【摘要】 在反应堆冷却剂丧失事故（LOCA）后，堆芯熔融物将对反应堆压力容器（RPV）下封头产生烧蚀作用，为此模拟和分析在堆芯熔融事故下RPV内壁的烧蚀及复杂力学行为对于RPV的设计、事故预防和缓解都具有重要意义。本文首先给出了近场动力学方法分析含裂纹扩展的热力耦合问题的积分列式。其次，在近场动力学方法框架下，提出了一种简便和高效的移动边界模型。其中，通过引一个标量场来直接表征物质点的烧蚀状态，使得在计算过程中不需要不断地更新计算域，从而提高计算效率。最后，采用该方法模拟了堆芯熔融物对RPV内壁的动态烧蚀和RPV在内压作用下的裂纹扩展，计算结果表明在堆芯熔融事故下RPV中同时存在弹性变形和塑性变形，而且还存在损伤断裂等复杂力学行为。更多还原

【Abstract】 After the severe loss of coolant accident(LOCA), the lower head of reactor pressure vessel(RPV) will be ablated by the core melt. Therefore, it is of great significance to simulate and analyze the ablation and complex mechanical behavior of the pressure vessel wall under the condition of core melt for the design, accident prevention and mitigation of RPV. This paper firstly presents the peridynamic formulation of coupling thermo-mechanical problem with crack propagation. Then, based on the peridyanmic framework, a simple and efficient moving boundary model is proposed. The abated status of the material points is directly characterized by introducing a scalar field, which makes it unnecessary to constantly update the calculation domain in the calculation process, thus improving the calculation efficiency. Finally, the present method is used to simulate the dynamic ablation of the core melt on the pressure vessel wall and the crack propagation of the pressure vessel under the action of internal pressure. The calculation results show that there are both elastic deformation and plastic deformation in RPV under the core melt accident, and there are also complex mechanical behaviors such as damage and fracture.更多还原