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The purpose of this paper is to present (1) the method of assessing the contribution of short-lived radioiodines to the thyroid for members of the public in Fukushima and neighbouring prefectures based on available data and (2) the results of a realistic assessment of such a contribution. The estimates of that contribution for the inhalation intake that occurred on the day of the main fallout (15 March 2011) are within 15 % of the dose to the thyroid from 131I. The contribution to the thyroid dose from intake of 132Te is higher than that from the intake of 133I by a factor of ~3. The contribution of short-lived radioiodines to the thyroid dose for the public in the case of inhalation intake occurring as early as March 12 might be as great as 30-40 %. [ABSTRACT FROM AUTHOR]

Aim. A detail consideration has been done to assess an importance of the contribution of gamma-emission of incorporated cesium radioisotopes to the exposure rate measured near the thyroid by the public survey for following the Chernobyl accident. Empirical ratios have been derived to take into account that contribution under interpretation of the results of survey meter monitoring of the public. Materials and methods. Model calculations for typical radionuclide intake by the residents living in contaminated territories after the Chernobyl accident have been carried out in order to assess the contribution of gamma-emission of incorporated cesium radioisotopes to the exposure rate measured near the thyroid by the survey. Under such calculations two the most important modes of intake have been considered: 1) inhalation and 2) ingestion with cow milk. Results. According to the estimates received the contribution of gamma-emission of incorporated cesium radioisotopes to the exposure rate measured near the thyroid during the first 20 days does not exceed 20% for the residents of southern areas of Gomel region and 30% for the residents of Mogil'yov region. During 60 days following the accident that contribution is estimated to be within (50-80) % for the residents of southern areas of Gomel region and (80-95) % for the residents of Mogil'yov region. Conclusion. For the period of intensive thyroid measuring in the southern areas of Gomel region (the second part of May) account of the contribution of gamma-emission of incorporated cesium radioisotopes is relatively unimportant, but for Mogil'yov region (the end of May) — it is important to account for. For the thyroid measurements conducted in June of 1986 it is important for all residents living in Belarus to take into account the contribution of gamma-emission of incorporated cesium radioisotopes.

Assessment of committed effective dose and the uncertainty of its calculation for different variants of 3H intake: 1) homogeneous and chronic, 2) single, is considered by the example of internal tritium doses that workers had got. It has been shown that in case of conditional measurement of 3H concentration in urine sample the estimate of tritium dose may vary within two orders of magnitude in the 95% confidence interval. The most effective way to reduce the range of uncertainty of dose estimation is to replace a quarterly monitoring with a monthly one. It leads to reduction of the range of uncertainty by one order of magnitude.

For correct assessment of health risks after low-dose irradiation, calculation of radiation exposure estimates is crucial. To verify the calculated absorbed doses, instrumental methods of retrospective dosimetry are used. We compared calculated and instrumental-based estimates of external absorbed doses in the residents of Dolon, Mostik and Cheremushki villages, Kazakhstan, affected by the first nuclear weapon test performed at the Semipalatinsk Nuclear Test Site (SNTS) on August 29, 1949. The 'instrumental' doses were retrospectively estimated using the Luminescence Retrospective Dosimetry (LRD) and Electron Spin Resonance (ESR) methods. Correlation between the calculated individual cumulative external absorbed whole-body doses based on typical input data and ESR-based individual doses in the same people was strong (r = 0.782). It was even stronger between the calculated doses based on individual questionnaires' input data and the ESR-based doses (r = 0.940). Application of the LRD method is useful for validation of the calculated settlement-average cumulated external absorbed dose to air. Reconstruction of external exposure can be supplemented with the data from later measurements of soil contamination with long-lived radionuclides, such as, 137Cs. Our results show the reliability of the calculational method used for the retrospective assessment of individual external doses., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Abstract: In recent years, the prospects that a nuclear device might be detonated due to a regional or global political conflict, by violation of present nuclear weapons test ban agreements, or due to an act of terrorism, has increased. Thus, the need exists for a well conceptualized, well described, and internally consistent methodology for dose estimation that takes full advantage of the experience gained over the last 70 y in both measurement technology and dose assessment methodology. Here, the models, rationale, and data needed for a detailed state-of-the-art dose assessment for exposure to radioactive fallout from nuclear detonations discussed in five companion papers are summarized. These five papers present methods and data for estimating radionuclide deposition of fallout radionuclides, internal and external dose from the deposited fallout, and discussion of the uncertainties in the assessed doses. In addition, this paper includes a brief discussion of secondary issues related to assessments of radiation dose from fallout. The intention of this work is to provide a usable and consistent methodology for both prospective and retrospective assessments of exposure from radioactive fallout from a nuclear detonation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government.)

