Abstract The AP1000 Passive Residual Heat Removal (PRHR) system plays a significant role as it helps to remove the core decay heat, using the In-containment Refueling Water Storage Tank (IRWST) as a heat sink. The IRWST is located above the core, promoting natural circulation and allowing to be the mid-term heat-sink for the reactor core. The thermo-hydraulic pool behavior during an accident has an influence in the containment pressure and temperature, as happens in the pressure suppression pool in BWR reactors. Due to the importance of the IRWST performance on the AP1000 containment, a numerical analysis of a scaled experiment has been done using the GOTHIC code. Firstly, an IRWST scaled-down model is created, a mesh sensitivity analysis is performed, and the results obtained are compared against experimental results available in the literature. It is found the importance of the mesh discretization for the proper thermal-stratification modeling. Then, the reference model setup and mesh are applied in a full-scale prototypic model. The mesh influence on the thermal stratification is analyzed, as well as its impact on the AP1000 containment pressure. The mesh and setup for the full-scale model are selected to be implemented in a full containment 3D model in future works.

中文翻译：

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AP1000 IRWST 数值分析与 GOTHIC

摘要 AP1000 被动余热去除 (PRHR) 系统发挥了重要作用，因为它使用安全壳内燃料补给水储罐 (IRWST) 作为散热器帮助去除堆芯衰变热。IRWST 位于堆芯上方，促进自然循环并允许成为反应堆堆芯的中期散热器。事故期间的热液池行为会影响安全壳压力和温度，就像 BWR 反应堆中的压力抑制池一样。由于 IRWST 性能对 AP1000 安全壳的重要性，已使用 GOTHIC 代码对规模实验进行了数值分析。首先，创建 IRWST 缩小模型，执行网格灵敏度分析，并将获得的结果与文献中可用的实验结果进行比较。发现网格离散化对于正确的热分层建模的重要性。然后，将参考模型设置和网格应用于全尺寸原型模型。分析了网格对热分层的影响，以及它对 AP1000 安全壳压力的影响。在未来的工作中，全尺寸模型的网格和设置被选择在全封闭 3D 模型中实施。