (Cs) is a soft, silvery white-gray metal that occurs in nature as ¹³³Cs. There are 11 major radioactive isotopes of Cs. Only three long have half-lives: ¹³⁴Cs (Half-life = 2.06 years), ¹³⁵Cs (Half-life 2.3 million years) and ¹³⁷Cs (Half-life 30.05 years) and they are beta particle emitters. ¹³⁴Cs ¹³⁵Cs and ¹³⁷Cs are produced by nuclear fission with high fission yields. ¹³⁷Cs is a major radionuclide in spent nuclear fuel, high level radioactive wastes resulting from the processing of spent nuclear fuel.^[1] ¹³⁴Cs ¹³⁵Cs and ¹³⁷Cs are the well-known nuclear forensic signature nuclides. HPGe Gamma-ray spectrometric technique have been used as the best nondestructive analytical tool for the analysis of ¹³⁴Cs and ¹³⁷Cs. Traceability of the IAEA member state laboratories involving in the measurement of environmental radioactivity has been verified through periodic proficiency tests (PT) organized under its ALMERA network.^[2] In 2021 PT, the IAEA sent the bamboo sample collected around FUKUSHIMA after the accident for the analysis and reporting of anthropogenic radionuclides (Ref. date 01/01/2021). The sample was analysed using high resolution gamma – ray spectrometer consists of a p-type HPGe with 60 % relative efficiency shielded with 10 cm graded shielding and coupled with DSP based 64 k MCA integral unit. The challenge was to analyse bamboo sample for which the standard reference materials are not available for calibration. Hence developed a method using liquid reference material spiked with ¹³³Ba and ¹⁵²Eu along with estimation of self-attenuation and coincidence summing correction as there is difference in physiochemical properties of the standard and sample. The sample spectrum was acquired for about 2 × 10⁵ sec, as shown in [Figure 1] and identified all the photo peaks due to ¹³⁴Cs and ¹³⁷Cs. The results were reported and subjected to evaluation criteria, discussed elsewhere.^[2] Our results passed in all the evaluation criteria and the comparison is shown in [Figure 2]. Then the activity levels were back calculated to the date of Fukushima accident i.e. march 11, 2011 and the ratio between ¹³⁴Cs and ¹³⁷Cs was calculated. It was found out that the ratio is 0.82, which is in line with the reported values and confirmed that the source for the Cs nuclides in the bamboo could be from unit – 2 of the Fukushima daiichi NPP complex.^[3]

Figure 1: HPGe Gamma-ray spectrum of Japanese bamboo sample

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Figure 2: Comparison of IAEA and HPD-LLCL ¹³⁴Cs and ¹³⁷Cs activity concentration (Ref.Date: 01/01/2021) in Japanese bamboo

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Acknowledgements

The authors would like to thank the IAEA for providing the samples and periodically organising the proficiency tests.

Keywords: ¹³⁴Cs, ¹³⁷Cs, Gamma spectrometry, HPGe, radioactivity

References

Argonne National Laboratory, EVS. ANL and DoE. In: Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas. Chicago: Argonne National Laboratory, EVS; 2005.
Osvath I, Tarjan S, Pitois A, Groening M, Osborn D. Appl Radiat Isot 2016;109:90-5.
Masamichi C, Terada H, Nagai H, Genki K, Satoshi M, Tatsuo T, et al. Sci Rep 2018;6:31376. [DOI: 10.1038/srep31376].

Abstract - 61434: Soil to vegetable transfer factor (F_v) for the radionuclides ¹³⁷Cs and ⁹⁰Sr at Kaiga region

Joshy P. James, T. L. Ajith, M. S. Vishnu, I. V. Saradhi¹, A. Vinodkumar¹

Environmental Survey Laboratory, Kaiga Generating Station, EMAD, BARC, Kaiga, Karnataka, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Soil to plant transfer factor (Fv) is one of the important parameters used in radiological environmental impact assessment studies. It is defined as the ratio of the concentration of radioactivity in the crop to the radioactivity per unit mass of the soil (IAEA,2010).This paper presents soil to vegetable transfer factor for the radionuclides ¹³⁷Cs and ⁹⁰Sr in Kaiga region, Karnataka where four PHWR units are in operation. Six types of non leafy vegetables commonly consumed by population of Kaiga region were planted in experimental field, near KGS site [Table 1]. The plants were irrigated with water from Kadra reservoir which receives, effluents from KGS. ¹³⁷Cs activity in vegetables was determined by gamma spectrometric analysis of ash samples using HPGe detector as per standard procedure.⁹⁰Sr activity in vegetables was determined using radiochemical analysis followed by beta counting. Moisture content, organic content and ash content with respect to fresh weight of vegetables is also estimated. Seven soil samples from experimental field, up to a depth of 10 cm was collected and processed as per standard procedure and were subjected to gamma-ray spectrometry using HPGe detector for ¹³⁷Cs estimation. Radiochemical analysis followed by beta counting was employed for the determination of ⁹⁰Sr activity in soil. Moisture content, organic content and pH of soil samples were determined by standard methods. The range of pH, organic content and moisture content of the soil samples in the field varied from 4.6 to 6.1, 5.6 to 20.0%and12.7 to 37.5% respectively.¹³⁷Cs activity in soil samples from study area is found to be varying from 3.7 to 14.9 Bq.kg^-1 drywt, with arithmetic mean value of 6.0 Bq.kg^-1 dry wt. ⁹⁰Sr activity in soil samples varied from BDL(<1.2) to 1.8Bq.kg^-1drywt with arithmetic mean value of 1.5 Bq.kg^-1drywt.¹³⁷Cs activity was found to be below detection limit (BDL) in all samples of papaya, banana and tomato.¹³⁷Cs activity in brinjal, bitter gourd and ladies finger samples was varying from BDL to 0.03, BDL to 0.08 and BDL to 0.04 Bq.kg^-1fresh wt, respectively. ⁹⁰Sr activity was found to be below detection limit (BDL)in all samples of tomato and ladies finger.⁹⁰Sr activity in banana, brinjal, bitter gourd and papaya was varying from BDL to 0.23,BDL to 0.03,BDL to 0.08 and BDL to 0.04 Bq.kg^-1fresh wt, respectively. These values are comparable with pre operational values reported in Kaiga region. The arithmetic mean values of soil to vegetable transfer factor of ¹³⁷Cs and ⁹⁰Sr are presented in [Table 1]. The values are varying from (5.00±0.17)×10^-3to (1.33±0.17)×10^-2for ¹³⁷Cs and from (2.0±1.3)×10^-2to (1.5±0.5)×10^-1for ⁹⁰Sr.The value of soil to vegetable transfer factor of ¹³⁷Cs in Indian environment is in the range of 0.016 -0.13 and for ⁹⁰Sr the value is in the range of values 0.007 -0.36. (Hedge et al, 2004). As per IAEA report soil to vegetable (non leafy) transfer factor for ¹³⁷Cs in tropical environment is varying from 5×10^-2to 1.1×10¹with mean value of 7×10^-1and for ⁹⁰Sr, the value is varying from 2.6×10^-1to 4.2 with mean value of 1.2 (IAEA,2010). In all above referred reports, soil to vegetable transfer factor (Fv) for ⁹⁰Sr is greater than that of ¹³⁷Cs. The similar observation is reported in the case of soil to leaf transfer studies carried out in the Kaiga environment (Joshy et al, 2011).

Table 1: Soil to vegetable transfer factor (Fv) for ¹³⁷Cs and ⁹⁰Sr at Kaiga region

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Keywords: transfer factor, soil, vegetable, environmental modelling, impact assessment

References

Hegde AG, Hemalatha P, Desai MV. Transfer Factors of Radionuclides and Elements in the Terrestrial and Fresh Water Environment of India (BARC/2004/E/003). 2004.
IAEA. Technical Reports Series No.472. Vienna: IAEA; 2010.
James JP, Dileep BN, Ravi PM, Joshi RM, Ajith TL, Hegde AG, et al. J Environ Radioact 2011;102:1070-7.

Abstract - 61437: Uranium association with minerals in mining wastes: Influence on mobility

A. C. Patra¹, C. G. Sumesh¹, V. K. Thakur¹, P. Lenka¹, S. Bhattacharya²,S. K. Jha^1,3, M. S. Kulkarni^1,3

¹Health Physics Division, Bhabha Atomic Research Centre, ²Theoretical Physics Division, Bhabha Atomic Research Centre, ³Homi Bhabha National Institute, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Mining of uranium bearing minerals is necessary for uraniumextraction to meet the power requirements of India. Mining and milling activities produce huge quantities of low active tailings, as wastes, which are contained in Tailings Ponds. The nature of tailings depends on the mineralogy of ore and host rock and their quantity depends on the composition of the ore body and mining methods. The mobility of an element from these tailings depends on elemental concentration, pH, particle size, cation exchange capacity, bulk density and porosity of the tailings etc.^[1] This necessitates complete physico-chemical, radiological, mineralogical and morphological characterisation of the tailings.In this study we aim to study mineralogical association of uranium in the tailings generated after removal of uranium by alkaline leaching process. Representative surface tailings samples collected from the study area were homogenised and analysed thereafter. X-ray diffraction studies were carried out on the samples, under ambient condition, on a Proto make AXRD (Bench top Powder diffractometer) using Copper Kα radiation (λ = 1.5418 Å). The data was recorded in θ-2θ geometry, in the 2θ range of 20° to 80° with a step size of 0.2°. Investigations on morphology and composition were carried out using a SEM-EDS system. The SEM measurements used a Philips XL-30 ESEM operating in low vacuum mode, precluding the need for a conductive coating on the sample. Samples were mounted by dispersing on conducting carbon tape. Measurements were carried out at an accelerating voltage of 30kV. EDS measurements were carried out in spot mapping mode using an attached Oxford instrument XMax30 Peltier cooled detector. Element identification was obtained by referencing to a built-in database, and the instrument was calibrated using known standard blocks. Physico-chemical characterisation revealed samples to be of silty loam category with silt content ranging from 69-85%; organic matter from 3-6%; pH from 9.4-10.2% and electrical conductivity from 2400-8125 μS/cm. Alkaline pH was observed, due the fact that tailings are discharges in alkaline condition. Low organic matter content is due to fresh discharge of these process wastes.^[2] X-Ray Diffraction revealed the existence of dolomite (Ca-Mg carbonate) as the primary mineralogical phase in tailings, similar to the parent rock [Figure 1]. This is in accordance with the fact that Ca was the most abundant major element, varying from 2-5%.From SEM-EDS measurements U association was observed to be primarily with Ca and Mg [Figure 2], indicating association of uranium with dolostone. The association of U with dolostone mineral is a primary factor limiting uranium mobility from these mill tailings, as also observed in some preliminary batch leaching experiments.

Figure 1: PXRD of waste sample

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Figure 2: SEM-EDS of waste sample

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Acknowledgement

Authors express their gratitude to Dr. D. K. Aswal, Director, HS&E Group for his kind support. Analytical support fromDr. Arvind A and Smt. A. Joseph of PSDD is also acknowledged.

Keywords: Mill tailings, minerals, mobility, uranium

References

Carmen Rivas M. Agric Res 2005.
Déjeant A, et al. Sci Total Environ 2016.

Abstract - 61440: TFWT and OBT concentration in fresh water fishes at Kadra reservoir

T. K. Reji, T. L. Ajith, R. M. Joshi, M. S. Vishnu, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, ESS, EMAD, BARC, Kaiga, Karnataka, ¹EMAD, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Very low level radioactive liquid effluents generated at Kaiga Generating Station are discharged to Kadra reservoir after dilution with condenser cooling water.^[1] Tritium is one of the constituents of effluent streams of Pressurized Heavy Water Reactors (PHWR). Tritium when present in the environment will get incorporated into the biota. Tritium in the biological matrices exists as Tissue Free Tritium (TFWT) and Organically Bound Tritium (OBT). There are very little data on the dynamics of TFWT/OBT in fishes in the reservoir ecosystem of the tropical countries. A clear understanding of the concentrations of these two forms in biological systems is important for environmental impact assessment. Water sample from the reservoir is collected on a weekly basis. Fish samples of the local variety were collected from the local fishermen who undertake fishing in the reservoir. Water samples were analyzed for tritium concentration using Liquid Scintillation Analyser (LSA), Hidex make 300 SL as per the standard procedure. The edible part of the fish sample was lyophilised for 3 to 4 hours to extract water from the sample. An aliquot of the extracted water is counted in LSA as per standard procedure and tritium concentration is expressed as Bq.l^-1. Technical Series Report No.472, predicts the OBT concentration in the fresh weight fish at a steady state

Where W_CFis the water content of the fish matrices. R_fis the partition factor. W_EQFis the water equivalent factor of the fish. [Table 1] gives the measured tritium activity concentration of the Kadra reservoir water, Tissue free water tritium activity of the fish and estimated OBT activity for the study period 2017-19. The annual average measured water tritium concentration during the study period varied from 11.4-23.2Bq.l^-1. The TFWT concentration in the fish species was also in the same range as given in [Table 1]. The water equivalent factor can be calculated reliably from the hydrogen contents of protein, fat, and carbohydrate 7%, 12%, and 6.2% respectively.^[2] The estimated average water equivalent factor for fish is 0.68 l.kg^–1dry weight. OBT concentrations in the edible part of the fish were estimated using equation (1) and were given in [Table 1]. It is observed that the OBT concentration estimated from the model assuming steady state conditions is comparatively less than the TFWT concentration. Normally measured OBT concentration is expressed in literature as Bq.l^-1 (combustion water of dry mass). However, the study on OBT variation with respect to species, age, body mass, bioaccumulation, etc. of the aquatic organism in the Kadra reservoir system and validation of the model results with measurement data is in progress. Committed effective dose (CED) due to consumption of fish is estimated for members of the public. Site-specific dietary data^[3] of this region is used for dose computation. The CED estimated for the representative person of Kaiga due to TFWT and OBT from the consumption of fish is 7.8-16 nSv.y^-1. The computed population dose was found to be negligible when compared to the population dose limit of 1000 μSv/y for the public. The results indicate that HTO concentration in fish is in equilibrium with tritium concentration in reservoir water. The steady-state OBT concentration in fish is estimated using a specific activity model published in TRS-472.

Table 1: Tritium activity concentration in water and fishes of Kadra reservoir

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Keywords: Kadra reservoir, OBT, PHWR, TFWT

References

Thermal Ecological Studies (TES: 2000-2004), A DAE-BRNS Co-Ordinated Research Project. p. 52-5.
IAEA. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments. Technical Reports Series No. 472, IAEA; 2010. p. 132-9.
James JP, Dileep BN, Mulla RM, Joshi RM, Vishnu MS, Nayak PD, et al. Evaluation of internal dose to members of the public at the Kaiga site, India, due to the ingestion of primordial radionuclide 40K. Radiat Prot Dosimetry 2013;153:56-63.

Abstract - 61448: A study of radioactive materials in Yamuna River across the Delhi stretch

Smriti Babbar,Moksh Babbar¹

Department of Radiological Testing, Saturn Quality Certifications Pvt. Ltd. Bahadurgarh, Haryana, ¹Department of Applied Physics, Delhi Technological University, Delhi, India

E-mail: [email protected]

The Yamuna river considered the lifeline of Delhi has undergone severe deterioration in the quality of water. Delhi stretches of Yamuna river is mere 22 kilometers from wazirabad to Okhla, it is 2% of the total length of the river but unfortunately, 70% of the total pollution loaded in the river Yamuna in Delhi. To restore the quality of River Yamuna Government of India had initiated an Action plans and policies (YAP I, II, and III) but the improvement is less ostensibly perceptible. River Yamuna enters the Delhi Stretch at the Palla Village and is exited from the Okhla Barrage, this study aims to analyse level of radioactive parameters such as Gross alpha, Gross beta, Cesium-137 and Uranium, upon its entrance and two more locations along its Delhi stretch. The testing for the same was performed at Saturn Quality certifications private limited, Bahadurgarh, Haryana. The presence of radioactive material can contaminate surface water bodies and be noxious to the environment humans, animals, and plants. Surface water is far easier to reach, which is why this becomes the most common source of potable water. The main sources of raw water in Delhi are through the river Yamuna (surface water and Western Yamuna Canal WYC), the Ganga (Upper Ganga Canal), Bhakra-Beas storage, groundwater through tube wells, and Ranney wells (specially designed high-capacity wells named after its founder Leo Ranney). The estimated water availability of NCT of Delhi from surface water sources, mainly the Yamuna, It enters Palla, Northwest Delhi, and then traverses through NCT and leaves at Jaipur in the South. The study covers the sampling, analysis, and determination of radioactive contamination levels during its course through the city. The samples were analysed for radioactive parameters and chemical parameters the readings so calculated are tabulated in [Table 1]. Observations:

Gross Alpha Activity – In samples 1 & 3 is below the minimum detection Limit (MDL) and for sample 2 it is below the permissible limit
Gross Beta Activity - Below permissible limit in all three samples
Uranium Activity - Below permissible limit in all three sample
pH- Within permissible limit in all three samples
TDS - Below permissible limit in all three samples
Cesium-137. Activity -Below Minimum Detection Limit (MDL) in all three samples.

Treatment as a precautionary measure: Transformation of agricultural waste such as banana peels into a valuable sorbent material can be used as a potential item for the treatment of radioactive contamination in water. This is also supported in our studies. It has been observed that the level of analysed radioactive parameters is low and the below the permissible limit.

Table 1: Level of analysed radioactive and other parameters in Yamuna river water samples taken from different locations

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Keywords: Cesium, gross alpha, gross beta, LED fluorimeter, radioactivity, UMF-2000, uranium, Yamuna River

References

Singh SK, Kaushik S. Qualitative study of Yamuna water across the Delhi stretch. Int J Adv Res 2018;6:1127-38.
Opeyemi A, et al. Application of banana peels nanosorbent for the removal of radioactive minerals from real mine water. J Environ Radioact 2016;164:369-76.

Abstract - 61456: Monte Carlo simulation of efficiency of an HPGe detector for environmental radioactivity measurements and uncertainty analysis

M. Margret, S. Chandrasekaran, C. V. Srinivas, B. Venkatraman

Environment Assessment Section, Environment Assessment Division, Safety, Quality and Resource Management Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Gamma ray spectrometry with HPGe detector has been used for identifying and quantifying the radionuclides in environment matrices.^[1] Accurate knowledge of detector efficiency appropriate to the specific measurement conditions is required in order to obtain high quality results.^[2] The full energy peak efficiency (FEPE) is usually determined using reference gamma standards or multi radionuclide sources. Simulation of the calibration procedure with a Monte Carlo(MC) method is an auxiliary tool for environmental radioactivity laboratories. In this work, FEPE of a p-type HPGe detector using MC simulation for a wide energy range 200 keV - 3000 keV has been described.

Materials and Methods: The measurements are carried out for 50% HPGe detector with three volume sources (RGU, RGTh, RGK) in 250mL geometry. The model includes crystal, crystal dead layer, lithium contact and aluminium end cap. The source has been modelled according to the manufacturer's specification and placed on-contact with the detector.

Results: In order to evaluate the FEPE values of an HPGe detector, about 200 simulation runs has been carried out to stabilize the model and also to validate the simulated response function for the said energy range. [Figure 1] displays the comparison between the experimentally observed full energy peak efficiencies and computed efficiencies of the detector. As seen in the graph, when the energy increases along the abscissa, the computed values of the FEPE falls and it follow the same trend as that of the experimental calculated value. The relative deviation between the computed and experimental FEPEs for the complete energy range is found. The results obtained by the simulations yielded estimated standard deviations of less than 5% between simulation and of the measurement. A quantitative evaluation of the variation of the FEP efficiency is also found by considering the ratio between the computed and experimental efficiency values. Even though there is a fluctuation in the studied energy ranges, the average ratio for all the energies is found to be closer to unity with an average uncertainty of less than 5%.

Conclusions: The full-energy peak efficiency of a germanium detector has been calculated using MC method for photon energies between 200 keV to 3000 keV. The combined standard uncertainty of the full-energy peak efficiency is calculated with a coverage probability of 0.95. The uncertainty in the low-energy efficiency is found to be high compared to the higher energy and is due to the absorption of gamma rays by the dead layers present in the P type detector. The observed differences are consistent with the estimated standard deviations of simulation and of measurement, which ranged less than 5%. The FEP efficiency curve has been constructed for the said energy ranges. The results are validated for IAEA 375 standard and the uncertainty is found to be less than 5%.

Figure 1: Measured and computed full energy photo-peak efficiency

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Keywords: HPGe detector, Monte Carlo simulation, natural radiation, soil radioactivity, uncertainty

References

Vargas MJ, Timón AF, Díaz NC. J Radio Anal Nucl Chem 2002;253:439-43.
Stancu E, Costache C, Sima O. Rom Rep Phys 2015;67:465-73.

Abstract - 61466: Efficient separation of Am³⁺using hydrophilic camphor-derived BisTriazinyl pyridine ligand

Kankan Patra, Vinit Kumar Mittal, T. P. Valsala

¹Nuclear Recycle Board, Bhabha Atomic Research Centre, Tarapur, Maharashtra, India

E-mail: [email protected]

Nuclear power is environmental friendly clean energy releasing low carbon compared to fossil fuel based energy. Since last two decades the progress of nuclear power is going on however the hazardous radioactive waste is the only barrier to nuclear industries. Out of several radionuclides Am³⁺ is one of them due to long half life on the other hand Am³⁺ can serve several positive beneficial application. Hence it is highly desirable to recover the Am³⁺ from radioactive waste with high efficiency and record selectivity. In this context two ligand classes have shown great promises one is terdentate 2,6-bis(1, 2, 4-triazin-3-yl)pyridine ligands (BTPs) and another one is quadridentate 6,60-bis (1, 2, 4-triazin-3-yl)-2,20- bipyridine ligands (BTBPs).¹ Here, we have projected camphor bis-2,6-(5,6,7,8- tetrahydro-5,9,9-trimethyl-5,8-methano-1, 2, 4-benzotriazin-3-yl) pyridine (CA-BTP) in octanol medium for effective Am³⁺ separation from HNO₃ medium. We have explained the bonding interaction between metal ions and the ligand with the help of Fourier Transform Infrared Spectroscopy ( FTIR) spectrum. It is very important to study the kinetics of the reaction to evaluate the optimum contact time. [Figure 1] So Am³⁺extraction study was carried out in presence of different contact time up to 60 min. Here the organic phase was 0.01M CA-BTP in octanol and aqueous phase was 1M HNO₃ medium spiked with Am³⁺ radiotracer. The activity of the 'Am' in aqueous and organic phase was estimated in different time interval to evaluate the distribution coefficient (D_Am) of americium metal from aqueous phase to organic phase. Experimental result revealed that the optimum contact time was 30 min where the maximum D_Am was achieved (D_Am=8.5). The effect of HNO₃ concentration variation on extraction efficiency of CA-BTP was studied [Figure 2]. It was observed that with the increases of HNO₃ concentration the D_Am increases and at 1M HNO₃ it become constant, so the optimum HNO₃ medium is 1M HNO₃. [Figure 3] represents the overall process of Am³⁺ extraction. [Figure 4] represents the FTIR spectrum of CA-BTP in octanol medium. FTIR confirm the bonding interaction between N atoms of the CA-BTP ligand and positively charges Am³⁺ metal ions ( 1400 and 1650 cm^-1). It is basically a strong acid base interaction, resulting high extraction efficiency. N=N which acts as donating group and vacant orbital ( 5f) of Am acts as a receiver and forming a strong bond, resulting higher uptake. We have successfully demonstrated the selective extraction of Am³⁺ using CA-BTP ligand in octanol medium. The optimum contact time was found 30 min. From experimental result it was observed that the 1M HNO₃ is optimum for achieving maximum extraction efficiency. FTIR spectrometry indicates the strong bonding between Am³⁺ and the ligand.

Figure 1: Effect of contact time on extraction efficiency of Am3+ from HNO3 medium

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Figure 2: Effect of HNO3 concentration on extraction efficiency of Am3+

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Figure 3: Schematic presentation of Am3+ extraction

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Figure 4: FTIR spectrum of CA-BTP in octanol

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Reference

Nilsson M, Andersson S, Drouet F, Ekberg C, Foreman MR, Hudson M, et al. Extraction properties of 6,6'- Bis-(5,6-dipentyl- [1, 2, 4]triazinyl-3-yl)- [2,2'] bipyridinyl (C5-BTBP). Solvent Extr Ionrg Exch 2006;24:299-318.

Abstract - 61467: Synthesis and characterization of zirconium-based metal−organic framework: A spectrometric study

Kankan Patra, Vinit Kumar Mittal, A. K.Sahu¹, T. P. Valsala, S N Achary²

Nuclear Recycle Board, Bhabha Atomic Research Centre, Tarapur, ¹Glass and Advanced Materials Division, Bhabha Atomic Research Centre, ²NEMS, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Metal organic frameworks (MOFs) based materials represent a new additional class of porous material which is constructed by strong bonds between metal ions as a cluster node and organic molecules as linkers. By appropriate selection of constituent's materials, MOFs can show large pore volume, very high surface area, and excellent chemical stability. MOFs based materials have gained significant attention as it has shown great promise towards environmental pollutants remediation. Recently Zirconium (Zr) based UIO-66-NH₂MOF has shown huge potential for pretechnate (TcO₄^–) removal from nuclear waste water.¹ Here, we have attempted to synthesis of highly potentials Zr based MOF known UIO-66-NH₂ synthesis and characterization through spectrometric tools. The starting material includes ZrCl₄, 2-aminoterephalic acid and dimethyl formamide (DMF). In a typical process, 0.168 gram of ZrCl₄ (0.72 mmol) and 0.1198 gram (0.66 mmol) of 2-aminoterephthalic acid were added to 10 ml DMF. [Figure 1] The resultant solution was stirred and subsequently heated at 120°C for 1 day in a 23 ml Teflon lined Parr autoclave. The product obtained was washed with DMF (2 x times) and ethanol (2x times) and air dried overnight. For acidification, ~150 mg of activated MOF was treated with HCL acid. The powder XRD pattern shows that the material retains its crystalline structure upon acidification. [Figure 2] Microstructural characterization of the MOF was carried out using a field emission gun – scanning electron microscope (FEG-SEM, ZEISS, AURIGA) equipped with EDS (OXFORD), [Figure 3]. It was observed that the individual particles are in the nano range but the powder appeared as agglomerated. [Figure 4] clearly showed the EDX data of activated UIO-66-NH₂. It showed (Wt%) 80.93 % of Zr, 12.06 % of Cl and 7.02 % of Cu present in MOF. The material showed excellent stability under alkaline ciondotion and the material has a potential for oxy anion removal. Zr based UIO-66-NH₂ MOF has been synthesized. From the PXRD pattern it is clear that it is crystalline in nature. From the SEM image it revealed that it obtained in nano scale range. From the EDX data, we can confirmed that hhe activated MOF contains active chloride ions (Cl^–).

Figure 1: Synthesis scheme of UIO-66-NH² MOF

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Figure 2: PXRD pattern of UIO-66-NH² MOF

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Figure 3: FE-SEM image of UIO-66-NH² MOF

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Figure 4: EDX data of UIO-66-NH² MOF

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Table 1: EDX Elemental analysisof UIO-66-NH₂ metal organic framework

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References

Custelcean R, Moyer BA. Eur J Inorg Chem 2007;2007:1321-40.

Abstract - 61479: Spatial distribution of radionuclides based on bio monitors

P. Kothai, Sangeeta J. Sartandel, Vandana Pulhani

Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Terrestrial radionuclides such as ²³⁸U, ²¹⁰Pb, ²³²Th and ⁴⁰K originate from crustal material and these radionuclides can be transported and dispersed in the atmosphere by resuspension of loose surface soil. They can also be removed from the atmosphere by dry or wet deposition of dust particles. The concentration of natural radionuclides in the atmosphere is also influenced by emissions from coal fired power plants and fossil fuel combustion. On the other hand, artificial radionuclide such as ¹³⁷Cs is associated with nuclear events/operations and the atmospheric deposition of the same varies with geographical location and precipitation. In the context of environmental pollution related studies bioindicators/monitors are consistently being used to verify the air quality, to indicate the pollution levels and to identify radionuclides present in the atmospheric particulate matter from natural and artificial sources. Especially, use of terrestrial mosses in the detection of radionuclides over large area has been reported in many studies, Malikova et al.^[1] In the present study moss samples were used as bio monitors in the measurement of radionuclides. Samples were collected from different sites around Trombay region which include industrial areas, traffic junctions and residential areas to study the impact of urbanization. Moss samples collected were separated from the substratum and cleaned from soil and other impurities and then air dried at room temperature. Again, samples were oven dried at 105°C at least for 24 hours, crushed, sieved and the homogenized samples were packed in plastic containers. The containers were sealed tightly for 30 days before the gamma spectrometric measurements to establish the radioactive equilibrium. Activity concentrations of the samples were measured using a BSI make High Resolution HPGe spectrometer with 50% relative efficiency and resolution of 2keV for 1332 keV Co-60 point source at 25cm height. Spectrum analysis was performed using Boson make MCA and Gamma PRO analysis software. Prior to sample acquisition HPGe detector was calibrated using certified reference materials such as IAEA-372 grass and IAEA-434 phospo gypsum for ¹³⁷Cs and natural radionuclides respectively. Average activity concentrations of radio nuclides in mosses of different sites are presented with errors in [Figure 1]. Results show activity concentrations of ¹³⁷Cs, ⁴⁰K, ²³⁸U, ²³²Th and ²¹⁰Pb are in the range of 0.8-11.4, 135-585, 4.5-19.8, 7.6-35.9 and 82.2-341.4 Bq/Kg. Among the naturally occurring radionuclides ⁴⁰K concentrations found to be higher in all the sites. ²³⁸U and ²³²Th concentrations were comparatively higher in the sample from site 2, where the site was located near a thermal power plant. Whereas samples collected in the vicinity of fertilizer plants (Site 5 and Site 10) indicated higher concentrations of ⁴⁰K and ²¹⁰Pb. In comparison with the concentrations of radio nuclides found in the soil samples collected nearby the moss sampling locations, moss samples showed 1.5-2 times higher levels of natural radio nuclides. Whereas anthropogenic radioisotope ¹³⁷Cs found to be 2-4 times higher in the moss samples than the respective soil samples. The contact of moss and soil in most of the sites were less as the moss samples were mostly collected from the walls and concrete structures. Which indicate moss samples as one of the accumulator of radiotoxic environmental pollutants from the atmosphere, Adrovic et al.^[2] Still the possibility of minimal absorption of radio nuclides from the soil in wet weather is considered negligible in this study. Study reveals monitoring of radioactivity using mosses can be used as a sensitive method for the detection of radionuclides. Also, biomonitoring using mosses can be made very effective by considering other environmental factors such as climatic conditions, prevailing wind direction and distance from the emission points etc. along with the biological features of mosses.

Figure 1: Activity concentrations of radio nuclides in moss samples

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Keywords: ¹³⁷Cs, biomonitoring, moss, radioactivity, spatial distribution

References

Malikova IN, Strakhovenko VD, Shcherbov BL. J Environ Radioact 2019;198:64-78.
Adrovic F, Damjanovic A, Adrovic J, Kamberovic J, Hadziselimovic N. Int J Modern Biol Res 2019;5:32-41.

