Radionuclide depositional history in the Solway Firth, U.K

The BNFL nuclear reprocessing plant at Sellafield in West Cumbria has discharged liquid radionuclide effluent into the Irish Sea since 1952. This contamination is incorporated into the sediment pool of the Irish Sea and is transported to the intertidal areas, where radiation doses can be received by members of the public. This study considers the variation in radionuclide distributions (137Cs and 241Am ) in one large area of salt-marsh at the head of the Solway Firth. The ratios of radionuclides between the terraces are compared to the decay corrected time integrated ratios of discharge from Sellafield, following on from which the terraces are grouped into four categories in accordance with the variation in rates of sedimentation. The total inventory of 137Cs and 241Am in three marshes is presented, and the activity per unit area between them is constant, at 0.16 - 0.17 TBq km-2. This implies that since Sellafield discharges began the net rate of sedimentation has been constant, even though on a marsh-wide scale variations can be discerned. (author)