反应堆压力容器防断裂设计的规范法和分析法比较

Comparison of Specification Method and Analysis Method for Fracture Prevention Analysis of Reactor Vessel

针对AP1000反应堆压力容器的上封头部分,采用规范法计算了反应堆启动和停堆瞬态下表面椭圆形裂纹前沿的应力强度因子。计算结果表明在反应堆启动过程中,上封头外表面裂纹比内表面裂纹更加危险;而停堆过程中,内表面裂纹比外表面裂纹危险。对于远离结构不连续区,环向和径向裂纹前沿的应力强度因子相差不大。但是对于临近结构不连续处,反应堆启动过程中环向裂纹比径向裂纹危险;而停堆过程中,径向裂纹比环向裂纹危险。经评价表明该缺陷符合ASME安全设计的要求。同时建立含真实裂纹的三维有限元模型进行了防断裂分析评价。通过两种方法的对比表明,传统的规范法比有限元方法偏保守。

Aiming at the upper head part of the AP1000 reactor pressure vessel, the stress intensity factor of elliptical surface crack front in reactor startup and shutdown transient state were calculated by standard method. The calculation results show that in the reactor startup process, outer surface cacks of the upper head are more dangerous than the inner ones; while in shutdown process, inner surface cracks are more dangerous than the outer ones. For the area away from the discontinuous structure zones, it has little difference between circumferential and radial crack front stress intensity factor. But for the adjacent structure discontinuity, circumferential cracks are more dangerous than radial cracks in the reactor start- up process; while in shutdown process, radial cracks are more dangerous than circumferential cracks. The evaluation shows that the defect conforms to ASME safety design requirements. At the same time, three- dimensional finite element model with real crack was established and evaluation of fracture prevention was analyzed. Comparison of two methods shows that the traditional standard method is more conservative than finite element method.