Abstract - 61481: Dose estimation of radionuclides on the consumption of seafood from Kalpakkam coast

S. Panigrahi, S. Bramha, S. Chandrasekaran, C. V. Srinivas, B. Venkatraman

Radiological and Environmental Safety Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]; [email protected]

The average individual dose rate from the marine environment is estimated to be 0.015 – 0.1 mSv/y. Although there are hundreds of radionuclides contributing to this, a limited number with a long half-life are radiologically significant and biologically important. ²¹⁰Po, ²¹⁰Pb of the ²³⁸U series has a relatively long half-life and depositional energy. Marine biota was found to contain high activity concentration of ²¹⁰Po and is considered to be the major contributor to radiation dose in humans (~0.11 mSv/yr). ²¹⁰Po is a particle reactor and is responsible for about 80% of the radiation dose to human beings from the marine environment. It has received attention as a hyperaccumulating radionuclide in edible portions of seafood and contributes to a higher radiation dose to humans via seafood. In this study, we collected 17 different marine fin fish and shellfish [Table 1] from Kalpakkam and analyzed them for different radionuclides. ²¹⁰Po was analyzed in all the samples, whereas,¹³⁷Cs, ⁴⁰K, ²³⁸U, and ²³²Th were analyzed only in 12 samples. Upon collection, samples were thoroughly cleaned and fresh weight was taken. The edible soft tissues were removed, lyophilized, charred, and packed for 28 days to ensure radioactive equilibrium between ²²⁶Ra, ²²⁸Ra, and its daughter products. The packed samples were counted in a gamma spectrometer with a HPGe detector. After radiochemical separation, ²¹⁰Po was auto-deposited in the silver discs. The discs were counted in an alpha spectrometer (efficiency 21%). The annual committed effective dose in the human body due to consumption of seafood was estimated using the following formula:^[1]

C_D = A_I ×D_F ×E_F,

where C_D is the committed effective dose (CED) in μSv, A_I is the activity intake (Bq), D_F is the dose conversion coefficient (μSv), and E_F is the exposure frequency (365 days yr^-1). Dose conversion coefficient used for ²¹⁰Po, ⁴⁰K, ²³²Th, and ²³⁸U are 0.43, 6.2x10^-3, 0.23, and 0.20 μSv Bq⁻¹, respectively.^[1],[2] Calculated CED to the public from the study ranged between 7.73–182.14 μSv yr^-1 for ²¹⁰Po through the intake of seafood [Table 1]. The observed dose was low compared to the reported values in different locations in India and the world. It is lesser than the previously reported values from Kalpakkam coast Gulf of Mannar, Kudamkulam coast, Baltic Sea, and Italy.^[3] This could be attributed to the sample size and variety of fishes observed in the said studies. Among the gamma emitting radionuclides ²³⁸U and ²³²Th were not detected in 7 samples and¹³⁷Cs was not detectable in any of the samples (MDA: ¹³⁷Cs:≤1.0; ⁴⁰K:9.0; ²³⁸U:2.6; ²³²Th: 2.6). The calculated CED was 1.91 – 6.60 (mean: 4.24) μSv/yr due to ⁴⁰K. Similarly, ²³⁸U contributed a dose of 0.0-0.47 (mean: 0.12) μSv/yr, and ²³²Th contributed 0.0-0.9 (mean: 0.26) μSv/yr to adults on the consumption (0.05 and 0.15 kg d^-1 for shellfish and finfish)^[3] of the studied seafood.

Total CED for adults as observed is lower than the world average value (0.29 mSv/yr by UNSCEAR, 2000),^[4] and the recommended total annual effective dose of 1.0 mSv/yr set by ICRP.^[5] 1.0 mSv/yr is the maximum acceptable level for the members of the public. Regular observations of radionuclides in all the edible fishes from the coast will help robustly assess CED. Consumption of seafood from this coast is safe from the radiological safety aspects.

Table 1: Committed effective dose due to ²¹⁰Po, ⁴⁰K, ²³²Th and ²³⁸U

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Keywords: Activity, effective dose, Kalpakkam, radionuclide, seafood

References

MARDOS. Dose Assessment from Marine Radioactivity, IAEA-TECDOC-838. MARDOS; 1995. p. 54.
USEPA. Report No. 13, EPA-402-R-99-001; 1999.
Panigrahi S, Mohanty AK, Samantara M, et al. Mar Pollut Bull 2021;173-B:113147.
UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation; 2000.
International Commission on Radiological Protection (ICRP). In ICRP 103, Annal; 2007.

Abstract - 61491: Measurement of Gross Alpha and Beta Activity Concentration in Potable Water Samples from BARC, Trombay and Mumbai Region

Sunita Singh, Rupali C. K. Kamat, Amit Verma, Sugandhi Suresh, V. M. Joshi, Vandana Pulhani, A. Vinod Kumar

Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Water is an indispensable component in our lives. Natural radioactivity (²³⁸U, ²³²Th series & ⁴⁰K) in drinking water contributes to population exposure via ionizing radiations and can vary depending on their source; hence, safety of potable water is of great concern globally. Qualitative and quantitative determination of these radionuclides is expensive, time-consuming due to their low concentrations in potable water. Gross alpha and beta measurement are very useful, fast, safe and low cost for initial screening of water. It gives essential information about the natural radionuclides in water and corresponding health hazard associated with water consumption. The aim of the study is to evaluate the gross alpha and gross beta radioactivity in potable water from nuclear facilities at BARC, Trombay and Mumbai region to assess the radiological quality and safety for consumption. Potable water samples were collected from different nuclear facilities at BARC, Trombay (62 nos.) and Mumbai region (10 nos.). The samples were preserved and processed as per the standard protocol.^[1] The activity concentration levels of gross alpha and beta in the potable water samples were measured using pre-calibrated ZnS (Ag) detector (% efficiency: 20-25) and low background gas flow proportional beta counter (% efficiency: 15-20), respectively. The alpha and beta specific activity concentrations were calculated using equation.1.

Where, E=Detector efficiency, V=Vol. (L) of sample

Estimation of annual effective dose: The annual effective dose due to ingestion of alpha and beta emitter through potable water for an adult was calculated using equation.2.

Where, AED =Annual Effective Dose due to ingestion of alpha, beta emitters, A = Gross alpha, beta activity concentration (Bq L^-1), WC=Annual water intake(LY^-1). DCF=Dose Conversion Factor [Table 1] for gross alpha and beta (WHO, 2011). In the present study, ingestion dose due to intake of potable water is computed, considering ²¹⁰Po, ²²⁶Ra (alpha emitters) and ²¹⁰Pb, ²²⁸Ra (beta emitters) as the major contributors. The ingestion dose due to ⁴⁰K is not taken into account for dose computation; owing to low age dependent effective DCF (6.2E-09 Sv Bq^-1). The gross alpha, beta activity concentration [Figure 1] in all the potable water from the study area ranged as ≤ 0.001-0.02 Bq L^-1 (GM: 0.007 Bq L^-1), ≤ 0.02-0.3 Bq L^-1 (GM: 0.06 Bq L^-1), respectively, are similar to that reported by Hemalatha et al., 2014^[2] as ≤ 0.001-0.04 Bq L^-1(gross alpha) and 0.02-0.06 Bq L^-1 (gross beta). The AED from alpha and beta emitters to adult population, due to intake of potable water (minimum 2L d^-1, with an annual intake rate of 730 L) is 0.007 mSv y^-1and 0.06 mSv y^-1, respectively. The results indicate that the observed activity concentration levels of gross alpha and beta is much lower than the World Health Organization^[3] reference level of 0.5 Bq L^-1 and 1 Bq L^-1, respectively. The observed AED due to intake of potable water in adult population from those working in nuclear facilities at BARC, Trombay is lower than the WHO recommended reference dose level of 0.1mSv y^-1 through drinking water. Hence, the ingestion of potable water may not pose a significant health hazard.

Figure 1: Gross alpha, beta activity concentration with WHO (2011) reference value in drinking water

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Table 1: Ingestion dose conversion factor (Sv Bq^-1)

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Keywords: Annual effective dose, gross alpha, gross beta, potable water, zinc sulfide detector

References

Singhal RK, Usha N, et al. J Desalination Water Treat 2009;12:143-8.
Hemalatha P, Sanu S, Raj et al. Proc. of NAC-V; 2014. p. 164.
World Health Organization. Guidelines for D.W Quality. Geneva: World Health Organization; 2011.

Abstract - 61492: Relation of wheat grain Cs transfer factor with soil properties

S. J. Sartandel¹, V. Pulhani^1,2, S. K. Jha^2,3

¹Environmental Monitoring and Assessment Division, ²Health Physics Division, Bhabha Atomic Research Centre, ³Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Soil-plant-human is a major pathway of radioactivity transfer and hence dose to human beings. Radio-cesium has been deposited on earth surface from global fallout of nuclear tests and accidents. The similarity of cesium behavior to potassium makes study of cesium transfer factors (TF) in agricultural areas important to understand the role of soil properties in mobilizing the radionuclide. Large variability in TF values is observed with major dependence on crop type, soil properties, climate type and agricultural practices. Models are also available for predicting the radionuclide uptake by crops/plants. But site-specific TF values are more realistic in assessing the environmental impact. Study carried to understand uptake by the wheat crop grown on six soil types varying in properties such as sand%, silt%, clay%, pH and Organic matter%. Each variety soil was spiked by ¹³⁴Cs tracer at the rate of 5 Bq g^-1 of soil using the protocol given in IAEA TECDOC-1497. Spiked soils were homogenized, filled in pots, air-dried and equilibrated. Each of the six spiked soils was further varied for the pH factor (pH1-3.5, pH2-4.5, pH3-5.5, pH4-control-nat pH, pH5-8.5, pH6-9.5 and pH7-11.5) and soil organic matter (OM) content ([email protected]/ha, [email protected]/ha, [email protected]/ha) making total of 66 variations. For each variation 3 replicate pots prepared. Wheat crop was grown, irrigated as per standard agricultural protocol and harvested on maturity. Wheat grain was separated, cleaned, freeze dried, ground packed in vials. Soil and grain samples from each pot were analysed by gamma spectrometry. For energy, efficiency calibration of soil, RGU RGTh standards in similar geometry was used and plotted for full energy peak efficiency versus the γ-rays energy. IAEA-2012 Hay used for the ¹³⁴Cs FEP efficiency of wheat grain. Annual participation in gamma spectrometric inter-comparison exercises of similar matrices i.e. vegetation, soil confirms quality assurance and data reliability. Transfer factor (TF) is defined as Eq.1 (IAEA TECDOC 1616).

134Cs wheat grain TF for control soils (without variation) ranged from 0.003-0.035. These were found comparable to the reported values 0.006-L.013 for wheat grain on Russian soil^[1] and the FAO^[2] range 0.01-0.016 for the cereals. With pH variation the TF ranged from 0.003–0.09 [Figure 1], and for OM variation [Figure 2] it ranged from 0.002-0.052. For most soil types, TF values were observed to be higher for low soil pH. Much variation was not observed with OM content but a minor trend observed of high TF with low OM%. Experimentally evaluated wheat grain TF for ¹³⁴Cs in general exhibits a non-linear dependence on soil parameters clay%, pH and OM% and may be represented in form of Eq.2.

TF = A x e^a.clay% x e^b.pH x e^c.OM% (2)

A is y-intercept and a, b & c are coefficient of variables clay%, pH and OM respectively. [Table 1] gives the regression parameters for the multiple regression analysis carried on log transformed equation with Ln (TF) as dependent variable with respect to independent variables clay%, pH and OM%. These parameters can be used to predict the wheat grain ¹³⁴Cs TF for a specific soil by evaluating the soil properties clay%, pH and OM%.

Figure 1: Wheat TF with pH variation for different soil. TF: Transfer factor

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Figure 2: Wheat TF with OM variation for different soil. TF: Transfer factor

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Table 1: Regression parameters of ¹³⁴Cs transfer factors with soil properties clay %, pH and organic matter %

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Keywords: ¹³⁴Cs, OM%, pH, uptake, wheat crop

References

Sanzharova, et al. IAEA-TECDOC-1497; 2003. p. 113-38.
Winteringham FP. FAO-Bulletin; 1989. p. 61.

Abstract - 61497: Characterization of ground water and speciation of Uranium

Abhigyan¹, Ranjan Prakash¹, A. C. Patra¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

The behavior of radionuclides in the environment, their uptake by the biosphere and their toxicity are mainly determined by physical and chemical properties, i.e., their speciation and to a lesser extent by their gross concentrations.^[1] Geochemical models are useful tools for prediction of solubility and mobility of species of radionuclides in the aquatic environment. Based upon a thermodynamic solubility and complexation database, the MEDUSA code determines the chemical equilibrium constant and the saturation indices of the different minerals. In the present study, 12 water samples were collected around 15km radius around the tailings pond of Tummalapalle site. In situ water quality parameters like pH, ORP and total dissolved solid (TDS) were measured using portable handheld instruments. The samples were filtered using 0.45 μm filter papers for the removal of suspended particulate matter. Major Ions present (Both cations and anions) in groundwater like Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, CO₃^2-, HCO₃^-, PO₄^3-, SO₄^2- were measured using techniques like ICP-OES, UV-Visible spectrophotometry, and titration method. Uranium analysis was done by using LED Fluorimeter. pH, redox potential, conductivity, TDS and U were found to be in the range 7.4-8.1, 166-403 mV, 0.27-2.36 mS/cm, 244-1700 mg/L and 7 to 89 μg/L(U has one outlier value of 2158 μg/L). Among the 12 groundwater samples, U concentration was found to be above the prescribed limit (AERB limit on U: 60 μg/L) in 3 samples. The major cations such as Na⁺, K⁺, Ca²⁺ and Mg²⁺were found to be in the range 50-1469 mg/L, 13-228 mg/L, 47-365 mg/L and 67-252 mg/L respectively. The major anions such as HCO₃^-, SO₄^2- and PO₄^3- were found to be in the range 263-722 mg/L, 23-911 mg/L and 0.01-0.26 mg/L respectively. Based on physiochemical parameters, U content present in water samples, speciation diagrams were generated using speciation code MEDUSA and presented below. In all the groundwater samples, the dominating species are UO₂(CO₃)₂^2-and UO₂PO₄^-. This may be because groundwater samples are marked by higher concentration of carbonate ions compared to other complexing ions, leading to the predominance of uranyl carbonate complexes. However, the presence of phosphatic dolostone in the Vempalle formation may also lead to uranyl phosphate complexes in the groundwater. There is no significant change in the speciation with variation in distance from tailings pond. It indicates that the Uranium present in groundwater and its species is not affected by the waste deposited in the tailings pond.

Figure 1: Speciation diagram of sample GW1 with pH = 7.3 and Eh = 403 mV

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Table 1: Dominant species in water samples

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Keywords: Speciation, uranium

Reference

Gunten V, Benes P. Speciation of Radionuclides in the Environment. (Technical Report). International Union of Pure and Applied Chemistry (IUPAC); 1994.

Abstract - 61498: Estimation of distribution coefficient of Uranium in soil

Abhigyan¹, Ranjan Prakash¹, V. Kumaraswamy¹, B. Naresh¹, S. K. Jha^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

The waste generated from Uranium ore processing plant in Tummalapalle is transferred to the tailings pond in form of slurry for containment. Major portion of the liquid part of the slurry is decanted and pumped back to the plant for reuse. A small portion of the liquid is retained with the solid in form of moisture. Uranium contained in the waste can migrate from tailings pond to the surrounding environment. So, it is necessary to understand the adsorption of Uranium in soil around the tailings pond to predict the migration of Uranium, if any to the surrounding environment and adjoining ground water. Distribution coefficient (K_d) for Uranium is the ratio of amount of Uranium adsorbed per unit mass of soil to the amount of Uranium remaining in the liquid at equilibrium. In the present study, 7 soil samples were collected from around uranium tailings pond in Tummalapalle. The soil samples (<2 mm) were homogenized and used for estimation of pH, Organic matter content and distribution coefficient of Uranium. pH and Organic matter content of soil were estimated by standard procedure.^[1],[2] K_d of soil was determined by batch sorption test. Standard protocol recommended by US Environmental Protection Agency^[3] was followed for the measurement of K_d. In this technique, one gram of homogenized soil sample (<2 mm size) was taken in a polypropylene centrifuge tube with a screw cap and was equilibrated with 30 ml of nearby groundwater for 12 h in a dual rotating shaker bath Model SK-300 with a shaking rate of 60 oscillations per minute at room temperature. The solution mixture was centrifuged at 16000 rpm for 30 min and filtered through 0.45-mm filter paper and the supernatant solution was discarded and the procedure was repeated to ensure that there is no change in the pH of the suspension as a result of the equilibration. 30 ml of ground water, spiked with 1ml of 10 mg/l Natural Uranium tracer (NIST), was then added to the soil and the suspension was kept in the shaker for equilibration (72 h). After equilibration, the solution was centrifuged; supernatant was filtered through 0.45-mm filter paper for the analysis of Uranium by LED fluorimeter and UV fluorimeter. The following formula was used for the calculation of the K_d.

Where C_o is the concentration of Uranium in initial solution(μg/l), C_e is the concentration of Uranium in solution at equilibrium (μg/l), V is volume of solution (l) and m is mass of soil (kg). The soil samples were found to be basic in nature with pH ranging from 7.4 to 8.7. The organic matter content in soil was found to be varying between 3.59 – 7.10%. The values of K_dfor Uranium were in the range 388-3259 (L/Kg). These values indicate high sorption ability of soil with regard to Uranium leading to low mobility of Uranium in water. The K_d values are similar to previously reported values for this area.^[4] The site specific K_dvalues will be useful as input in the transport models used for prediction of the migration of Uranium from the tailings pond to the surrounding aquatic environment. Further, more samples have to be collected and analysed for understanding of correlation of K_d with different parameters.

Table 1: Soil properties and distribution coefficient

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Keywords: Distribution coefficient, uranium

References

Methods of Test for Soils, Part 22: Determination of Organic Matter (CED 43: Soil and Foundation Engineering) IS 2720-22; 1972.
Methods of Test for Soils, Part 1: Preparation of dry soil Samples for Various Tests (CED 43: Soil and Foundation Engineering) IS 2720-1; 1983.
EPA (U.S. Environmental Protection Agency). Understanding Variation in Partition Coefficient, K_d, Values. Volume I: The K_d Model, Methods of Measurement, and Application of Chemical Reaction Codes. Washington, D.C: Office of Radiationand Indoor Air, EPA (U.S. Environmental Protection Agency EPA 402-R-99-004A; 1991.
Mishra S, Maity S, Pandit GG. Estimation of distribution coefficient of natural radionuclides in soil from Uranium mines and its effect with ionic strength of water. Radiat Prot Dosimetry 2012;152:229-33.

Abstract - 61499: Radioactive disequilibrium in soil and tailings

Abhigyan¹, Ranjan Prakash¹, A. C. Patra¹, S. Chinnasaki¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Radioactive disequilibrium is the disruption of the state of secular radioactive equilibrium in the natural radioactive series. Natural radioactive disequilibrium arises due to geochemical processes, like leaching and erosion, operating in the environment. Chemical process involved in extraction of Uranium from ore results radioactive disequilibrium in tailings. In this study, a total of 7 soil samples (SS) were collected from around the tailings pond and 7 tailings samples (TS) were collected from the tailings pond of Tummalapalle site. Soil and tailing samples were packed and sealed plastic bottles of 250ml capacity and stored for 28 days so that the progeny of radium and thorium attains secular equilibrium with their daughter products. The gamma spectrometry of the samples was carried out for estimation of activity of various radionuclides by ORTEC n-type coaxial HPGe detector. The activity concentration of radionuclides U-238, Ra-226, Th-232and K-40 was found to be in the range 29-47 Bq/kg, 30-81 Bq/kg, 21-47 Bq/kg and 47-1436 Bq/kg respectively for soil samples and 979-1306 Bq/kg, 2554-3978 Bq/kg, 14-17 Bq/kg and 383-444 Bq/kg respectively for tailings samples. The average activity concentrations of 36 Bq/kg, 31 Bq/kg and 552Bq/Kg for U-238, Th-232 and K-40, respectively, in soils from the Tummalapalle region, are in general similar to the worldwide average activity concentrations.^[1] The activity ratio (AR) of Ra-226/U-238, when plotted for soils from tailings pond varies from minimum of 1.03 to maximum of 2.25 with an average of 1.44 and standard deviation of 0.42. The activity ratio values greater than one for Ra-226/U-238 as observed for soils indicate a preferential retention or enrichment of 226-Ra as compared to U-238. This can be explained by the contrasting properties of the two radionuclides. Uranium remains in the +6 oxidation state in oxidizing environments and is soluble. In oxidizing environments Ra-226 associates with minerals like Fe hydroxides and becomes immobile. If secondary U minerals are present in oxidized environments Ra may also leach out from these minerals, although some Ra is adsorbed onto Fe-hydroxides.^[2] Since top soils can be considered to be open systems, the conditions there may be oxidizing, leading to uranium mobility and/or radium retention. The nature of rock in Tummalapalle is dolomite. More than 80% of the host rock body is carbonate rock. Uranyl carbonate is highly soluble in water as compared to uranyl oxide, thus its mobility is more; which leads to increased environmental distribution of uranium and its daughter products in Tummalapalle. The activity ratio of Ra-226/U-238, when plotted for tailings varies from minimum of 2.47 to maximum of 3.64 with an average of 2.96 standard deviation of 0.54. The higher activity ratio value 226-Ra/U-238 for tailings is because of leaching of Uranium in the process plant. For an average of 65 – 70% recovery of Uranium from ore, activity ratio for Ra-226/U-238of around 2.85 – 3.33 is expected in the tailings. The activity ratio Ra-226/U-238, for tailings was found to be in the range of 2.47 – 3.64 with an average of 2.96. This clearly indicates the selective leaching of Uranium from ore in Alkaline leaching process which is being followed for ore processing at Tummalapalle site.

Figure 1: Variation in AR of Ra-226/U-238 in soil

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Figure 2: Variation in AR of Ra-226/U-238 in tailings

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Keywords: Alkaline leaching, disequilibrium, tailingsuranium,

References

UNSCEAR. Sources, Effects and Risks of Ionizing Radiations United Nations. New York: UNSCEAR; 2000.
Condomines M, Loubeau O, Patrier P. Recent mobilisation of U-series radionuclides in the Bernardan U deposit (French Massif Central). Chem Geol 2007;244:304-15.

Abstract - 61504: Reactive transport simulation in groundwater using local radial point interpolation Meshless method

K. Swetha¹, T. I. Eldho², L. Guneshwor Singh³, A. Vinod Kumar^1,4

¹Homi Bhabha National Institute, ²Department of Civil Engineering, Indian Institute of Technology Bombay, ³Health Physics Division, Bhabha Atomic Research Centre, ⁴Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Industrial or nuclear facilities generally have several effluent storage components/tanks, pipes carrying effluents, waste disposal facilities etc. which can become potential sources of inadvertent release of contaminants. Such leakages may enter the groundwater system and contaminate it. Contaminant transport models may be used to track the movement of the contaminants and also help in any remediation. Various numerical methods available for contaminant transport modeling include finite difference method, finite element method, boundary element method, etc. These conventional methods are mesh or grid based which require the construction of a mesh. Meshless methods are a new class of techniques that does not require a mesh for modeling. In this study, a weak form method known as meshless local radial point interpolation method (LRPIM) is used for developing the contaminant transport model of a reactive species in groundwater. LRPIM uses the weak form discretization of the governing equation^[1] and uses the Multiquadrics radial basis functions (MQ-RBF) for shape function approximation.^[2] LRPIM facilitates easy implementation of Neumann boundary condition. In this study LRPIM models are developed to simulate reactive transport of a solute species. First-order decay type reaction is considered in the study. For demonstration of the application of LRPIM, a 2D aquifer of size 50 × 50 m is considered as shown in [Figure 1]. Other parameters used in this study are dispersion coefficient = 0.1 m²/day and velocity = 0.4 m/day. A concentration of 5 mg/l is injected along the left side boundary from 10 m to 40 m of the aquifer for 30 days and zero concentration on all other boundaries. A first-order decay reaction with decay constant (λ) as 0.0025 d^-1 is considered in this study. The LRPIM model^[3] is developed with a nodal distance (d_c) of 1.25 m. The simulation is carried out for 100 days. The breakthrough curves were obtained for the observation wells [as shown in [Figure 1]]. The results obtained from LRPIM model is compared with the analytical solution^[4] as shown in [Figure 2]. It is observed that the LRPIM model agrees very well with the analytical solution, indicating that LRPIM models may be effectively used for reactive transport modelling in groundwater.

Figure 1: Aquifer configuration

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Figure 2: Concentration contours after 100 days

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Keywords: Contaminant transport, Reactive transport, Meshless method, Local radial point interpolation method, Analytical solution

References

Freeze R, Cherry J. Groundwater, Englewood Cliffs, NJ: Prentice-Hall. Hoboken, New Jersey: United States; 1979.
Liu GR, Gu YT. An Introduction to Meshfree Methods and Their Programming. Berlin, Germany: Springer; 2005.
Swetha K, Eldho TI, Guneshwor Singh L, Vinod Kumar A. Groundwater flow simulation in a confined aquifer using local radial point interpolation Meshless method (LRPIM). Eng Anal Bound Elem 2022;134:637-49.
Goltz M, Huang J. Analytical Modeling of Solute Transport in Groundwater: Using Models to Understand the Effect of Natural Processes on Contaminant Fate and Transport. Vol. 1. Hoboken, New Jersey: John Wiley & Sons, United States; 2017.

Abstract - 61522: Comparative study on public dose evaluation using new ECPDA and existing method at rawatbhata site

S. N. Tiwari, Rajpal Gill, A. K. Gocher, I. V. Saradhi¹, A. Vinod Kumar¹

Environment Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Environmental Survey Laboratory at Rawatbhata Rajasthan site carries out environmental surveillance by measuring radioactivity content in air, water and dietary items collected up to 30 km radial distance from NPP site. In addition, micro-meteorological data are also monitored regularly for atmospheric dispersion calculations. Using these data, external and internal dose to the representative person at Rawatbhata Site is calculated in compliance to prescribed dose limit of 1mSv/y, at 1.6 km exclusion boundary during normal operation. In order to comply with recommendations of Expert Committee for Public Dose Computation and Dose Apportionment (ECPDA), internal, external and total effective dose to public were computed for the year 2020 and 2021 for Rawatbhata Site and discussed. Doses are calculated considering the activity concentrations in the environmental matrices of air, water, food, etc., the dietary habits of local people and dose coefficients (Sv/Bq) for the different radionuclides. External, internal and total effective dose to members of public are calculated are per old methodology (Hegde, 1998) and by new ECPDA methodology.^[2] In new methodology Plume shine and immersion dose of released isotopes of FPNG, Ar-41, Cs-137 and I-131 is to be calculated for each land sector for adults and infant separately and maximum of these is assigned as external dose to representative person. However as per old methodology, sector averaged values of plume shine dose to adults were calculated and assigned as external dose. For plume shine dose calculations from FPNGs weighted average energy of 0.196 Mev is to be used instead of 0.7 Mev used earlier. Also default values of protection factor to account for occupancy and shielding for type of houses had been introduced for realistic dose assessment in new method not used earlier. For age specific dose calculation due to ar-41 and FPNG a factor of 1.22 and 1.50 is to be multiplied with the adult dose to derive dose due to infant. Another major change is introduction of internal dose through TFWT and OBT due to consumption of fish, water, plant, animal products. Also, as per new ECPDA methodology, inhalation dose for tritium is to be multiplied by 1.5 to combined inhalation and skin absorption dose. External, internal and total dose to representative person of public (adult and infant) at site boundary is computed as per existing and new ECPDA methodology for Rawatbhata site for the year 2020 and 2021 and shown in [Table 1]. It is observed that external dose has increased by using new methodology and is attributed to the use of maximum value of plume shine dose at this site. The internal dose calculated by new and old methodology agree. Default parameter values of breathing rate (8400, 1400) m³/a and ingestion rate of water and beverages (0.73, 0.26) m3/a for adult and infant category of representative population at this site. However, site specific parameter values are to generated for realistic dose computation as per new methodology. It is demonstrated that computed values of public dose to adult and infant population by new methodology is much less than dose limit of 1mSv/y at this site.

Table 1: Comparison of total effective dose (external and internal) at 1.6 km during the year 2020 and 2021

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Keywords: External dose, internal dose, total effective dose

References

IAEA Safety Series 19, 2001, Generic Models for Use in Assessing the Discharges of Radioactive Substances in the Environment; 2001.
ECPDA (rev-1), 2016, Report of Expert Committee for Public Dose Computation and Dose Apportionment; 2016.
Rout S, Ravi PM, Tiwari SN, et al. A Handbook on Public Dose Assessment around Nuclear Installations.

Abstract - 61533: A preliminary study of specific activity of ¹⁴C in biota samples at Kalpakkam site

K. R. Sreedevi, J. Thulasi Brindha, T. Jesan, A. Thilakavathi, K. S. Rao, C. Manonmani, Anitha Manu, S. Ramkumar, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Kalpakkam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

¹⁴C a pure beta emitter with an energy of 156 keV(E_max) is present in the environment naturally due to cosmic ray interaction as well as in nuclear reactor through neutron induced reactions. During normal operation of nuclear installations a fraction of produced ¹⁴C is released to the environment within the prescribed limit. The ¹⁴C thus released, is assimilated by the plants during photosynthesis which may contribute additional dose to members of public through ingestion pathway. To estimate the dose if any, the levels of ¹⁴C in biota samples are to be measured. A feasibility study for the estimation of specific activity of ¹⁴C in biota samples using thermal oxidation and liquid scintillation counting technique was initiated at Kalpakkam. This paper presents the results of analysis of ¹⁴C in mango leaf samples at three different locations. Mango leaf samples were collected on monthly basis from two locations at a distance of < 1.6 km and 5 km and quarterly from a location at a distance of 18 km. Samples were dried in hot air oven. The dried samples were manually powdered and an aliquot of the dried sample is subjected to combustion using pyrolyser which is designed for separation of carbon from samples in the form of CO₂ for the estimation of ¹⁴C activity. The oxidised water containing tritium and CO₂ containing ¹⁴C were trapped in 0.1N HNO₃ and a mixture of Carbon trap and Carbon count (10 ml + 10 ml) respectively. This mixture was counted in liquid scintillation analyser. Carbon content of the sample is estimated using the ash content after pyrolysis.^[1]

Carbon content (%) = 100 - (ash wt.(%) + mass % O₂ (53.3) in C₆H₁₂O₆).

MDA for this method is 35 Bq/kgC for a counting time of 200 min. The measurement of ¹⁴C in biota samples involves various steps such as combustion, oxidation, absorption of generated ¹⁴CO₂in the trap solution and then counting in LSA. To reduce the errors associated with all the steps optimisation of various parameters were carried out. One of the major hindrance observed was chemi-luminescence during counting in LSA. This was reduced by cooling for a longer period and modification in software. Quality assurance of the method could not be carried out due to lack of certified reference material. Specific activity of ¹⁴C in mango leaf samples collected from three different locations are given in [Table 1]. Specific activity of ¹⁴C ranged from 218 to 296 Bq/kg C. There was no observed variation in specific activity with distance as observed from the mean. [Table 2] depicts the monthly variation of ¹⁴C in location at 5 km for a period of six months. The observed variation is within 1σ. The preliminary study of measurement of ¹⁴C in mango leaf samples was carried out at Kalpakkam using Pyrolyser. The study confirms the use of Pyrolyser furnace technique for measurement of specific activity of ¹⁴C in biota samples. The activity levels thus measured ranged from 218 to 296 Bq/kg C, the maximum observed activity was within 1.6 km. However the dose estimated will be very less and in the order of μSv.

Table 1: Specific activity of ¹⁴C in mango leaf samples

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Table 2: Monthly variation of specific activity of ¹⁴C in mango leaf samples

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Keywords: ¹⁴C, biota samples, LSA, pyrolyser

Reference

D' Souza RS, Rashi Nayak S, Mohan MP. Optimisation of a batch thermal combustion method using a tube furnace oxidation system (Pyrolyser) and LSC for carbon – 14 Determination in environmental matrices. J Environ Radioact 2020.

Abstract - 61536: Evaluation of site-specific dry deposition velocity using the ⁷Be tracer at Rawatbhata, Rajasthan

A. K. Jain, Tejpal Menaria, Balram Meena, S. N. Tiwari, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

⁷Be is a natural cosmogenic radionuclide continuously produced in the upper troposphere and lower stratosphere by spallation of light nuclei (N and O) by high energy protons and neutrons of galactic cosmic rays. ⁷Be is a short-lived (T_1/2:53.5 days) nuclide formed predominantly in the stratosphere and emits gamma energy of 477.6 keV. About 70% of the ⁷Be is produced in the stratosphere, with the remaining 30% in the troposphere. ⁷Be atoms readily react to form BeO or Be (OH)₂ molecules in air which have physico chemical properties and behavior similar to ¹³⁷Cs. Hence ⁷Be can be used as a tracer to study deposition pattern and kinetics of ¹³⁷Cs in the Rawatbhata environment. Hence dry deposition velocity and deposition rate of ⁷Be were studied during period 2017-2021 at Rawatbhata environment. Air particulate samples were collected on Glassfibre filter paper using high volume sampler (Poltech make,1.1 m³/min). Samples for dry deposition study were collected on polyethylene sheet (coated with grease, 1.6 m² area) placed in a steel tray located on roof top of the laboratory. Samples were collected during the non-rainy season and measured by HPGe detector (Eurisys make, 400cc, RE:110%). Efficiency and energy calibration of the detector was carried out using certified reference material from IAEA. Activity correction in ⁷Be activity was applied to compensate for decay loss during the sampling and counting of sample in HPGe. The dry deposition rate (deposited m²/d) is given as

where (di ) dry is the dry deposition rate of the activity (mBq/d.m²), C is the total dry deposition activity (mBq) in D days, A is the area of exposure (m²).

