A post-Chernobyl survey of radionuclides in Wales, August-October 1986

Following reports of fallout over Western Europe after the Chernobyl accident, measurements have been made of increases in Cs-134 and Cs-137 in soils from a grid network of 27 permanent grassland reference sites throughout Wales. This sampling grid was established in 1984 to provide baseline measurements of the accumulated deposition of radionuclides. In addition, at 9 selected locations in the survey grid, sampling of arable soils, hay, barley, wheat and potatoes has been repeated to assess the increases in caesium. In a limited number of soil and/or grass samples, Sr-90 and plutonium have been analysed, and radioactive caesium has been measured in sewage. The main objective of the survey is to establish the extent of radionuclide accumulations in soil and crops at the present time, from both weapons fallout (pre-Chernobyl) and the recent accidental release from the USSR. The survey will provide information to assess the significance of the current levels of radionuclides in soil and crops by reference to generalised derived limits (GDL's) for radiological assessment. Analysis of hay, barley, wheat and potato crops shows regional differences in Cs-137 content that are related to the levels of Chernobyl fallout established by the grassland grid survey. The concentrations in crops are below 3% of the generalised derived limits except for hay where 23% of the GDL is found in north-west Wales. (author)