A laboratory study of 239,240Pu, 241Am and 243,244Cm depuration by edible winkles ( Littorina littorea L.) from the Cumbrian Coast (NE Irish Sea) radiolabelled by the Sellafield discharges

Abstract

The depuration of 239,240Pu, 241Am and 243,244Cm from edible winkles labelled by the radioactive liquid waste discharges from Sellafield have been measured under laboratory conditions. Monthly samples of winkles were collected from a beach near Sellafield over a year. Each monthly batch was transferred to Lowestoft and was depurated in uncontaminated seawater for up to seven weeks. Depuration of all three radionuclides was initially rapid and similar and could be described by a mathematical two compartment model. The biological half-time for the initial elimination was about one to two days and accounted for about 70 to 90% of the activity within the winkles when collected. Further depuration losses had biological half-times ranging from about 30 to 900 days depending on radionuclide and time of year. The estimated radionuclide assimilated fractions for winkle flesh ranged from 5 to 40% of the activity content when collected. Although the biological half-times for depuration of the assimilated activity varied by month for all three radionuclides, there was no clear pattern of change with water temperature. The study results suggest that depuration of winkles before cooking would reduce their 239,240Pu, 241Am and 243,244Cm activity content by about 40 to 50% resulting in a significant reduction in the internal radiological dose for consumers.