Assessment of radiological impact and for planning and preparedness programs, monthly atmospheric dispersion patterns at Kalpakkam have been studied using observed surface meteorological data during 2015–2020. The influence of meteorological factors such as wind speed, wind directions, percent of calm, atmospheric stability, and rainfall on dispersion patterns has been evaluated. The higher wind speed range (>4 m/s) is observed from 11:00 h to 19:00 h with an average wind speed of 4.17 m/s and the highest value observed in the month of May. Extremely stable F category and percent of calm observed to be lowest in the month of June. This study reveals that the high concentration area is toward seaside sectors during the southwest monsoon season from June to September and the remaining months, January to May and October to December, the most probable dispersion toward southwest, South, and North covering land sectors. Wet deposition due to maximum rainfall and more rainy days in the month of November during the northeast monsoon. The study provides site-specific information on dispersion patterns, an essential tool and crucial support for risk management with respect to radiological impact, monitoring and assessment in normal and emergency scenarios of a nuclear facility, and guiding resources for siting and design of the new facility in and around Kalpakkam.

Transfer coefficient from grass to milk (F_m) for ¹³⁷Cs and ⁴⁰K was computed based on the activity measurement data in the respective matrix at Kakrapar Gujarat site, India, during 2013 - 2019. The annual geometric mean value of ¹³⁷Cs activity in grass and milk samples varied from 0.13 to 0.48 Bq/kg dry wt. and 0.03 to 0.14 Bq/l, respectively. Activity observed during the year 2013 - 2019 is comparable with preoperational baseline activity level, which indicated its fallout origin. The site-specific F_m has varied between 1.0E-02 to 3.71E-02 d/l with a GM of 2.22E-02 d/l (¹³⁷Cs) and between 6.69E-03 to 1.54E-02 d/l with a GM of 9.63E-03 d/l (⁴⁰K), respectively. The annual effective dose due to the ingestion of ¹³⁷Cs and ⁴⁰K through milk consumption was found to be 0.036 μSv/y and 16.94 μSv/y, respectively. The result is an useful input for the estimation of radiation dose to human beings in accidental conditions.

The contribution of the aquatic water body to the tritium (³H) flux in the atmosphere near the discharge point of Kakrapar Gujarat Site has been assessed by collecting and analyzing the ³H activity in the air moisture and in the water sample near the aquatic discharge point. The observed air ³H activity near the discharge point was in the range of ≤0.20–19.8 Bq/m³, whereas the predicted ³H activity at the same location due to the atmospheric release through stack varied from 0.10 to 0.15 Bq/m³. The range of water ³H activity through the discharge point varied from ≤10 to 3482 Bq/l. The ³H flux (water to air transfer) was estimated and found to be in the range of ≤5.90E+01 – 2.05E+04 Bq/m²/s. The observation shows that during radioactive aquatic releases, there is an increase in the ³H activity levels in the water vapor near the aquatic discharge point. The observed ³H activity levels in air samples were extremely low to contribute any additional dose to the member of the public as compared to the public dose obtained from natural background sources.

The ambient gamma (γ)-radiation levels were measured in various types of dwellings in and around Vellore district. The survey was performed by using a portable Micro-R Survey Meter NUCLEONIX in different types of dwellings. The background γ-radiation exposure inside the dwelling was obtained in a total of 632 dwellings located in 30 different geographical positions in Vellore and nearby places. From the measured dose values, the radiation exposure indexes were estimated such as absorbed dose rate (ADR) and annual effective dose (AED) for the population. The present study has taken an initiative to formulate the environmental γ-radiation reference level for indoor γ-radiation level in and around Vellore district, Tamil Nadu. The calculated highest mean AED was found in concrete dwellings at 0.58 ± 0.07 mSvy⁻¹. The highest ADR was found to be 1219 μGy/yr in tiled house. Furthermore, the work was extended to find the correlation between the temperatures, time, and type of house with radiation for a day with 2 h of regular time interval in these four types of houses and analyzed with response surface methodology.

Natural radioactivity content in different types of building materials obtained from Chennai city has been determined. In this study, the most commonly used building materials such as clay bricks, cement, sediment, tiles, marbles, and granite have been considered for quantifying natural radioactivity content using gamma-ray spectroscopy. The annual effective dose (AED) values obtained in this study, varying from 0.04 mSv to 0.57 mSv, are deduced from the natural radioactivity content; these are lower than the European Commission Report 112 recommended level of 1 mSv. Therefore, the use of all the building materials in question, collected from in and around Chennai, in the construction of dwellings is considered to be radiologically safe for the inhabitants.

Five empirical equations, namely, FAO-56 Penman–Monteith, Hargreaves–Samani, Makkink, Turc, and Priestley–Taylor are utilized in the estimation of evapotranspiration for the month of May in 2018 for Trombay site in Maharashtra. Evapotranspiration from a given surface is a function of incoming solar radiation, net radiation, ground heat flux, air temperature, relative humidity, and wind speed. Daily average measurements of these parameters are utilized in the empirical equations for the estimation of evapotranspiration. These estimated values are compared with the measured data from pan evaporimeter installed at Trombay. The measured data from the pan evaporimeter are corrected using the pan coefficient Kp which in turn is also estimated using empirical equations. The average value of the pan coefficient Kp is 0.8 for the site. The average measured value of evapotranspiration is 4.7 mm/d for May 2018, whereas the values estimated using the five empirical equations range from 3.3 mm/d to 12.7 mm/d. Among the five equations, the Turc equation was found to be in the best agreement with the measured values of evapotranspiration. Such studies are useful in the estimation of groundwater recharge, latent heat flux, and agriculture meteorology.

The article presents an overview of the occupational radiation protection aspects of experimental sodium diuranate transferring and handling processes required for refining utilization. The health physics aspects and associated monitoring programs necessary to adequately measure and control radiological exposures to workers during the process is described here. A particle size distribution study was also carried out and estimated the activity median aerodynamic diameter (AMAD) for the process. The AMAD varied from 4.6 to 7.7 μm and geometric standard deviation ranged from 1.9 to 2.8. Obtained data serve the purpose of comparison for formulating a detailed radiological safety protocol during regular operation.