In the present study, the cavity module of the MELCOR code is used for the simulation of molten corium concrete interaction (MCCI) during the late phase of postulated large break loss of coolant (LB-LOCA) accident in the APR1400 reactor design. Using the molten corium composition data from previous MELCOR Simulation of APR1400 under LB-LOCA accident, the ex-vessel phases of the accident sequences with long-term MCCI are recalculated with stand-alone cavity package of the MELCOR code to investigate the impact of water ingression and melt eruption models which were hitherto absent in MELCOR code. Significant changes in the MCCI behaviors in terms of the heat transfer rates, amount of gases released, and maximum cavity ablation depths are observed and reported in this study. Most especially, the incorporation of these models in the new release of MELCOR code has led to the reduction of the maximum ablation depth in radial and axial directions by ∼38% and ∼32%, respectively. These impacts are substantial enough to change the conclusions earlier reached by researchers who had used the older versions of the MELCOR code for their studies. and it could also impact the estimated cost of the severe accident mitigation system in the APR1400 reactor.

在本研究中，MELCOR 程序的空腔模块用于模拟 APR1400 反应堆设计中假设的大破裂冷却剂损失 (LB-LOCA) 事故的后期阶段的熔融皮质混凝土相互作用 (MCCI)。使用先前 MELCOR 模拟 APR1400 在 LB-LOCA 事故下的熔融真皮成分数据，使用 MELCOR 代码的独立腔包重新计算具有长期 MCCI 的事故序列的船外阶段，以研究水的影响MELCOR 代码中迄今没有的侵入和熔体喷发模型。在本研究中观察并报告了 MCCI 行为在传热率、释放的气体量和最大腔体烧蚀深度方面的显着变化。最特别的是，这些模型在新版 MELCOR 代码中的结合导致径向和轴向的最大烧蚀深度分别减少了 38% 和 32%。这些影响足以改变使用旧版 MELCOR 代码进行研究的研究人员早先得出的结论。它还可能影响 APR1400 反应堆中严重事故缓解系统的估计成本。