Environmental radioactivity in Caithness and Sutherland: Pt. 11

The aims of this study were (i) to assess the applicability of a National Radiological Protection Board (NRPB) foodchain model to the Caithness and Sutherland area, and (ii) to determine the contribution of different radionuclide sources to activities in measured total deposition in the same region. The NRPB model predicts the movement of radionuclides through the foodchain, and in this study was validated by comparing model outputs with measured crop data (ryegrass and clover). Five radionuclides (137Cs, 90Sr, 239+240Pu, 238Pu, 241Am) were considered at 5 field plot sites in Caithness and Sutherland. The predictive ability of the model varied between radionuclides, and the success of the comparison depended to some extent on the quality of the measured field data. This study also considered the contribution of different radionuclide sources to activities in total deposition. The potential sources were divided into three categories, Dounreay stack inputs, sea-to-land transfer, and the combined contribution from nuclear weapons testing and Chernobyl fallout. (author)