Numerical simulation of anisotropic ablation of siliceous concrete - Analysis of CCI-3 MCCI experiment by MPS method

The molten corium-concrete interaction (MCCI) phenomenon was analyzed with the Moving Particle Semi-implicit (MPS) method by carrying out a numerical simulation of CCI-3 experiment. The interaction of the fully oxidized PWR core melts with a specially-designed two-dimensional siliceous concrete test section was analyzed, focusing on investigating the anisotropy in cavity ablation with siliceous concrete. The phase transition of the melt and the concrete was modeled based on a phase transition model for mixture. The effects of aggregates on the lateral and axial ablation were investigated by simulating two specially designed cases: one with aggregates in concrete and the other without aggregates in concrete. The simulation results by MPS method reproduced the anisotropic cavity ablation profile and the overall axial and lateral ablation rates agreed well with the experimental measures. The experimental and MPS results both indicated that the crust on the interface between the basemat and melt pool played an important part in axial concrete ablation process by hindering the axial ablation. The simulation results by MPS method also provided an evidence to support the theory that aggregates were the cause of anisotropic ablation profile in cavity with siliceous concrete because aggregates could delay the axial basemat ablation more significantly than the lateral one and influence the power split in the melt pool.