Radioecological modeling of specific volume activities of I-131 and Cs-137 in the atmosphere of polluted regions of Russia after the Chernobyl accident

The dynamic radioecological model and the database of the IAEA EMRAS project, a method for reconstructing the specific volume activity of I-131 in the atmosphere over the areas affected by the Chernobyl accident was developed and put into practice. This method made it possible to significantly reduce the values indicated in the reference database of radioecological data by about 2-2.5 times. Two variants of the specific activity of Cs-137 and I-131 in the atmosphere were reconstructed: a) according to the minimum density of radioactive fallout and according to "dry" fallout in areas and settlements; b) according to the reconstruction results, almost complete compliance is noted, with an accuracy of up to 5% with a standard geometric mean deviation of 1.5. The results of calculations of the minimum pollution densities of Cs-137 and I-131 in districts and settlements showed good agreement with the reference data. The average values of the ratios of calculated data to reference data ranged from 0.97 to 1.3, the ratios of standard deviations ranged from 1.7 to 2.3. The effective precipitation recovered during the period of major radioactive fallout in populated areas was compared with the specific volume activities of Cs-137 and I-131 in the atmosphere and the density of their precipitation typical for these areas. As a result of the study, a complete set of interrelated initial data was formed, necessary for studying the dynamics of the distribution of radionuclides along the trophic chain within the framework of the calculated radioecological model.