核电厂安全壳喷淋系统隔离阀上阀座开裂原因分析

摘要

本文应用残余应力测试、化学分析、金相观察、硬度检测及断口分析,结合有限元应力分布分析等方法,对核电厂安全壳喷淋系统隔离阀上阀座开裂进行了原因分析.实验室分析结果表明,阀座环向残余应力数值较低,裂纹源未发现腐蚀现象,基体组织与硬度测试均未见异常.化学成分测试表明,材料成分满足标准要求.有限元计算结果表明,阀座受到了异常的过载应力.综合分析表明,上阀座开裂的原因主要是由于受力过载,并且针对根本原因制定了对应的改进措施.%The root cause for the fracture of upper valve seat of isolation valve of Containment Spray system (EAS) was investigated by residual stress testing, chemical analysis, metallographic analysis, hardness test and fracture analysis, combined with finite element analysis method. Through the laboratory analysis, the residual stress along the circumference direction was too low to cause the fracture and no corrosion phenomenon was found near crack origin. Also the metallographic structure and the hardness test were shown no abnormal phenomenon. The chemical element content was also qualified to the standard. Overload phenomenon was shown through the FEA analysis. The root cause of the fracture was shown to be overloading and corrective actions were adopted to prevent the incident reoccurring.