|NEWS AND INFORMATION
|Year : 2013 | Volume
| Issue : 1 | Page : 45-46
News and Information
Ex-BARC, Mumbai, India
|Date of Web Publication||21-Nov-2013|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pushparaja. News and Information. Radiat Prot Environ 2013;36:45-6
New ICRP publication: Assessment of radiation exposure of astronauts in space; ICRP publication no. 123, 2013
G. Dietze, D. T. Bartlett, D. A. Cool, F. A. Cucinotta, X. Jia, I. R. McAulay, M. Pelliccioni, V. Petrov, G. G. Reitz, T. Sato
Astronauts, during their occupational activities in space, are exposed to ionizing radiation from natural radiation sources present in the environment. The exposure assessment and risk-related approach described in this report is clearly restricted to the special situation in space, and should not be applied to the system of radiological protection followed on Earth.
The report describes the terms and methods used to assess the radiation exposure of astronauts, and provides data for the assessment of organ doses. Chapter 1 describes the specific situation of astronauts in space, and the differences in the radiation fields compared with those on Earth. In Chapter 2, the radiation fields in space are described in detail, including galactic cosmic radiation, radiation from the Sun and its special solar particle events, and the radiation belts surrounding the Earth. Chapter 3 deals with the quantities used in radiological protection, describing the Publication 103 system of dose quantities, and subsequently presenting the special approach for applications in space; due to the strong contribution of heavy ions in the radiation field, radiation weighting is based on the radiation quality factor, Q, instead of the radiation weighting factor, wR. In Chapter 4, the methods of fluence and dose measurement in space are described, including instrumentation for fluence measurements, radiation spectrometry, and area and individual monitoring. The use of biomarkers for the assessment of mission doses is also described. The methods of determining quantities describing the radiation fields within a spacecraft are given in Chapter 5. Radiation transport calculations are the most important tool. Some physical data used in radiation transport codes are presented, and the various codes used for calculations in high-energy radiation fields in space are described. Results of calculations and measurements of radiation fields in spacecraft are given. Some data for shielding possibilities are also presented. Chapter 6 addresses the methods of determining mean absorbed doses and dose equivalents in organs and tissues of the human body. Calculated conversion coefficients of fluence to mean absorbed dose in an organ or tissue are given for heavy ions up to Z = 28 for energies from 10 MeV/u to 100 GeV/u. Doses in the body obtained by measurements are compared with the results from calculations, and biodosimetric measurements for the assessment of mission doses are also presented. In Chapter 7, operational measures are considered for assessment of the exposure of astronauts during space missions. This includes pre-flight mission design, area and individual monitoring during flights in space, and dose recording. The importance of the magnitude of uncertainties in dose assessment is considered.
Annex A shows the conversion coefficients and mean quality factors for protons, charged pions, neutrons, alpha particles, and heavy ions (2 <<i> Z ≤ 28), and particle energies up to 100 GeV/u (source: www.icrp.org).
Iaea produces new booklet on "Sealed radioactive sources-2013"
The IAEA's new 40-page booklet entitled "Sealed Radioactive Sources" is an easy-to-read introduction to the management (tracking, storage, and disposal) of these sources. It provides information on potential radiation hazards and accident prevention, as well as many real-world case studies.
Radioactive sources are used not only in medical treatment, but also in prospecting for oil and gas, measuring the density of soil for construction projects, and sterilizing food and medical equipment. A sealed source is a radioactive material in solid form that is permanently sealed in a capsule. The sources can be quite small, yet some contain radioactive material that can be harmful, even fatal, if handled inappropriately. Sources that are no longer in use are usually called "disused" or "spent" source.
- Disused sources are defined as sources that are no longer used and there is no intention of using them again in the practices they were authorized for.
- Spent sources (a subset of disused sources) are those that are no longer suitable for their intended purposes as a result of radioactive decay.
Even when a sealed source is no longer useful, it is still harmful to people and the environment because it continues to emit radiation.
If lost or not properly controlled, disused sealed sources can be a threat to human health and the environment. Exposure to large doses of radiation from an unshielded high activity source can be lethal or cause severe radiation injury. If the source capsule is damaged, the radioactive material can be released and dispersed, resulting in contamination to the environment.
Sources may cause harm when they are stolen and used for nefarious purposes, or when misplaced by those who are responsible for their care and storage. To prevent these things from happening, the IAEA has a number of publications that give specific technical instructions to governments, nuclear regulators, and users of sealed sources.
This document is written specifically for government agencies, the public, and medical and industrial sectors whose responsibility is to prevent accidents that result when organizations lose control of the sealed radioactive sources in their care. Readers will learn about how to spot a sealed radioactive source and how to reduce risks from sealed radioactive sources in industry, medicine, and metal recycling. It provides sound advice to first responders during a radiological emergency, and to border control officers who may come across radioactive sources being smuggled between countries. A good number of relevant photographs are given for easy understanding.
Worldwide, the number of sources that are considered disused is very large and warrants dedicated efforts for their management in a safe and secure manner (source: www.iaea.org).