Radioecological impact from radionuclide releases into the rivers

Absract. The radiological impacts from radionuclide releases into Techa, and Yenisei Rivers in Russia are discussed. The dose assessments for human and natural biota are calculated using the methodology of multiple pathways of exposure. In the Mayak complex area the collective dose to the Techa River population during 19491956 was 6,200 man-Sv. The collective dose from radioactive discharges of the Krasnoyarsk complex into Yenisei River during the period 1958-1991 was about 1,200 man-Sv. A major contributor to this dose was consumption of the fish from Yenisei River (about 70 %). The doses to the natural biota are considerably higher than those to humans by a factor of 10-1000. This difference is most pronounced in the periods of significant radioactive releases. Especially high levels of exposure to biota were demonstrated for Techa River in the period of maximum discharges of radionuclides. A dose rate level of 10 mGy/day to natural biota was exceeded.