The dry deposition velocity (m/d) is given as

where C_a is the concentration of ⁷Be in air (Bq/m³)

Dry deposition rate calculated for the period 2017 to 2021 is given in [Figure 1]. Year wise minimum value of deposition rate (mBq/(d*m²) ranged from 30.3 to 180.0 with mean of 116.9 while maximum value ranged from 544.6 to 1090.0 with mean value of 863.8.Yearly mean concentration of ⁷Be in air ranged from 2.2 to 6.0 mBq/m³. Site-specific dry deposition velocity (m/d) is also calculated during this period and shown in [Figure 2]. Its minimum value ranged from 7.6 to 66.3 with mean of 35.3 while maximum value ranged 181.3 to 310.5 with mean 239.0, which is comparable to values reported in literature, ranged from 86.4 to 2937.6 m/d (Papastefanou et al., 1995; Chamberlain, 1953; Peirson et al., 1973; Todd et al., 1989; Young and Silker, 1980; Turekian et al., 1983; Mc Neary and Baskaran, 2003; Pham et al., 2013). Overall mean of dry deposition rate and deposition velocity during the study period is 473.7 (mBq/(d*m²) and 132.9 m/d. which is comparable to values reported in Neuberberg (138.2 m/d, Germany), Kaiga, Kakrapara and Narora (India). Dry deposition rate and deposition velocity during the study period is 473.7 (mBq/(d*m²) and 132.92 m/d for Rawatbhata site environment. In case of any requirement this data can be utilized to study deposition kinetics of Cs-137. The evaluated data will be also used for realistic public dose estimation using ECPDA methodology.

Figure 1: Dry deposition rate (mBq/[d×m²])

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Figure 2: Dry deposition velocities (m/d)

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Keywords: Air particulate, Be-7, dry deposition rate, dry deposition velocity

Reference

Arnold J, Al Salih H. Beryllium-7 produced by cosmic rays. Science 1995;121:451-3.

Abstract - 61540: Study on variation of gross beta activity and suspended particulate matter in air sample at Rawatbhata Rajasthan Site

Mohit Sisodia, A. K. Jain, S. P. Tailor, M. C. Meena, S. N. Tiwari, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Environmental survey laboratory at Rawatbhata site is established near the vicinity of nuclear power plants to monitor the impact of their operation on atmospheric, aquatic and terrestrial domain of surrounding environment. Continuous measurement of gross beta activities in air is important to monitor the trend of radioactive contamination of air particulate matter through natural and anthropogenic activities leading to human exposure. Main contributor of gross beta in air particulate are ¹³⁷Cs, ⁴⁰K and daughter products of uranium and thorium series radionuclides. During this study, data of gross beta activity and suspended particulate matter (SPM) in air along with rainfall data was collected during the period Jan 2001 - Dec 2021. Study of beta radioactivity suspended in environment and its correlation with rainfall pattern was also carried out. Monitoring of atmospheric environment is carried out by collecting air particulate samples on continuous basis on glass fibre filter paper using high volume air sampler kept at one metre height with average flow rate of 1.0 m³/min. Air particulate samples were collected on filter paper medium and brought in suitable geometry for further counting in low background beta counting system. Samples are changed after one-week period. Until Jan 2018 gross beta activity was measured using gas flow beta counter (ECIL make, BKG : 1.4 CPM, efficiency 32-35% for K-40). Plastic scintillator based beta counter is being used since Jan 2018 (Nucleonix make, BKG: 1.2 CPM, efficiency 20-21 % for K-40). Minimum detectable levels achieved for old and new beta counting systems is 0.25 mBq/m³ and 0.20 mBq/m³ respectively. Suspended particulate matter is determined gravimetrically by dividing net mass of dust load collected on the filter paper by total volume of air passed. Gross beta activity in air particulate samples are tabulated as Quarter I, II, III and IV for the periods of Jan-Mar, Apr-June, July-sept and Oct- Dec respectively. For quarter I and quarter IV, mean gross beta activities and SPM are 1.53 mBq/m³ and 135 μg/m³ and 1.49 mBq/m³ and 126 μg/m³ respectively. Correlation studies between mean gross beta activity and average monthly rainfall (mm) is R²= 0.62 and between SPM and average monthly rainfall is R²= 0.63. It is observed that in Quarter III, mean gross beta activity and SPM are minimum and are 0.77 mBq/m³ and 77 μg/m³ respectively. Quarter III is a monsoon season at Rawatbhata site and maximum rainfall is observed in this period. However, for quarter II, gross beta activities and average rainfall follow a different pattern as compared to other three quarters. In this quarter, maximum value of SPM is 171 μg/m³ and poor correlation observed between SPM and gross beta activity compared to other quarters.

Figure 1: Quarterwise variation in gross beta activity from January 2001 to December 2021

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Table 1: Mean of Gross beta activity and suspended particulate matter

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Keywords: Air particulate, gross beta, suspended particulate matter

References

Gomez Escobar V, Vera Tome F, Martin Sanchez A. J Environ Radioact 1996;31:273-85.
Jha MK, et al. 15^th DAE BRNS Symposium NUCAR-2021, BARC, Mumbai.
Kitto ME, et al. Health Phys 2006;90:31-7.

Abstract - 61542: Estimation of ecological half-life of ¹³⁷Cs in fish around Kalpakkam site

A. Thilakavathi, T. Jesan, K. R. Sreedevi, S. Ramkumar, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Kalpakkam, Tamil Nadu, ²Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

¹³⁷Cs is one of the fission product with long physical half-life of 30.2 years, high fission yield of 6.2%and a high bioavailability due to its similarity to potassium. The concept of effective ecological half-life has been introduced to estimate the recovery time of radioactive pollution if any in the environment for the assessment of long term exposures due to release of radionuclides to the environment. This describes the decrease in contaminant concentration in ecosystem over time taking into account loss by physical decay and removal mechanismswhich reduce the radionuclide concentration by physical, chemical and biological processes. The effective ecological half-life is specific value to radionuclides and environment into which they are released. Kalpakkam being a coastal site, sea food is one of the major dietary items. ¹³⁷Cs enter fishes via food-chain and also directly from sea water. Ecological half-life of ¹³⁷Cs would be controlled by effective environmental half-life of ¹³⁷Cs in surrounding sea-water as there is a difference in the effective environment half-lives between the open ocean and the coastal seawaters. Consequently, the rate of the influence by seawater in the area would produce the differences in the effective ecological half-lives among fish species. This paper presents the ecological half-life of ¹³⁷Cs in fish around Kalpakkam and this can be used for radio-ecological models. Fish samples (280nos.) were collected from 8 different locations around Kalpakkam during 2007-2021 and analysed for ¹³⁷Cs (662 keV) by gamma spectrometry using HPGe detector. Ecological half-life (T_eco) of ¹³⁷Cs for fish samples collected around Kalpakkam site was estimated by the following equation:

Where T_rad is radioactive half-life of ¹³⁷Cs (30.2 years) and T_eff is effective half-life which is given by:

Where λ_eff (effective loss rate constant) is estimated from the slope of the graph between Log transformed ¹³⁷Cs activity and time. ¹³⁷Cs activity in fish ranged from ≤ 0.02 - 0.30 Bq/kg fresh. The geometric mean and geometric standard deviation of ¹³⁷Cs activity calculated for 15 years (2007 – 2021) in fish ranged from 0.02 – 0.08 and 1.00 – 2.11 Bq/kg fresh respectively. The observed activity levels are less and comparable to pre-operational base line activity levels indicating that there is no build-up of Cs-137 activity due to operation of PHWRs at Kalpakkam site^{. [1,2]} The variation seen in activity is only due to statistical fluctuations. [Figure 1] shows the activity and log transformed activity of ¹³⁷Cs in fish samples over 15 years. λ_eff obtained from the slope of the graph was found to be 0.063 and T_effwas calculated as 11.0 years. From this ecological half-life of ¹³⁷Cs for fish was estimated to be 17.3 years and this gives the total rate of removal of ¹³⁷Cs activity from fish. This was compared with other study in which ecological half-life of ¹³⁷Cs varied from 0.3–52.6 years andit varied with different fish species and locations.^[3] The study demonstrated that variation in ¹³⁷Cs activity in fish were due to global fallout levels and there is no increase of ¹³⁷Cs activity due to operation of nuclear facilities at Kalpakkam site. Ecological half-life of ¹³⁷Cs for fish was estimated to be 17.3 years and was found to be comparable to those reported worldwide.

Keywords: ¹³⁷Cs, ecological half-life

Figure 1: ¹³⁷Cs activity in fish (2007-2021)

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References

Wagh SS, Patra AK, et al. Evaluation of transfer actor and ecological half life of ¹³⁷Cs in terrestrial matrices around Kakrapar Gujarat Site. India During 2021;1993-2019.
Thilakavathi A, et al. Evaluation of ¹³⁷Cs and ⁹⁰Sr in Sea Food Sample in Kalpakkam Environment –A Decade Study. North Carolina: IARP; 2014.
Yoshimura M, Akama A. Difference of ecological halflife and transfer coefficient in aquatic invertebrates between high and low radiocesium contaminated streams. Nat Res Sci Rep 2020.

Abstract - 61551: Terrestrial and cosmic radiation pattern around the proposed NPP site at Kovvada, Andhra Pradesh

G. P. Verma¹, S. K. Sahoo¹, A. Gupta¹, P. Prusty¹, S. K. Jha^1,2, M. S. Kulkarni^1,2

¹Health Physics Division, Bhabha Atomic Research Centre, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

External exposure of natural background radiation is due to terrestrial and extra-terrestrial radiations. Source of radioactivity of these two components also influence the inhalation and ingestion dose to members of the public.^[1] Study of background terrestrial and cosmic radiation are of scientific and societal relevance for assessment of natural background radiation whereas it is of greater pertinent for a nuclear power station prospecting site. Kovvadda in Srikakulam district of Andhra Pradesh is identified as site for establishing 6 x 1208 MW light water reactors. Generation of baseline background data is mandatory to appraise the impact of the upcoming power station and also to assess the build-up activity in different compartments of the ecosystem during operation and post-operation phase. Field study has been carried out during April, 2022 to survey around the proposed site for six nuclear power stations at Kovvada. Radiation survey meter was used to monitor the gamma radiation levels at one-meter height from the earth surface which comprised of both terrestrial and cosmic components. The cosmic radiation contribution was estimated adopting the UNSCREAR published methodology^[2] from the altitude data of each location registered during field study using a navigation unit (Garmin Oregon 550). Subtraction of this estimated cosmic component from the measured gamma radiation level at one-meter will give the terrestrial gamma radiation. Estimates of cosmic ray dose rate component is carried out using following equations (1) and (2) for ionizing radiation dose component and neutron dose component (for the z<2 km) respectively (UNSCEAR 2008, 2010).

E_i(Z) = Ei(0)[0.21e^{−1.649 Z} + 0.79e^0.4528Z] (1)

E_N(Z) = Ei(0)e^Z (2)

Where; Ei(0)is dose rate level at sea level, Ei(Z) is dose rate level at altitude Z and Z is the altitude in kilometers. From field study, it was observed that the ambient gamma radiation levels found to vary in the range of 125 – 240 nSv/h with an average value of 164 ± 35 (1σ) nSv/h. Considering the altitude of the locations around Kovvada, the estimated cosmic radiation level is varied from 33.7 to 34.4 nSv/h (Average value: 33.9 ± 0.2 (1σ) nSv/h). The divergence in ambient gamma radiation is ascribed to heterogeneous spatial distribution of natural radionuclides while the coastal site and plain surface are attributed to the convergence in estimated cosmic radiation. Observation of relatively higher ambient gamma radiation levels around the site than the national and global average levels is correlated to the visible occurrence of monazite laced sands along the coast belt which is anticipated along the eastern coast of the country. The estimated terrestrial radiation, which was estimated by subtracting cosmic components from measured gamma radiation doses, is found to vary in the range of 91 – 206 nSv/h with a mean value of 133 ± 35 (1σ) nSv/h [Table 1]. No national or international prescribed limits are applicable for these naturally derived radiations and also the levels are comparable to the radiation levels reported in other parts of country and across the globe. However, the ambient gamma radiation levels around the Kovvada site will be monitored continuously, as a safety practice and screening radiological indicator, during operational to assess the impact of the facility.

Table 1: The estimated terrestrial radiation around various location the proposed site

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Keywords: Cosmic, dose, exposure, Kovvada, public

References

Bouville A, Lowder WM. Radiat Prot Dosim 1988;24:293-9.
UNSCEAR 2008. Sources and Effects of Ionizing Radiation, United Nations, New York; 2010.

Abstract - 61555: Radiological mapping of Vellanathuruthu Village, Kollam, Kerala

S. Ajeshkumar, K. Sreekumar, R. Sujata, M. Harikumar, S. K Jha, M. S. Kulkarni

Health Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India

E-mail: [email protected]

The Natural High Background Radiation Area (NHBRA) extending over a stretch of 23 km in the coastal belt of Neendakara and Kayamkulam in Kerala is known for rich deposits of monazite and other beach sand heavy minerals. The Mineral Separation Plant of Indian Rare Earths (India) has setup a mining plant at Vellanathuruthu region of Alappad village of Karunagappally block. The site lies between the latitude of N 9° 02' 44 to 9° 03' 74 and longitude 76° 50'61 to 76° 56'77. The paper presents the data of radiological monitoring of this area. Monazite contains naturally radioactive thorium (7.5-8%) and uranium (0.3%). Radioactivity of 232Th and nat.U in monazite are 300-320Bq/kg and 36 Bq/g respectively. UNSCEAR 2000 formula for estimating ambient dose rate due to ground deposited natural radionuclides ( thorium, Uranium and 40K) gives a value of approximately 1.43μS/h dose rate at 1m height per monazite content in percentage.

External Gamma radiation monitoring: Radiation survey and data logging in different locations of the Vellanathuruthu village was carried out using EnV RaD LoG radiation survey meter. Soil samples were collected from a few selected locations for estimation ofmonazite. Approximately 400g of soil samples up to a depth of 30 cm were collected from different locations using auger soil collection tool. 100 ml samples weighing 170-190 g were collected in a standard 100 ml container. A 3“x3” NaI(Tl) based multichannel analyser was standardized for this geometry using standard Monazite source of 0.65% (1 g monazite in 155 g sand) kept on contact with detector. [Figure 1] shows monazite sample spectra using 3“x3” NaI(Tl) detector. Counting efficiency and minimum detectable activity (MDA) of Monazite for different gamma energies are calculated using 1 g of Monazite with 325Bq of 232Th activity. MDA was calculated based on integral counts within region of interest (ROI). Soil samples are analysed keeping on contact with detector. The percentage (%) Monazite content was estimated for each soil sample from respective locations from their gamma spectrometric analysis using thorium as principal radionuclide.

Water Sample Analysis: Drinking water from 10 wells was analyzed for gross alpha and gross beta activity after concentrating by chemical precipitation. ZnS (Ag) based alpha counter and anti-coincidence low beta counter were used for activity estimation. The gross alpha and gross beta activity in the well water samples ranged from 0.007-0.016 Bq/l and 0.034 - 0.109 Bq/l respectively. These values were significantly lower than WHO limit for drinking water. Radiation survey and data logging of over 100 locations were done. The measured radiation dose were 0.4 – 2.7 μSv/h depending on the monazite content in the soil. Soil samples collected from five locations were analysed for estimation of monazite in it. The outdoor dose rate and Monazite content estimated using gamma spectrometry at selected locations are tabulated. A factor called Ambient dose rate per Monazite percentage ((μSv/h)/ % Monazite) is defined to study the variation of dose rate with reference to Monazite content of the soil. Mapping of ambient radiation dose rate at Vellanathuruthu was done using Google Earth platform.

Figure 1: Monazite sample spectrum using 3”x3: NaI(Tl) detector

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Table 1: Radiation dose rate and Monazite content at Vellanathuruthu Village

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Keywords: Monazite, natural high background area, radiation survey

References

Chougaonkar MP, et al. Profiles of doses to the population in the high background radiation areas in Kerala, India. J Environ Radioact 2003;71:275-97.

Abstract - 61558: Distribution of ²¹⁰Po, ²²⁶Ra and ²²⁸Ra in drinking water and ²²⁶Ra/²¹⁰Po ratio around Banswara District, Rajasthan

Tejpal Menaria, D. S. Rathore¹, S.N. Tiwari, I. V. Saradhi², A Vinod Kumar²

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, 1Mohan Lal Sukhadiya University, Udaipur, Rajasthan, ²Environmental Monitoring and Assessment Division, Mumbai, Maharashtra, India

E-mail: [email protected]

Polonium and radium are naturally occurring radioactive elements that are commonly present in water and its concentration in ground water depend on lithological, geological, and other conditions of the area. Ground water plays a vital role in the migration and redistribution of radio nuclides in the environment. Ingestion is a major pathway for internal exposure in which drinking water contributes to about 85% of ingested exposure. Polonium and radium are initially absorbed and redistributed in other parts of the body with time which results in a high organ dose due to its long effective half-lives. Recommended guidance levels for ²²⁶Ra ²²⁸Ra and ²¹⁰po in drinking water are 1, 0.1 and 0.1BqL^-1, respectively. In this study ²¹⁰Po, ²²⁶Ra and ²²⁸Ra have been analysed in drinking water samples, collected from various locations of southern regions of Rajasthan. Water samples (5Liters) were chemically treated to separate isotopic elements and were counted for gross alpha and beta activity analysis. The conventional method, auto deposition of ²¹⁰Po on a silver disc in an acidic medium using ascorbic acid, was adopted. After electrodepositing of ²¹⁰Po on silver disc, radiochemical separation of lead and radium as sulphate, was precipitated by 1:4 H₂SO₄ under heating condition. This precipitated (Ba(Ra) SO₄and PbSO₄), was treated with EDTA under heating condition and pH (4.2-4.5) was adjusted with glacial acetic acid, which caused radium to co-precipitate as Ba(Ra)SO₄, while lead sulphate (PbSO₄) remained dissolved in solution. Secular equilibrium of ²²⁸Ac with ²²⁸Ra was established and Ba(Ra)SO₄ was again chemically precipitated by 1:4 H₂SO₄. The determination of ²²⁶Ra was carried out by measuring the alpha activity using a low background gross alpha counter while the solution was added HF to separate ²²⁸Ra as La(Ac)F₃. ²²⁸Ra was determined by a low-background gas-filled beta counting system. Recoveries were evaluated by adding ²²⁶Ra and ²¹⁰Po source as tracer. The concentrations of ²¹⁰Po,²²⁶Raand ²²⁸Ra in drinking water ranged from 2.2-4.5, 1.3-3.8 and 7.6-37.0 mBqL^-1, respectively while mean of ²¹⁰Po,²²⁶Ra and ²²⁸Ra 3.0, 2.1 and 20.8 mBqL^-1, respectively which were comparable with global average values reported in UNSEAR(2000) and TRS-310, IAEA(2014). ²²⁶Ra to ²¹⁰Po ratio is ranged from 0.5 to 1, with mean of 0.7, which concludes that ²²⁶Ra to ²¹⁰Po is un equilibrium in water. The estimated committed effective doses for ²¹⁰Po, ²²⁶Ra, and ²²⁸Ra by ingestion are ranged, 2.9-5.8, 0.5-1.5 and 7.5-37.5μSvy^-1, respectively with mean, 3.9, 0.8 and 20.6μSvy^-1, respectively. No significant correlation was observed among these radionuclides. Higher concentration of ²²⁸Ra is observed in water sample but effective dose is less than the dose received by ²¹⁰Po due to its high specific activity of ²¹⁰Po. Doses received by the population of this region were much lower than recommended guidelines. Consumption of drinking water does not pose any unacceptable health effects to the population of this region w.r.t. analyzed samples

Table 1: Statistical analysis of ²¹⁰Po, ²²⁶Ra and ²²⁸Ra in water sample

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Keyword: ²¹⁰Po, ²²⁶Ra, ²²⁸Ra, gross alpha and beta activity

References

International Commission on Radiation Protection (ICRP, 119).
World Health Organization. Guideline for Drinking Water. World Health Organization; 2017.
Environmental Radiological Laboratory Procedure; 1998.

Abstract - 61563: Standardisation of Sr resin for milk sample during emergency

Anitha Manu, T. Jesan, J. Thulasi Brindha_,K. R. Sreedevi_, K. S. Rao, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Kalpakkam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

⁹⁰Sr has a radiological half-life of 28.9 years. It is a significant fission product of ²³⁵U (5.8% mass yield),^[1] it decays to ⁹⁰Y by emitting a beta particle of 546KeV. ⁹⁰Sr could be present in environment following a nuclear incident.^[2] In emergency the rapid estimation of ⁹⁰Sr in milk is essential since milk is a substantial pathway of radio strontium intake in human body. It follows the similar chemistry of calcium and gets easily incorporated into bones.^[3] Unidentified contaminated milk could lead to an unacceptable radiological dose to the public, thus rapid and reliable analytical methods for the determination of ⁹⁰Sr in milk are essential for an emergency situation. The analysis time is an important factor for identifying whether the milk is contaminated with radioactive materials. Eight milk powder samples spiked with ⁹⁰Sr NPL standard were analysed by chromatographic separation using Sr-resin and conventional nitrate separation technique. The radiochemical recovery was estimated for each sample by gravimetric method. Sr Resin method: This method is based on the rapid determination of ⁹⁰Sr in milk.^[2],[4] The milk powder 40g was dissolved in 300ml water at 65°C. Strontium carrier (20mg) was added and pH adjusted to 5.2 with citric acid and NaOH. 40ml of cation exchange resin (Dowex 50W x 8) was added to milk, stirred and supernatant decanted after settling. The resin was transferred to a glass column after thoroughly washing with water. Calcium, Strontium and Barium from the column were eluted with 400ml of 4N NaCl. Precipitated the carbonates by adding Na₂CO₃and NaOH to the eluate. The precipitate was dissolved in 8N HNO₃ and evaporated twice with HNO₃in order to change chemical form of Sr to nitrate. The residue was dissolved in 20ml of 8N HNO₃ and loaded on Sr-resin column (3.5 to 4g Sr Resin 100-150 μm TRISKEM make) preconditioned with 50ml of 8N HNO₃. Washed the column with 100ml of 8N HNO₃to remove interfering elements and elute Sr with 30ml of deionised water precipitated as carbonate and counted in liquid Scintillation analyser (LSS). The minimum detectable Activity was found to be 0.1Bq/L. Conventional methodology drying, wet ashing and nitrate separation was also done as per ERL manual.^[5] Activity concentration of ⁹⁰Sr by chromatographic and conventional separation was determined. [Figure 1] gives the percentage recoveries of ⁹⁰Sr. The percentage recoveries by using chromatographic resin ranged from 71.6 to 91.5 with a mean of 83.5 % and conventional nitrate separation 55 to 70 with a mean of 62.5%. The analytical results indicate that the chromatographic separation gives higher recovery compared to conventional nitrate separation method. The conventional method is time consuming as the removing of organic matter in milk, involves drying, ashing and wet ashing which takes 4-5 days. So, it is major disadvantage during emergency, where as in chromatographic separation there is no destruction of organic matter. The rapid estimation of Sr extraction by chromatographic resin was found to give higher radiochemical recovery when compared to conventional nitrate separation method. The total analysis time for a sample takes less than 24 hours. Therefore, the preferred method is column chromatographic separation using Sr resin during emergency situations.

Figure 1: Comparison of percentage recoveries of ⁹⁰Sr

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Keywords: Emergency, milk, Nitric Acid (HNO₃), strontium

References

Guérin N, Riopel R, Rao R, Kramer-Tremblay S, Dai X. An improved method for the rapid determination of (90) Sr in cow's milk. J Environ Radioact 2017;175-176:115-9.
IAEA. A Procedure for Rapid Simultaneous Determination of ⁸⁹Sr and ⁹⁰Sr in milk Using Cerenkov and Scintillation Counting. Austria: Analytical Quality in Nuclear Application Series No. 27; 2013.
Stamoulis KC, Ioannides KG, Karamanis DT, Patiris DC. Rapid screening of 90Sr activity in water and milk samples using Cherenkov radiation. J Environ Radioact 2007;93:144-56.
Kim CK, Al-Hamwi A, Törvényi A, Kis-Benedek G, Sansone U. Validation of rapid methods for the determination of radiostrontium in milk. Appl Radiat Isot 2009;67:786-93.
Hegde AG, et al. Environ Radiological Laboratory Procedure Manual, HPD, BARC; 1998.

Abstract - 61567: Temporal variation of PM₁₀, PM_2.5 and PM₁ adjacent to a nuclear facility and their correlation with meteorological attributes

J. S. Dubey¹, S. K. Sahoo¹, A. Gupta¹, S. Santra^2,3, S. K. Jha^1,3 and M. S. Kulkarni^1,3

¹Health Physics Division, Bhabha Atomic Research Centre, 2Nuclear Physics Division, Bhabha Atomic Research Centre, ³Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Relevance of temporal profile of coarse (PM₁₀), fine (PM_2.5) and ultrafine (PM₁) particulate matter (PM) around a nuclear facility is very high to understand and elucidate the synonymous behaviour of radioactive aerosol likely to be generated during normal operational phase and in an accidental situation. The pattern of PM varies greatly at the recipient site which governed by the nature of source, source term, environmental processes and meteorological conditions. Study of PM10, PM2.5, and PM1 were undertaken at BARC Hospital Building, Anushaktinagar in the present study and their correlation with the meteorological parameters. Continuously PM₁₀, PM_2.5 and PM₁ were monitored using an Environmental Dust Monitor (Grimm EDM 164) from the last 6 months along with temperature, relative humidity, wind speed at a flow rate of 1.2 lpm and sampling interval of 10 mins.^[1] The compact Environmental Dust Monitor is an optical particle counter that detect, count and segregate particulate matter based on their size (0.25 – 32 μm) by the scattered light using a diode laser (660 nm) radiation source. Particle sizes are measured on the principle of Mie Theory on the correlation between the particle size, wavelength of incident light, scattering angle. The sampler is placed on the terrace (~50 meter from the ground) of the BARC Hospital Building. From the data, it was observed that the mass concentration of PM₁₀, PM_2.5 and PM₁ over the six months varied in the range of 22.9 – 373 μg/m3, 5.1 – 170 μg/m3, 2.2 – 132 μg/m3, respectively. The National Ambient Air Quality Standards for PM₁₀and PM_2.5 are 100 μg/m3 and 60 μg/m3 for 24 hours average.^[2] There is no standards prescribed for PM₁ in India. Observed mass concentration of PM₁₀and PM_2.5 at the study site are higher than the NAAQS in multiple days and similar inferences are reported by other regional/national agencies. The monthly average mass concentration of three classes of particulate matters is given in Figure1. Decreasing trend of particulate matter from December to May could be observed which is correlated to meteorological parameters.^[3] Undulating variation of particulate matters with time is also correlated with the meteorological parameters [Figure 2]. Correlation matrix of the particulate matters and meteorological parameters are analysed in the paper. In addition to this, particulate matters are collected on filter papers which are subjected to radiological analysis.

Figure 1: Temporal variation of PMs

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Figure 2: Diurnal variation of PM₁₀, PM_2.5 and PM₁

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Keywords: Meteorological parameters, PM₁, PM₁₀, PM_2.5, temporal variation

References

Dahari N, Latif MT, Muda K, Hussein N. Influence of meteorological variables on suburban atmospheric PM2.5 in the Southern Region of Peninsular Malaysia. Aerosol Air Qual Res 2020;20:14-25.
NAAQS. National Ambient Air Quality Standard, Central Pollution Control Board; 2009.
Mehadi A, Moosmuller H, Cambell D, Ham W, Schweizer D, Tarnay L, et al. Laboratory and field evaluation of real time and near real time PM2.5 smoke Monitirs. J Air Waste Assoc 2020;70:158-79.

Abstract - 61568: Activity concentrations of ⁷Be, ⁴⁰K, ²³²Th, ²²⁶Ra, and ²¹⁰Pb in air samples of uranium mineralized region in North Karnataka, India

I. Yashodhara¹, K. Sudeep Kumara², N. Karunakara^1,2

¹Centre for Application of Radioisotopes and Radiation Technology, Mangalore University, ²Centre for Advanced Research in Environmental Radioactivity, Mangalore University, Mangalagangothri, Karnataka, India

E-mail: [email protected]

Introduction: The radionuclides present in the environment can enter the human body through various pathways. The radionuclides which reach foodstuffs to the greatest extent are those which are freely transferred through biological systems. Cosmogenic radionuclides such ⁷Be make their way into the terrestrial environment and waterways though various mechanisms including wet and dry deposition. Other radionuclides like ⁴⁰K, ²³²Th, ²²⁶Ra and ²¹⁰Pb are present in air with very low activities. Gogi – a village in Shahapur taluk in Yadgiri district of Karnataka, India has been identified as uranium mineralized area. This baseline study has established crucial database on prevailing natural radioactivity in the atmospheric air and it would help in radiological impact assessment in future due to potential mining activities of the minerals in the Gogi region.

Materials and Methods: Airborne particulate samples were collected on a glass fibre filter paper using a high volume air sampler (APM 460 BL - Envirotech, India) with flow rate of 1 m³ min^-1 and sampling time of 24 hours. After sampling, the filter paper was analysed for ⁷Be, ⁴⁰K, ²³²Th, ²²⁶Ra and ²¹⁰Pb activity concentrations using gamma spectrometry employing a 38% relative efficiency p-type closed-end co-axial low background HPGe detector (Canberra, USA) having an energy resolution of 2.1 keV at 1.33 MeV with an operating voltage of 4000 volts.^[1]

Results and Discussion: The range and mean values of ⁷Be, ⁴⁰K, ²³²Th, ²²⁶Ra and ²¹⁰Pb in air samples are presented in [Table 1]. As expected the activity concentrations of primordial radionuclides ⁴⁰K, ²³²Th, and ²²⁶Ra are very low and their median values were 3.1 mBq m^-3, 1.8 mBq m^-3, and 0.3 mBq m^-3, respectively. The ²¹⁰Pb activity concentration varied in the range of <0.1 - 4.0 mBq m^-3 with a median value of 1.2 mBq m^-3.The activity concentration of ⁷Be varied in the range of 1.1-6.5 mBq m^-3 with a median value of 3.7 mBq m^-3. The ⁷Be activity observed in the Gogi region is similar to that reported for the Kaiga region (2.4-7.2 mBq m^-3).^[2] The UNSCEAR^[3] has reported that the ⁷Be in the temporal zone is about 3.0 mBq m^-3, and the mean value observed in the present study matches well with this value. The ²¹⁰Pb activity concentration observed in the Gogi region is comparable with those reported for Kaiga region (0.3-1.1 mBq m^-3)^[2] as well as for other parts of the world. The literature values for ⁴⁰K, ²²⁶Ra and ²³²Th radionuclides in the air for Indian environs could not be found in spite of an extensive survey. The mean values obtained for ⁴⁰K, ²²⁶Ra, and ²³²Th in the surface air of Gogi region are higher when compared to the values reported for Spain - 0.026 mBq m^-3 for ⁴⁰K, 2.1 μBq m^-3 for ²²⁶Ra, and 1.1 μBq m^-3 for ²³²Th^[4] and other parts of the world (0.2-0.9 μBq m^-3 for ²³²Th and 1.2-3.3 μBq m^-3 for ²²⁶Ra.^[5] These higher values may be because of the higher soil derived particles in the ambient air of Gogi region. [Figure 1] presents the variation of radionuclides in the air with different seasons of the calendar year. The activity concentration of ⁷Be was higher in the month of January (winter season) when compared to other seasons, which may be attributed to the ingression of continental air masses due to the wind regime from the northeast.

Figure 1: Variation of radionuclide activities in the atmospheric air with seasons

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Table 1: Activity concentrations of radionuclides in the atmospheric air

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References

Karunakara N, Yashodhara I, Sudeep KK, Tripathi RM, Menon SN, Kadam S, et al. Results Phys 2014;4:20-7.
Karunakara N, Yashodhara I, Ujwal P, Rao C, Somashekarappa HM, Ravi PM. National Conference on Accelerator and Low Level Radiation Safety, New Delhi, 2009, Nov 18-20, 53-54.
Annex E. United Nations Scientific Committee on the effects of Atomic Radiation (UNSCEAR), United Nations Publication, New York; 1982.
Valles I, Camacho A, Ortega X, Serrano I, Blazquez S, Perez, S. J Environ Radioact 2009;100:102-7.
Annexe B. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR); 2000.