Abstract: A methodology of assessment of the doses from external irradiation resulting from the ground deposition of radioactive debris (fallout) from a nuclear detonation is proposed in this paper. The input data used to apply this methodology for a particular location are the outdoor exposure rate at any time after deposition of fallout and the time-of-arrival of fallout, as indicated and discussed in a companion paper titled "A Method for Estimating the Deposition Density of Fallout on the Ground and on Vegetation from a Low-yield Low-altitude Nuclear Detonation." Example doses are estimated for several age categories and for all radiosensitive organs and tissues identified in the most recent ICRP publications. Doses are calculated for the first year after the detonation, when more than 90% of the external dose is delivered for populations close to the detonation site over a time period of 70 y, which is intended to represent the lifetime dose. Modeled doses in their simplest form assume no environmental remediation, though modifications can be introduced. Two types of dose assessment are considered: (1) initial, for a rapid but only approximate dose estimation soon after the nuclear detonation; and (2) improved, for a later, more accurate, dose assessment following the analysis of post-detonation measurements of radiation exposure and fallout deposition and the access of information on the lifestyle of the exposed population., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government.)

Abstract: This paper describes a relatively simple model developed from observations of local fallout from US and USSR nuclear tests that allows reasonable estimates to be made of the deposition density (activity per unit area) on both the ground and on vegetation for each radionuclide of interest produced in a nuclear fission detonation as a function of location and time after the explosion. In addition to accounting for decay rate and in-growth of radionuclides, the model accounts for the fractionation (modification of the relative activity of various fission and activation products in fallout relative to that produced in the explosion) that results from differences in the condensation temperatures of the various fission and activation products produced in the explosion. The proposed methodology can be used to estimate the deposition density of all fallout radionuclides produced in a low yield, low altitude fission detonation that contribute significantly to dose. The method requires only data from post-detonation measurements of exposure rate (or beta or a specific nuclide activity) and fallout time-of-arrival. These deposition-density estimates allow retrospective as well as rapid prospective estimates to be made of both external and internal radiation exposure to downwind populations living within a few hundred kilometers of ground zero, as described in the companion papers in this volume., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government.)

The estimation of the thyroid doses received in Belarus after the Chernobyl accident is based on the analysis of exposure-rate measurements performed with radiation detectors placed against the necks of about 130,000 residents. The purpose of these measurements was to estimate the 131 I activity contents of the thyroids of the subjects. However, because the radiation detectors were not equipped with collimators and because the subjects usually wore contaminated clothes, among other factors, the radiation signal included, in addition to the gamma rays emitted during the decay of the 131 I activity present in the thyroid, contributions from external contamination of the skin and clothes and internal contamination of organs other than the thyroid by various radionuclides. The assessment of the contributions of the external and internal contamination of the body to the radiation signal is divided into two parts: (1) the estimation of the radionuclide activities deposited on, and incorporated in, various parts of the body, and (2) the responses of the radiation detectors to the gamma rays emitted by the radionuclides deposited on, and incorporated in, various parts of the body. The first part, which is presented in this paper, includes a variety of exposure scenarios, models, and calculations for 17 of the most abundant gamma-emitting radionuclides contributing to the thyroid detector signal, while the second part is presented in a companion paper. The results presented in the two papers were combined to calculate the contributions of the external and internal contamination of the body to the radiation signal, and, in turn, the 131 I activities in the thyroids of all subjects of an epidemiologic study of thyroid cancer and other thyroid diseases among 11,732 Belarusian-American cohort members who were exposed in childhood and adolescence.