Distribution of plutonium as background in sediment at the Tokai offing

The Tokai Works of PNC is located in Tokai area facing the Pacific, in which a plutonium development laboratory and a fuel reprocessing plant are in operation. To monitor the effect of the liquid wastes released from the two facilities on the marine environment, the special survey of marine sediments was carried out, in addition to the routine environmental monitoring. The level and distribution of plutonium as actinide due to radioactive fallout, before reprocessing operation, is described. Plutonium concentration tends to be low in the south of Tokai and high in the north. The plutonium from fallout may be in the form of particles, and deposits on sediments and the vertical mixing of marine sediments may influence the plutonium concentration. The sea bed in the south is sandy, and in the north, silty. This is correspondent to the tendency of plutonium concentration. (J.P.N.)