Numerical investigation of fluid–solid interaction during debris bed formation based on MPS-DEM

The core may melt down and a debris bed with specific shape may be formed on the lower head of Reactor Pressure Vessel (RPV). The solid-to-solid collision has not been concerned thoroughly in the previous studies. In order to solve the problems of fluid–solid interaction and solid collision, the MPS-DEM code is developed based on Moving Particle Semi-implicit (MPS) method and Discrete Element Method (DEM). In this paper, the MPS models, DEM models are introduced, and the coupling method is validated by particle flow and collapse tests. Besides, the two-dimensional (2D) and three-dimensional (3D) simulations of the QUEOS-Q21 test are performed. The results of numerical simulation are in accordance with that of experiments, which indicates that the MPS-DEM method has the potential to be applied to study the movement characteristics of the debris particles during the debris bed formation without heat transfer, and has application prospect in the severe accident analysis.