核电厂凝汽器换热管裂纹故障分析与处理

Failure Analysis and Treatment for Crack of Condenser Tuber at Nuclear Power Plant

针对某核电厂凝汽器换热管出现裂纹故障,通过材料失效分析,查明了换热管局部高频振动是碰磨痕迹和裂纹产生的原因。通过换热管振动失效模式分析和理论计算,排除了换热管出现共振的可能性,同时基于换热管出现裂纹前机组特殊瞬态运行工况分析,确定故障产生的原因是流体弹性激振诱发换热管振动,而凝汽器设计安全裕度考虑不足则是引发故障的根本原因。进而有针对性地提出了合理加装防磨条、识别管束振动高风险区域以及设计改进等处理方案。

For a nuclear power plant condenser tube cracks,using the material failure analysis,the local high-frequency vibration of the tube was identified as the causeof clash wear traces and crack generation.Through the failure mode analysis and theoretical calculation of the heat transfer tube vibration,the possibility of resonance of the heat transfer tube was eliminated.Based on the analysis of the special transient operating conditions of the unit before the cracking of the heat transfer tube,the cause of the failure is the vibration of the tube induced by the fluid elastic excitation was determined,and the insufficient consideration of the safety margin of the condenser design was the root cause of the failure.Furthermore,the reasonable installation anti-wear laths,identification of high risk area of tube bundle vibration and design improvement were proposed.