Radionuclides distribution in artificial reservoir V-17 (old swamp)

Reservoir V-17 (Old Swamp) was formed as a result of the construction of dams in 1952 and 1954 (MAYAK Production Association),located in a natural depression relief. Intermediate level liquid radioactive wastes (ILLW) have been discharged to this reservoir since 1949. The water surface area of the lake is 0.13 km2 with the volume of 0.36 Mm3. The maximum depth is 6.5 m with the average value of 2.8 m. Among 74 PBq deposited to the reservoir, the major portion is concentrated in the bottom sediments (as determined in 2007). The aim of this study is to determine radionuclide distribution among abiotic and biotic aquatic components, that includes study of various radionuclides distribution between water and bottom sediments, their speciation and evaluation of condition of zooplankton community. As a result of field research at the reservoir, 4 sampling locations were chosen from which bottom sediments, water samples and some hydrobionts were collected. Pore waters were separated from the wet sediments by high-speed centrifugation. All samples were analyzed by gamma spectrometry using HPGe detector Canberra GR 3818.The radioactivity of tritium in the pore and lake waters was determined by liquid-scintillation spectrometry. The strontium-90 was detected by Cherenkov counting of the daughter 90Y. The preliminary data show for sediments samples: for 137Cs amount varies from 75,5 KBq/g to 232 KBq/g, 154Eu - from 460 to 990 Bq/g, 241Am - from 1 to 4 KBq/g, 134Cs - from 50 to 220 Bq/g; for water samples: large contribution from strontium-90 and tritium (varies from 2 to 25 Bq/g). Pore water contains medium amount of radionuclides between sediments and water samples. For 137Cs varies between 160 to 1100 Bq/g, 154Eu - from 0,1 to 0,3 Bq/g, 241Am - from 0,3 to 11 Bq/g, 134Cs - from 0,1 to 1,7 Bq/g. Variation depends on the sampling place. Activity distribution among hydrobionts was studied by digital Radiography using Imaging Plate. First results shows un-uniform distribution of radionuclides on the hydrobionts bodies. Also showing some radioactive particles, that stick to the hydrobionts surface. Document available in abstract form only. (authors)