熔融物碎裂特性的MPS研究

Study on Molten Fuel Fragmentation Behaviors Using Moving Particle Semi-Implicit Method

在核反应堆堆芯融化事故中,熔融物液滴与液池的相互作用是严重事故中的重要现象,较难进行数值模拟。采用移动粒子半隐式(MPS)方法对熔融物冲击液池以及熔融物在液池中的碎裂过程进行数值模拟。结果表明:熔融物球在冲击液池过程中会迅速变得扁平,同时出现Rayleigh-Taylor(RT)不稳定性和边界层剥离现象。在碎裂初始阶段熔融物前沿的速度会迅速下降15%。熔融物碎裂行为的模拟结果与实验模拟结果符合较好,验证了MPS模拟熔融物行为的合理性。

In a core-melt nuclear reactor accident, the important phenomenon, the interaction between molten fuel and residual water, is difficult to simulate numerically. In the present study, MPS （Moving Particle Semi-implicit Method） is employed to simulate the molten fuel ball impacting liquid pool and its fragmentation behaviors during falling into the water pool and in the water tank. The simulation results indicate that during the impacting process, the molten fuel ball becomes flat and Rayleigh-Tayor instability occurred and the boundary layer stripped. In the initial phase, its velocity rapidly decreased about 15%. The results showed a good agreement with the picture observed in experiments, which verified the rationality of molten fuel behavior simulated using MPS.