Research on radionuclide migration in coastal waters under nuclear leakage accident

In coastal waters, the phenomenon of migration and diffusion of radionuclides plays an important role in emergency decision-making and mitigation of accidents in the nuclear power plant. Based on Lagrangian and Euler methods, radionuclide diffusion models have been established for use in coastal waters of the nuclear power plant, respectively. The model resolution is 1′ × 1′ and the model reliability is verified. The principle of radionuclide migration has been analyzed. Studies are made on the influence of tidal currents and decay effect, on radionuclide concentration. Lagrangian results show that radionuclides advance by way of rotation due to the influence of semidiurnal tidal waves. Euler results show that radionuclides concentrate toward the shore during the high tide, and the radionuclide concentration is high. Radionuclides migrate toward the sea during the ebb tide, and the radionuclide concentration is low. The concentration of Cs-137 near the source can be reduced by an order of magnitude with one week. The radioactivity of I-131 is about 70% lower than that of Cs-137 after two weeks. It can provide theoretical basis for emergency measures.