Discharges of nuclear waste into the Kola Bay and its impact on human radiological doses

The civilian nuclear icebreaker facility, RTP “ATOMFLOT,” is located in Kola Bay, Northwest Russia, as are several nuclear installations operated by the Russian Northern Fleet. A treatment plant at the Atomflot facility discharges purified nuclear waste into the bay at an annual rate of 500 m3. As a result of plant modifications this rate will soon increase to 5000 m3/yr. Evidence of minor leakages of 60Co are reported by Matishov et al. (1999) in the vicinity of Atomflot as well as near several military installations in Kola and the adjacent Motovsky Bays. 137Cs levels reported in the present study for seawater and seaweed collected from locations within the bays are at expected levels except in the vicinity of Atomflot, where the 137Cs level in a seaweed sample was 46±5 Bq/kg w.w. indicating significant uptake of radionuclides to biota. Uptake also may be occurring in higher trophic levels of the food web through environmental exchange and/or biotransformation. We consider the impact of the present and anticipated discharges from Atomflot through a radiological dose assessment for humans consuming fish from Kola Bay. Mixing and transport of nuclear waste is simulated using a simple box model. Maximum doses, assuming consumption of 100 kg/yr of fish, are below 10−9 Sv/yr; the planned ten-fold increase in the discharge of treated waste will increase the doses to below 10−8 Sv/yr. Using data on radionuclide levels in sediments and assuming equilibrium partitioning of radionuclides among sediment, seawater and fish, we estimate that the total doses to humans consuming fish from different areas of Kola and Motovsky Bays, including adjacent to military-controlled nuclear installations, are ≈10−7 Sv/yr. Nuclear activities in Kola and Motovsky Bays thus far have had minimal impact on the environment. Discharges from the treatment plant currently account for less than 0.2% of the total dose predictions. The increase in discharges from the treatment plant is not expected to change significantly the relative importance of sources contributing to radiological doses related to human consumption of fish.