【作者】 尹开锯； 唐武； 王浩； 洪晓峰； 徐祺； 邱绍宇； 唐睿； 陈勇；

【Author】 YIN Kai-ju;TANG Wu;WANG Hao;HONG Xiao-feng;XU Qi;QIU Shao-yu;TANG Rui;CHEN Yong;State Key Laboratory of Electronic Thin Films and Integrated Devices,University of Electronic Science and Technology of China;Laboratory of Science and Technology on Reactor Fuel and Materials,Nuclear Power Institute of China;

【机构】 电子科技大学电子薄膜与集成器件国家重点实验室； 中国核动力研究设计院反应堆燃料及材料重点实验室；

【摘要】 国内某核电站弯管发生泄漏,根据国际原子能机构的国际核事件分级准则,国家核安全局将其确定为一级事件进行管理。通过对该失效部件进行化学成分分析、力学性能测试、断口扫描电镜观察、能谱分析和显微组织分析,结果显示材料显微组织中存在大量的冷加工滑移带,硬度390 HV_0.1,屈服强度581 MPa,裂纹为脆性断裂,裂纹沿晶扩展,断口呈冰糖块花样。在微动回路中模拟电站水化学条件下,完成了故障再现试验,并采用流电压降（DCPD）测定其裂纹扩展速率,在325℃、2 ppm溶解氧条件下失效部件应力腐蚀裂纹扩展速率为6×10^-7～7×10^-7mm/s。综合分析得出,弯管的失效性质为晶间应力腐蚀开裂,材料处于冷加工状态是弯管失效的原因。更多还原

【Abstract】 The elbow pipe in domestic NPP（nuclear power plant） had the leakage,thereby Chinese national nuclear bureau manage it as class 1 events according to the classify criterion for international nuclear events by IAEA（international atomic energy associate）.Then the failure components were tested with items of chemical compositions analysis,mechanic property tests,SEM（scan electronic microscopy） observation of fracture morphology,energy spectrum and micro-structure analysis,the results show that there are plenty of cold-worked slip band in micro-structures,hardness is 390 HV_0.1,yield strength is 581 MPa,the crack is embrittle and grow along grain boundary,the fracture present crystal characteristics.The tests were finished in the simulated water in micro-dynamic loop,and the technique of DCPD were used to measure the crack propagation rate,the results show that the crack propagation rate of such failure components is 6×10^-7～7×10^-7 mm/s in 325 ℃ with 2 ppm dissolved oxygen.After the comprehensive analysis,the failure mode of the pipe is inter-granular stress corrosion crack（IGSCC）,the reason for such failure is the cold worked condition.更多还原