Abstract - 61569: Determination of isotopic fractionation in the thermal oxidation process used for the determination of Carbon-14 activity measurements in biota samples

K. K. Arya, Bharath, T. R. Reshmi¹, M. Sudheesh¹, N. Karunakara

Centre for Advanced Research in Environmental Radioactivity, Mangalore University, Mangalagangothri, Karnataka, ¹Centre for Water Resources Development and Management, Kozhikode, Kerala, India

E-mail: [email protected]

Carbon-14 (¹⁴C) is produced naturally by cosmic ray nuclear reactions in the atmosphere and by anthropogenic activities such as nuclear weapons, testing and nuclear facilities. Because of the biological importance of carbon, the long half-life of ¹⁴C, and incorporation into living material, monitoring ¹⁴C in the vicinity of the power plants is essential. It is a common practice to correct ¹⁴C specific activity values for isotopic fractionation between the stable isotopes ¹³C and ¹²C. Isotopic fractionation of stable carbon isotopes or the ¹³C/¹²C ratio (termed as δ¹³C) involves alterations in the ratios of isotopic species as a function of their atomic massesdue to natural biochemical processes (e.g.: photosynthesis). The corrected specific activity values are referred to as “normalised” to indicate that measured activity is modified to -25 ‰ (per mille) with respect to the international reference standard for carbon isotopes Vienna Pee Dee Belemnite (VPBD).^[1] Isotopic fractionation can also occur in the ¹⁴C activity measurement process due to incomplete reactions during different stages of sample collection in the field and processing in the laboratory (e.g. sampling process of CO₂ from the atmosphere, carbonisation of terrestrial and aquatic samples through combustion process in the laboratory. Previously we demonstrated^[2] a method based on the combustion of samples in a tube furnace system (pyrolyser, Raddec international UK), trapping the evolved CO₂in CarbosorbE (PerkinElmer, USA) and subsequent liquid scintillation counting for ¹⁴C determination in biota. The isotopic fractionation can occur in this method during i) the combustion of the sample to evolve CO₂, which is a phase transition process,and ii) duringthe transfer of the produced CO₂to the absorber. To determine the extent of isotopes fractionation, the samples were analysed for δ¹³C values before combustion in the combustion system. Also, the CO₂ produced from the combustion were transformed into BaCO₃ form and analysed to determine the δ¹³C values using an isotopic ratio mass spectrometer (IRMS). Samples chosen for isotopic fractionation analysis are wood samples (C3 plant) and oil samples derived from grasses (C4 plant).The δ¹³C results of virgin samples (before combustion) and BaCO₃ derived from combustion are given in [Table 1]. The δ¹³C values confirm that isotopic fractionation did not occur in the combustion process of wood samples. On the other hand, isotope fractionation occurred in the case of oil samples. Hence, in such cases, the ¹⁴C specific activity values should be corrected for δ¹³C. A detailed study on the temperature dependence of isotopic fractionation during the combustion process is now progressing.

Table 1: δ¹³C values of wood and oil samples

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Keywords: Carbon-14, combustion, isotopic fractionation, oil, wood

References

Stenström KE, Skog G, Georgiadou E, Genberg J, Johansson A. A Guide to Radiocarbon Units and Calculations. Lund University, Department of Physics Internal Report; 2011. p. 1-17.
D'Souza RS, Rashmi Nayak S, Srinivas Kamath S, Bharath S, Arya Krishnan K, Mohan MP, et al. Optimisation of a batch thermal combustion method using a tube furnace oxidation system (Pyrolyser) and LSC for Carbon-14 determination in environmental matrices. J Environ Radioact 2021;226:106345.

Abstract - 61574: Tritium transfer to vegetation and partitioning as OBT and TFWT in Mumbai Region

Rupali C. K. Kamat, Sunita Singh, Sonali Bhade¹, Y. P. Gautam, Vandana Pulhani, A. V. Kumar

Environmental Monitoring and Assessment Division, ¹Radiation Safety and Systems Division, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India

E-mail: [email protected]

Tritium is a radioactive isotope of hydrogen that is produced naturally and is also generated during operations of nuclear facilities. It is a low-energy beta emitter, with the same chemical forms as hydrogen and rapidly mixes with air moisture, exchanges with water in other environmental reservoirs such as soil, plants and animals. This possibility to get distributed in whole environment and biological systems poses a health risk due to inhalation and skin absorption of air, ingestion of drinking water and food containing tritium. Soil and vegetation absorb tritium from their surroundings as HTO, which is metabolized and stored as Organically Bound Tritium (OBT). OBT is incorporated into organic compounds such as sugars, proteins, starches, lipids, cell structural materials and amino acids. HTO or “Tissue-Free-Water-Tritium” (TFWT) is very mobile compared to OBT which has a significantly longer retention time in biological organisms and systems than HTO. The longer retention time leads to higher dose consequences of OBT relative to HTO. The current study was carried out to estimate the OBT and TFWT contents in vegetation with short growth period and corresponding soils. Vegetation sample commonly consumed such as mustard, fenugreek, red and green spinach, curry leaves, beans, radish etc. and soil in the field which the plants were growing were collected. The processed vegetation and soil samples were freeze dried to extract water free of plant tissue. Once the tissue-free water tritium was extracted from the sample, the remaining portion was dried to a constant weight. The OBT was extracted using a Pyrolyser system and all the samples were counted by a low-background liquid scintillation counter. The TFWT measures was calculated as Bq kg^-1 of the vegetation and soil sample using the moisture content. The combustion water (CW) collected for each sample was measured and water equivalent was calculated to estimate the OBT activity in Bq kg^-1. The combustion water equivalent was found to be in the range 0.2-0.4 for vegetation and 0.08-0.13 for soil samples studied. A minimum detection limit of 14.9 Bq L^-1_CW (5.3 Bq kg^-1) for 5 g of vegetation and 29.8 Bq L^-1_CW (2.9 Bq kg^-1) for 10 g of soil was obtained. The concentrations of the TFWT and OBT in the samples studied are given in [Table 1]. The OBT to TFWT ratios ranged between 0.14-1.05 in the vegetation samples and from 0.66-6.09 in soil samples. The highest ratio is observed in bean's soil and similar trend is seen in the beans growing in it. OBT concentrations in a similar range are reported by Kim and Korolevych^[1] in same type of vegetables. The OBT/TFWT values in soil are mostly greater than 1 representing the long-term reservoir of tritium from surrounding environment. But the ratios in vegetation are mostly less than unity indicating the isotopic discrimination in metabolism of tritium in biological processes either due to higher mass or insufficient time due to short growth period of these plants. The transfer factor of tritium as [OBT]_plant/[OBT]_soilin all the vegetables except red spinach was in the range 1.2-1.8 showing equilibrium between the two systems. The source of OBT in the plants needs to be identified by further studies.

Table 1: Organically bound tritium and tissue-free-water-tritium in soil and vegetation

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Keywords: Organically bound tritium, tissue-free-water-tritium, vegetation

Reference

Kim SB, Korolevych V. J Environ Radioact 2013;118:9-14.

Abstract - 61575: Dilution study of tritium using control charts in Rana Pratap Sagar Lake at Rajasthan Atomic Power Station Rawatbhata

A. P. Srivastava, Ajay Kumar Gocher, S. N. Tiwari, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Monitoring and Assessment Division, BARC, Environmental Survey Laboratory, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Rajasthan Atomic Power Station consists of six units of PHWRs of capacity 220 MW(e). Heavy water is used as the primary coolant and moderator in the reactor system. Tritium (³H) is continuously produced during steady and stable reactor operation mainly by neutron activation of deuterium atoms. It is discharged in Rana Pratap Sagar (RPS) Lake through liquid effluents in a controlled manner for subsequent dilution before reaching the public domain. ³H being an internal hazard requires continuous monitoring throughout the lake which is used as a potable water source by the population residing nearby. Continuous sampling and monitoring of ³H activity is carried out to control the activity level and assess the degree of dilution at various locations. The conventional dilution study involves the use of dye or radioactive material as a tracer in the lake. It requires large infrastructure, tedious field work, and clearance from various regulatory bodies. As an alternate, this paper uses statistical analysis of the monitored environmental data to assess the dilution in a simpler way. ³H data of thirty years duration was subjected to the statistical analysis to produce control values and relative degree of dilution of ³H activity in various locations of RPS lake during the steady and stable operation of nuclear reactors. Since huge data was collected, it was convenient to impose control limits on quarterly average data of ³H activity location-wise. So, a new data set was formed by taking the quarterly average of ³H activity for 30 years time span. Using this dataset subgroups containing six data points (n=6) were formed and arranged on an increasing timescale. The mean and range of all subgroups were calculated. Also, the grand mean (X̄) and average range (R) of the population data set were calculated.^[1] Using standard X̄ - R chart program made in Excel datasheet, control limits were imposed on the quarterly mean of ³H activity data using coefficients^[2] D₃, D_4, and A₂ for sample sizen=6. The formula for control limits is presented in [Table 1]. The central line for average (X̄) represents the mean base level and the central line for range (R) represents the variability of ³H activity. This paper estimates the level of dilution at various locations in RPS Lake indirectly based on ³H data distribution at these locations. At discharge location baseline activity and variability were found to be maximum indicating the least dilution. As we go downstream from the discharge point, we observe a decline in base-level activity and associated variability. It indicates the degree of dilution increases along the downstream sampling locations of the lake. The paper also identifies the statistically identical sampling locations in RPS Lake. Estimated mean base level activities at various locations are much less that the WHO guidance level of 10,000 Bq/l of tritium in drinking water.

Figure 1: Control limits of tritium activity location-wise (highest and lowest horizontal lines represent UCL and LCL respectively. Middle line represents the CL). UCL: Upper control limit, LCL: Lower control limit, CL: Central line

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Table 1: Formula for control limits

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Table 2: Base level and variability of ³H activity in Rana Pratap Sagar lake

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Keywords: Control charts, tritium, mean, variability, X̄ - R Charts

References

Handbook of Course on Environmental Data Interpretation, Compilation, Analysis, Presentation and Reporting (January 28 to February 01, 2008). SQR & OR Unit Indian Statistical Institute (ISI) Delhi Centre; p. 151-6.
Loveday R. A Second Course in Statistics. 2^nd ed. Publishing House Cambridge University Press.

Abstract - 61585: Quality assurance through participation in proficiency test for low levels of anthropogenic radionuclides using gamma spectrometry

P. Lenka¹, A.C. Patra¹, S.K. Jha^1,2, M.S. Kulkarni^1,2

¹Health Physics Division, ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Radio-analytical laboratory (RAL), Health Physics Division, Bhabha Atomic Research Centre has been engaged in low level radioactivity measurements in environmental matrices using high resolution gamma-ray spectrometry. The measurements were part of various projects like baseline studies, monitoring around operating nuclear facilities, environmental monitoring for dose assessment and regulatory requirements, establishing coastal marine radioactivity database etc. The samples include soil, sediment, vegetation, water, food stuff, building materials etc. The measurements have to deliver reliable, traceable and comparable results to be accepted by regulatory bodies both at national and international levels. The commonly accepted procedure for assessing the quality of the measurement results by regulatory and accreditation bodies is through participation in different international proficiency tests with ac ceptable results. RAL regularly participates in annual IAEA proficiency tests (PT) for analysis of natural and anthropogenic radionuclides in environmental samples as a part of routine QA/QC checks to ensure the quality of analysis procedures and results. As part of these tests, environmental samples like fresh water, marine water, soil, sediment, biota and vegetation samples were analysed for gamma emitting radionuclides using HPGe gamma spectrometric systems. This paper is mainly based on the analysis of all water samples as part of these tests in last five years for long lived anthropogenic radionuclides comprising of fission and activation products. After Fukushima reactor accident, much focus has been given to analysis of anthropogenic radionuclides in water samples as marine aquatic route is one of the main pathways for long range transport of long-lived radionuclides. The samples collected by IAEA were spiked with natural and anthropogenic radionuclides, stabilized by acidification (pH<2) and homogenized before sending to different labs all over the world including one QC sample (IAEA, 2021). Total amount of radioactivity in the samples were less than the exemption levels, both in terms of radioactive concentrations and absolute activity values as one of the goals of the PT is to assess the performance of laboratories at low level radioactivity. The samples received were weighed and thoroughly mixed before transferring to standard counting geometry for gamma spectrometric analysis using a coaxial HPGe detector of 40 % R.E. with resolution of 1.78 keV for 1332 keV ⁶⁰Co gamma line, calibrated for energy and efficiency using standard reference materials. Gamma spectra were acquired for minimum 1,60,000s for good counting statistics^[2] and decay corrected activities were measured with respect to the reference date using standard formulae. Corrections were applied for attenuation, matrix and geometry. Uncertainty of the results were estimated as combined standard uncertainty at 1σ level taking into account all known uncertainty components and the results submitted to IAEA. The results were assessed for accuracy and precision by IAEA as per standard evaluation criteria (IAEA, 2021). Among all the radionuclides analysed, the analysis for long-lived anthropogenic radionuclides ²⁴¹Am, ¹³³Ba, ⁶⁰Co, ¹³⁴Cs, ¹³⁷Cs, ¹⁵²Eu is summarized in this abstract. The overall performance evaluation showed that 26 measurements, involving above radionuclides, out of 30 met the PT criteria and were deemed 'accepted' for both accuracy and precision. [Figure 1] below shows the analysis result for low level ¹³⁷Cs in water samples over last five years. The evaluation results showed the capability of the laboratory for analysis of anthropogenic radionuclides in water samples. It can be concluded that the gamma spectrometric system was in a state of quality control over the past five years and measurement results have continuously improved.

Figure 1: Results for low level ¹³⁷Cs in water

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Keywords: Anthropogenic radionuclides, gamma spectrometry, proficiency test

References

IAEA-TEL-2021-03 WWOPT and IAEA-TEL-2021-04 ALMERA Proficiency Test Report. Available from: https://nucleus.iaea.org/sites/ReferenceMaterials/Pages/Interlaboratory-Studies.aspx.
Lenka P, Jha SK, Gothankar SS, Tripathi RM, Puranik VD. J Env Radioact 2009;100:509-14.

Abstract - 61586: Assessment of natural radioactivity and gamma dose in the Western Ghat region, India

K. Sudeep Kumara¹, I. Yashodhara², N. Karunakara^1,2

¹Centre for Advanced Research in Environmental Radioactivity, Mangalore University, ²Centre for Application of Radioisotopes and Radiation Technology, Mangalore University, Mangalagangothri, Karnataka, India

E-mail: [email protected]

Introduction: Western Ghats region of India has a unique identity owing to the heavy precipitation, scenic beauty, ridges and valleys, geological structure, heavily eroded lateritic soil at the downward side and fertile soil supporting evergreen forest at the topside. Due to heavy precipitation, recycling through leaf litter in forest areas, and continuous soil erosion, radionuclides and heavy minerals are likely to be unevenly distributed in the Western Ghat. Literature indicates that the monazite deposits along the West Coast of India might be due to the weathering of the mineral-rich rocks in the Western Ghats and transportation along the river to the Arabian Sea.^[1] While detailed studies have been reported by our group on radiation levels and radionuclide concentrations along the coastal region of the West Coast of India, studies on these aspects within the Western Ghats have not been carried out previously. This paper reports the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in the soils, and the external gamma absorbed dose rates.

Material and Methods: Soil samples were collected from 27 sampling stations around the Western Ghats of Karnataka. The samples were processed following the standard procedure.^[2] The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in the soil samples were determined using gamma spectrometry employing a 50% relative efficiency p-type low background HPGe detector (Lynx, Canberra Industries Inc., USA) and GENIE-2000 software. The detector efficiency calibration was performed using the IAEA quality assurance reference materials: RG U-238, RG Th-232, and RG K-1. The counting time of the standard and sample was 30000 sec. The total gamma dose (D) due to the presence of ²²⁶Ra, ²³²Th and their daughter products, and ⁴⁰K were computed as under (UNSCEAR, 2008):

D(nGy h^-1)= 0.462C_U+0.604C_Th+0.0417C_K (1)

Results and Discussion: The concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in the soil varied in the range of 5.4-76.7 Bq kg^-1, 9.4-167.8 Bq kg^-1, and 64-961.5 Bq kg^-1, respectively with the corresponding geometric mean values of 29.9 Bq kg^-1, 47.6 Bq kg^-1, and 240.0 Bq kg^-1 [Table 1]. The study revealed a highly non-uniform distribution of these radionuclides in the region, with activity concentration in the soil varying significantly within a small area, which is due to the heavy precipitation and geological structure of this region. The values recorded in this study are comparable to those reported for the West Coast and other regions of India^[3] and the worldwide average value.^[4] The dose values calculated from soil radioactivity (Eq. 1) are presented in [Table 2], and they ranged from 16.6 to 171.2 nGy h^-1with a geometric mean value of 56.2 nGy h^-1, which is similar to the average world value of 54 nGy h^-1[4] and the all India average value of 69 nGy h^-1.^[5] The annual effective dose due to terrestrial radionuclides are also presented in [Table 2] and the overall mean value 0.1 mSv y^-1 which is similar to average value for India and the worldwide.

Table 1: Comparison of primordial radionuclide concentrations in soils

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Table 2: Comparison of gamma absorbed dose rate and annual effective dose

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References

Primal, et al. J Radioanal Nucl Chem 2014;302:813-7.
EML, US Department of Energy. Ed. 26; 1983.
Karunakara, et al. Natural radioactivity in South West Coast of India. Int Congr Ser 2005;1276:346-7.
Annex. B. UNSCEAR. Vol. 1,; 2008.
Annexe B. UNSCEAR.; 2000.

Abstract - 61589: Estimation of resuspension factor using ⁷Be for Kaiga site

R. M. Joshi, J. P. James, Sanyam Jain, M. S. Vishnu, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, ESS, EMAD, BARC, Kaiga, Karnataka, ¹EMAD, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Resuspension occurs when the wind exerts a force exceeding the adherence of particles to the surface materials. The forces in action are the weight of the particle, the adherence and the aerodynamic loads related to the flow of wind.Another process for resuspension is the mixed effect of rain and wind on particle detachment.^[1] The characterization of resuspension factors is a complicated environmental task because of the number of processes involved. The extent of the resuspension depends on the material (particle size, shape, adherence), the surface type (roughness, humidity), the time elapsed since deposition and the intensity of soil processing. Atmospheric resuspension of radionuclides can be a secondary source of contamination after a release has stopped, as well as a source of contamination for people and areas not exposed to the original release. The resuspension of particles deposited on any surface is described by the resuspension factor, K_r in m^–1, which is determined as the ratio of the radioactivity per unit volume of air C_a(Bq.m^–3) and the radioactivity deposited on the ground C_s(Bq.m^–2).^[1]

In the present study, Cosmogenic radio nuclide ⁷Be is used for estimating the resuspension factor at the Kaiga site. The resuspension factor, K_r is calculated using equation 1. Air and soil sampling are carried out around Kaiga and samples are processed as ESL procedure manual. ⁷Be concentration in air and soil is estimated using p-type 50% relative efficiency High Purity Germanium detector. Conversion of concentration of soil from Bq.kg^-1 to Bq.m^-2 was carried out by multiplying surface soil density. Default effective surface soil density value is used in the calculation (130 kg.m^-2). From [Table 1],the estimated resuspension factor K_r varies from 5.5E-06 to 1.0E-05 with Geometric Mean (GM) value is 6.4E-06. Since the Kaiga region is covered with thick forest area and heavy rainfall there is a possibility of mixed effects of both wind and rainfall in atmospheric resuspension. These factors are applicable during an emergency and can also act as a secondary source of contamination after release has stopped.^[2] The Kaiga site K_r values are comparable with the reported IAEA value of 10^-6 for rural sites (TRS 472, 2010). Reported resuspension factor for ¹³⁷Cs varied from 10^-9 to 10^-5atvarious locations in Europe.^[3] This is due to spatial variation and particle size. Another reason may be heavy rainfall at Kaiga region which attributes to resuspension. It was observed that from [Table 1], there exists a temporal variation in magnitude for K_rvalues. This indicates that K_r values are time-dependent. Similar observations were also reported by Garger et al., 1998.^[2] The resuspension factor implies an equilibrium relationship between two paramete.rs. Another parameter that explains resuspension in terms of time is resuspension rate Λ. It is product of resuspension factor (m^-1) and deposition velocity (m.s^-1).^[3]

It was reported that at Kaiga dry deposition rate for ⁷Be is 3.0E-04 m.s^-1. Using estimated resuspension factor values, the resuspension rate Λ at the Kaiga site is 1.9E-11 s^-1.

Resuspension of radionuclide is generally estimated using various mathematical models. The site-specific resuspension factor is applicable in estimating direct air concentration during an emergency. At Kaiga region source of resuspension is a mixed effect of wind and rainfall.

Table 1: Resuspension factor Kr (m^-1) for ⁷Be at Kaiga site

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Keywords: ⁷Be, resuspension

References

Technical Report Series-472. Hand Book of Parametric Values for Prediction of Radionuclide Transfer in a Terrestrial and Freshwater Environment. IAEA; 2010. p. 23-4.
Garger EK, Hoffman FO, Thiesen KM, Galeriu D, Kryshev AI, Lev T, et al. J Environ Radioact 1999;42:157-75.
IAEA-TECDOC-1616. Quantification of Radio Nuclide Transfer in Terrestrial and Freshwater Environments for Radiological Assessments. IAEA; 2009. p. 63-5.

Abstract - 61598: Distribution of uranium in groundwater from Kanyakumari region, Tamil Nadu, and its correlation with physio-chemical parameters

S. N. Bramha, S. Suja, S. Chandrasekaran, C. V. Srinivas, R. Ravisankar¹, B. Venkatraman

Indira Gandhi Centre for Atomic Research, Kalpakkam, ¹Governament Arts College, Tiruvannamalai, Tamil Nadu, India

E-mail: [email protected]

Uranium, a naturally occurring element with heterogeneous distribution, is found in widely varying concentrations in groundwater depending on the specific site and geological material. Water passing through and over geologic formations can dissolve the Uranium. Hence, it exists in an aqueous solution having oxidation states +3, +4, +5, and +6. Uranium is increasing in concentration in some parts of Punjab, Kerala, and Tamil Nadu.^[1] The physicochemical parameters provide important first-hand in-situ information about the suitability of water for drinking purposes.^[2] Groundwater samples collected from the Kanyakumari district were analyzed for the presence of Uranium. Twenty-two samples were collected, and [Figure 1] shows the sampling locations. The grid sampling technique has been adopted for water sample collection. The water sample was taken from the center of each grid or the nearest populated areas. Uranium measurements in water samples were measured using a Metrohm potentiometer. [Figure 2] presents. The contour map of Uranium concentration in water samples. It varies from 0.87 to 12.73 ppb. Physico-chemical parameters such as pH and Electrical conductivity (EC) are measured using a multi-parameter probe. An ion chromatography system (Dionex) was utilized to measure the concentrations of cations and anions in the groundwater samples. Correlation analysis measures the strength of the linear relationship between two variables and computes their association. The correlations coefficient was performed at a significant level of 0.01 (N=22), using STATISTICA 8.0 software development by StatSoft. The Pearson correlation coefficient matrix of Uranium, as well as physicochemical parameters, was calculated. [Table 1] shows that except for Na+, no strong correlation was noticed between Uranium and other water quality parameters. Leaching of uranium-containing minerals like Uraninite, Pitchblende, Coffinite, etc. can introduce Uranium into aquifers. Under oxidizing conditions, uranium host rock oxidizes to the +6 state and combines with O₂ to form UO₂⁺⁺, which is comparatively more stable and highly mobile. This will get dissolved in contact with water and thus leaches into nearby water sources like groundwater reservoirs.

Figure 1: Contour map showing the spatial distribution of the Uranium in Kanyakumari districts, Tamil Nadu

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Figure 2: Location map showing groundwater sample locations of Kanyakumari districts, Tamil Nadu

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Table 1: Correlation matrix for uranium and other physico-chemical parameters of groundwater sample

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References

Singh M, Garg VK, Gautam YP, Kumar A. Spatial mapping of Uranium in groundwater and risk assessment around an atomic power station in India. Environ Eng Manage J (EEMJ) 2016;15.
Bajwa BS. Uranium and Other Heavy Toxic Elements Distribution in the Drinking Water Samples of SW-Punjab, India – A Potentially Dangerous Trend. In Proceedings of the First National Conference on Radiation Awareness and Detection in Natural Environment: Abstracts and Souvenir; 2015.

Abstract - 61606: Speciation simulation and sorption mechanism of ²³⁸Pu in waste repository groundwater

Chao Chen, Tian Xie, Jun Zhu, Yunfeng Shi, Aiming Zhang, Bing Lian

Department of Nuclear Environmental Science, China Institute for Radiation Protection, Taiyuan, China

E-mail: [email protected]

The assessing of the mobility and fate of radionuclides escaping from radioactive waste disposal facilities in the environment relies on the use of numerical models capable of simulating all of the important processes along their complex geological environment. Adsorption models usually subsumes processes such as element chemistry and their chemical reactions with the surrounding environment, ion exchange or incorporation processes which have to be considered in long-term safety assessments for radioactive waste repositories. pH and redox conditions are recognized as the most important parameters that influence these sorption and migration processes. The studies on the batch experiments were carried out under different host rock formations for waste repositories, a theoretical model of nuclide migration in soil and groundwater environment was constructed, and the irreversible adsorption reaction mechanism of the micro-interface was studied through static adsorption-desorption data. And speciation distribution of ²³⁸Pu in groundwater systems were calculated, using PHREEQC software with the recent thermodynamic data published by OECD/NEA to understanding the sorption, diffusion and migration behaviors. The static adsorption and desorption experiments adopt batch method, and the test medium different host rock formations for waste repository from an arid mining area in Gansu Province, China. According to the field measurement, the pH value in the groundwater was 7.48 and Eh was 125.7mV. The solid-liquid ratio of 1:10 g/mL was added into the centrifuge tube, and the nuclide activity concentration was measured after adsorption and desorption equilibrium to obtain the adsorption and desorption isotherms. The PHREEQC software was further used to study the speciation changes of ²³⁸Pu in the groundwater of the pre-selected area of the waste repository under the conditions of changing pH and redox conditions. The results show that the absorption isotherms of ²³⁸Pu doesn't coincide with its desorption isotherms. According to the metastable equilibrium adsorption theory, ²³⁸Pu has an irreversible adsorption-desorption process, ion exchange and surface complexing are the main way of adsorption. The adsorption isothermal line is basically in accordance with the Freundlich adsorption isotherm. Utilizing the Equilibrium program in PHREEQC software package, the species and concentration-controlling factor of ²³⁸Pu in waste disposal facilities groundwater were investigated .Results indicate that Pu(OH)_4,Pu(SO₄)₂^-, and PuSO₄⁺ are the predominant species in this groundwater .The results also indicate that ²³⁸Pu concentration in this groundwater is mainly controlled by the precipitation of saturated minerals as Pu(OH)₄. When keeping Eh constant at 125.7mV, ²³⁸Pu concentration is controlled by the mainly species of elemental Pu(SO₄)^2-, PuSO₄⁺, Pu³⁺, Pu(OH)₄, Pu(OH)₃⁺ and Pu(OH)₂²⁺ with the changing of pH condition that the groundwater composition is not changed .When keeping pH constant at 7.48, the mainly species will be Pu(SO₄)₂^-, PuSO₄⁺, Pu(OH)₄, PuO₂OH and PuO₂OH⁺ with the changing of Eh condition.

Figure 2: Location map showing groundwater sample locations of Kanyakumari districts, Tamil Nadu

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Table 1: Species of Pu in groundwater from radioactive waste disposal repository

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Keywords: Irreversible adsorption, migration, radionuclide, species distributiowith the changing of Eh conditionn

References

Khalili F, Al-Banna G. Adsorption of uranium(VI) and thorium(IV) by insolubilized humic acid from Ajloun soil-Jordan. J Environ Radioact 2015;146:16-26.
Cook M, de Caritat P, Kleinschmidt R, Brugger J, Wong VN. Future migration: Key environmental indicators of Pu accumulation in terrestrial sediments of Queensland, Australia. J Environ Radioact 2020;223-224:106398.

Abstract - 61607: Study on tritium and iodine species transport through porous granite: A nonsorption effect by anion exclusion

Yunfeng Shi, Song Yang, Aiming Zhang

Department of Nuclear Environmental Science, China Institute for Radiation Protection (CIRP), Taiyuan, China

E-mail: [email protected]

Recently, several studies have investigated the advection–dispersion behavior of cationic radionuclides, such as ²³⁸Pu, ²³⁷Np, ¹³⁷Cs, and ⁹⁰Sr to evaluate the safety of the migration of various radionuclides in deep geological environments. At present, cationic radionuclides in liquid show high adsorption ability on mineral surfaces because of the permanently negative charges by isomorphous substitution in the crystal lattice of a mineral. Migration of cationic radionuclides in host rocks would be retarded, but anionic radionuclides (i.e., ³⁶Cl, ⁹⁹Tc, ¹²⁹I) show exclusive or repulsive behavior by Coulomb's force. Few studies on safety assessments (SA) for HLW disposal focused on the anion exclusion effect of anionic nuclide transport in granite and other host rocks . In addition, because of HTO does not receive cation adsorption and anion exclusion during migration, it is often used in comparative experiments. In this study, advection-dispersion experiments were designed to build a transport model through a calibration/validation process, and the transport behavior of tritiated water (HTO) and various iodine species (iodide: I^̄ and iodate: IO₃^̄) was studied on a dynamic compacted granite column. Breakthrough curves (BTCs) were plotted under various flow rates (1-5 mL/min). BTCs showed that the non-sorption effect by anion exclusion was observed only in I^̄transport because the retardation factor (R) of I^̄was lower than that of HTO (R=1). The anion exclusion effect was influenced by the immobile zones in the column. The non-sorption effect by anion exclusion (R<1) was only observed for I^̄at 5.0nced by the immobile zones in the coluy higher Coulomb's repulsive force may be caused by the smaller hydration radius of I^̄ than that of IO₃^̄. It can be seen from the [Figure 1] that since the injection method of solute is to continue to inject for a period of time and then stop the injection, all penetration curves are “s” type . Specifically, when the injection amount of solute reaches about one column pore volume, the ratio of solute activity concentration in the effluent quickly reaches the peak value, and then the concentration rapidly decreases to zero after continuous injection of clean water. [Figure 2] shows a comparison of the migration behaviors of I^̄and IO₃^̄under different flow rates. The closer it is to the dielectric surface, the more negative its potential becomes (the more obvious the repulsion). Comparison of the ion radii of I^̄and IO₃^̄showed that the ion radius of I^̄was smaller than that of IO₃^̄. Therefore, I^̄can pass through the diffusion layer and become closer to the medium surface during migration. At the same time, the greater the migration speed of ions, the greater the kinetic energy generated, the closer the energy to the medium surface, the stronger the anion exclusion effect, and the more obvious the acceleration during migration. However, it is difficult for IO₃^̄to become close to the medium surface because of its large ion radius and weak anion exclusion. Thus, the acceleration during migration was not obvious.

Figure 1: The ADE experimental breakthrough curves (BTCs). (a) HTO; (b) I^¯; (c) IO₃^¯ (Measurement error causes C/C₀>1)

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Figure 2: Schematic model of I^¯ and IO₃ ^-transport at various flow velocities

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Keywords: Anion exclusion, granite, iodine, nonsorption, two-region non-equilibrium

Reference

McCarter C, Rezanezhad F, Gharedaghloo B. Transport of chloride and deuterated water in peat: The role of anion exclusion, diffusion, and anion adsorption in a dual porosity organic media. J. Contam Hydrol 2019;225:103497.

Abstract - 61612: Atmospheric diffusion characteristics research of airborne radioactive substances on complex terrain NPPs

Junfang Zhang, Sha Huang, Yunpeng Li, Minghua Lyu, Jiangyu Yan

Department of Nuclear Environmental Science, China Institute for Radiation Protection, Taiyuan, China

E-mail: [email protected]

Nuclear Power Plants in complex terrain generally have the following characteristics: complex terrain and low annual mean wind velocity, which are not conducive to the diffusion of airborne radioactive pollutants. In addition, natural draft cooling tower is usually used for NPP as a heat dissipation system. The waste heat of the power plant is mainly released into the atmospheric environment through cooling water, which will cause a series of environmental problems such as shadow of plume, ground deposition of drift droplet etc. Compared with other NPPs, the existence of large cooling towers in the buildings of NPP sites increases the complexity of the underlying surface around the site. On the other hand, the thermal plume emitted during the operation of the cooling tower has a certain temperature difference with the surrounding ambient air, and its buoyancy will have impact on the flow of the surrounding airflow, and may also affect the diffusion of radioactive plume emitted by the chimney. Therefore, it is of practical significance to carry out research on such issues. In order to further reveal the influence of complex underlying surface and tall buildings on the atmospheric transport and diffusion of airborne radioactive pollutants emitted by the chimney during the operation of NPPs, the atmospheric diffusion characteristics of NPPs are comprehensively analysed by means of field test, wind tunnel experiment and CFD numerical simulation. The contents include: field tracer experiment of atmospheric diffusion on NPP, wind tunnel experiment and CFD numerical simulation of the influence of natural ventilation cooling tower on atmospheric diffusion in NPP, obtaining the model and diffusion parameters reflecting the atmospheric diffusion characteristics in the site area. The results show that the tall buildings such as cooling tower in NPP have obvious effect on the local wind field, which is closely related to the engineering layout, wind direction and terrain around the site. By the impact of the cooling tower and thermal plume, wind speed on wind direction axis decreases significantly with double-speed loss area appears; the thermal plume is found enhancing pollutants dispersion, increasing spreading range, decreasing the maximum concentration and significantly enlarging the vertical diffusion. The influence of the surrounding air flow and pollutant dispersion from a cooling tower closely relates to the relative position of the chimney and cooling tower. When the line connecting cooling tower and chimney parallels the wind direction, the influence is significant. Meanwhile, the impact of the thermal plume on pollutant dispersion is related to the height difference and relative position between the releasing source and the cooling tower.

