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我国核电厂主管道的材料主要有铸造奥氏体不锈钢(CASS)和锻造不锈钢(wss).针对CASS和WSS两种材料的主管道,依据美国核管会的SRP3.6.3进行主管道硬前漏(LBB)评估的对比研究.考虑热老化效应获取可信的材料性能数据,根据材料性能差异采用极限载荷法或J积分撕裂模量汇交法计算临界裂纹尺寸.根据Henry均匀非平衡双相流模型计算泄漏裂纹尺寸,并通过环向表面裂纹和贯穿裂纹的扩展分析论证了裂纹疲劳扩展不会导致管道的突然断裂.研究结果表明,WSS材料和CASS材料相比具有更好的LBB性能.“,”As to the LBB evaluation performed in China,the materials are cast austenitic stainless steel (CASS) or wrought stainless steel (WSS).In this paper,LBB assessment in the guidance of SRP 3.6.3 was performed to evaluate the main loop piping lines of CASS and WSS.The adjustment due to thermal aging is performed to achieve reasonable material properties.J integral/tearing modulus approach is used to determine the critical crack size of CASS pipe and limit load approach is used to determine the critical crack size of WSS pipe.Leakage flaw size is determined based on Henry\'s homogeneous non-equilibrium critical flow model.In order to demonstrate that fatigue crack growth is not a potential source of pipe rupture for the evaluated piping lines,the fatigue crack growth of a postulated circumferential part-through-wall crack and the fatigue crack growth of a circumferential through-wall crack are analyzed.The results show that WSS material is better than CASS material in LBB capability.