Radioactive effluent releases from Rokkasho reprocessing plant (2). Liquid effluent

In Japan, Rokkasho Reprocessing Plant (RRP) is going to start the operation in service as the first large-scale commercial reprocessing plant of spent fuels which has annual reprocessing quantity of 800tUpr in maximum. RRP started active test with spent fuels on March 31, 2006. In the active test, the performance of reprocessing, removal of radioactive nuclides from gaseous and liquid effluent, and so on are verified. In this presentation, concerning liquid effluent is reported. When spent fuel assemblies are sheared and dissolved, radioactive liquid waste containing 3H and 129I is released to the sea. In order to limit the public dose as low as reasonably achievable, RRP removes radioactive materials by the help of filtering, evaporation, etc, and then releases liquid effluent through a maritime release pipe that allow to make dispersion and dilution very efficient. Concerning the radioactive liquid effluent to be released into the environment, the target values of annual release quantity have been defined in our Safety Rules based on the estimated annual release quantity at the design stage of RRP. By monitoring the radioactive material in effluent, RRP controls it not to exceed the target values in order to keep the public dose as low as reasonably achievable. RRP will reprocess 430 tUpr spent fuel (about 460 fuel assemblies for PWR, and about 1250 fuel assemblies for BWR) during active tests. The amounts of radioactive liquid waste during active test are evaluated to be less than the target values. In addition, public dose from external exposure and ingestion of marine food, influenced by RRP during active test is evaluated low sufficiently. (author)