Figure 1: Turbulent kinetic energy near cooling tower of NPP. (a) x-z plane, (b) x-y plane

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Figure 2: Weighted average diffusion parameters of cooling tower with or without thermal plume emission

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Keywords: Atmospheric diffusion, complex terrain, radioactive substances

References

Michioka T, Sato A. Wind tunnel experiment for predicting a visible plume region from a wet cooling tower. J Wind Eng Ind Aerodyn 2007;95:741-54.
Lucas M, Mart1nez PJ. On the influence of psychometric ambient conditions on coo ling tower drift deposition. J Heat Mass Transf 2010;53:B594-604.

Abstract - 61620: Determination of ^239+240Pu in environmental aerosol

Pengxiang Li, Ruijun Wang, Yuhu Han, Xiaona Ren, Xuyuan Ma, Ke Du, Feng Zhang

Department of Nuclear Environmental Science, China Institute for Radiation Protection, Taiyuan, China

E-mail: [email protected]

The content of ^239+240Pu in environmental aerosols in China was analyzed by using anion exchange resin separation and α spectrometer. The total recovery rate was 60.8%~94.6%, The minimum detectable limit of ^239+240Pu in aerosols was 0.008μBq/m³ (volume V=30 000m³, recovery Y=0.8, measurement time t=72 h). The sampling amount of aerosol in common environment needs more than 30 000 m³. In the emergency situation and the post-treatment plant aerosol sampling amount is 10000 m³, The ²¹⁰Po content in aerosol is 4~6 orders of magnitude higher than ^239+240Pu, In the analysis, we should pay attention to the influence of ²¹⁰Po on ^239+240Pu measurement. The experimental results show that the content of ^239+240Pu in common environmental aerosols in China is 0.009-0.099μBq/m³. In China, A, B, C D, E, F, G and other places each set up an aerosol collection point, from October 2014 to March 2015 to collect a sample, The collection volume of aerosol per month is generally around 10,000 m³. Due to the very low content of ^239+240Pu in the aerosol, the aerosol filters of the above-mentioned months were combined to analyze ^239+240Pu. [Figure 1] shows the results of the analysis of ^239+240Pu content in aerosols. The analysis results in [Figure 1] show that the content of ^239+240Pu in environmental aerosols in different places of China is 0.009-0.099μBq/m³, and the mean value is 0.056μBq/m³. which is at the same level as that in the United States,^[1] South Korea^[2] and Spain.^[3] G has the lowest content of 0.009±0.004μBq/m³, A-2, A-3 and F have the highest content of 0.099μBq/m³. The samples of A aerosol collected in April 2011, May 2011 and 2014.10-2015.03, respectively, had ^239+240Pu content of 0.085, 0.099, 0.099μBq/m³, and the data were stable. The method obtained the whole process radiochemical recovery rate of 60.8%~94.6%, and the average value was (78.8±11.7)%. The alpha energy peaks of ²¹⁰Po were found in the alpha spectra of ^239+240Pu measurements in aerosols, as shown in [Figure 2]. The content of ²¹⁰Po in aerosols of seven provinces was determined by silver sheet self-deposition method, as shown in [Table 1]. From [Figure 2] and [Table 1], it can be seen that the alpha energy peak of ²¹⁰Po (5.31 MeV) is adjacent to the alpha energy peak of ^239+240Pu to be measured (5.16 MeV). The energy difference between the two peaks is 150 KeV. The resolution of the commonly used Au-Si surface barrier probe alpha spectrometer can reach < 25 KeV (probe area φ=600mm²). The source can be completely separated under good conditions. However, if the coating thickness is slightly thicker in the process of source preparation, ²¹⁰Po tailing will easily occur, which will interfere with the resolution of the alpha energy peak of ^239+240Pu. In this paper, ²¹⁰Po content in environmental aerosols of seven provinces is 0.10~1.56 mBq/m³, is 10^-4~10^-3Bq/ m³ level , while ^239+240Pu content in aerosols is 10^-6~10^-5Bq/m³, ²¹⁰Po content is 4-6 orders of magnitude higher than ^239+240Pu. In the analysis, we must pay attention to the influence of ²¹⁰Po on ^239+240Pu measurement.

Figure 1: Aerosol ^239+240Pu Contents in 7 different places of China

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Figure 2: α spectrum of ^239+240Pu in aerosol samples (A-3 sample)

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Table 1: ²¹⁰Po and ^239+240Pu contents in aerosols in several different places of China

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Keywords: ²¹⁰Po effect, ^239+240Pu, aerosol, detection limit, tracer method

References

U.S. Atomic Energy Commission, the U. S. Energy Research, Development Administration, the U. S. Department of Energy. The High Altitude Sampling Program. NUSTL. Available from: http://[email protected].
Choi MS, Lee DS, Choi JC, Cha HJ, Yi HI. ^{239 +240}Pu concentration and isotope ratio (²⁴⁰Pu/²³⁹Pu) in aerosols during high dust (Yellow Sand) period, Korea. Sci Total Environ 2006;370:262-70.
Chamizo E, et al. Measurement of plutonium isotopes, ²³⁹Pu and ²⁴⁰Pu, in air-filter samples from Seville (2001-2002). Atmos Environ 2010;44:1851-8.

Abstract - 63108: Numerical groundwater flow model based on alternating direction implicit technique

Manish Chopra, Faby Sunny, R. B. Oza

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Numerical groundwater flow model is developed for simulating the groundwater flow in domain of interest using finite difference method employing Alternating Direction Implicit (ADI) scheme for solving differential equation of groundwater flow (Eq. 1).^[1] The salient features of the model are: applicable to unconfined and confined aquifers; includes different types of boundary conditions; option for Gauss elimination and Gauss Seidel with relaxation methods of solution; has provision for source and sink terms and variable time steps. Model will be useful for generating groundwater flow field in watershed area of waste disposal sites for radiological impact assessment applications.

Here, T_x/y/z = Transmissivity [L²T^-1]= K_x/y/z b, b = Saturated aquifer thickness [L], K_x/y/z = Saturated hydraulic conductivity [LT^-1], h = Hydraulic head [L], S = Storativity [unitless], q = Recharge(+)/Pumping rate(-) per unit area [LT^-1]. For unconfined aquifer, b is replaced by variable h and Storativity by Specific yield. Alternating direction implicit (ADI) Scheme: In ADI scheme, implicit finite difference discretization method is employed along columns (x-axis) for first 1/3^rd time step, along rows (y-axis) for second 1/3^rd time step and along vertical (z-axis) for third 1/3^rdtime step. During calculation along one dimension, the known values at neighbouring nodes (eg. I, j-1,k and I,j+1,k) along the other two dimensions at previous time step are used as shown in Eq. 2 (Rastogi, 2007)^[1] (z-terms include terms similar to y-terms).

Similar equations are used along y and z-directions. [Figure 1] shows a typical head distribution output from the model including one injection and one pumping well. Model verification: The model is verified by comparison of head values at observation wells OB1, OB2 & OB3 as given in [Table 1] for test case provided in Mategaonkar and Eldho (2011).^[2] In this test problem, the aquifer domain consists of three zones having different characteristics and three pumping wells and one injection well [Figure 2].

Figure 1: Typical output of the model

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Figure 2: Test case pictorial description

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Table 1: Comparison of alternating direction implicit, finite element method and peripartum cardiomyopathy results

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Keywords: Groundwater, head distribution, implicit finite difference, numerical model

References

Rastogi AK. Numerical Groundwater Hydrology. Mumbai: Penram International Publishing (I) Pvt Ltd; 2007.
Mategaonkar M, Eldho TI. ISH J Hydraulic Eng 2011;17:71-87.

Abstract - 63109: Numerical model based on alternating direction implicit technique for contaminant transport in groundwater

Manish Chopra, Faby Sunny, R. B. Oza

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Numerical model for simulating contaminant transport in groundwater is developed using finite difference method employing Alternating Direction Implicit (ADI) scheme for solving advection dispersion equation as given in Eq. 1 (Nair et al., 2010)^[1] where (m-1) and m represent parent and daughter radionuclides, for m = 1, the last term becomes zero. The salient features of the model are: model is applicable to conservative/non-conservative contaminants; includes different types of boundary conditions; option for Gauss elimination and Gauss Seidel with relaxation methods of solution; provision for source and sink terms, variable time steps; includes in-situ progeny production to avoid impact underestimation. Model will be useful for radiological impact assessment of geological waste disposal facilities.

Various terms in the Eq. 1 are defined elsewhere (Nair et al., 2010)^[1] and S is source. These equations are solved numerically by employing the ADI scheme alternatively for three directions using 1/3^rd of the time step in each case. The discretization along x-axis is shown for parent in Eq. 2 (z-terms include terms similar to y-terms). Similar equations are used along other two directions. Model verification: The model is verified by comparison of the computed results for test problems with the reported values. In test case 1, ADI scheme is verified by solving a 2D transient heat problem (differential equation similar to Eq. 1) for which both the analytical solution and numerical solution using ADI are available and comparison of results is shown in [Figure 1].^[2] Model is further verified by comparison with analytical/numerical solutions for sample problems of contaminant transport in groundwater. [Figure 2] shows results for 2D advection dispersion problem.^[3] Model demonstrates very good reproduction of reported results.

Figure 1: ADI scheme verification using 2D transient heat problem

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Figure 2: Verification for 2D advection dispersion problem. EFGM: Element-Free Galerkin Method

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Keywords: Contaminant transport, groundwater, implicit finite difference, numerical model

References

Nair RN, Sunny F, Manikandan ST. Appl Math Model 2007;34:2300-11.
Halif NA, Rusli N. ASM Sci J 2019;28-33.
Kumar RP, Dodagoudar GR. Int J Numer Anal Methods Geomech 2009;34:661-88.

Abstract - 63110: Short term prediction system: A tool to forecast meteorological variables on a short time scale

R. Shrivastava, Indumathi S. Iyer and R. B. Oza

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

During accidental conditions at power plant sites, forecast of meteorological variables like wind speed, wind direction and atmospheric stability category are necessary for simulation of atmospheric dispersion at local/regional scales. Numerical Weather Prediction (NWP) models coupled with atmospheric dispersion algorithms are frequently utilized for atmospheric dispersion estimates.^[1] Even though numerical weather forecast models can provide a time dependent three dimensional flow field, the time and computational resources required to obtain these data and thereby arrive at any decision may limit their application. Hence, in recent times, machine learning algorithms like Artificial Neural Networks (ANN) and Autoregressive Integrated Moving Average (ARIMA) are becoming popular in weather forecasting.^[2] In this study, a model namely Short TErm Prediction System (STEPS) is developed based on ARIMA technique for forecast of meteorological variables like air temperature, solar radiation, wind speed and wind direction based on locally measured data. Following are the features of STEPS:

Input to STEPS: Hourly measurements of last 7 days (7 cycles) of meteorological data
Output of STEPS: Next 3 days of prediction
Platform: R/RStudio (both free and Windows/Linux based)
Execution time ~ 45 minutes (including pre-processing time).

STEPS uses the auto.arima function to determine the optimum order of the ARIMA model based on minimum Akaike's Information Criterion (AIC).^[3] The results of a sample case study are described in [Figure 1] and [Figure 2] for wind speed and wind direction respectively. Here, the forecast duration is 72 hours (29.03.2022 to 31.03.2022). Wind data are measured on Mod Lab terrace using an ultrasonic anemometer. Data are averaged for an interval of ten minutes. Ten minutes measured data are further converted to hourly average values for use in STEPS model. From [Figure 1] and [Figure 2], it is seen that the diurnal variation and values of wind speed and direction are well represented in the model output for 24, 48 as well as 72 hours forecasts. Across the length of 24 hours forecast, the average error in prediction of wind speed is ~ 0.5 m/s (maximum error ~ 1 m/s) and the same for wind direction is ~ 34⁰ (maximum error ~ 100 ⁰). It should be noted that for this particular case study, the errors in wind speed and wind direction for 48 hours and 72 hours forecasts are of similar order. At present it is difficult to provide a reasoning for this and more simulations are required to confirm this trend. With multiple measurements of meteorological parameters, the STEPS model can be used in simulation the atmospheric flow field at nuclear power plant sites as well as consequent atmospheric dispersion and dose estimation.

Authors wish to thank Shri B. B. Ghorpade for assistance in operation of meteorological instruments at Trombay site.

Figure 1: Comparison of observed wind speed with 24, 48 and 72 h forecasts

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Figure 2: Same as above for wind direction

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Keywords: Autoregressive integrated moving average, meteorological variables, prediction, short time scale

References

Huh CA, Lin CY, Hsu SC. Regional dispersal of fukushima-derived fission nuclides by East-Asian monsoon: A synthesis and review. Aerosol Air Qual Res 2013;13:537-44.
Corba BS, Kasap P. Wind speed and direction forecasting using artificial neural networks and autoregressive integrated moving average methods. Am J Eng Res 2018;7:240-50.
Akaike H. A new look at the statistical model identification. IEEE Trans Autom Control 1974;19:716-23.

Abstract - 63111: A comparative study on various missing data imputation techniques

R. Shrivastava, Indumathi S. Iyer, R. B. Oza

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Missing data are frequently encountered in the operation of field instruments due to several reasons like instrument failure, power failure, meteorological extremes, and/or errors in data acquisition systems.^[1] Several techniques of imputation of missing data like linear interpolation, last observation carried forward, interpolation based on moving averages, mean, median and mode, seasonally split/seasonally decomposed interpolation are commonly used. These algorithms are available in the imputeTS package in R.^[2] An algorithm has been developed in R programming language utilizing the above techniques. Besides these, Numerical Weather Prediction model (NWP) like The Air Pollution Model (TAPM) can also be utilized for generation of meteorological data.^[3] Also on a short time scale of 1 to 3 days, models based on machine learning methods can be used. Out of the various imputation techniques in inputeTS package, only a few namely seasonal splitting and seasonal decomposition are suitable for imputation of meteorological data and they are analyzed further. The present study compares various techniques for missing data imputation on a time scale of 1 day (08.01.2020), 3 days (08.01.2020 - 10.01.2020) and 15 days (08.01.2020 – 22.01.2020) with the actual measurements. The variables compared are wind speed, wind direction, air temperature, relative humidity, solar and net radiation. Results of the same are presented in [Figure 1]. The Mean Absolute Error (MAE) is computed for all the variables in the different techniques used and presented in [Table 1]. The choice of the best technique is dependent on the duration of missing data. For missing data of short duration, seasonally split/seasonally decomposed interpolation technique as well as models based on machine learning methods are good enough. However, when the duration of missing data extends into few weeks/months, NWP model output may be utilized for imputation. In such cases STEPS or seasonal decomposition technique are not suitable.

Figure 1: Comparison of observed and imputed data

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Table 1: Mean absolute error in various techniques

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Keywords: Imputation, imputeTS, missing data

References

Yozgatligil C, Aslan S, Iyigun C, Batmaz I. Comparison of missing value imputation methods in time series: The case of Turkish meteorological data. Theor Appl Climatol 2013;112:143-67.
Available from: https://cran.rproject.org/web/packages/imputeTS/imputeTS.pdf.
Hurley PJ, Physick WL, Luhar AK. TAPM: A practical approach to prognostic meteorological and air pollution modelling. Environ Model Softw 2005;20:737-52.

Abstract - 63201: Ingestion dose variation due to uncertainty in the composition of aquatic food

Faby Sunny, Manish Chopra, R. B. Oza

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Nuclear Power plants may release small amount of radioactivity into the aquatic environment under normal operating conditions within the stipulated regulations. Ingestion of aquatic food is one of the most important pathways which may result in dose to the humans due to routine releases into the water bodies.

The dose due to ingestion is estimated using the equation:

where D_ing,m,iis the committed annual effective dose through ingestion of aquatic food 'm' containing nuclide, i (Sv y^-1), C_i is the concentration of radionuclide, i (Bq m^-3), CF_m,i is the bioaccumulation factor of aquatic food, m for nuclide, i (Bq kg^-1 per Bq m^-3), I_m is the annual consumption of aquatic food, m (kg y^-1), E_ing,iis the ingestion dose coefficient of nuclide, i (Sv Bq^-1) and f_m is fraction of contaminated aquatic food, m in the total consumption. Present study deals with the effect of uncertainty in the aquatic food composition and the difference in the resulting bioaccumulation factors on the ingestion dose rate. To understand the importance of aquatic food composition four typical radionuclides (Pu-239, Cs-137, Sr-90 and Ru-106) (1 Bq m^-3 each) were assumed to be present in the surface water body. Four different scenarios are considered in this study: Scenario 1: Assuming the dietary intake (18.3 kg) of aquatic food as entirely consisting of fish, using the bioaccumulation factors given in ECPDA. Scenario 2: Assuming the dietary intake (18.3 kg) of aquatic food for adult as entirely consisting of shell fish, using the bioaccumulation factors given in ECPDA. Scenario 3: Assuming the dietary intake (18.3 kg) of aquatic food for adult comprising of 68% fish and 32% shell fish as per the percentage of catch given by CFMRI^[1] for Maharashtra, using the bioaccumulation factors given in ECPDA. Scenario 4: Assuming 68% fish, 23% crustacean and 9% mollusks (cephalopods) as per the percentage of catch given by CFMRI,^[1] using the bioaccumulation factors for fish given by ECPDA and for crustacean and cephalopods given by IAEA.^[3] It can be observed that the variation in bioaccumulation factors [Table 1] for shell fish (ECPDA) and fish is maximum for Ru-106 with a factor of 1000, followed by Pu-239 and Cs-137. The bioaccumulation factors (BF) for fish and shell fish are same in case of Sr-90. These factors are directly reflected in the Ingestion dose rate values (normalized with respect to scenario 1) estimated for theses radionuclides [Table 2] for scenario 1 and 2. As expected, the ingestion dose rate values in scenario 3 are in between those of scenarios 1 and 2 where both fish and shell-fish are the constituents of the aquatic food diet. Similarly, in scenario 4, the shell fish is further divided into its constituents i.e. crustaceans and mollusks (cephalopods). The difference in the bioaccumulation factors of crustaceans and mollusks from that of shell fish is directly translated into the ingestion dose of scenarios 3 and 4 [Table 2]. Significant variation in ingestion dose values in different scenarios brings out the importance of having accurate site specific dietary data in estimation of the ingestion dose.

Table 1: Radionuclide dependent parameters

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Table 2: Normalzed ingestion dose rates with respect to scenario 1 due to radionuclide in different scenarios

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Keywords: Aquatic food, bioaccumulation factor, composition, dose estimation, uncertainty

References

CFMRI. Annual Report 2016-17, Indian Council of Agriculture Research. Kerala, India: Central Aquatic Fisheries Research Institute; 2017.
ECPDA. Methodology for Computation of Public Dose and Dose Apportionment for DAE Facilities-Atmospheric and Aquatic Pathways, AERB Expert Committee for Public Dose Computation and Dose Apportionment; 2020.
IAEA. Sediment Distribution Coefficients and Concentration Factors for Biota in the Marine Environment. Vienna: Technical Report Series No. 422, International Atomic Energy Agency; 2004.

Abstract - 63300: Electrostatic coagulation and concentration decay of bipolar and unipolar charged aerosols

U. Pujala^1,2, A. Kumar^1,2, V. Subramanian^1,2, B. Venkatraman^1,2

¹Radiological and Environmental Safety Division, IGCAR, Kalpakkam, Tamil Nadu, ²HBNI, Training School Complex, Mumbai, Maharashtra, India

E-mail: [email protected]

Studies on aerosol charging phenomenon and charged aerosol dynamics are of interest in the nuclear industry as they encounter radioactive aerosols during severe accidental conditions of nuclear reactor. The environmental source term (EST) is being predicted with time evolution of suspended aerosol concentration in the containment. Under this condition, the aerosols are radioactive and charged to various magnitude by 2 processes i.e. radioactive decay (self-charging) and with bi-polar ion field generated due to radiation field (diffusion charging)Yeh et al., Gensdarmes et al.^[1],[2] The dynamics of radioactive aerosols additionally get affected by the type of charged condition and the charge on aerosol. In this context, charged aerosol dynamics models need to be developed and validated with experimental observations. In the present study, experiments are carried out using non-radioactive standard liquid poly-disperse PAO (Poly Alpha-olefin) aerosols, charged with bipolar and unipolar ions to obtain different charge levels. Electrostatic Aerosol Neutraliser (EAN) is used to obtain different charge conditions and charge levels by independently controlling the concentrations of positive and negative ions mixing with aerosols. It is to be noted that, the charge acquired by the aerosols under unipolar ion field would be varied accordingly w.r.t concentration of the aerosols and ions, which in-turn resembles radioactive aerosols (charged with different magnitude). The charged aerosols with EAN were hovered inside grounded 1 m³ chamber to study the dynamics. The real-time aerosol concentration decay and size growth were measured using Electrical Low-Pressure Impactor (ELPI). The PAO aerosols are chosen, as the material and aerosol densities are equal (0.82 g/cc) and also cause minimal experimental uncertainties in ELPI measurements with respect to number and charge size distributions Maricq and Xu.^[3] The density of 0.82 g/cc is used to determine the evolution of mobility equivalent (or actual) size distributions with time for baseline and charged conditions. The initial number concentration of aerosols (N₀) generated in all the runs is around 1.38E06 (± 1.55E04) /cm³. In baseline condition average number of charges per particle (j_fr) is 0.02 and hence neutral. In the bipolar conditions, the bipolar ion asymmetry ratios are 1.55 and 1.92 at the voltage pairs of (3.7, -6) and (3.7, -4) respectively that resulted in total aerosol averaged charge (j_fr) values of 1.25 and 1.87. In unipolar conditions, the average n_it product provided at voltage pairs of (0,-6.5) and (6,0) are 1.3E11 and 2.43E11 s/m³ respectively that resulted in j_fr values of -3.45 and 4.22. The number concentration decay of aerosols (N Vs t) is plotted in [Figure 1] and the factors of concentration decay and size growths are compared in [Table 1]. The unipolar aerosol size growth is decreased compared to baseline due to electrostatic repulsion acting against the Brownian agglomeration process. In bipolar conditions, there is no observable enhancement in size growth for the sub-micrometer dielectric PAO aerosols with tested charge levels. In both the conditions, concentration decay is enhanced compared to baseline line conditions, in proportional to the space charge j_frdue to additional deposition over chamber surface by image force and electrostatic repulsion [Table 1]. This study supports the consideration of the radioactive aerosol charging phenomenon for evaluating the source term estimations. Modelling and validation of charged aerosol dynamics is under progress.

Table 1: Comparison of concentration decay and size growth factors

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Figure 1: Comparison of concentration decay

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Keywords: Electrical aerosol neutraliser, electrical low pressure impactor, PAO aerosol, radioactive aerosol

References

Yeh HC, Newton GJ, Rabee OG, Boor DR. J Aero Sci 1976A;7:245-53.
Gensdarmes F, Boulaud D, Renoux A. J Aero Sci 2001;32:1437-58.
Maricq MM, Xu N. J Aero Sci 2004;35:1251-74.

Abstract - 63368: Assessment of ingestion dose to members of public from marine biota

Sugandhi Suresh, Sangeeta Sartandel, V. M. Joshi, Vandana A. Pulhani

Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Natural radionuclides are ubiquitous in the marine environment with activity concentrations varying as per the regional background, geological processes in terrestrial rocks such as weathering, erosion and mineral recycling. Anthropogenic radioactivity is introduced in marine system due to global fallout generated by atomic weapon tests, discharges from nuclear facilities, reprocessing plants and nuclear accidents. The aim of the present study, is to have the data base of both natural and anthropogenic radioactivity concentrations in marine biota from different habitat, which would be helpful to conceptualise bio concentration of radionuclides, identify biomarkers/hyper accumulators, radiological risk assessment to humans and to tackle the nuclear emergency scenario. Varieties of marine biota such as benthic crustaceans (Crab: 15 nos.), benthic cockle (Bivalve: 16 nos.), pelagic crustaceans (Prawn: 10 nos.) and pelagic fish (50 nos.) were collected from Thane Creek in Mumbai, India and were analysed for natural (⁴⁰K, ²¹⁰Po, ²²⁶Ra, ²²⁸Ra) and anthropogenic (⁹⁰sr,¹³⁷Cs) radioactivity by adopting standard protocol.^[1] The logarithmic geometric mean (GM) activity concentration of natural and anthropogenic radioactivity are represented in [Figure 1] and [Figure 2]. It is observed that the anthropogenic activity concentration is lower by an order or two in comparison to natural radioactivity. Ingestion dose to Members Of Public (MOP), was evaluated from the activity concentration of natural, anthropogenic radionuclide's [Figure 3] for an annual intake of 14.6 kg. The ingestion dose to MOP due to natural radioactivity are 2-3 orders of magnitude higher as compared to that from anthropogenic radioactivity. Among the natural radionuclide, activity concentration of ²¹⁰Po in benthic cockle > crustacean (benthic, pelagic) > fish, followed by ⁴⁰K [Figure 1]. Though activity concentration of naturally occurring ⁴⁰K in pelagic fish is higher in comparison to biota from other habitat, its contribution to ingestion dose for MOP is only 4%. Naturally occurring ²¹⁰Po, in marine food shows global average activity concentration of 2.4 Bq kg^-1, 6 Bq kg^-1 and 15 Bq kg^-1 in fish, crustaceans and mollusks,^[2] respectively. The ²³⁸U series radionuclide ²¹⁰Po, an alpha emitter with physical half-life of 138 days in the with a high dose conversion factor (2.4x10^-7Sv Bq^-1), making it a dominant contributor towards ingestion dose. As per UNSCEAR 2000, ²¹⁰Po contributes 85 μSv y^-1 to a total effective age weighted average of 140 μSv y^-1 from naturally occurring U, Th series in food and drinking water.^[2] Japan with the highest per capita levels of fish consumption in the world reported a committed effective dose to humans from ²¹⁰Po as 1.3 mSv y^-1 while, U.S.A. with 2-3 fold lower seafood consumption than Japan has reported as 0.6 mSv y^-1.^[3] Present study, reveals that 99.9% contribution towards ingestion dose to MOP is from natural radionuclides while, the anthropogenic radionuclides are contributing just 0.1%. Therefore, the marine biota may be considered to be safe for consumption from radiological point of view.

Figure 1: Natural radioactivity in biota

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Figure 2: Anthropogenic radioactivity in biota

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Figure 3: Ingestion dose to MOP. MOP: Members of public

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Keywords: ²¹⁰Po, ⁴⁰K, ⁹⁰Sr, anthropogenic, habitat, natural

References

Hegde AG, Verma PC, et al. BARC/2009/E/004; 2009.
Annex B. UNSCEAR Vol. 1; 2000.
Nicholas SF, Karine BS, et al. Proc Natl Acad Sci U S A 2013;110:10670-5.

Abstract - 63394: Extreme value analysis of meteorological parameters observed during the period (1961 – 2020) for Tarapur Maharashtra Site, Tarapur India

Vedesh K. Varakhedkar, S. Vanave, A. Baburajan, I. V. Saradhi¹

Environmental Survey Laboratory ESS, EMAD, BARC, Tarapur, ¹ESS, EMAD, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

The design of engineering structures requires an understanding of extreme weather conditions that may occur at the site of interest, which is very essential so that the structures can be designed to withstand weather stresses. In this paper, an analysis of extreme values of meteorological parameters observed at Tarapur for the period 1961-2020 is presented. The parameters considered are extreme air temperatures, maximum wind speed and estimated maximum gust wind speed at 10m height, and extreme rainfall data. The annual extreme values are arranged in ascending order for maximum and descending order for minimum and each data point is assigned a rank 'm'. The probability of non-excedence of a particular magnitude 'X' of the data point of the rank 'm' was obtained as P (X) = m / (M+1) where 'M' is the total number of data points. The data was plotted for a linear fit between the data variables and reduced variate as a function of the probability of non-accedence / excedence. The correlation coefficient between Y vs X_pand ln(Y) vs X_p for all the variables was used to decide for the type of distribution that data follows Xp = -ln [-ln {P (Xp)}] is the reduced vitiate. Least square fit (LSF) method and Lieblein Order Statistic Method (OSA) are used to find distribution parameters using the below equations:

Gumbel/Fisher-Tippet Type-I distribution

Frechet distribution / Fisher- Tippet Type 2 distribution

α,β,ϒ are identified as location, scale and shape parameters of the distribution function. Mean Recurrence Interval (MRI) or return period is defined as

MRI = 1 / [1-P(x)] years

The order statistics approach treats the property of the ordered data sets i.e. obtained by ranking the data in increasing or decreasing order of relative magnitude for maximum and minimum calculations, respectively.^[1]

Results and Discussions: The extreme value analysis reveals that the variables such as Annual maximum air temperature (AMXAT), maximum annual rainfall (MXARF), annual maximum monthly rainfall(AMMRF), annual maximum wind speed at 10m (AMW), and annual maximum 5 minute gust wind speed at 10 m (AMGW_5m) follow Fisher-Tippet Type-1/ Gumbell distribution, whereas annual minimum air temperature (AMIAT), annual maximum hourly rainfall (AMHRF), annual maximum daily rainfall (AMDRF) and minimum annual rainfall (MIAR) follow Fisher-Tippet Type-2/Frechet distribution function. A factor of 1.15 is used to estimate gust wind speed for 5 minutes from hourly maximum wind speed at 10 m height.^[2] Extreme values corresponding to return periods of 100 and 500 years are worked out using distribution functions derived from LSF and OSA. These derived extreme values are particularly useful for arriving at suitable design values to ensure the safety of any civil structure in the Tarapur area with respect to stresses due to weather conditions. A good comparison is observed between extreme value statistical analysis using graphical LSF method and a numerical method OSA using Lieblein order statistics approach for extreme meteorological parameter at Tarapur. AMW for MRI 500 years using LSF is 21.7 m/s, which falls in “F0” in Fujita scale, i.e.Tarapur site has potentially a gale Tornado. AMWusing OSA for MRI of 500 years 19.0 m/s and evaluated 1σg = +1.1 m/s, therefore the confidence interval within which 68.3% event will fall is denoted by 21.8+1.3 m/s. MRI values computed here are in good agreement with earlier published data for Tarapur site, Patel.^[3]

Table 1: Mean Recurrence Interval of different meteorological parameters

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Keywords: Distribution parameters, Lieblein Order Statistics Technique, mean recurrence interval

References

Lieblein J. A New Method of Analyzing Extreme Value Data, Technical Note 3053. Washington DC: 1954.
AERB SG. Extreme Values of Meteorological Parameters' (AERB/NF/SG/S-3). Mumbai: AERB; 2008.
Patel PV. Extreme Value Analysis of Meteorological Parameters Observed During the Period 1961-2000 at Tarapur. Internal Report BARC; 2001.

