Abstract This paper presents the integrity analyses of a model reactor pressure vessel (RPV) subjected to pressurized thermal shocks (PTS). The analyses are performed with a one-way multi-step strategy that includes the thermo-hydraulics, thermo-mechanical and fracture mechanics analyses to simulate three hypothetical loss of coolant accidents (LOCA). The thermo-hydraulics analyses are performed with the system code TRACE and a three-dimensional (3D) model of the RPV, providing the input for the structural analyses with the finite element code ABAQUS. These employ a sequential use of global model (entire RPV) and submodels (a portion of the RPV containing the crack), where the eXtended Finite Element (XFEM) approach is employed to compute the stress intensity factor (SIF) of a postulated crack in the RPV wall. The results first present a verification of the multi-step strategy with the FAVOR code for uniform temperature distribution in the RPV wall. Under uniform temperature and pressure load, a significant effect of the nozzle geometry on the asymmetric stress distribution is demonstrated. The second part of the results shows that the stresses and the SIFs are also sensitive to the non-uniform temperatures due to the presence of the cooling plumes. It is also confirmed that the analyses with ABAQUS and FAVOR provide very similar results for the medium and large break LOCA transients. For the small break LOCA, the FAVOR code underestimates the SIFs due to the missing nozzle geometry in combination with system pressure. Finally, the paper corroborates that the use of TRACE and XFEM, within the one-way multi-step simulation strategy, reduces the computational costs and the number of assumptions and approximations needed for feasible and relivable 3D fracture mechanics analyses of the RPV with consideration of the cooling plume effect.

中文翻译：

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非均匀冷却下反应堆压力容器的断裂力学分析与联合 TRACE-XFEM 方法

摘要 本文介绍了受加压热冲击 (PTS) 影响的模型反应堆压力容器 (RPV) 的完整性分析。分析采用单向多步策略进行，包括热液压、热机械和断裂力学分析，以模拟三种假设的冷却剂损失事故 (LOCA)。热工水力分析使用系统代码 TRACE 和 RPV 的三维 (3D) 模型进行，为使用有限元代码 ABAQUS 的结构分析提供输入。这些采用全局模型（整个 RPV）和子模型（包含裂纹的 RPV 的一部分）的顺序使用，其中使用扩展有限元 (XFEM) 方法来计算假设裂纹的应力强度因子 (SIF) RPV 墙。结果首先用 FAVOR 代码验证了多步策略，以实现 RPV 壁中均匀的温度分布。在均匀的温度和压力负载下，喷嘴几何形状对不对称应力分布的显着影响被证明。结果的第二部分表明，由于冷却羽流的存在，应力和 SIF 对非均匀温度也很敏感。还证实，使用 ABAQUS 和 FAVOR 的分析为中型和大型断裂 LOCA 瞬变提供了非常相似的结果。对于小断点 LOCA，由于缺少喷嘴几何形状和系统压力，FAVOR 代码低估了 SIF。最后，本文证实了在单向多步仿真策略中使用 TRACE 和 XFEM，