核反应堆压力容器主螺栓孔堆焊缺陷分析与质量控制

Defect analysis and quality control of main bolt hole surfacing on nuclear reactor pressure vessel

核反应堆压力容器是核电站的心脏,主螺栓孔的堆焊质量关系着反应堆压力容器能否正常开关操作,将影响核电厂的运行安全和运行时间。针对某反应堆压力容器制造过程中主螺栓孔堆焊存在的PT/UT检测不合格问题,分析焊接缺陷产生的原因为:(1)局部区域电弧不稳,焊缝区域保护不良;(2)焊接工位不佳,焊工操作难度大。提出了相应的改进措施,如:将手工堆焊改为机械氩弧焊,火焰加热改为电加热板加热;就工件状态进行针对性培训;加强待焊面的清理,强化操作要求。上述措施经现场验证明显提高了主螺栓孔堆焊PT/UT的一次合格率,对后续项目RPV的制造提供了技术积累和工程经验。

Nuclear reactor pressure vessel is the heart of nuclear power plant.The surfacing quality of main bolt hole is related to the normal operation of reactor pressure vessel,and will affect the operation safety and operation time of nuclear power plant.Aiming at the unqualified PT/UT detection problem of main bolt hole surfacing in the manufacturing process of reactor pressure vessel in a factory,the causes of welding defects are analyzed as follows:(1)Unstable arc in local area and poor protection of weld area;(2)Poor welding station makes it difficult for welders to operate.The corresponding improvement measures are put forward,such as changing manual surfacing to mechanical argon arc welding,and changing flame heating to electric heating plate heating;conduct targeted training on workpiece status;strengthen the cleaning of the surface to be welded and strengthen the operation requirements.After field verification,the above measures have significantly improved the first pass rate of main bolt hole surfacing PT/UT,and provides valuable technical accumulation and engineering experience for the manufacturing of RPV in subsequent projects.