Dispersion and accumulation of radionuclide in sediment of Urazoko Bay, 2

Further studies on the transport in sea water and accumulation in marine sediment of the radionuclides, released from a nuclear power plant, on Urazoko Bay, Fukui Prefecture were reported. The partition of radionuclides among the particle size fractions of a sediment sample indicated that the accumulation of 60Co, 137Cs and 54Mn in the sediment were dominated substantially by the sorption on the particle surface in sea water, and the patterns of their sorption were considerably similar to each other. In regard to the 60Co contamination of marine sediments in an area of about 13 km2 around the nuclear power plant, 60% of the 60Co contamination were retained in Urazoko Bay, which occupies only 7% of the bottom surface of the region. It is clear that a part of 60Co accumulated in the sediment of Urazoko Bay gradually moved to the outerward. (auth.)