核压力容器接管安全端堆焊修复对失效评定曲线的影响

Effect of Dissimilar Metal Weld Overlay between Pipe-nozzle of Nuclear Pressure Vessel and Safe End on Failure Assessment Curves

核压力容器接管安全端异种金属焊接接头在服役中通常会产生高温高压水环境下的应力腐蚀裂纹扩展。目前减轻和修复这种裂纹的技术为在安全端管接头外表面堆焊一层更抗腐蚀的镍基合金(Alloy52M)材料。通过ABAQUS有限元分析,构建了堆焊修复后结构的失效评定曲线,分析了堆焊层厚度、裂纹深度和裂纹位置对失效评定曲线的影响。结果表明:随着堆焊层厚度的增加、裂纹深度的减小及裂纹位置向接管嘴的移动,失效评定曲线上移,结构的安全性增加。当对堆焊修复接头区的裂纹进行评定时,需要建立与堆焊修复后安全端结构尺寸、裂纹尺寸、裂纹位置和材料性能相关的准确的失效评定曲线。

Primary water stress corrosion cracking（PWSCC） has often been produced in the dissimilar metal welded joints between pipe-nozzles of nuclear pressure vessels and safe ends.The weld overlay of Alloy52M with higher corrosion resistant has usually been made to repair or mitigate this PWSCC.Based on the detailed three-dimensional finite element analyses,the failure assessment curves（FACs） of the dissimilar metal welded overlay structure were constructed,and the effects of the weld overlay thickness,crack depth and crack location on the FACs have been analyzed.The results show that with increasing the weld overlay thickness,decreasing the crack depth and moving the crack location to the pipe-nozzle,the failure assessment curves shift upward,which increases the safety of the structure.To accurately assess the integrity of the DMWJ structure with weld overlay,the FACs related to the weld overlay size,the crack size,the crack location and the material properties should be constructed.