ANALYSIS OF THE LONG-TERM DYNAMICS OF EXTERNAL DOSES OF THE POPULATION AFTER THE CHERNOBYL ACCIDENT

Abstract

The paper presents an analysis of the dynamics of individual doses of external exposure among the population living for almost 20 years in the territories affected by the radioactive contamination due to the Chernobyl NPP accident. The dynamics of the average effective dose of the external exposure of the inhabitants in the period of 5 to 20 years after the Chernobyl fallout is well described by processes that consider the radioactive decay of cesium radionuclides and their natural migration. The distribution of individual doses of external exposure among residents, normalized to the average dose in the settlement corresponds to a logarithmically normal law with the time-stable parameters: the geometric mean ~ 0.9 and geometric standard deviation ~ 1.5, which allows, in particular, predicting the dose for the critical group of population or for a representative person. Comparison of the mean effective doses of external exposure of the settlement residents estimated based on the results of two different measurement technologies (using TLD-method and measurements of dose rates in air in various settlement locations) indicated their good agreement for the 17 years period after the fallout. For two settlements, where measurements were performed in 2003, the relative differences in mean effective doses did not exceed 12%. It allows using the previously developed model of external exposure for dose estimation to the population residing on the territories contaminated after the Chernobyl accident.