Assessment of radiological effects on the regional environment due to the operation of the Tokai Reprocessing Plant

The regional environmental radiological effects were assessed for the past 25-year operation of the Tokai Reprocessing Plant (TRP). The assessment was basically performed with the environmental radiological monitoring data around the TRP. For the environmental monitoring, various kinds of terrestrial and marine samples including air dust, surface soil, polished rice grain, leafy vegetable, milk, seawater, seabed sediments, fish, shellfish and seaweed were collected in the surrounding environment of the TRP. Radionuclides such as 3H, 14C, 90Sr, 137Cs and 239,240Pu in the environmental samples were determined by radiochemical methods. However, they showed no significant short-term increase or long-term accumulation of radionuclides discharged from the TRP. Therefore, the public dose was evaluated using the mathematical models and the discharge data of radionuclides. The estimated annual effective dose for the public was about 0.1% of the annual effective dose limit recommended by the ICRP. The assessment showed that there were no significant radiological effects on the environment and the public due to the 25-year operation of the TRP.