Since the accident in the Fukushima Daichii Nuclear Power plant specific attention has been paid to the analyses and possible mitigation of severe accidents, as well as to design extension conditions. There is also a growing interest in applying not only the so-called best estimate codes to evaluate the postulated severe accident sequences, but to complement these studies with uncertainty analyses. The Phébus FP (Fission Product) research program, conducted by IRSN and CEA, aimed to study the physical phenomena that govern core degradation as well as, the release, transfer, and deposition of fission products and their behaviour in the containment. In this paper the degradation phase of the Phébus FPT3 experiment is modelled and simulated with the help of the best estimate system code ATHLET-CD 3.2, the core degradation module of AC². The study is complemented by an uncertainty analysis as well, applying the so-called GRS method. The paper considers uncertain model (e.g. parameters concerning Zr oxidation) as well as experimental (e.g. material properties) parameters and determines the 95/95 tolerance limits for the main figures of merit. Furthermore, a sensitivity analysis is performed, and the Spearman’s rank correlation coefficient is determined for each uncertain input parameter.

自福岛第一核电站事故以来，特别关注严重事故的分析和可能的缓解措施，以及设计扩展工况。人们对不仅应用所谓的最佳估计代码来评估假定的严重事故序列，而且用不确定性分析来补充这些研究的兴趣也越来越大。Phébus FP（裂变产物）研究计划由 IRSN 和 CEA 进行，旨在研究控制堆芯退化以及裂变产物的释放、转移和沉积的物理现象及其在安全壳中的行为。在本文中，借助最佳估计系统代码 ATHLET-CD 3.2（AC 的核心退化模块）对 Phébus FPT3 实验的退化阶段进行建模和模拟。² . 该研究还辅以不确定性分析，应用所谓的 GRS 方法。该论文考虑了不确定模型（例如有关 Zr 氧化的参数）以及实验（例如材料特性）参数，并确定了主要品质因数的 95/95 容差限制。此外，还进行了敏感性分析，并为每个不确定的输入参数确定了 Spearman 秩相关系数。