ACTIVITY CONCENTRATION OF RADIONUCLIDE AND EXTERNAL DOSE RATE IN BOTTOM DEPOSITS OF BRIT LAKE IN THE CHОRNOBYL EXCLUSION ZONE

Abstract

The profiles of the vertical distribution of the gamma dose rate and activity concentrations of 90Sr, 137Cs, 154Eu, and 241Am in the bottom sediments of Brit Lake were obtained. The lake is located within the dammed section of the Krasnenska floodplain of the Pripyat River in the Chоrnobyl Exclusion Zone (51.44844°; 30.06020°). The values of the dose rate and activity concentration of 137Cs in the sediments reached 23 μGy h−1 and 43 Bq∙cm−3. In the lake Brit radioactive contamination of bottom sediments did not depend on the depth of the lake due to the washing of radionuclides from the water intake. A weak correlation was observed between values of in-situ measured and calculated gamma dose rates in bottom sediments. The average calculated and measured dose rates of gamma radiation in bottom sediments of the lake varied within the range of 1.3-19 μGy h−1 and was compatible with the internal radiation dose to fish (5-15 μGy h−1). Contribution of radionuclide content in water to the gamma dose rate does not exceed 2 nGy h−1. In October 2021, appropriate equipment for acoustic 3-D telemetry and individual dosimetry of various fish species was installed in the lake to reduce uncertainty in estimates of doses of external exposure to aboriginal fish in the lakes