Marine environmental assessment system of radionuclides around Japan

Kobayashi, Takuya ; Togawa, Orihiko 

A marine environmental assessment system STEAMER is developing for predicting the short-term (30days) dispersion and assessing the collective dose to the Japanese population due to radionuclides released to the ocean. The computer code system for short-term predictions of radionuclide dispersion is a combination of the Princeton Ocean Model (POM) for predicting ocean currents and a particle random walk model SEA-GEARN for oceanic dispersion of dissolved radionuclides. The system has been applied to a hypothetical accident of a nuclear submarine if it sinks in an offshore region around Japan, by using measured currents, temperature, salinity and meteorological regional objective analysis data (RANAL). Another computer code system DSOCEAN is also applied to the same hypothetical accident in order to compare the results of radionuclide dispersion in the ocean and the collective dose to the Japanese population. An equidistant-grid compartment model combined with a model of the geostrophic current analysis is used in DSOCEAN.