Abstract - 63421: Seasonal trends of meteorological parameters at Kudankulam Coastal site

B. Preetha, Jayasudha, Thomas George, B. Vijayakumar, I. V. Saradhi¹,A. Vinod Kumar¹

Environmental Survey Laboratory, Kudankulam Nuclear Power Project, Kudankulam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

The radioactivity discharged to the environment from power plants are carefully controlled and regulated as per technical specification limits by incorporating design safety features in the reactor. In case of release of gaseous radioactive effluents to the environment, though much below permissible limits, exposure to the public may occur by various pathways. External exposure occurs during the passage of the radioactive plume. The doses at different receptor locations due to dispersion of the released gaseous effluent activity can vary depending on the meteorological conditions and effect of topography. In order to estimate the public exposures due to the plume dispersion, the meteorological parameters like wind speed, wind direction and stability category are essential. This paper presents the seasonal trends of meteorological data for five year period (2016-2020). The meteorological systems are mounted on a 30 m tower at two levels 10 m and 30 m height. A continuous logging data acquisition system accepts the data from the tower mounted sensors. MetDAS (Meteorological Data Acquisition Software), an online data acquisition and analysis software developed for Micrometeorological Laboratories by Environmental survey Laboratory, Kudankulam is used for data analysis.^[1] The data so collected are analyzed for preparing Joint Frequency Distribution (JFD) and Triple Joint Frequency Distribution (TJFD). TJFD presents distribution of three meteorological variables wind speed, wind direction and stability class. The present study was undertaken for the 5 years (2016-20) and was categorized seasonally for South West monsoon, North East monsoon, summer and winter for data trending. 96 % of data was used for trending. Considering the frequency of persistency of wind direction for different seasons (2016-2020), it was observed that clam condition is < 2%, and receptors near to the release point will receive the minimum exposure. It is observed that the most predominant wind directions are N, NNE, W, WSW and SW, hence the corresponding affected sectors would be S, SSW, E, ENE and NE. Affected sectors S, SSW, E and ENE are in sea sectors while affected sector NE is a land sector, where public exposure could result [2]. The analyses of meteorological parameters are as follows. Wind Speed: It influences the airborne dispersion of gaseous effluent. Higher wind speed promotes dispersion. The analysis of hourly wind speed data shows that average wind speed was 12-19 Kmh^̄1 .The persistence of wind speed classes observed for all the four seasons indicated higher wind speed frequencies in the wind speed class 20 to 28 kmh^-1. Wind Direction: Wind normally does not blow from the same direction for long duration. It has been observed that the persistence of wind direction N, NNE, W, WSW and SW are the most predominant in all the wind speed classes for all four seasons. Mostly the plume direction sectors are in sea. Wind roses for the two seasons are shown in [Figure 1] for 30 m height. Stability Category: Passquill Gifford stability class determines the turbulence in the atmosphere. It is observed that persistence of neutral category D (59%) is more throughout the year followed by unstable category A, B and C (25%) and stable category E and F (16 %).

The most predominant wind directions observed during the study period are N, NNE, W, WSW and SW and corresponding affected sectors are S, SSW, E, ENE and NE. Mostly, the plume sector is in sea. The neutral category weather is observed predominant during the study period. The predominant wind speed class is 20-28 Kmh^-1 followed by 12-19 Kmh^-1 and 29-38 Kmh^-1. High wind speed and neutral category weather prevailing in Kudankulam site support and aid good dilution of gaseous releases.

Figure 1: (a) Wind rose for winter. (b) Wind rose for summer

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Keywords: Triple joint frequency distribution

References

Thomas, et al. Computer Programme for Micro-Meteorological Data Analysis; 2003.
Patil SS, et al. Study on Meteorological Parameter during Pre-monsoon Period at Trombay for Environmental Impact Predictions (NSE-19).

Abstract - 63422: Development of Kalman filter based source term estimation method and its testing using observed dose rates

Dipan Kundu, Shanu Karmakar, C. V. Srinivas, S. Chandrasekaran, B. Venkatraman

Environmental Assessment Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Source term is an important input for dose projections using atmospheric dispersion models during accident condition. Back calculation using atmospheric models and environmental data is one of the widely used approaches of source term estimation. In this method, the dispersion models are run using inversion techniques. Among different inversion techniques Kalman Filter^[1] method is one of most popular and useful technique for source term estimation and dose rate prediction in the field of radiation facilities.^[2] Kalman Filter (KF) is basically a predictor-corrector recursive algorithm for instantaneous state estimation of linear dynamical system from a set of measurements, containing noise. In this study we implement Extended Kalman Filter (EKF) method with Gaussian Plume model (GPM) for short range dispersion from a nuclear facility and using ground-based dose rate observations. A Python based in-house EKF algorithm is developed to compute source term taking the case of routine release of Ar⁴¹ (E = 1.3 MeV) from Madras Atomic Power Station (MAPS), Kalpakkam, India. In case of routine release the system equation i.e., time evolution of release rate (X_t) and measurement equation (y_t) i.e. dose rate measurement are given by Equations 1 and 2.

Where, D (X_t) is GPM equation, w(t)is white noise with covariance Q in source term and v(t) is white noise with covariance R in measurement. These noises are mutually uncorrelated. EKF updated state (

) at time t is provided in Equation 3.

Where,

is the predicted source term before measurement and K_t is the Kalman Gain.

For the study three gamma monitors in the South-West (SW) sector of MAPS stack are selected during north-easterly wind flow during the period February, 2021 to estimate routine release rate from MAPS and predict dose rate at each detector locations. Atmospheric input data such as wind speed, wind direction, atmospheric stability are collected from an onsite 50 m high meteorological tower. Indigenously developed GM-tube based Autonomous Gamma Dose Logger (AGDL) provides time series of gamma dose rates at each detector locations. Due to large fluctuations in the wind flow, winds which lie within ±5^O of the study sector are taken into considerations. ∝R is assumed to be 20% of mean dose rate at each AGDL and Q is lowered from 10¹⁸ Bq².s^-2 upto the value 10¹⁵ Bq².s^-2, where there is in-significant change in updated source term in two successive time steps. The observed and model predicted dose rate for AGDL-4 and source term for 10 min sampling time are shown in [Figure 1] and [Figure 2] respectively. Note that the actual source term is derived from daily release value and so it is uniform. Statistical parameters like mean bias (MB), root mean square error (RMSE) and correlation coefficient (CC) for 155 no of observations from AGDL-2 and 4 are provided in [Table 1]. It is found that the EKF estimated time series of dose rates are found to follow observed trends (bias is very small) and CC is quite good ~0.6. Error in model predicted dose rate is significantly lower, RMSE ~ 0.04 μSv/h. Model predicted mean source term is 2.5 times higher compared to observations. Results suggest that KF technique provides reliable estimates of source term and predicts reasonable dose rates in case of routine Ar⁴¹ releases from MAPS. Accuracy can be improved by taking a greater number of dose rate observations.

Figure 1: Observed and model predicted dose rate

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Figure 2: Model predicted release rate along with actual release rate

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Table 1: Statistical parameters

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Keywords: Kalman Filter, inversion technique, dose rate prediction, source term estimation.

References

Kalman RE. J Basic Egypt 1960;82:35-45.
Drews M, et al. Radiat Prot Dosimetry 2004;111:257-69.

Abstract - 63423: Estimation of dose rate to biota for the protection of environment from use of ionising radiation

Vaibhav Jain, Ritu Raj, S. P. Lakshmanan, S. K. Dubey

Directorate of Radiation Protection and Environment, Atomic Energy Regulatory Board, Anushaktinagar, Mumbai, Maharashtra, India

E-mail: [email protected]

This paper deals with the estimation of dose rate to biota which mainly includes flora and fauna for addressing protection of environment applying recently evolved approach by ICRP.^[1] Trends indicate the need to demonstrate (rather than to assume) that the environment is being protected. The objective of the estimation is to obtain the margin from the applicable acceptance criteria in the form of derived consideration reference levels. The dose is estimated for 'reference animals and plants' similar to representative person for the protection of public. A typical prospective calculation have been carried out for large mammal (Deer) in terrestrial and fish in marine ecosystem for the annual authorised effluent releases as a source term from a Nuclear power station of twin unit. Gaussian Plume model is used for Atmospheric dispersion considering recent 5 year local meteorological data. External exposure due to radioactive material in the atmosphere, water, soil and sediments and Internal exposure from radioactive material absorbed by plants or ingested or inhaled by animals are considered. For fish it is assume that they remain in the water so the occupation factor in water will be 1 and for terrestrial animal it is assume as per their occupation in different medium. To estimate transfer of radionuclides to biota when measured activity concentrations are not available, the Concentration Ratio (CR) approach based on empirical data suggested by ICRP is used.^[2] It is the ratio of the activity concentration of radionuclide in whole-body of biota to the activity concentration of radionuclide in the ecosystem media. The product of activity concentration in the environmental media, external dose coefficient and time fraction spent by RAP (reference animals and plants) in particular medium or location (occupational factor) gives the absorbed dose rate for a given pathway. ICRP defines Dose Coefficients (DCs) as coefficient relating an absorbed dose rate in the whole body, or in a part of it, and radionuclide activity concentration in the body for internal exposure, or in the environment in the case of external exposures. The DCs for various RAPs are tabulated in ICRP 108^[1] and ICRP 136.^[2] The total adsorbed dose rate are calculated which is sum of external and internal and compared with Derived Consideration Reference Levels (DCRLs) for determining the impact on environment. For example the estimated dose to a large mammal using the technical specification release values for a typical twin unit station of PHWR is 0.278 μGy/d (0.278%) against a DCRL (Derived Consideration Reference Levels) value of 100-1000 μGy/d. Dose assessment was also done using versatile International Code ERICA (Environmental Risk from Ionising Contaminants: Assessment and Management) for Tier 2 assumption^[3] for the same release value which led to value of 0.554 μGy/d. It is important to note that release rate is only 5% of technical specification values which would result in dose estimation of 0.0139 μGy/d. Therefore, it is concluded that a huge margin w.r.t Derived Consideration Reference Levels is available for the dose to flora and fauna.

Keywords: Dose coefficients, dose rate, environment, reference animals and plants

References

ICRP. Environmental Protection – The Concept and Use of Reference Animals and Plants. ICRP Publication 108. ICRP; 2008.
ICRP. Dose Coefficients for Nonhuman Biota Environmentally Exposed to Radiation. ICRP Publication 136. ICRP; 2017.
Brown J, Alfonso B, Avila R, Beresford NA, Copplestone D, Prohl G, et al. The ERICA tool. J Environ Radioact 2008;99:1371-83.

Abstract - 63424: Sea breeze hours at Kudankulam Coastal site and its impact on annual dose

P. Jayasudha, Thomas George, B. Preetha, B.Vijayakumar, I. V. Saradhi¹

Environmental Survey Laboratory, Kudankulam Nuclear Power Project, Kudankulam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

The Sea breeze is important weather phenomena along coastlines. It is thermally driven circulation that result from the differences in heat capacities of water and land. Due to vertical pressure gradient, Thermal Internal Boundary Layer (TIBL) develops near the coast.^[1]During this period, the initial dispersion of elevated releases from stack near coastline, is governed by stable sea-land airflow and get fumigated to the ground when it intersects the growing TIBL at any downwind distance. Kudankulam site (Latitude 8^o 9' 52” N and Longitude 77^o 42' 41” E) is located along the coast of Gulf of Mannar, it has two units of 1000 MWe each of pressurized water reactor type (VVER) under operation and four units under construction. A well-equipped micro meteorological laboratory (MM Lab) is located at 0.7 Km, WNW from the site. 2015-2019 (5 years) hourly average meteorological data is collected and analysed for this study. The onset of Sea breeze is assessed 07:00 hours onwards, based on wind direction from 58° to 248° (sea directions), decrease in temperature, increase in relative humidity and increase in wind speed. Sea breeze hours are calculated until 17:00 hours without shift in wind direction (from 58° to 248°). After 17:00 hours at tropical location, progress of thermal boundary layer (TIBL) is not possible due to occurrences of neutral and stable stability categories in land area. In prevailing sea breeze conditions, the development of TIBL affects the concentration distribution of releases from elevated stack releases near coastline due to sea breeze fumigation (SBF). Annual SB hours (SBH) are found to range from 8.5 to 10.5 %. Maximum sea breeze hours, 9.7 to 10.4 % (60- 70 hours/month) are observed in March to May Summer. Except the month of August, SBH are found to range from 3.5 to 6.0 % (30-40 hours/month). Fig 1 illustrates monthly variation of sea breeze hours (%). During the period of study (2015-19), the total yearly sea breeze hours varied from 750 to 850 hours out of 8760 hours. In 2015, there were only 750 sea breeze hours due to heavy rainfall (1179 mm) and more rainy days (92 days) compared to other years of study. It is evident that sea breeze hours are inversely related to rainfall and or rainy days. [Table 1] shows seasonal variation of sea breeze hours (%) in relation to rainy days and sea breeze days. At Kudankulam site, rainfall is only moderate and maximum rain fall is recorded in North East Monsoon (Oct-Dec) and minimum during other months. The synoptic geostrophic wind flow patterns on the east coast of India like South West monsoon, North East monsoon and the westerly winds prevailing during summer have profound influence on the SB development at Kudankulam site.^[2] Annual sea breeze hours during 2015-19 at Kudankulam site are observed to be 9.8 % which will not substantially impact the annual public dose or concentration estimation of released effluents. For regulatory purposes, Gaussian Plume Model is being used which is more conservative in long term annual dose estimation. Further, a fumigation factor of 1.1 is also used for public dose estimation for all sea sectors as recommended by ECPDA for conservative purposes.^[3]

Figure 1: Monthly variation of sea breeze hours (%)

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Table 1: Seasonal variation of annual SB hours % and relation with rainy and SB days

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Keywords: Sea breeze fumigation

References

Jesan T, Anand C, Manonmani PM, Ravi R. Tripathi M. Identification of Sea Breeze at Kalpakkam Site, (NSE-20) DEC-2018 Gandhinagar, Gujarat; 2018.
Srinivas CV, Venkatesan R, Somayaji KM, Bagavath Singh A. Numerical study of sea breeze circulation observed at a tropical site Kalpakkam on the east coast of India under different synoptic flow situations. J Earth Syst Sci 2006;557-74.
Expert Committee for Public Dose Assessment and Dose Apportionment (ECPDA), Report on Methodology for Computation of Public Dose and Dose Apportionment for DAE Facilities, December, 2023.

Abstract - 63426: Statistical analysis of seven years (2013-2019) diffusion climatology of Kudankulam Coastal site

Thomas George, P. Jayasudha, Preetha, B. Vijayakumar, I. V. Saradhi¹

Environmental Survey Laboratory, Kudankulam Nuclear Power Project, Kudankulam, ²Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Measurements of meteorological parameters are essential for estimating the dispersion and distribution of atmospheric effluents released from nuclear power plant. Information on the site diffusion climatology is essential for estimating concentration distribution of gaseous effluents released from nuclear facilities on long term annual basis. This report presents the annual diffusion climatology of the site for the period of seven years from 2013-2019 on individual year-wise as well as seven yearly averaged annual basis. KKNPP site has a well equipped Micro meteorological laboratory (MMLab) located at 0.7 km, WNW from the site. A 30 m self supporting lattice tower is established and meteorological measurements are made at two levels 10 and 30 m. MetDAS, an online data acquisition and analysis software which can perform a variety of data analysis like TJFD, JFD, daily & hourly averages, statistical analysis, wind rose plotting, wind profiling, dose calculation, isodose curve plotting is used for data analysis. Diffusion climatology data prepared based on TJFD gives distribution of cumulative harmonic wind speed in the form of

corresponding to a particular direction for each stability class, where Ui is average wind speed in km/h for i^th hour. 'N' is the total number of observations for the particular wind direction and stability class. 'χ₀' is the stability dependent normalized sector averaged ground level air concentration of a radionuclide in Bq/m³ for unit release rate in Bq/s. This parameter is termed as cumulative harmonic wind speed and is used in computing long-terms concentrations of radio nuclides and the corresponding dose from atmospheric release. The procedure for computation of concentration and dose is given in the manual Hukkoo et al.^[2] This data can be used for predicting cumulative annual concentration / dose-estimates in any direction for a year. [Table 1] shows the variation in individual year χ/Q and sector weighted standard deviation during the study period for various downwind distances. Year-wise variation in the sector weighted average annual dilution factor '(χ/Q)' in a particular direction using respective year's diffusion climatology are varying 27.3 %, 18.2 %, 17.5 %, 17.0 % and 11.8 % for radial distances of 1.6 Km, 2 km, 5 km, 10 km and 15 km respectively of the seven yearly mean value. This suggests that the use of any representative year's diffusion climatology will not lead to an uncertainty of more than 27.3 % in the long term estimation of concentration/dose estimates.

Table 1: Variation in individual year χ/Q value and sector weighted standard deviation during the period (2013-2019)

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Keywords: Diffusion climatology

References

Indumati S, Sunny F, Panchal S, Oza RB, Pawar UR, Daoo VJ. Statistical Analysis of Five yearly (1997- 2001) Diffusion Climatology of Trombay, BARC/2002/E/035.
Hukkoo RK, Bapat VN, Shirvaikar. Mannual Dose Estimation from Atmospheric Releases, BARC-1412; 1988.
Pasquill F. Atmospheric Diffusion. Wiley; 1974. p. 492.

Abstract - 63461: A simple approach to estimate tsunami height at the eastern coast of India

Soubhadra Sen, C. V. Srinivas, S. Chandrasekaran, B. Venkatraman

Safety, Quality and Resource Management Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Tsunamis are long wavelength sea waves which get amplified when they approach a coast. For safety analysis, an estimation of coastal tsunami height is important and so a number of sophisticated codes (Tunami, Geowave, Delft3D etc.) have been developed. These codes use fault parameters and the bathymetry of a region for the simulation of a tsunami. While estimations with coarse meshes provide sufficient accuracy for deep sea areas, shallow water regions require fine grids. This increases the computational cost and so scaling laws become useful. For this purpose, Green's Law^[1] is a popular choice. In this present work, a new scaling method is proposed and tested for the eastern coast of India. The new method relates a coastal tsunami height (H) with the nearby deep sea wave height (h) using the angular deviation (α) of the beach from the principle direction of tsunami propagation.

In this equation, K is an empirical amplification factor which is a function of the properties of a beach (slope, geology etc.). Several trails and errors to fit waves of past events have resulted in Eq. (1). [Figure 1] pictorially shows important aspects of the proposed method considering the tsunami of 2004. The points A, B, C represent one of the epicenters, a point on the main direction of tsunami propagation and an observational beach in respective order. A numerical code (Delft3D) with coarse meshes (0.1 degree) is used to estimate the near shore deep sea wave height h (at a place near a beach where the water depth is approximately 100m). The subsequent estimation of coastal tsunami height is performed by using Eq. (1).

The applicability of the proposed approach is tested considering two historical events (26^th December, 2004 and 31^st December, 1881). To use Eq. (1), the determination the constant K is needed and so the event of 2004 is numerically simulated and the observed coastal tsunami heights (H) are used for the estimation of K [Table 1]. Then Eq. (1) is applied to calculate the coastal tsunami heights of 1881 event [Table 2]. As the value of K can change with the size of the meshes, the same extent of domain (77.0E to 98.5E and 1.0S to 21.4N) and same uniform grids (0.1 degree) are used in all the calculations. From the tables, it is clear that the proposed method provides reasonably good estimate of coastal tsunami height of this region. For calculations, the fault parameters of the tsunamis considered here are adopted from the paper of Selvan and Kankara.^[2]

Loc. = Location, H-est. = Estimated coastal tsunami height, H-obs. = Observed coastal tsunami height, Che. = Chennai, Nag. = Nagapattinam

It is needed to mention that the observed coastal tsunami height of a place indicates the average value of elevated water levels at that place ignoring the finer variations within that region. Finally, it can be stated that as the results are reasonably accurate, the new approach can be used in future calculations.

Figure 1: Tsunami waves of 2004 (after 135 minutes)

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Table 1: Estimation of ‘K’ (from 2004 tsunami)

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Table 2: Coastal tsunami height of 1881 event

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Keywords: Bathymetry, tsunami, tsunami height

References

Lamb H. Hydrodynamics. 6^th ed. New York: Dover; 1932.
Selvan SC, Kankara RS. IJOCS 2016;7:62-9.

Abstract - 63485: A study on aerodynamic roughness lengths at Kalpakkam tropical coastal station, India using micrometeorological observations

P. N. Sujatha, S. Chandrasekaran, C. V. Srinivas

Environment Assessment Section, Environmental Assessment Division, SQRMG, IGCAR, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

The wind speeds near the earth surface vary according to surface roughness, which varies due to the presence of vegetation, topographic objects and surface structures. Numerical model simulations are known to be very sensitive to land-surface parameters such as surface roughness length etc. The zero-plane displacement 'd' and aerodynamic roughness length 'z_o'are parameters of the logarithmic wind profile, and characteristic of the surface that are required in a multitude of meteorological modelling applications. In the present study, aerodynamic roughness lengths are estimated from wind speed measurements under neutral atmospheric conditions for Kalpakkam site. The study is conducted using 31 days of sonic anemometer data in each season covering winter, summer, southwest and northeast monsoon. In addition, the diurnal variation of various turbulence parameters such as friction velocity, sensible heat fluxes, drag coefficient (C_D) are studied. Following the similarity theory, the mean wind in the surface layer can be approximated as (Ramachandran et al., 1994).^[1]

L is the Monin Obukov length defined as

Under neutral stability conditions, z/L = 0 z / L = 0 {\displaystyle z/L=0} , the equation is simplified to

Linear regression of this equation gives a straight line with slope from which z_o is estimated. The value of 'd' depends on the average vegetation height. Kalpakkam is a coastal site with plain terrain and the vegetation comprises mainly grass, dry and irrigated crop lands. Hence 'd' is taken as 0.05 m). The horizontal wind speed and u_* are estimated from ultrasonic anemometer measurements. The sensible heat flux (SHF) and Aerodynamic Drag coefficient (C_D) is measured from eddy correlation method^[2] as

Where C_P is the specific heat at constant pressure.

Where Ū is the mean wind speed given as

The study was carried out only for the near neutral stable conditions of atmosphere (−0.01 < z/L < 0.01). The Sonic Anemometer measures the fluctuating wind components along the three orthogonal co-ordinate directions N–S(u), E–W(v) and the vertical (w) based on the transit time of ultrasonic acoustic signals. This instrument is mounted at elevation of 10 m on a 50 m height meteorological tower located at Edaiyur site within Kalpakkam DAE complex and its data is archived at a 10 Hz sampling rate. The straight line fit of u versus u_x/k gives the slope which is used to estimate the aerodynamic lengths as given in [Table 1]. The sensible heat flux was maximum in the noon hours and of the order of 466 W/m² in summer, 200 W/m² in monsoon and about 350 W/m² in winter. The magnitude of C_D was greater in slightly moderate unstable to near neutral conditions. Surface roughness parameters are estimated from wind speed measurements under neutral atmospheric conditions for Kalpakkam site using micrometeorological observations. The value of roughness parameter is found to be 0.22, 0.33, and 0.35 and 0.38 m for winter, summer, SW monsoon and NE monsoon season respectively. In addition, the diurnal variation of various turbulence parameters such as friction velocity, sensible heat flux and C_D are studied.

Table 1: Estimated surface roughness length values for different seasons

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Keywords: Roughness lengths, sonic anemometer data, turbulence parameters, zero-plane displacement

References

Ramachandran R, et al. Variability of surface roughness and turbulence intensities at a coastal site in India. Boundary Layer Meteorol 1994;70:385-400.
Stull RB. An Introduction to Boundary Layer Meteorology. Netherlands: Atmospheric Science Library Kluwer Academic Publisher; 1993.
Arya SP. Introduction to Micrometeorology. 2^nd ed. Academic Press; 2001. p. 420.

Abstract - 63494: Spatial Ingestion dose estimation based on remote sensing derived land use/ land cover data for emergency response

C. V. Srinivas, P. T. Rakesh, Shanu Karmakar, S. Chandrasekaran, B. Venkatraman

Environmental Assessment Division, SQRMG, IGCAR, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Radiation dose projections involving atmospheric dispersion and deposition calculations are highly needed for initiating protective actions in the event of accidental releases from nuclear power plants. Ingestion of contaminated food is one of the major pathways of radiation exposure during nuclear emergencies. Estimation of ingestion dose is complex due to uncertainties in the information on food supplies in the emergency domain. Information on the crop lands, pasture lands etc. is needed to obtain reliable estimates of ingestion dose during a nuclear emergency. Here, a method based on Remote sensing derived Land Use/ Land Cover (LULC) data is proposed for spatial ingestion dose estimation.

Materials and Methods: The method involves modelling of dispersion and deposition calculation, subsequent transfer to the environment and humans following Slaper et al.^[1] This involves the processes of transfer to vegetation / crops by direct interception of radioactive cloud and uptake from the soil, transfer to human beings by consumption of contaminated crops and indirectly through consumption of milk and meat from animals which consumed the contaminated grass (grass, cow, milk/meat pathway). The time integrated deposition is computed using FLEXPART dispersion model for a given source term using WRF atmospheric model predicted meteorological parameters for a release period of upto 3-days. The soil concentration in the plough layer (Cs), and plant concentration (Cp) are computed following IAEA^[2] considering they are directly proportional to the deposition and considering the water balance, plough layer thickness, soil density and soil affinity for radionculdies. Four major food types (vegetables, cereals, milk and meat) are considered. To define the areas of croplands and food crops etc. the LULC derived from the MODIS remote sensing data is used. It is considered that people consume the locally produced food substances in the dose calculation program. The overall human ingestion of radionuclides is computed as

where Ai is the total intake of radionuclide under consideration (Bq), Ip is the human intake of food product p(kg day-1), Fb,p is the reduction factor for removal of radionuclides by preparation process, td is the time in days between harvesting/ milking/ slaughtering and consumption. λ is a decay constant of radionuclide (day^-1). The total ingestion dose is computed is computed as

where Ding is the total ingestion dose (Sv) for radionuclide I, DCing is the dose conversion factor for ingestion (Sv/Bq) for the radionuclide i, and Ai is the total intake of radionuclide.

Results and Discussion: Calculated ingestion dose by simulations for a postulated accident case at Kalpakkam site for 17–20 February 2020 assuming a source term (FPNG 3.11E+17 Bq; Particulates/Volatiles 3.37E+16 Bq) is presented in [Figure 1]. The ingestion dose followed the deposition pattern. Computed ingestion dose is found to be nearly 40% of the total exposure for the assumed source term. The ingestion dose module is incorporated in the Online Decision Support System (ONERS) operational at Kalpakkam for dose projections. It is proposed to utilize the IRS-P6 (Resourcesat-1) derived high resolution land cover data to better represent the cropping pattern in Indian scenario for the ingestion dose calculation.

Figure 1: Simulated ingestion dose (mSv) for the postulated release

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Keywords: Ingestion dose, land use/land cover, Remote Sensing

References

Slaper H, Blaauboer RO, Egginkm GJ. A Risk Assessment Method for Accidental Releases from Nuclear Power Plants in Europe. RVIM Report No. 743030002. 3720 BA, Bilthoven (NL); 1994. p. 85.
IAEA. Generic Models and Parameters for Assessing the Environmental Transfer of Radionuclides from Routine Releases Exposures of Critical Groups. Safety Series No. 57. Vienna: International Atomic Energy Agency; 1982.

Abstract - 63495: Sensitivity analysis of air mass trajectories to vertical transport methods

Indumathi S. Iyer, R. Shrivastava, R. B. Oza

Environmental Modeling Section, RSSD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Trajectory models track the air parcels in the atmosphere and are used in several fields of atmospheric science. However, the errors resulting from interpolation of wind, spatial and temporal resolution of the model, starting position, truncation errors, and assumptions in the vertical wind estimation lead to uncertainty in the trajectory assessment. The present study is focused on the impact of different methods of vertical motion estimation on the trajectory accuracy in HYSPLIT model. HYSPLIT model computes backward and forward trajectories using an advection algorithm by integrating the initial position of an air parcel in time.^[1] HYSPLIT utilizes meteorological data from Numerical Weather Prediction models like WRF/TAPM to predict the trajectory paths. By default, it uses vertical velocity from the numerical model inputs to estimate the vertical motion. In the absence of such data, HYSPLIT provides different options to estimate vertical velocity from other meteorological parameters. The various options available in HYSPLIT to estimate vertical velocity are; from meteorological model (Reference case), isobaric (Case1), isentropic (Case2), constant density (Case3), isosigma (Case4), integral of divergence of horizontal wind (Case5). The cases mentioned in the brackets correspond to the test cases for which results are presented here considering vertical velocity from meteorological model as Reference Case. The study domain is centred at BARC Trombay site. In the present study, trajectories were simulated for 72 hours, from 4^th-6^th Mar 2021, using hourly meteorological inputs from WRF model and the different vertical motion options. Additionally, to determine the sensitivity of trajectories to spatial resolution, the simulations were also carried out for different grid sizes viz., 1km and 3km. The results from the various simulations are compared using the standard measures of trajectory dispersion such as the Absolute Horizontal Transport Deviation (AHTD), Absolute Vertical Transport Deviation (AVTD).^[2] Here, the trajectory obtained using vertical velocity supplied by WRF model is assumed to be the true/reference trajectory with which the deviations are computed. [Figure 1] gives the maximum transport deviation estimated for the two spatial resolutions using various vertical motion methods. It is seen that the inherent uncertainties in the vertical transport method leads to large deviations in the trajectory motion, both in the horizontal (ranging from 85–110 km) as well as vertical directions (ranging from 1.6-4.0km). The vertical transport deviations are higher for the finer grid size (1 km). This may be attributed to the enhanced resolution of the terrain heights in 1 km grid size than in 3 km grid size. [Figure 2] shows the terrain, derived from WRF model, used in HYSPLIT model for the different grid sizes. From [Figure 1], it may be concluded that for the present scenario, the isoentropic option can be used in the absence of vertical velocity data from the NWP.

Figure 1: Trajectory statistics AHTD (km), AVTD (km) for the various cases w.r.t. the reference trajectory for 1 km and 3km spatial resolution

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Figure 2: Terrain as derived from WRF model used by HYSPLIT for 1 km and 3km spatial resolution

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Keywords: Air mass, HYSPLIT, trajectory

References

Roland D, Hess G. NOAA Technical Memorandum ERL ARL-224; 1997.
Harris JM, Draxler RR, Oltmans SJ. J Geophys Res 2005;110.

Abstract - 63496: Spectral analysis of meteorological parameters at Trombay

Indumathi S. Iyer, R. Shrivastava, R. B. Oza

Environmental Modeling Section, RSSD, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Wavelet transform is one of the latest tools for trend detection studies. It decomposes time series into time–frequency space to determine their characteristics such as trends, periodicity, discontinuities and change points.^[1] In the present study, Wavelet transform method is used to analyze the spectral characteristics of air temperature and rainfall data collected at Trombay site for the period 1996-2012. Wavelet coherence analysis between the parameters is also carried out to evaluate cross-correlation between the time series.^[2] R package and its libraries are used in the analysis. The Continuous Wavelet Transform (CWT) employs Morlet wavelet (Eq.1) as “mother” wavelet to decompose the series data.

The Morlet wavelet transform of the time series x_t is then defined as the convolution of the series with a set of “wavelet daughters” generated by the mother wavelet by translation in time by τ and scaling by s, given in Eq. (2).

Here ψ* denotes the complex conjugate. The power spectra of monthly average-maximum-minimum air temperature and monthly rainfall are shown in [Figure 1]. The inverted-U shaped line in the spectrum represents the cone of influence (COI) which defines the significant region that should be considered in the analyses. It is seen from the figure that the monthly average, maximum temperature and rainfall spectra show a weak bi-annual and strong annual cycle. Monthly minimum temperature has a strong annual cycle as expected. The coherence analyses between the temperature and rainfall series are shown in [Figure 2]. The arrows in the plot represent the lead/lag phase relations between the two series. Coherence plots show that rainfall leads monthly average temperature series by ~2 months whereas; monthly maximum temperature leads monthly rainfall by ~3 months. There is no lead or lag between monthly minimum temperature and monthly rainfall. Thus, spectral analysis using Wavelet Transform of long-term climatological series helps to identify the large-scale and small-scale spectral components and to link the periodicities of various time series with each other. They can be further used to find missing data or reconstruct data for forecasting.

Figure 1: Wavelet spectra of monthly average, monthly maximum, monthly minimum temperature and monthly rainfall

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Figure 2: Coherence spectra between (a) monthly average temperature and rainfall (b) monthly maximum temperature and rainfall (c) monthly minimum temperature and rainfall

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Keywords: Coherence, R package, trend detection, Wavelet transform

References

Simon B, Rezaul C. Int J Climatol 2009;30:458-73.
Abolfazl N, Khalil K, Siavash G. Atmos Res 2022;274:106187.

