CRDM耐压壳顶部螺母咬死分析与处理

The Analysis and Repair for Nut Bite Failure on the top of CRDM Pressure Housing Assembly

秦山320MWe机组控制棒驱动机构耐压壳部件在大修检查时,发现圆螺母经常出现咬死故障,容易引起耐压壳本体损伤,导致大修作业的延误,具有极大的安全风险。本文针对该故障现象,介绍了耐压壳部件的相关结构组成,对导致螺母咬死的原因进行分析和讨论,并制定了处理措施,解决个别螺母完全咬死的问题,通过研发可行的专用工具,分别处理咬死螺母的拆卸和损伤螺纹修复两个难点问题,并对耐压壳部件进行改进,增加专用石墨垫片,优化螺母结构,减少咬死概率。通过该问题的成功处理,避免了耐压壳本体的损伤风险,保证了设备的安全可靠性,为其它类似结构的处理提供了维修借鉴和经验,值得采用和推广。

When inspect the CRDM Pressure Housing Assembly during the overhaul of Qinshan 320MWe unit,found that round nuts frequently came across nut bite failure,which can easily cause the damage of Pressure Housing Assembly body damage,lead to delay the overhaul work,and have a great safety risk.Focusing on the failure phenomenon,this thesis describes the structure of Pressure Housing Assembly,analyses and discusses the real reason leading to round nut bite failure,and makes the measures to solve the problems of individual nut bite failure,by designing the viable special tools to handle these two difficult issues respectively,which are the removal of seizure nut and the repair of damage thread,and improves the Pressure Housing Assembly by increasing the special graphite gasket,optimizes the structure of nut and reduces the probability of seizure failure.By successfully solving the problems,it can avoid the damage risk of Pressure Housing Assembly body,ensure the safety and reliability of the component,and provide reference and experience for the repair of other similar structures.It is worth using and spreading.