Distribution of natural radionuclides in soils of Kaiga environ

The establishment of baseline data on natural radiation background and understanding of distribution and basic dynamics of primordial radionuclides in the environment of Kaiga, where two nuclear power reactors of capacity 235 MWe each are coming up, would be of great importance to assess the degree of impact on the environment. Employing standard radiochemical methods and nuclear techniques concentrations of 226Ra,210Pb,210 Po and 228Ra were measured in soil samples of Kaiga environ. A gas flow type low background beta counting system was installed to carry out the counting of the beta activity. An ZnS(Ag) alpha counting system of efficiency 30% was used to measure alpha activity. Activity ratios were evaluated using the measured concentration of radionuclides. The concentration of226Ra was found to vary from 3.18 to 21.58 Bq/kg, and that of228Ra from 5.16 to 17.86 Bq/kg. It was interesting to find that the concentrations of these two radionuclides were almost equal in soil samples of Kaiga environ. Also the concentration of 210Pb and 210Po was found to be significantly high in these samples. Further, 210Pb and 226Ra were found to be in disequilibrium. Implications of these findings are discussed and also compared with literature values reported for other environs. (author). 13 refs., 2 tabs