Mobility of radionuclides in the Irish Sea sediments

The Sellafield reprocessing plant is one of the major sources contributing to fission products to the Arctic Sea. According to recent assessments, a total of 41PBq137Cs and 6.2PBq90Sr has been discharged into the Irish Sea since the 1960s. The object of the present work was to study mobilization of Cs-isotopes and 90Sr from contaminated Irish Sea sediments, and to obtain kinetic information on water-sediment interactions. The conclusion of the present paper is that the concentration of 137Cs and 90Sr in waters and sediment collected close to Sellafield effluent outlet is very high compared to other marine systems. 137Cs is strongly fixed to inert sediment fractions, while 90Sr is mobile. The Irish Sea sediments may act as a sink for 137Cs released from Sellafield today. Irish Sea sediments represent also a potential diffuse source for the release of 90Sr present as mobile exchangeable spicies to the water phase. 5 refs., 6 figs