Agroclimatical model for estimation of radionuclides transport along food chains and internal doses of the population

The authors have developed an agroclimatical model for estimating radionuclides transport along food chains and internal doses for the population in case of a radiation accident. The model accounts for the key factors influencing formation of internal doses: weather conditions in the year of the accident, dynamics of growth and development of agricultural crops, agricultural practices, features of fodder storage and consumption by cattle, diet of city dwellers and rural population. The main principles and relations of the proposed model are presented. The effect of deposition date on integral intake of 131l and 137Cs by city and rural population have been estimated for the agroclimatical conditions of the south of Bryansk region in 1986. It is shown that the agricultural practice and cattle diet have a major effect on integral intake of 137Cs by humans. For integral intake of 131l the model gives the expected result: with depositions in the spring-summer period the major contribution to milk contamination is made by pasture vegetation and the integral intake of 131l by humans is determined by milk consumption. The calculation results suggest that for depositions in April-May, when the pasture vegetation was growing vigorously, the value of the internal dose is significantly dependent on weather conditions. In addition to estimation of 131l internal thyroid dose the developed approach makes possibly to estimate mean effective 131l contamination density around a population points based on results of individual thyroid radiometry. Comparison of the 131l intake by thyroid in residents estimated by three different models using data of direct thyroid radiometry shows that on the one hand, they are close and on the other, there is significant difference in 131l effective contamination density reconstructed from radiometric results.