Three-dimensional numerical simulation of the HECLA-4 transient MCCI experiment by improved MPS method

•The explicit pressure model was incorporated into MPS code to enhance computational speed.•3-D simulation of a MCCI test was presented with improved MPS method.•The phenomenology of MCCI progression was revealed by improved MPS method. The molten corium-concrete interaction (MCCI) is an important phenomenon after the failure of pressure vessel in a severe accident of nuclear reactor. It has been verified that the original Moving Particle Semi-implicit (MPS) method has the capacity to simulate some MCCI experiments. In this study, the original MPS method has been improved by including the explicit pressure calculation model to reduce the computational cost and enhance the computational speed. Then, the improved MPS method was validated by simulating the classical dam break problem, and the results agreed well with that of the original MPS method. Afterwards, the HECLA-4 transient MCCI test performed by VTT was simulated by the improved MPS method with a three dimensional particle configuration of about one million particles. The basemat and sidewall ablation fronts, melt pool temperature and concrete temperature at different positions predicted by MPS were in good agreement with the experimental results. All the above-mentioned simulations proved that MPS method using explicit pressure model is capable of simulating MCCI and related heat and mass transfer in multicomponent phase flow.