Methodology of Internal Dose Reconstruction for A Russian Population after the Chernobyl Accident

Abstract

General methodology for reconstruction of the internal dose in groups of inhabitants of the Chernobyl accident area is considered, and practical techniques for reconstruction of the 131 I absorbed dose in thyroid and the effective doses of 137 Cs and 134 Cs radiation are examined. The techniques are based on the results of radiation monitoring performed since 1986 in the Bryansk, Tula, Orel and Kaluga regions of Russia. The WBC measurements of the thyroid or whole body provide the data most relevant to internal dose, and are of first priority for dose reconstruction. Radionuclide intake estimation with food products is considered as the second priority and application of radioecological models as the third priority when measurement data are absent. For the calculation of internal dose intake functions are suggested that describe both consequences of vegetation surface contamination with 131 I and 134,137 Cs in the early period and long-term radionuclide transfer via root systems. The first experimental data on the dependence of 131 I concentration in milk on time, and on density of soil contamination with 137 Cs in four regions of Russia are given. A strong connection between 131 I concentration in milk and thyroid dose in inhabitants based on 131 I in thyroid measurements is proved. Regularities revealed are used for thyroid dose reconstruction in Russian inhabitants. The results explain the phenomenon of the increased thyroid cancer morbidity in areas with low radioactive contamination.