Abstract - 63502: Environmental radiological surveillance and impact assessment around Trombay

Sanu S. Raj, Sugandhi Suresh, Sangeeta Sartandel, Vandana Pulhani, A. Vinod Kumar

Environmental Radioactivity Measurement Section, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Anthropogenic radionuclides in environment are mainly contributed due to nuclear weapon testing, nuclear accidents and normal operation of nuclear facilities, etc. Their release can have potential health effects on general population, especially if they have long half-lives, and high mobility in the environment. Hence, an environmental surveillance in the public domain in a planned regular manner is essential to assess the impact of releases from nuclear facilities. This will help to demonstrate the radiological safety of members of public (MOP) and the environment beyond doubt. This paper provides the compilation of the environmental surveillance and measurements carried out at off-site locations of BARC, Trombay during 2011-2020 to evaluate the individual radionuclide content in the environmental samples and assess the annual effective dose imparted to the public. Off-site environmental surveillance of BARC, Trombay with 21 monitoring locations covers an area within 1.6-30 km radial distance with respect to CIRUS-Dhruva research reactor complex. A total number of about 300 samples per year from atmospheric (air moisture), marine (sea water, sediment, shore sand, solar salt, biota) and terrestrial (fresh water, soil and vegetation) environment are collected and parameters such as external radiation levels, tritium in air moisture, and activity concentration of gross alpha, gross beta,⁹⁰Sr, ¹³⁷Cs were measured.^[1] Quality Assurance is ascertained by participation in the international inter comparison exercises conducted by IAEA such as IAEA-TEL and IAEA-RML Proficiency Tests and also in inter-laboratory exercise annually. Quality Control is maintained by analyzing Standard Reference Materials. The activity concentrations in all the matrices studied in the 1.6 to 30 Km radial distances did not vary significantly and were close to the fallout levels during the last decade. The cumulative annual effective dose to public was computed from ingestion of ⁹⁰Sr and ¹³⁷Cs (biota, salt) and ³H (potable water), inhalation of tritium and external exposure from sediment [Figure 1]. The activity concentration and the annual intake rates,^[2] used as input parameters for estimation of annual dose imparted to the members of public are given in [Table 1]. The dose conversion factors as recommended by ICRP (ICRP119, 2013). The average cumulative dose over the decade 0.43±0.1 μSv y^-1 is significantly lower than the limit of 1000 μSv y^-1 prescribed by the regulatory agency and a very small fraction compared to the ingestion doses received due to naturally occurring radionuclides in the environment.

It is observed that the levels of radioactivity have remained almost in the same range as observed during earlier years. The regular environmental surveillance of the Trombay facility demonstrates the environment friendly operations, good regulatory control and assurance of safe practices.

Figure 1: Annual effective dose to members of public

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Table 1: Activity concentration for ⁹⁰Sr, ¹³⁷Cs and ³H

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Keywords: Anthropogenic, environmental surveillance, public dose

References

Hegde AG, Verma PC, et al. BARC/2009/E/004; 2009.
Dey NN, et al. BARC/1991/I/013; 1991.
ICRP publication 119; 2013.

Abstract - 63518: A comparative study of different methodology used for estimation of atmospheric stability classes at Rawatbhata Rajasthan Site environment

Rajpal Gill, M. C. Meena, M. K. Meena, S. N. Tiwari, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan^{, 1}Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Atmospheric stability plays an important role during estimation of dispersion of airborne pollutant in ambient atmosphere. Atmospheric stability defines intensity of turbulence and vertical acceleration of pollutants in atmosphere. For estimation of pollutant concentration by various dispersion model's atmospheric stability is an important input parameter. Micrometeorological parameters i.e. wind speed, cloud cover, solar and net radiation, wind directions fluctuations, temperature gradient etc are used to determine atmospheric stability. In this study different stability classification methods were compared with the Pasquill and Gifford stability categories. Pasquill and Gifford^[1] characterize six atmospheric stabilities designated as A (highly unstable), B(moderately unstable), C(slightly unstable),D(neutral),E (slightly stable),F(moderately stable). The micro-met setup at ESL RAPS continuously measures wind speed, wind direction, air temperature, solar radiation, net radiation and records data at every one min interval. Wind speed and wind direction are measured at 10 m, 30 m and 100 m height and air temperature at 1.2 m and 100 m height of 120 meter tall meteorological tower. Solar radiation, net radiation and cloud cover were used for atmospheric stability calculations. Recorded meteorological data from August 2017 to June 2020 is used for this study. Various methods used for estimation of atmospheric stability are Temperature gradient method (△T/△Z), Wind direction fluctuation method (σ_θ), Bulk Richardson Number R_iB,and Richardson Number R_i.Atmospheric stability is estimated by different methods as Temperature gradient method, Wind direction fluctuation method, Richardson and Bulk Richardson Number at RR Site and compared with modified Pasquill and Gifford method,^[2] which is most widely, used and accepted method for stability estimation worldwide. The comparison of occurrence of atmospheric stability computed by other methods with respect to modified Pasquill and Gifford method are shown in [Table 1]. It is observed that different methods showed wide variation with respect to Pasquill and Gifford classification and single method is not sufficient for stability estimation in the entire range (A to F).

It is observed from above table that stability class A, all methods are in good agreement except R_iB. For stability class B, the best agreement is observed with R_imethod followed by σ_θ whereas △T/△Z showed poor agreement. For stability class C, R_iBshows good agreement with Pasquill and Gifford. For stability class D, the best agreement is with σθ and △T/△Z. For stability classes E &F, the best agreement are observed with R_i, R_iB and △T/△Z, whereas σ_θ shows poor agreement. Richardson method shows best correlation with Pasquill Gifford method compared to other methods. Correlation coefficient (R) and Normalized mean square error (NMSE) were 0.95 and 0.10, respectively for Richardson method with Pasquill method which ratifies the agreement of this method with Pasquill Gifford methodology for stability class estimation. It is observed from above study that no single method is a satisfactory indicator over the entire range of stability classes (A to F). Comparative study between these parameters and stability classes showed fluctuations with large deviation. Richardson number and △T/△Z methods showed good agreement in comparison to other methods. These methods can be used during non-availability of solar radiation and net radiation measurement system. Delta T can be measured with ease and stabilities can be generated online and hence is found to be a suitable method along with PG method.

Table 1: Percentage occurence of stability classes by different methods

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Keywords: Pasquill and Gifford, solar radiation, stability, wind speed

References

Pasquill F. The estimation of the dispersion of windborne material. Meteorol Mag 1961;90:1063.
Mohan M, Siddiqui TA. Analysis of various schemes for the estimation of atmospheric stability classification. Atmos Environ 1998;32:3775-81.

Abstract - 63519: Correlation of SODAR system and meteorological tower measurements at Rawatbhata Rajasthan Site

M. C. Meena, Rajpal Gill, M. K. Meena, S. N. Tiwari, I. V. Saradhi¹, A Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Meteorological parameters like wind speed and wind direction are used in estimation of dispersion of airborne pollutant in ambient atmosphere during normal and emergency condition at nuclear sites. With the increased interest in remote sensing of wind information in recent years, it is important to determine the reliability and accuracy of new wind measurement technologies if they are to be replaced or supplement the conventional tower-based measurements. In this study Sonic Detection and Ranging (SODAR) system (Model VT-1) measured wind speed and direction data are compared with the similar data collected by a nearby meteorological (met) tower at RR Site. Hourly averaged wind speed and wind direction data at 30m and 100m height from met tower and SODAR system were used for one complete year. SODAR System is installed at distance of 1.2 km from the met tower and is having 60 feet difference in elevation. Measurements from the met tower were correlated with the SODAR system data at two measurement heights. SODAR data was filtered to remove low-quality, rain duration measurement and spurious data, similarly met tower data was also filtered to remove wind speed data less than 0.5 m/s. After configuring and filtering the wind speed and wind direction data, the correlation coefficients of SODAR and met tower are shows in [Figure 1] and [Figure 2] and wind rose plots of 30m and 100m heights were compared in [Figure 3] and [Figure 4], respectively. Correlation coefficient of wind speed is found to less than 0.90 likely due to distance and elevation difference between two systems. Average wind speeds and ratio were also calculated [Table 1] for the two measurement heights to further examine the data from SODAR and met tower. Wind speed from the SODAR is lower than tower-based measurements likely due to difference between vector and scalar averaging of wind data in SODAR and tower based measurements. [Figure 1] and [Figure 2] shows graphical representation of wind speed and wind direction data of SODAR and met tower measurement at 30m and 100m heights along with correlation coefficients, respectively. In this study SODAR and met tower measurements were examined and nearly similar trend were observed in regard to the comparison of wind speed and direction. Good agreement was found in comparison of wind direction with a correlation coefficient above 0.92.

Figure 1: SODAR vs met tower wind Speed at 30m and 100m

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Figure 2: SODAR vs met tower wind direction at 30m and 100m

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Figure 3: SODAR and met tower wind Rose at 30m height

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Figure 4: SODAR and met tower wind Rose at 100 m height

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Table 2: Average wind speeds and ratio

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Keywords: Correlation, SODAR system, wind direction, wind speed

References

Liz W. Guidelines for Triton Data Analysis and Comparison to Nearby Met Tower Measurements, Rev. 3.1. Second Wind; 2010.
Second Wind. Guidelines for Siting a Triton by Met Towers, Trees and in Complex Terrain. User Manual; 2009.

Abstract - 63538: Statistical analysis of extreme value of meteorological parameters observed during 1978–2021 at Rawatbhata Rajasthan Site

M. K. Meena, Rajpal Gill, M. C. Meena, S. N. Tiwari, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, EMAD, BARC, Rawatbhata, Rajasthan, ¹Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Knowledge of extreme weather condition is essential to design engineering or civil structures to withstand these extreme weather conditions. Meteorological parameters play an important role in designing of such structures. This paper presents a study on extreme value analysis of meteorological parameters such as temperature, Pressure, rainfall, wind speed and atmospheric pressure measured at Rawatbhata Rajasthan site for the year 1978 to 2021. Wind speed data collected by anemometer at 30m height and extreme value analysis of wind speed for 5min (gust) and hourly average values, temperature and atmospheric pressure were measured by RTD, hygrograph and barograph, respectively and hourly average values are used for extreme value analysis. Ranges of measured meteorological parameters at Rawatbhata site for 1978 –2021 are given in [Table 1]. The data was examined for linear and logarithmic fit between the data variables and reduced variants as a function of probability of non-exceedance. Correlation coefficients between Y vs Xp and ln(Y) vs Xp for all variables were found out in order to choose best fit equation for straight line in plot of Y vs Xp , which can be written as

Y = α + β₁ × Xp (1)

where Xp is reduced variant corresponding to P(x), defined as

Xp = −ln(−ln[p(x)]) (2)

Similarly, the equation for straight line of graph ln(Y) and Xp is

Equation (1) and (3) transformed into two widely used extreme value distribution function as.

Fisher –Tippette Type I:

Fisher –Tippette Type II:

In Eq. (4) and (5), α and β₁ can be identified as location and scale parameters of the type –I distribution function and β₂ and ϒ as the scale and shape parameters of the type – II distribution function respectively. Distribution parameters of extreme values of measured parameters were calculated. For parameters obeying Fisher Tippette Type-I and Fisher Tippette Type-II, it was found that the correlation coefficients between Y Vs Xp and Ln(Y) Vs Xp ranged from 0.953 to 0.993 and 0.954 to 0.994 respectively. Based on the degree of correlation between Xp and Y (or ln Y), it is observed that the meteorological variables of maximum temperature, Gust wind speed, Pressure, annual and monthly rainfall obey Fisher–Tippet Type-I distribution function and other parameters obey Fisher-Tippet Type-II distribution function. Extreme value distribution function parameters had been established for all the meteorological parameters measured at Rawatbhata site for the Mean Recurrence interval (MRI) of 50, 100 and 1000 years in [Table 2].

Table 1: Ranges of measured meteorological parameters from 1978 to 2021

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Table 2: Estimates of extreme meteorological parameters for mean recurrence interval for 50, 100, and 1000 years

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Keywords: Extreme value, Fisher Tippette method, mean recurrence interval

Reference

Regulatory Body (AERB): Safety Codes Document. AERB Safety Guide of “Extreme Values of Meteorological Parameters” AERB Safety Guide No. AERB/NF/SG/S-3. Mumbai: Government of India; 2008.

Abstract - 63544: Site specific power law exponent value (p) using power law wind speed extrapolation at Kalpakkam Site

S. Ramkumar, T. Jesan, C. Manonmani, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Environmental Monitoring and Assessment Division, Kalpakkam, Tamil Nadu, 1Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Extrapolations of input wind speed to the stack height are practiced in dispersion model used for regulatory applications. In this regard, Site specific Power law exponent p value plays an important role. This study aims to generate Site specific Power law exponent value (p) for wind speed extrapolation. Observed meteorological parameter wind speed at Kalpakkam coastal site for seven years period from 2014 to 2020 has been used in this study. The extrapolation of wind speed from one height to other using different methods is compared with the observed wind speed value for year 2021. A 50 m tower mounted with wind sensors at various elevations at 10, 30 and 50 m levels for measurement of wind speed and wind direction is available at Kalpakkam.

Sutton Method of Extrapolation: Expression is used in many engineering applications as a scaling law to obtain wind speed at desired height for a given wind speed at measurement height.

^pWhere U (Z) is mean wind speed at height Z above ground level and U (Z₁) is wind speed at some reference height Z₁ typically 10 m.^[2] p is the power law exponent. Exponent p depends on atmospheric stability. Sutton recommended 0.111, 0.143 and 0.333 values for p under Unstable, Neutral and Stable condition.

Irwin Method of Extrapolation: Irwin, wind profile power-law exponents are a function of stability, surface roughness and the height range over which they are determined.^[1] Site-specific values of power-law exponent may be determined with two levels of wind data by solving equation for p:

Substitute the value of p from equation (1) to equation (2)

Surface roughness may vary as a function of wind azimuth and season of the year. In Kalpakkam site surface roughness length (Z₀) is estimated to be ranging from 0.26m -0.84m.^[3] Average p value for each stability class for a period 2014-2020 is obtained by using the equation for 3 different height combinations and all three heights together for wind speed and compared with Sutton method for Kalpakkam site. [Table 1] gives the average p value of stability class A to F. It is found that p value calculated by Irwin method using 50,30m height wind speed compares well with Sutton method as compared to others combinations for Kalpakkam site. Calculated average p value of stability class A to F was used to determine the wind speed at 50m height and compared with actual month wise measured average wind speed using wind sensor at 50 m height for the year 2021 and graph was plotted. [Figure 1] shows actual month wise measured average wind speed using wind sensor and extrapolated average wind speed at 50m height using power law calculated p value. Extrapolated wind speed compared well with actual measured wind speed using wind sensor at Kalpakkam site. This study shows site specific Power law exponent value (p) using power law of extrapolating wind profile closely approximates the observed average wind speed at desired height.

Figure 1: Variation of wind speed at 50m height

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Table 1: Average P value for stability class

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Keywords: Dispersion model, extrapolation, power law exponent, stability class, wind speed

References

Environmental Protection Agency (EPA). Meteorological Monitoring Guidance for Regulatory Modeling Applications. U.S.A: Environmental Protection Agency; 2000.
Hukkoo RK, Bapat VN, Shirvaikar VV. BARC-1412 Manual of Dose Evaluation from Atmospheric Releases. 1988.
Jesan T, Manonmani C. IARP 32 Estimation of roughness length Z₀for Kalpakkam site. 2016.

Abstract - 63547: Sensitivity of horizontal resolution, land-use/land-cover, land surface model and boundary layer physics in operational WRF simulations in Online Nuclear Emergency Response System

Shanu Karmakar, Dipan Kundu, J. R. Rajeswari, P. T. Rakesh, C. V. Srinivas, S. Chandrasekaran, B. Venkatraman

Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

In this work sensitivity of horizontal Domain Resolution, Land-use/Land-cover (LULC), Land Surface Model (LSM) and Planetary Boundary Layer (PBL) physics in WRF model^[1] for optimal numerical weather and dispersion predictions in Online Nuclear Emergency Response System (ONERS-DSS) is studied. A series of 3-day simulations with 6 hr spin-up are performed for 7 Nuclear Power Plant (NPP) sites using Global Forecast System (GFS) initial conditions on 10^th April, 2017 at 0.5°×0.5° and 3 hr resolution. The model outputs are compared with site specific meteorological tower and Radiosonde observation. The model physics includes WDM6 microphysics, Kain-Fritsch convection in parent domain, MM5 Surface layer and RRTM/Dudhia for longwave/shortwave radiation scheme. First, model sensitivity to horizontal resolution is studied using two model configurations [3-domains 18, 6, 2 km; 2-domains 9, 2 km resolutions] [Figure 1]. Subsequently, further sensitivity tests are conducted for two land cover data (MODIS vs NRSC LULC), two land surface physics [NOAH vs NOAH-MP LSM] and two PBL physics [YSU vs MYNN2.5 PBL physics]. Dominant wind sector for Narora is NW and WNW during April. It doesn't change diurnally due to inland location and strong ventilation conditions in the site. [Figure 2] and [Table 1] show that there is not much difference in predictions between 2km and 3 km resolutions. The 3 km single domain is advantageous over multiple domains of 2 km, as it provides high resolution simulations for all NPP sites for dispersion analysis and also for tracking large scale weather phenomena. Mean bias and RMSE estimates suggest 3km can be used for capturing mesoscale events. Further sensitivity tests conducted with 3km domain suggests that:

NRSC-NOAHMP-YSU (green line) combination better simulates the variation in both wind speed at 10m and temperature at 2 m [Figure 3]. It also better simulates the vertical structure up to ~6 km among other combinations [Figure 4].
Better simulations with NRSC data are due to 24 India specific land categories compared to 21 categories in MODIS. NOAHMP better simulates the near surface parameters due to improved physical processes e.g. dynamic vegetation, ground water module, explicit canopy etc. Similarly, YSU better simulated the vertical atmospheric structures as it treats nonlocal turbulent eddies which are dominant in convective layer compared to local small eddies in MYNN2.5. The NRSC-NOAHMP-YSU combination produces optimal weather prediction for ONERS DSS.

Authors thank Director IGCAR for support.

Figure 1: 2km (left) and 3 km (right) study domain

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Figure 2: Surface observation at Narora for DR sensitivity

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Figure 3: Surface observation of wind speed @10 m (left) and temperature @2 m (right)

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Figure 4: Radiosonde observation of wind speed (left) and potential temperature (right)

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Table 1: Statistical estimates

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Keywords: Land surface model, land-use/land-cover, Online Nuclear Emergency Response System, planetary boundary layer, resolution, WRF

Reference

Skamarock, et al. NCAR/TN-475+STR; 2008.

Abstract - 63562: Analysis of atmospheric stability pattern on rainy days at Kalpakkam Site

C. Manonmani, T. Jesan, S. Ramkumar, I. V. Saradhi¹, A. Vinod Kumar¹

Environmental Survey Laboratory, Kalpakkam, Tamil Nadu, ¹Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

The atmospheric stability plays an important role in the dispersion of releases and environmental impact assessment of a site. Kalpakkam receives rainfall from both Southwest and Northeast monsoon around eight to nine months in a year. In this study, the atmospheric stability categories distribution during rainy days was carried out for the year 2021. The wind speed and wind direction at Kalpakkam site are measured by NRG make anemometer and wind-vane sensors attached to 50 m height meteorological tower at 3 different levels (10 m, 30 m and 50 m) above the ground. Rainfall was measured using tipping bucket rain gauge and rainy day is defined as a day having rainfall greater than or equal to 0.1mm. The tower location is at 5.6 km radial distance from MAPS at Anupuram DAE Township, Kalpakkam. Atmospheric stability is diffusion parameter and is a derived quantity based on measured meteorological variables. The stability of the atmosphere is most often parameterized in terms of discrete stability classes. Based on Pasquill-Gifford scheme, stability categories were classified into extremely unstable A, moderately unstable B, slightly unstable C, neutral D, slightly stable E and moderately stable F.^[1] The atmospheric stability categories were estimated based on standard deviation of the wind direction with 10 m height wind speed.^[2] The total rainfall is 2090.2mm in the year 2021. The monthly maximum and minimum rainfall was 1151.8mm (22 days) and 5.2mm (1 day) observed in the month of November and February respectively. The maximum rainfall observed in a day was 124.4mm in the month of November. [Figure 1] reveals that the frequency of occurrence of A is 45.8% with 1 rainy day in the month of April and the rain fall is 14.8mm. Stability category B is predominant in January (31.5%) and December (29.2%) with the monthly average rainfall 22.8mm and 20.2mm respectively. There is no rainfall in the month of March. The occurrence of stability C is relatively less throughout the year except February and August. In February, predominant stability category D is observed with the frequency of 50% with the rainfall of 5.2mm in one day. From April to June frequency of occurrence of D is less than 5%. In February rainy days, there is no occurrence of stability A, E and F. The occurrence of stability category E is found greater than 12% except in the month of June. The observed frequency of stability category F is 39.6% in June and number of rainy days is 6. The maximum average rainfall is 52.4mm observed in the month of November. [Figure 2] shows the frequency of stability categories, for the year 2021 and during 79 rainy days in year 2021 and the correlation of stability categories with rainfall. During 2021 rainy days the stability category F increased and positively correlated with rainfall. Correlation of stability A, B and C with rainfall is insignificant and stability D and E are negatively correlated with rainfall. During rainy season, stability F occurs with higher frequency (24.6%) followed by stability A (22.2%), stability B (20.1%), stability E (16.7%), stability D (10.5%) and stability C (5.9%). During rainy days the stable category F tends to be predominant for the year 2021 and positive correlation with rainfall.

Figure 1: Monthly average distribution of stability classes, rainfall and rainy days

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Figure 2: Correlation of stability category with rainfall

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Keywords: Dispersion, rainfall, stability class

References

Hukkoo RK. Manual of Dose Evaluation from Atmospheric Releases. 1988.
Environmental Protection Agency (EPA). Meteorological Monitoring Guidance for Regulatory Modelling Applications. U.S.A: Environmental Protection Agency; 2000.

Abstract - 63622: Wind tunnel study on flow and diffusion around hill under stable stratification

Yunpeng Li, Ruojie Li, Junfang Zhang, Minghua Lyu, Sibo Lyu ,Yanhui Pan

Department of Nuclear Environmental Science, China Institute for Radiation Protection, Taiyuan, China

E-mail: [email protected]

The atmospheric dispersion of radioactive contaminants has always attracted wide attention because it can cause a detrimental effect on the environment in the short term. The dispersion characteristics of airborne pollutants in the vicinity of nuclear power plants are of great significance to the site selection, construction, operation and decommissioning of nuclear power plants. Most of the proposed nuclear power plants are built on plateaus, mountains and hills. Due to the thermal and dynamic effects of the rolling terrain, the flow field of the complex terrain is particularly complex, and there are multi-layer structures of valley wind, over hill flow and thermel stratification. Thermel stratification affect the height and structure of the atmospheric boundary layer as well as the wind speed, temperature and turbulence intensity profiles in the boundary layer, which play a major role in pollutant dispersion at the actual atmosphere. Wind tunnel experiment is an important means to study this kind of problem because it has the advantages of both the authenticity of field test and the repeatability and low cost of numerical simulation. This experiment is carried out in the atmospheric boundary layer wind tunnel of the China Institute for Radiation Protection, which is equipped with a thermel stratification simulation system. The simulation of the non-neutral atmospheric boundary layer can be realized by adjusting the inlet temperature profile. The hill is used as the research object to study the influence of different thermel stratification (neutral: Re_δ = 2.15utr⁴,Ri_δ = 0; stable: Re_δ = 2.0sta⁴,Ri_δ = 0.76) on the flow and diffusion of pollutants.

The results show that:

Under the neutral and stable layer stratification, the hill cause a significant decrease of the near-surface velocity and turbulence intensity in the wake region. In the area near the hill, the neutral and stable layer stratification have little influence on the flow field, and the farther away from the hill, the greater the influence of stable layer stratification on velocity, longitudinal and vertical turbulence intensity. when atmospheric stratification is stable, the longitudinal velocity and turbulence intensity was lower than under neutral conditions
The pollutants appear to wash down in the vertical direction. The stable thermal stratification inhibits the diffusion of pollutants in the vertical direction, which causes an increase in concentrations. The maximum normalized concentration appears near the hill. As the downwind distance increases, the height of the concentration peak decreases. And compared with neutral thermal stratification, the height of the concentration peak is lower.

Figure 1: Velocity profile, turbulence intensity profile, temperature profile under neutral and stable stratification

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Figure 2: Normalized concentration contour at the central plane under neutral and stable stratification

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Table 1: Main parameters under neutral and stable stratification

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Keywords: Diffusion, flow, hill, stable stratification, wind tunnel

References

Kanda I, Yamao Y. Passive scalar diffusion in and above urban-like roughness under weakly stable and unstable thermal stratification conditions. J Wind Eng Ind Aerodyn 2016;148:18-33.
Zhao Y, Li H, Kubilay A, et al. Buoyancy effects on the flows around flat and steep street canyons in simplified urban settings subject to a neutral approaching boundary layer: Wind tunnel PIV measurements. J Sci Total Environ 2021;797:149067.

Abstract - 64258: Stable isotope ratio as indicator to understand the source of groundwater in the Tummalapalle, Andhra Pradesh

V. B. Yadav, S. K. Jha¹

Environmental Assessment and Monitoring Division, BARC, ¹Health Physics Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

The wet precipitation has specific value (signature or fingerprint) of stable isotopic ratio depending on source of water and geographical. The groundwater retains the isotopic fingerprint of its source water during recharge process and practically remains unaltered in the aquifer unless the waters are subjected to exchange with oxygen of rocks and/or higher temperature. The stable isotope composition of water is used to study the origin and movement of subsurface waters, recharge and discharge of groundwater, interaction between surface waters and groundwaters, interconnections amongst the aquifers and many other hydrological processes. Aim of present study was to understand the source of groundwater and any contamination from tailing pond in Tummalapalle mining site, Andhra Pradesh. The water samples (groundwater, surface water, rain water) from different location (at different distance from pond) around the tailing pond and at different depth, were collected as per recommended guidelines. The samples were analysed for isotope ratio of oxygen and hydrogen (δ¹⁸O and δD) using Isotope Ratio Mass Spectrometer (IsoPrime 100) coupled with Elemental Analyser (EA-IRMS). Uranium concentration in the water samples was estimated in the sample by UV Fluorometer. Physicochemical parameters of water samples were measured using a multiparameter as per CPCB guidelines. The Quality Assurance and Quality Control of the measurement was ensured by adopting standard methodologies for required analysis as per recommended protocol.^[3] The range of δ¹⁸O and δ²H in groundwater was found to be -5.23‰ to -2.36‰ and -30.88‰ to-9.29‰ with an average of -3.60±0.83 ‰ and -20.70±6.05 ‰ respectively. The δ¹⁸O and δ²H in pond water receiving precipitation water and located around 4-7 km from tailing pond was found to be as -2.71±0.23 ‰ and -25.28±0.44 ‰ respectively. The δ¹⁸O and δ²H decantation pond water was found to be as -0.95±0.41 ‰ and -11.40±3.52 ‰ respectively. Regionalized Cluster-based Water Isotope Prediction (RCWIP) Model used for δ¹⁸O and δ²H isoscape in precipitation have predicted the average delta value (at 3 locations near to tailing pond) as -4.7±1.02‰ and -29.0±8.3‰^[1] respectively. The average monthly δ¹⁸O and δ²H in rain water sample collected from nearest GNIP station (Bangalore; 167.5 km away from tailing pond) is reported as -4.01‰ and -19.01‰ respectively. The δ¹⁸O and δ²H value in groundwater is similar to that of GNIP-Bangalore station values. The RCWIP-model δ¹⁸O and δ²H value also in the range that of groundwater. The δ¹⁸O and δ²H in all the groundwater, precipitation water and pond water are found around Global Meteoric Water Line (GMWL) [Figure 1]. The best fit of groundwater δ¹⁸O and δ²H values has slope of 2.5 indicating there is evaporative infiltration of precipitation water into groundwater table. The isotopic ratio in groundwater samples, distance from the tailing pond, and depth at which groundwater samples were collected did not show a systematic correlation. A linear fit of the groundwater delta values (δ¹⁸O versus δ²H) values intersects the GMWL line at ( -4.06, -22.48), which is similar to the average rain water delta values. Furthermore, there was no correlation observed between the physicochemical parameters (pH, salinity, conductivity, and total dissolved solid) and the δ¹⁸O and δ²H values.

Conclusion: The source of groundwater in the study well is appears to be evaporative infiltration of precipitation water and it seems no mixing of tailing pond water to groundwater in the study area.

Figure 1: δ18O versus δ2H plot for Groundwater, GMWL and LMWL

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Keywords: Groundwater, isotope ratio, physicochemical parameter, rainwater, uranium

References

Terzer, et al. Hydrol Earth Syst Sci 2013;17:1-16.
CPCB. MINARS/27/2007-08; 2008.
IUPAC. Pure Appl Chem 1995;67:649-66.

Abstract - 64587: Elemental (CNS) and isotopic (δ¹³C and δ¹⁵N) characterization of local sources to atmospheric dust at Trombay Mumbai using EA-IRMS

V. B. Yadav, Vandana Pulhani, and A Vinod Kumar

Environmental Assessment and Monitoring Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Air particulate matter was analysed to assess carbon content

3. Atmospheric dust is collected at the terrace of Modular Laboratories, BARC, Trombay, Mumbai using High Volume Sampler

4. The samples were analysed for Carbon, Nitrogen and Sulphur concentration and δ13C, δ15N values using Isotope Ratio Mass Spectromete

5. Average δ13C and δ15N values observed in the present study indicated the source of the particulate matter is pre-dominantly originated

Due to massive urban growth the atmospheric particles are exceeding the permissible concentration in many urban environments causing health hazards to human. Analysis of larger particle (size > 10μm) may provide the source of the locally originated particulate matter. In the present study the atmospheric dust is collected at the terrace of Modular Laboratories, BARC, Trombay, Mumbai using High Volume Sampler during pre-monsoon (February-May) and post-monsoon (October-December) seasons from 2016 to 2020. The samples were analysed for Carbon, Nitrogen and Sulphur concentration and δ¹³C, δ¹⁵N values using Isotope Ratio Mass Spectrometer (IRMS, make: IsoPrime 100) coupled with Elemental Analyser (EA, make: varioPyro Cube).

Results and Discussion: The samples collected in the pre-monsoon was found to have N (%), C (%), S (%) and TC/TN contents in the range 1.17%-1.96% (1.73±0.25%), 6.31%-8.39% (7.38±0.72%), 0.61%-1.10% (0.84±0.13%) and 3.43-6.22 (4.38 ±0.86%) respectively. The samples collected in the post-monsoon were found to have N (%), C (%), S (%) and TC/TN value as 1.17%-1.89% (1.47±0.185%), 6.00%-9.19% (6.95±1.04%), 0.55%-0.91% (0.84±0.13%) and 3.18-6.91 (4.80 ±0.94%) respectively. Compared with pre-monsoon samples, post-monsoon samples have lower average N (%), C (%) and S (%) content [Table 1], which may be explained by reduced suspended matter due to washout with rainwater and lower resuspension of soil due to damp conditions. It was also observed that these elemental concentrations increase as we approach the monsoon season (i.e., from February to May). A lower ratio of TC/TN is observed in this study than it is in other cities in India, which can be attributed to its isolated location.^[1] The average δ¹³C value in pre-monsoon and post-monsoon season was found to be -24.28±0.54‰ and -24.95±1.45‰ respectively. Similar result was found in the previous study carried out in the coastal city Goa having δ¹³C value as -24.99±0.29‰. The observed δ¹³C result is an intermediate value of aerosols emitting from pre-dominant C-3 type vegetation burning (avg. δ¹³C: −28‰) and coal combustion (avg. δ¹³C: −22‰). Study at urban location in Mumbai reported δ¹³C value varying from –27.0‰ to –25.4 ‰ which is lower than that the present study.^[2] There is very small variation observed throughout the sampling period expect in few samples. The lowest value in the sample (Feb-2018; δ¹³C: -28.02) is due to anthropogenic activity like burning of coal tar for water proofing of the terrace before monsoon during that period.^[3] The δ¹⁵N values in pre-monsoon and post-monsoon was found to be varying from 2.07‰ to 8.97‰ and 3.12‰ to 7.55‰ with an average of 5.22±1.92‰ and 4.57±1.32‰ respectively. Similar, lower δ ¹⁵N value (4±2‰) was also found in the Panaji (about 100 m inland from coast), a Coastal city of Goa [1]. Previous study carried out at Indian Institute of Technology Bombay (IITB) campus; Mumbai showed the δ ¹⁵N value range as 18.1 to 25.4 ‰ with an average of 21.3±1.8 ‰.^[2] The sampling site was about 10km inland from the Arabian Sea and the source of the particulate matter was assigned as mixed anthropogenic activities and the specific sources such as fossil fuel and biomass burning.^[2] The higher average δ ¹⁵N value observed in pre-monsoon seasons (5.34 ± 1.72‰) compared to that in post-monsoon seasons (4.45± 0.84‰) may be explained as reduced contribution of particulate matter originated from the crustal origin due to damp condition of soil after monsoon. In this study, the depleted δ¹⁵N value of atmospheric dust compared to previous study in Mumbai^[2] is probably because: (i) the main contributor to atmospheric dust in the region is crustal/re-suspended soils, liquid fossil fuel and sea salt spray; (ii) there is no domestic establishment near the sampling location; (iii) the sampling location is close to Mumbai Harbour Bay; and (iv) vehicular movement is very limited.

Conclusion: Considering the average δ¹³C and δ¹⁵N values observed in the present study the source of the particulate matter is pre-dominantly originated from crustal soil, sea salt spray and liquid fossil fuel.

