Moving particle semi-implicit simulation on the molten Wood’s metal downward relocation process

In the case of a severe accident involving nuclear reactors, an important aspect that should be considered is the leakage of molten material from the inside of the reactor into the environment. These molten materials damage other reactor components, such as electrical tubes, grid plates and core catchers. In this study, the moving particle semi-implicit (MPS) method is adopted and improved to analyze the two-dimensional downward relocation process of molten Wood’s metal as a representation of molten material in a nuclear reactor. The molten material impinges the Wood’s metal plate (WMP), which is mounted on a rigid dummy stainless steel in a cylindrical test vessel. The breaching process occurs because of heat transfer between the molten material and WMP. The formed breach areas were in good agreement with the experimental results, and they showed that the molten Wood’s metal spread above the WMP. The solid WMP fraction decreased with time until it reached the termination time of the simulation. The present results show that the MPS method can be applied to simulate and analyze the downward relocation process of molten material in the grid plate of a nuclear reactor.