多维熔融物与冷却剂相互作用分析程序COSMETRIC的开发与验证

基于MCBA-SIMPLE算法开发了自主化的多维熔融物与冷却剂相互作用分析程序COSMETRIC。为验证该程序，针对熔融物与冷却剂相互作用实验KROTOS的典型工况进行了模拟计算。通过与KROTOS37实验结果对比，验证了程序模拟高温熔融物与冷却剂混合过程中熔融物液柱碎化、熔融物液滴迁移以及冷却剂蒸发的能力；通过与KROTOS21实验结果对比，验证了程序对蒸汽爆炸压力脉冲峰值及传播速度预测的合理性。在此基础上，对KROTOS21爆炸工况计算的初始空泡份额、熔滴水力学碎化无量纲时间和熔融物碎片初始直径等参数进行了敏感性分析，评估了这些参数对最终压力脉冲的影响。敏感性分析结果发现，较大的初始空泡份额会抑制压力峰值和传播速度；增大熔融物碎片初始直径和水力学碎化无量纲时间，会提升压力波传播速度，降低压力峰值。

Development and Validation of Multidimensional Fuel and Coolant Interaction Analysis Code COSMETRIC

The fuel-coolant interaction analysis code COSMETRIC was developed based on MCBA-SIMPLE algorithm. The code was validated against the representative test cases of KROTOS facility. Comparison between the simulation and KROTOS37 experiment results shows that the code is competent to simulate the corium melt fragmentation and drastic evaporation of coolant during the premixing phase. The code also proves to be reliable to predict the amplitude of peak pressure and propagation speed of pressure shock in explosion phase through comparison with the KROTOS21 test results. Sensitivity analysis was carried out to further evaluate the influence of the initial void fraction, the dimensionless time scale in the hydrodynamic fragmentation model and the initial fragment size on the magnitude of pressure shock. It is found that lager initial void fraction leads to lower pressure shock and slower propagation speed, while the increased initial fragment size and dimensionless time scale can reduce pressure magnitude but increase the propagation speed.