NUMERICAL SIMULATION OF MELT SPREADING USING MODIFIED MOVING PARTICLE SEMI-IMPLICIT METHOD

Abstract

Predicting the behavior of molten corium under reactor pressure vessel (RPV) failure has been receiving attention in recent nuclear research field. Lagrangian based computational fluid dynamics (CFD) calculation is considered as an appropriate numerical method to calculate molten corium behavior whose solidification behavior is unable to be simulated in typical Eulerian CFD method. The additional methodology for detailed computational simulation about thermal behavior must be developed to interpret various phenomena because original Lagrangian CFD calculation can only compute fluid dynamics without thermal calculation. Thus, a heat transfer and solidification module of the Moving particle Semi-implicit (MPS) Method was developed in this study. Developed modules were modeled including computation of the phase change and metal oxidation, surface tension of various metal particles to calculate spreading of molten metal and crust formation, gas generation phenomena. Especially, solid-liquid transition and change of hydrodynamic properties, radiation heat transfer, and chemical reaction should be included in the modules to calculate over a wide range of temperature from 200 K to 3000 K. In order to validate the developed modules, melt spreading behavior including solidification behavior of molten metal was calculated to benchmark FARO L26S experiment which analyzed behavior of mixture of molten uranium oxide and zirconium oxide as candidate for benchmark. The comparative data between the experimental and computational results showed a good agreement with little difference in a mass and range of crust formation, a length of front edge and spreading area.