Study on Factors Influencing the Diffusion and Migration of Radionuclide Offshore in Nuclear Power Plant Accidents

Studying the diffusion and migration mechanism of radionuclide in an offshore environment under accidental conditions of nuclear power stations is of great significance to emergency decision-making and nuclear accident mitigation. The migration mechanism of radionuclide in the ocean was studied. For the short-term situation, a multi-factor coupled model was established and the effects of turbulent diffusion, decay and adsorption sedimentation on the radionuclide concentration were analyzed. The results show that the radionuclide concentration decreases with turbulent diffusion. In the short-term, the decay of radionuclide has no effect on the concentration of 137Cs, but has a significant effect on the concentration of 131I. The maximum adsorption sedimentation rate of suspended matter to radionuclide is about 1%, which can be neglected in the short-term simulation and needs to be considered in the long-term simulation. The model can better simulate the variation of radionuclide concentration.