Radiation situation in the territory of the uranium legacy site in the Bambakai Valley (Transbaikal Territory)

The article presents the results of a study of the current radiation situation at the uranium legacy site located in the territory of the Bambakai Valley (Transbaikal Territory), formed in the period from 1973 to 1989 due to the discharge of mine water. During the radiation survey, the method of pedestrian gamma survey was used to measure the ambient dose equivalent rate. Soil sampling was carried out to study the radionuclide specific activities in the soil. The activity of gamma-emitting radionuclides in the samples was measured with a stationary gamma spectrometer. The activities of 210Po and 210Pb were measured after their radiochemical extraction from samples. It was found that the values of ambient dose equivalent rate in the territory of the valley varied over the wide range from 0.1 to 1.4 µSv/h in the areas under manmade contamination. The estimated average value of the gamma background for this place is 0.14±0.02 µSv/h. The specific activities of 238U, 226Ra, 235U, 210Pb and 210Po in the surface 10-cm soil layer at the site are from 10-40 times higher than the background values. The most part of radionuclides in the soil is in the acid-soluble form. Effective doses of the workers involved in hay harvesting in the area of the fallow land do not exceed 1.5 µSv/year. Doses of terrestrial environmental media (grass, earthworms) are 100 and more times lower than the safe level of exposure to biota.