Table 1: Average value of the measured parameters

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Keywords: Atmospheric dust, elemental composition, isotope ratio, isotope ratio mass spectrometer

References

Agnihotri, et al. Atmos Environ 2011;45:2828-35.
Aggarwal, et al. Atmos Chem Phys 2013;13:4667-80
Koegh, et al. Energy Fuel 1991;5:232-327.

Abstract - 64624: Comparative assessment of greenhouse gas emission of nuclear power: Process-based and hybrid life cycle assessment of a pressurised reactor in China

F. F. Wu^1,2, Y. Wang^1,2, J. Kang^1,2, J. Yang^1,2, B. Lian^1,2

¹China Institute for Radiation Protection, Shanxi, China, ²Key Laboratory of Radiation Environment and Health of the Ministry of Ecology and Environment, Shanxi, China

E-mail: [email protected]

Nuclear power, regarded as a kind of green energy, plays an important role in carbon emission reduction (UNECE, 2021).^[1] A unified and standardized greenhouse gas (GHG) emissions accounting framework for the nuclear power plant has not been established. Different views existed on the accounting boundaries, GHG types, accounting methods and other aspects in existing studies, which was not conducive to the comparative study of accounting results. Compared with thermal power generation, nuclear power generation does not directly consume carbon based fuel and generate air pollutants. However, from the perspective of the whole life cycle, GHG emissions will be generated in the stages of nuclear fuel exploitation, extraction, processing, use and recycling, as well as nuclear power plant construction and decommissioning (Warner and Heath, 2012; Pomponi and Hart, 2021).^[2,3]The GHG framework of nuclear power was established based on the life cycle theory [Figure 1]. In this framework, both space and time boundaries were considered in the system boundary, and GHG types included carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). The process-based and hybrid life cycle assessment methods were used to calculate the GHG emission of a pressurised reactor in China. As shown in [Figure 1], the space boundary included phases of the nuclear fuel cycle frontend (Uranium mining and milling, conversion and enrichment and fuel fabrication) and backend (spent fuel reprocessing and waste disposal), as well as equipment manufacturing and construction, operation and decommissioning of nuclear power plants. The transportation phase was excluded. The direct and indirect GHG emissions were calculated during the phases mentioned above. The time boundary was determined in combination with the nuclear fuel cycle and nuclear power plant cycle. Based on the phase division of nuclear power life cycle, GHG with different types were calculated. The escaped CH₄should be considered during uranium mining, thus the CO₂ equivalent was calculated with CH₄and CO₂ emission. During Uranium milling, conversion and enrichment as well as decommissioning phases, CH₄ and N₂O were released except for CO₂. Moreover, CO₂, CH₄and N₂O emissions shall be calculated in the waste disposal phase. A process-based life cycle assessment refers to a mix of processes and products. Using the process-based life cycle assessment, the GHG emission was calculated based on the material and energy consumption for each stage shown in [Figure 1]. The emission factor and activity data were key parameters (Wang et al., 2019).^[4] Hybrid life cycle assessment aims to combine the strengths of the process-based life cycle assessment and Input-output based life cycle assessment. Input-output analysis is an economic technique, which uses input-output tables (matrices of sector-based monetary transactions) to map resource consumption and pollutants release throughout the whole economy (Crawford, 2011).^[5] A detailed description on strengths and challenges in hybrid life cycle assessment can be found in previous study by Pomponi and Hart (2021).^[3] The results indicated that the GHG emission of non-carbon dioxide (CH₄ and N₂O) accounted for about 17% of the total greenhouse gas emission using the prepossess-based life cycle assessment. The process-based and hybrid methods ranged between 8.56~10.69 gCO₂ e/kWh and 14.61~22.74 gCO₂ e/kWh. In addition to system boundary, greenhouse gas types and assessment method, the operating life, technology and energy consumption level of nuclear power plants were major factors that affected the accounting results of greenhouse gas emissions. The results have certain reference values for the policy and strategy formulations for facilitating the development of nuclear power generation.

Figure 1: Stage division of nuclear power life cycle life cycle

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Keywords: Green gas, hybrid life cycle assessment, nuclear power, process-based life cycle assessment

References

UNECE. Technology Brief Nuclear Power. UNECE Task Force on Carbon Neutrality. Geneva: UNECE; 2021.
Warner ES, Heath GA. Life cycle greenhouse gas emissions of nuclear electricity generation. J Ind Ecol 2012;16:S73-92.
Pomponi F, Hart J. The greenhouse gas emissions of nuclear energy – Life cycle assessment of a European pressurised reactor. Appl Energy 2021;290:116743.
Wang L, Wang Y, Du HB, et al. A comparative life-cycle assessment of hydro-, nuclear and wind power: A China study. Appl Energy 2019;249:37-45.
Crawford R. Life Cycle Assessment in the Built Environment. 2011.

Abstract - 65180: Design, testing and installation of a shrouded aerosol sampling probe at demonstration fuel reprocessing plant

K. C. Ajoy, A. Dhanasekaran, D. N. Sangeetha, K. Paramasivam¹, C. Murugesanan¹, P. Devesh Ramanan¹, G. Elaiyaraja¹, R. Santhanam

Safety, Quality and Resource Management Group, IGCAR, ¹Reprocessing Group, IGCAR, Kalpakkam, Tamil Nadu, India

E-mail: [email protected]

Stack sampling is one of the critical elements of an air sampling program in a nuclear facility. Shrouded probes perform better than the standard iso-kinetic probes during drastic flow variations near the aerosol sampling point.^[1] A shrouded probe was designed and fabricated to meet the effluent monitoring requirements of an upcoming reprocessing facility called Demonstration Fuel Reprocessing Plant (DFRP). Performance evaluation of the probe was done at the HEPA filter test facility using standard polydisperse aerosols. Further, its performance was verified for 10 μm aerosols using the “DEPOSITION 2001a” code in accordance with the ISO standard (ISO - 2889, 2015). The aim was to design a probe that would perform within the allowable limits of transmission ratio for a velocity variation of ± 50 % at the sampling point. The schematic of a shrouded probe was obtained from literature surveys and it was tailored for our requirements. The flow velocity at the sampling point was expected to be around 15 m/sec and the extreme boundary conditions for the performance test was set at 8.0 to 24.0 m/sec. [Figure 1] shows the shrouded probe which is fabricated in-house using SS 304 L. The Probe ID is machined to 26.2 mm, while the shroud ID is machined to 78.0 mm, with an overall length being 233.0 mm for the probe and 340.0 mm for the shroud, respectively. The average surface roughness is maintained better than 0.8 and 1.6 microns in the internal and external regions of the shrouded probe to minimize the depositional losses due to surface irregularities. The shrouded probe was tested at the HEPA filter testing laboratory using the test rig commissioned as per British standard, BS 2831. Though the test rig is designed to test standard HEPA filters, the probe was fixed at the test location using a special arrangement to hold it at the centre of the test rig. Testing is done by introducing Polyalphaolefin (PAO) aerosols at various velocities starting from 8.0 m/sec to 24.0 m/sec in steps of approx. 2 m/sec while maintaining a constant sampling flow rate at 100 L/min through the probe. A portable aerosol counter is used to measure aerosol concentration (0.3 μm – 2.0 μm) in the air stream. The transmission ratio of aerosols is calculated from the upstream and downstream counts. [Figure 2] shows the schematic of the experimental arrangement. As the atomizer could not generate substantial aerosols beyond 2 microns, the transmission ratio was estimated using the deposition code for aerosol sizes of 5 μm and 10 μm to verify the qualifying criteria quoted in the ISO document. [Table 1] shows the transmission ratio observed for aerosols of various sizes. Experimental validation is done till 2 μm, while the simulation showed that the transmission ratio varied from 0.94 to 0.96 for 5 μm and 0.88 to 0.92 for 10 μm aerosols, within the acceptable range of 0.8 to 1.3 as per the ISO standard. Based on the test results and simulation, it is concluded that the proposed design is qualified for effluent sampling at DFRP. The probe was installed in the exhaust duct and connected to the stack sampling system for continuous monitoring of discharged effluents. The same design of the shrouded probe can be used for other nuclear facilities where a drastic variation in flow velocity is expected.

Figure 1: Top view and side view of the probe

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Figure 2: Schematic of the experimental arrangement

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Table 1: Transmission ratio for various particle sizes at different flow velocities

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Keywords: Effluents, isokinetic, sampling, shrouded probe, transmission ratio

References

McFarland AR, et al. Environ Sci Technol 1989.
Sampling Airborne Radioactive Materials from the Stacks and Ducts of Nuclear Facilities. ISO-2889; 2015.

Abstract - 65193: An update on beryllium ambient air concentration in Navi-Mumbai, India – 30 years status

Ankur Chauhan¹, Munish Kumar^1,2, Mahesh K. Kamble¹, Alok Srivastava¹

¹Industrial Hygiene and Safety Section, Health, Safety and Environment Group, Bhabha Atomic Research Centre, ²Physical Sciences, Homi Bhabha National Institute, Mumbai, Maharashtra, India

E-mail: [email protected]

Introduction: Beryllium (Be) being a lighter metal with high mechanical strength finds wider applications in space, defense, atomic energy and other industries. Various activities like mining, processing and combustion of coal and hydrocarbon may lead to increase in atmospheric concentration of Be above natural levels. The ambient Be background levels are generally attributed to windblown Be dust from earth surface and trace level radioactive component viz. ⁷Be and ¹⁰Be from interaction of cosmic rays particles with atoms of oxygen, nitrogen in the stratosphere and troposphere. ⁷Be is a cosmogenic radionuclide with a half life of 53.3 days and present in trace quantities in the atmosphere (1-10 mBq/m³) and can be related to various atmospheric changes as it acts as a radioactive tracer. Be is categorized as carcinogenic to humans and is chemically toxic, with its chemical toxicity comparable to heavy elements and is an element of concern for environmental monitoring. In view of this, information on Be concentration (⁹Be) in ambient air at Navi-Mumbai is provided for last three decades using literature survey available up to 2003 and subsequent measurements performed at Navi Mumbai up to 2020.

Materials and Methods: The methodology adopted for environmental sampling is collection of air on Whatman EPM 2000 glass fiber based filter paper for 24 hours using well calibrated high volume environmental sampler at a flow rate of ~1 m³/min. and analysis is performed for ⁹Be as well as ⁷Be. Stable ⁹Be is measured using acid based digestion and measured using GF-AAS techniques. Data collected over last 30 years for ⁹Be is analyzed and presented. In addition, radioactive ⁷Be is analyzed by Gamma spectroscopy using high purity Ge detector.^[1]

Results and Discussion: [Figure 1] gives details about ambient air concentration of ⁹Be from 1991-2020 which includes minimum as well as maximum values.^[2],[3] In addition, the seasonal variation of ⁹Be concentration for 2000-01 is given in [Figure 2]. From [Figure 1], it can be seen that the typical range of ⁹Be concentration in air varies from (0.01-2.50) ng/m³ from 1991-2020. From seasonal variation, the typical value in monsoon period is (0.09-0.40) whereas the ⁹Be concentration is (0.05-1.50) ng/m³in the non-monsoon period. Our recent measurement on ⁷Be shows the ambient concentration to be ~7.5 mBq/m³ and matches well with the measurements performed by earlier co-workers.

Conclusions: The typical ambient Be concentration is found to be ~0.30 ng/m³ with some values ranging up to 2.50 ng/m³ occasionally as observed previously. It is observed from the study that the yearly average concentration of Be in air is practically constant although small variations/fluctuations due to environmental changes prevail. However, not substantial variation is observed in the background ⁹Be values during last 30 years indicating that there is not much impact on ⁹Be background due to various industrial activities.

Figure 1: Yearly minimum and maximum ⁹Be air concentration

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Figure 2: Seasonal variation of average concentration of 9Be

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Keywords: ⁷Be, ⁹Be, ambient beryllium (Be) concentration, radioactivity and environmental survey

References

Iurian AR, Millward GE. IAEA; 2019. p. 29-44.
Thorat DD. J AIHA 2003;64:522-7.
Bhat PN, Pillai KC. J Water Air Soil Pollut 1997;95:133-46.

Abstract - 65310: Behaviour of iodine in soil pore water

Sonali Yadav, Sabyasachi Rout, Amol Chandrakar, Akhaya Patra, Vandana Pulhani, I. V. Saradhi, A. Vinod Kumar

Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Iodine is an essential trace element for human and animal health that regulates a range of physiological processes including production of thyroid hormones. Since iodine plays an important role in physiological processes, radioactive iodine can strongly affect human health. Therefore, it is necessary to investigate the behaviour of iodine in the soil system. Iodine can exist in several forms, including iodide (I^-), iodate (IO₃^-), molecular iodine (I₂), and organic iodine.^[1],[2] Therefore, it is very difficult to predict the bioavailability in a soil system due to the different mobilities among its possible species. However, there is a consensus that I^– has higher mobility than IO₃^-and organic iodine. Therefore, a study was conducted, to investigate the speciation of I^- in soil pore water and geochemical reactions leading to the change in speciation or redox transformation in the soil-water system. For the study, a lysimetric tank was installed in the field with a setup for the collection of pore water from different depths (20, 30, 40, 50, and 70 cm). The soil inside the tank was amended with 40 L of 1000 mg/L iodide solution. Soil pore water samples were collected at different intervals, such as after 1, 7, 14, and 21 days. Background pore water sample was collected one day before the amendment. Physico-chemical characterization of the pore water samples was carried out in terms of pH, Cl^-, NO₃^-, SO₄^2-,I^-, IO₃^-, Na⁺, K⁺, Mg²⁺, Ca²⁺ and NH₄⁺. Investigation of major ions data indicates that the signatures of I^-and IO₃^- are not found in the sample collected just one day after amendment. However, the samples collected after 7 days onward contain traces of I- and IO₃^- in few samples. Surprisingly, samples collected from the depth of 50 cm possess the highest level of IO₃^- and over the period from 7 to 21 days the concentration decreases from 197 to 47 mg/L,. Data shows that, there is a signature of the NH₄⁺ ion in the sample where IO₃^-is detected. In order to understand the relationship between the major ions or effect of major ions on iodide concentration correlation coefficient has been determined. [Figure 1]a and [Figure 1]b present the correlation of iodate and iodide with other physico-chemical parameters of soil pore water. [Figure 1]a shows that IO₃^- has a strong positive relationship with SO₄^2-, Na⁺, K⁺, Mg²⁺, NH₄⁺ and a moderate relationship with Cl^-. However, it has a negative relationship with NO₃^- and I^-. [Figure 1]b indicates that, I^- is strongly correlated with Cl^-, NO₃^-, Ca²⁺, moderate relationship with Na⁺, Mg²⁺ and negatively correlated with IO₃^-, SO₄^2-, K⁺ and NH₄⁺_. Correlation analysis revealed that, there is some complex interplay-taking place, which leads to the transformation of the iodide to iodate. Figure revealed that, IO₃^- shows strong positive correlation with NH₄⁺and negative correlation with NO₃^- whereas I^- shows positive correlation with both ions. This indicates that oxidative transformation of I^- to IO₃^- is accelerated by reduction of NO₃^-to NH₄⁺ mediated by microbial activities. Hence, the following geochemical reaction mechanism has been proposed:

8 I^-+6 NO₃^-+18 H₂O↔ 8 IO₃^-+ 6 NH₄⁺+12 OH^-

However, the reaction seems to be abiotic in nature, detection of IO₃^- at particular depth indicates biotic factors may be playing an important role. This needs further investigation. The study shows that, NO₃^-play important role in oxidative transformation of I^- to IO₃^- in soil pore water system. The decrease in IO₃^-concentration with time can be correlated with its sorption on metal hydrous oxides (ferric and aluminium oxides), since IO₃^-sorb on Fe-Mn oxides faster than I^-. The study provides preliminary data on behavior of I^- in soil pore water.

Figure 1: Correlation of (a) iodate and (b) iodide with physicochemical parameters of soil pore water

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Keywords: Iodine, pore water, speciation

References

Yamada H, et al. Soil Sci Plant Nutr 1999;45:63.
Hou X, et al. Anal Chim Acta 2009;632:181.

Abstract - 65355: Development of an in-house mapping solution for environmental and radiological surveillance

Manish K. Mishra, D. G. Mishra, Vandana Pulhani, A. Vinod Kumar

Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India

E-mail: [email protected]

Geospatial solutions are expensive and require dedicated workforce to keep it updated and error free. Some commercial mapping solution providers like Google, Apple, ESRI, Tomtom etc. provide search facility free for common public, while they charge millions to customers for their geo-location services, fleet management & tracking etc. on a yearly basis. This only provides the end product and never share their database. Majority of such service providers are either based in USA or in Europe, making constant internet connectivity an essential requirement for using mapping-services. Additionally, these services are business centric and profit oriented. Mapping sources hosted by other open-source service providers are also ultimately hosted on AWS, Azure, Google Cloud etc. and are vulnerable due to limited customizations, bias and privacy breach.^[1] NRSC (ISRO) provides geospatial data on their open portal but it does not specifically cater to the needs of radiation protection. The EMAD and Computer Division of BARC started working on preparation of an opensource and locally served (over intranet and AnuNet-restricted internet) web-map server which could store all the relevant data in its local servers, cater it as per need to the end users of DAE (Department of Atomic Energy). EMAPPING (i.e., Environmental Monitoring, Assessment, Planning & Preparedness Interface on GIS) is a service which has been developed using completely open-source software (geoserver, apache, pgAdmin, postgreSQL, postGIS) as well as data available in public domain, sourced from hundreds of websites and census databooks for use in DAE, India. All the data were taken from open-source portals (OSM, SOI, USGS, ESA, BHUVAN etc.) under creative commons license (CC-BY-SA) and verified from portals like Wikimedia, Google Earth/Map, Copernicus Sentinel etc., to name a few. These data were stored and managed through Geoserver using PostGIS module of PostgreSQL database and Apache tomcat server.^[2] The mapping application does not require installation of any software on the machine, as it can be accessed through native browser of the operating system (e.g., Firefox, MS Edge, Chrome etc.). Secondly, it is independent of the OS and the architecture of the machine, the only requirement is that the machine should have AnuNet accessibility (DAE Network). It is served through dedicated Linux server on the AnuNet (AnuMegh cloud service of DAE), which is a dedicated pan-India intranet service connecting DAE units. It keeps the data secure through single-sign on authentication (SSO) and is only accessible to DAE employees. Keeping data on servers which are stored and served through servers located physically on our won sovereign soil makes it immune to disruption by international service providers and limit their misuse by unintended users. We have georeferenced, digitized, extracted and generated an overwhelming amount of GIS data (around 1 terabyte redundant database of spatial and non-spatial data). The E-mapping web-portal can be used to plot GPX, KML and SHP file by drag & drop. It can be used for measuring geodesic length, area and perimeter instantly. It can be used for network routing. A dedicated emergency preparedness module is accessible with customizable parameters. The E-mapping service is still evolving and will soon provide more robust services on a single platform.

Figure 1: A snapshot of emapping service browser developed by EMAD

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Keywords: FOSS, GIS, indigenous

References

Damiani ML, Cuijpers C. Privacy challenges in third-party location services. 2013 IEEE 14^th Int Conf Mobile Data Manage 2013;2:63-6.
Geoconcept. WMS and WMTS – Web Services Documentation of Geoconcept Web; 2022. Available from: https://mygeoconcept.com/doc/gcweb/docs/en/gcweb-ws-book/web-services-ogc.html.

Abstract - 65462: Distribution pattern of uranium and thorium in coal and coal-fly ash samples from Indian thermal power plants

P. Sandeep, Sukanta Maity, Suchismita Mishra, D. K. Chaudhary, C. B. Dusane, Anilkumar S. Pillai, A. Vinod Kumar

Environmental Monitoring and Assessment Division, Health Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

E-mail: [email protected]

Environmental radiation background is mostly caused by ²³⁸U, ²³²Th decay series, and ⁴⁰K. Uranium (U) and thorium (Th) are widely found in different environmental matrices (soil, water, air, etc.). In few environmental matrices these radioactive elements get enriched due to natural or anthropogenic processes and one example of such matrices is coal fly ash (CFA) (Bhattacharyya et al., 2008). In India, about 110*10⁶ tons of CFA is generated through thermal power plants (TPPs) which in future may increase to about 230*10⁶ tons.^[2]In the present study, CFAs (8nos. from eight different TPPs) and coal (2nos. from two different TPPs) were collected to investigate U and Th distribution and enrichment factors of these metals in CFA w.r.t feed coal. Approximately 500 grams of each sample (CFA and Coal) was collected in a clean polyethylene bags. 1.5 gram of fly ash sample was digested using a mixture of concentrated HF, HNO₃, and H₂SO₄ in a microwave digestion system and analyzed for U, Th using Triple Quadrupole-ICP-MS (Thermo Fisher Scientific make, iCAP model). This instrument is having high sensitivity and low detection limits (up to parts per trillion levels) for targeted elements. [Figure 1] shows the distribution of U and Th present in Coal and CFA samples. U and Th concentrations are observed in the range 7.3-12.5 μg/g and 30.6-35.8 μg/g, respectively in CFAs. There is a variation in the U concentration among the sample, whereas narrow range of concentration variation was observed for Th. In the case of coal samples, U and Th concentration are in the range of 1-5 μg/g, and is comparable to the values observed in the soil samples. The current study results are compared (Table 1) with the literature reports and is found that the current study results are in comparable range reported worldwide. Enrichment factor of U and Th in CFAs with respect to coal from same TPP is calculated using the measured concentrations and the values are found in the range as given in [Table 2]. Here, FA5 and FA7 represent the CFA samples. The study results suggest that CFA gets enriched with metals in TPPs. However, it is evident from literature survey and from present study that the reported concentrations and enrichment factors are moderate.

Figure 1: Distribution of U and Th in coal and CFA samples from Indian thermal power plants. CFA: Coal fly ash

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Table 1: Comparison of U and Th content reported in coal fly ashes from various countries with the current study

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Table 2: Enrichment factor of U and Th in coal fly ash w.r.t coal

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Keywords: Coal fly ash, enrichment, ICP-MS, thorium, uranium

References

Truong TH, Vu Ngoc B, Bui Ngoc T. Nuc Eng Technol 2022;54:1431-8.
Dhadse S, Kumari P, Hagia BL. J Sci Ind Res 2008;67:11.
Bhattacharyya S, Donahoe RJ, Patel D. Fuel 2009;88:173-1184.
Dai S, Seredin VV, Ward CR, Jiang J, Hower JC, Song X, et al. Int J Coal Geol 2014;121:79-97.
Affolter RH, Groves S, Betterton WJ, Benzel W, Conrad KL, Swanson SM, et al. Reston, VA, USA: U.S. Geological Survey; 2011. p. 19.
Silva LF, Ward CR, Hower JC, Izquierdo M, Waanders F, Oliveira ML, et al. Coal Comb Gasif Prod 2010;2:51-65.

Abstract - 65580: Dose due to the ingestion of non-exchangeable organically bound tritium in the vicinity of Kaiga Nuclear Power Plant

R. Nayak, R. S. Dsouza, S. Bharath, B. N. Dileep, P. M. Ravi, N. Karunakara

Centre for Advanced Research in Environmental Radioactivity, Mangalore University, Mangalagangothri, Karnataka, India

E-mail: [email protected]

Tritium (³H, a radioactive isotope of hydrogen, T_1/2= 12.3 y, average beta energy = 5.7 keV) is produced by nuclear reactions that occur naturally in the upper atmosphere due to the interaction of high-energy cosmic rays with oxygen and nitrogen atoms. Anthropogenic sources of this radioisotope in the environment are nuclear weapons testing, fuel reprocessing plants, heavy water production facilities, nuclear power plants (NPPs), radiopharmaceutical industries, etc. Among the NPPs, tritium release from the PHWRs is higher when compared to other types of reactors. The estimated discharge from the PHWRs is ~ 3.70 × 10³GBq.GW(e)^-1.a^–1 and 2.59 × 10⁴ GBq.GW(e)^-1.a^–1 through gaseous and liquid effluents, respectively, mainly in tritiated water (HTO) form. The HTO released into the atmosphere mixes with air moisture and enters the terrestrial and aquatic ecosystem. Tritium present in plant tissues can be classified into (i) tissue-free water tritium (TFWT) and (ii) tissue-bound tritium (TBT) or organically bound tritium (OBT). OBT is further differentiated into two pools (i) the exchangeable pool (E-OBT) and (ii) the non-exchangeable pool (NE-OBT). The Centre for Advanced Research in Environmental Radioactivity (CARER) conducted a detailed study on the standardisation of methods for determining OBT activity in environmental matrices. Upon standardisation, a large database on OBT was established for environmental biota in the vicinity of the PHWR NPP at Kaiga site, India. The samples were collected from the sampling stations distributed in the 2.3–5 km, 5–10 km, and 10–20 km radius zones of the NPP. Vegetables, cereals, and fruit samples were collected from the local farmers. The collected samples were oven dried at 90 °C, powdered, and combusted in a tube furnace system after the removal of E-OBT. The details of the method developed were described in Nayak et al., 2020.^[1] The NE-OBT activity in the samples was determined by liquid scintillation spectrometry. The minimum detectable activity for NE-OBT measurement was determined to be 8.6 Bq L^-1 of combustion water a counting time of 12,000 s. From the measured NE-OBT activity, the ingestion dose for the inhabitants of the Kaiga region was determined as follows:

E_{ing, p} = C_{p, i} × H_p ×DF_ing

Where, E_ing_,_pis the annual effective dose from consumption of nuclide i in foodstuff p (Sv y^-1),

C_p_,iis the activity of radionuclide i in foodstuff p at the time of consumption (Bq kg^-1, fresh mass)

H_pis the consumption rate for foodstuff p (kg y^-1), and

DF_ing is the dose coefficient (ingestion) for OBT (4.1 × 10^-11Sv Bq^-1).

Table 1 presents the NE-OBT activity in fruits, vegetables, and cereals collected from the Kaiga NPP region. The annual effective dose to the population in the 2.3-5 km zone due to ingestion of NE-OBT along with vegetables and fruits, attributable to the release from the Kaiga NPP, was 0.0038 μSv y^-1. The corresponding value due to the consumption of rice was 0.158 μSv y^-1. The dose values decreased with the increase of distance from the NPP. The dose values recorded for the 10-20 km zone were similar to those recorded for the control site situated ~350 km from the NPP, confirming no impact of the NPP beyond 10 km.

Table 1: Annual effective dose due to the ingestion of nonexchangeable.organically bound tritium

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Keywords: Dose, Kaiga Nuclear Power Plant, tritium

Reference

Nayak RS, D'Souza RS, Kamath S, Mohan MP, Karunakara N. Experimental database on water equivalent factor (WEQp) and organically bound tritium activity for tropical monsoonal climate region of South West Coast of India. Appl Radiat Isot 2020;166:109390.

Abstract - 65613: Development of automatic monitoring device for tritium and carbon -14 in gas effluent

Bao Li, Yang Youkun, Lian Bing, Li Jinhao, Guo Chen, Yang Hailan, Wang Ruijun

Department of Nuclear Environmental Science, China Institute for Radiation Protection, Taiyuan, China

E-mail: [email protected]

Tritium and carbon-14 in gas effluent are important nuclides for monitoring radiation environment of NPPs. In the monitoring, it is necessary for personnel to sample, collect samples and transport them to the laboratory for sample treatment and analysis, and professional technicians are required. Based on bubble sampling and liquid scintillation measurement of gaseous tritium and carbon-14, an automatic monitoring device for tritium and carbon-14 in gas effluent was established. Automatic monitoring device for tritium and carbon -14 in gas effluent mainly includes PLC control cabinet, automatic sample processing part, measuring instrument and remote control module. The automatic sample processing part includes the automation of sampling, sample preparation and sample injection. The overall structure is divided into two parts, including the conveyor belt driving device, the control system, the steps of adding liquid, capping the bottle cap, and mixing evenly. No human operation is required. The structure of the device is shown in [Figure 1]. The control of the monitoring device includes manual and automatic modes. The control panel includes manual interface, operation interface and parameter interface. Manual interface can control each unit separately; The interface can be operated by sections, including sampling, sample preparation, sample injection, or run fully automatically. The parameters can modify the opening time of peristaltic pump and the running time of screw transmission device, and then control the amount of liquid added and the operation of test bottle. Select fully automatic operation, and the processes of sampling, sample preparation, sample injection, waste liquid discharge, cleaning and sewage discharge will be carried out automatically. Perform performance test on the device, including accuracy test of liquid addition, repeatability test of measuring instruments and relative deviation test of measuring results. When the preset water mass is 8g, the deviation of automatic sample preparation is 0.63%~ 1.25%, and when the preset water mass is 12g, the deviation of automatic sample preparation is 0.75%~1.25%.Table 1 lists the accuracy test data of automatic sample preparation and liquid addition.

For the tritium water quality control sample with tritium activity concentration of 53.07 Bq/kg, the relative deviation of the average value of six repeated measurements is 2.26%.

For tritium water samples with tritium activity concentration of 29.877 Bq/L, the relative deviation of tritium activity concentration of 20 samples is -8.18% ~15.7%, and the relative deviation of the average value is 7.81%. The developed automatic monitoring device for tritium and carbon-14 in gas effluent can realize segmented control or fully automatic operation of sampling, sample preparation, injection and cleaning, which greatly reduces the workload of personnel. The test results of the automatic monitoring device for tritium and carbon-14 in gas effluent show that the deviation of liquid addition is less than 2%, the relative deviation of repeated measurement is less than 3%, and the relative standard deviation of tritium water sample with known activity concentration is less than 16%, which can be used for monitoring tritium and carbon-14. The developed automatic monitoring device still needs further research and experiments to be perfected, and in the follow-up research, the measurement control and data transmission should also be considered.

Figure 1: Automatic monitoring device structure of tritium and carbon -14 in carrier effluent

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Table 1: Experimental data of automatic sample preparation and liquid addition accuracy test

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Keywords: Automatic, carbon-14, gas effluent, tritium

References

Sampling and Determination Method of Carbon 14 in Air. EJ/T 1008-96.
Measurement of the Radioactivity in the Environment – Air: Tritium – Test Method Using Bubbler Sampling. ISO/DIS 20045.

Figures

[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23], [Figure 24], [Figure 25], [Figure 26], [Figure 27], [Figure 28], [Figure 29], [Figure 30], [Figure 31], [Figure 32], [Figure 33], [Figure 34], [Figure 35], [Figure 36], [Figure 37], [Figure 38], [Figure 39], [Figure 40], [Figure 41], [Figure 42], [Figure 43], [Figure 44], [Figure 45], [Figure 46], [Figure 47], [Figure 48], [Figure 49], [Figure 50], [Figure 51], [Figure 52], [Figure 53], [Figure 54], [Figure 55], [Figure 56], [Figure 57], [Figure 58], [Figure 59], [Figure 60], [Figure 61], [Figure 62], [Figure 63], [Figure 64], [Figure 65], [Figure 66], [Figure 67], [Figure 68], [Figure 69], [Figure 70], [Figure 71], [Figure 72], [Figure 73], [Figure 74], [Figure 75], [Figure 76], [Figure 77], [Figure 78], [Figure 79], [Figure 80], [Figure 81], [Figure 82], [Figure 83], [Figure 84], [Figure 85], [Figure 86], [Figure 87], [Figure 88], [Figure 89], [Figure 90], [Figure 91], [Figure 92], [Figure 93], [Figure 94], [Figure 95], [Figure 96], [Figure 97], [Figure 98], [Figure 99], [Figure 100], [Figure 101], [Figure 102], [Figure 103], [Figure 104], [Figure 105], [Figure 106], [Figure 107], [Figure 108], [Figure 109], [Figure 110], [Figure 111], [Figure 112], [Figure 113], [Figure 114], [Figure 115], [Figure 116], [Figure 117], [Figure 118], [Figure 119], [Figure 120]

Tables

[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12], [Table 13], [Table 14], [Table 15], [Table 16], [Table 17], [Table 18], [Table 19], [Table 20], [Table 21], [Table 22], [Table 23], [Table 24], [Table 25], [Table 26], [Table 27], [Table 28], [Table 29], [Table 30], [Table 31], [Table 32], [Table 33], [Table 34], [Table 35], [Table 36], [Table 37], [Table 38], [Table 39], [Table 40], [Table 41], [Table 42], [Table 43], [Table 44], [Table 45], [Table 46], [Table 47], [Table 48], [Table 49], [Table 50], [Table 51], [Table 52], [Table 53], [Table 54], [Table 55], [Table 56], [Table 57], [Table 58], [Table 59], [Table 60], [Table 61], [Table 62], [Table 63], [Table 64], [Table 65], [Table 66], [Table 67], [Table 68], [Table 69], [Table 70], [Table 71], [Table 72], [Table 73], [Table 74], [Table 75], [Table 76]

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