Saratov JOURNAL of Medical and Scientific Research

Gavrilin Y.I.

State Scientific Research Center n.a. A.I. Burnasyan — Federal Medical Biophysical Center of Federal Medical Biological Agency, Senior Research Scientist, Candidate of Technical Sciences

Estimation of the contribution of gamma-emission of incorporated cesium radioisotopes in interpretation of the results of the public survey to assess the thyroidal iodine content following a radiation accident at the nuclear power plant

Summary:

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.

AttachmentSize
2014_04-01_800-804.pdf1.02 MB

Accounting of 131l decomposition under retrospective assessment of its deposition on the basis of determination of 129l deposition

Year: 2013, volume 9 Issue: №4 Pages: 802-805
Heading: Hygiene Article type: Short message
Authors: Gavrilin Yu.l., Margulis U. Ya., Androsova A.A.
Organization: State Scientific Research Center n.a. A.I. Burnasyan — Federal Medical Biophysical Center of Federal Medical Biological Agency
Summary:

It is known that after the Chernobyl accident on the territories with deposition density of 137Cs less than 3.7x10" Bq/kg insufficient number of direct thyroid measurements for the public and a limited number of the spectrometrical measurements of 131l in soil were conducted. At the same time, in the case of availability of representative number of the estimates of the 131l ground deposition density for the territory under consideration, reliable estimates of the average dose to the thyroid for the public in a given settlement can be derived, for example for an adult population with further assessment of the doses for the residents of the other age-groups. In this regard, reconstruction of the ground deposition density of 131l (during the significant period of thyroid dose formation) on the basis of the determination of the ground deposition density of 129l is very helpful for reconstruction of the estimates of the thyroid dose for the residents of the settlements, for which the estimates of the 137Cs deposition density are available. However, to find a solution was necessary to resolve a specific but important task that distinguished from 129l (half-life is equal to 1.6x107 years) the level of 131l (half-life is equal to 8.04 days) was substantially decreasing during the period of thyroid dose formation. The
given article aimed a justification of approaches to account of radioactive decay of 131l in the course of determination of its ground deposition density on the basis of determination of the ground deposition density of 129l at the late stage after the accident.

AttachmentSize
2013_04-01_802-805.pdf448.07 KB