承压热冲击下RPV承载力影响因素的数值分析

为研究承压热冲击下含缺陷的核反应堆压力容器(RPV)的极限承载力，借助ABAQUS软件建立含表面裂纹的RPV的3D有限元模型．通过热-力耦合分析，分别得到筒体区和喷嘴区的瞬态温度场和应力场．考虑到实际RPV断裂试验工作具有相当大的危险性，使用扩展有限元法(XFEM)对裂纹的扩展情况进行数值模拟．通过对含有不同位置和尺寸裂纹、具有不同壁厚容器的极限承载力分析，得到满足强度条件的各临界裂纹尺寸．结果表明，当表面裂纹距喷嘴口的距离达到一定程度，其长度对RPV结构的极限承载力不构成影响．在喷嘴区，随裂纹距喷嘴口距离的减小，临界裂纹尺寸迅速减小，喷嘴口上仅允许深长比较小的浅表面裂纹出现．

Numerical Analysis of the Influence Factors of the Bearing Capacity of RPV under Pressurized Thermal Shock

To study the ultimate bearing capacity of a nuclear reactor pressure vessel (RPV) with defects under pressurized thermal shock, the 3-D finite element model containing the surface crack is established by ABAQUS software. Through the thermo-mechanical coupling analysis, the transient temperature fields and stress fields of the cylinder area and the nozzle area are obtained. Considering that the actual fracture test of RPV is very dangerous, the extended finite element method (XFEM) is used to simulate the crack propagation. Through the analysis of the ultimate bearing capacity of the vessels of various thicknesses with different crack sizes and different crack locations, the critical crack sizes are obtained to meet the strength requirements. The result shows that the length of the surface crack has no effect on the ultimate bearing capacity of the RPV structure when its distance from the nozzle reaches a certain extent. In the nozzle area, the critical crack sizes decrease rapidly with the decrease of the distance from the nozzle. Only the shallow surface crack with relatively small depth-to-length ratio is allowed on the nozzle.