PHEBUS FPT0~FPT2实验堆芯降级过程数值模拟

严重事故下，由于堆芯冷却剂丧失引起的堆芯裸露、过热和熔化过程对后期安全壳完整性、裂变产物行为等具有重要影响。法国辐射防护与核安全研究所主导的PHEBUS-FP研究项目旨在研究轻水堆严重事故下堆芯降级过程以及裂变产物行为。本文使用ATHLET-CD程序对PHEBUS-FP中的FPT0、FPT1和FPT2进行建模计算，主要分析堆芯过热，包壳氧化，堆内材料熔化、迁移及再定位过程。计算结果表明：不同蒸汽流量、不同加热功率将导致不同堆芯降级进程，在趋势上计算值与实验值吻合；模型的限制导致了部分计算值的偏差，本文讨论了包壳氧化与燃料再定位现象中的模型参数。

Numerical Simulation of Core Degradation Process in PHEBUS FPT0-FPT2 Experiment

The core degradation that results from loss of coolant, including core heat-up, cladding oxidation, and fuel damage and relocation, plays an important role on the integrity of containment and the behavior of fission products. The PHEBUS-FP program has been conducted by the French Institute de Radioprotection et de Sûreté Nucléaire (IRSN), studying the core degradation process and the behavior of fission product. PHEBUS FPT0, FPT1 and FPT2 were simulated using ATHLET-CD code in this paper, focusing on core heat-up, cladding oxidation, and fuel damage and relocation. The results indicate that different steam flows and different heating powers will lead to different core degradation processes, which are in good agreement with experimental data in tendency. And the model parameters in cladding oxidation and fuel relocation were analyzed to discuss the discrepancy of calculation results.