Development of method to calculate concentration of radionuclides in the ocean by ocean general circulation model

The sea transportation of the fresh MOX fuel is planned from Europe to Japan through the several routes on the world ocean. The purpose of this study is to develop a new assessment method and to conduct a case study, in which concentration of radionuclides in the ocean is evaluated due to the hypothetically submerged fresh MOX fuel into the deep ocean. The three-dimensional ocean general circulation model (NCAR Ocean model) is newly employed for the assessment method to calculate concentration of the radionuclides released from the submerged package. The calculated results by this method are in good agreement with the previous observational data of the anthropogenic radionuclides (137Cs, 90Sr and 239,240Pu) in the ocean. These radionuclides were released to the environment and injected to the ocean as fallout by the atmospheric nuclear bomb testings from 1945 to 1980s. For a case study, this method was applied to evaluate the concentration of radionuclides due to a hypothetical accident of transportation of fresh MOX fuel, and it is concluded that this methods is effective for this kind of applications. (author)