基于局部干法的核电水池覆面缺陷焊接修复工艺研究

Research on the welding repair process for defects on the cladding of nuclear power plant pools based on partial dry techniques

针对核电站乏燃料水池钢覆面出现的腐蚀缺陷等问题,采用了局部干法水下TIG焊接的修复方法对覆板进行焊接修复。首先,利用设计的压力环境模拟系统进行0.3MPa压力范围内干式焊接试验,获得不同压力下的覆板焊接最佳工艺;基于干式环境最佳焊接参数,开展局部干法水下焊接工艺探索,并对焊接接头切样进行金相检测。宏观金相结果显示:焊缝成形良好,无裂纹、气孔;微观金相检测结果表明:显微组织基体为呈枝晶状的奥氏体,枝晶间为铁素体,未发现显微裂纹和夹杂物,为核电站乏燃料水池覆板的在役修复奠定了基础。

In response to the corrosion defects and other issues on the steel cladding of the spent fuel pool in nuclear power plants,this article adopted the repair method of local dry underwater TIG welding to repair the cladding.Firstly,the designed pressure environment simulation system was used to conduct dry welding tests within a pressure range of 0.3MPa,and obtain the optimal welding process for the cladding under different pressures.Based on the optimal process parameters in a dry environment,an exploration of local dry underwater welding process was carried out,and metallographic testing was conducted on the cut samples of the welded joints.The macroscopic crystal phase results showed that the weld formed well without cracks or pores,and the results of microscopic crystal phase testing indicated that the microstructure matrix was dendritic austenite,with ferrite between dendrites,no fiber cracks or precipitates were found.This paper lays the foundation for the in-service repair of the spent fuel pool cladding in nuclear power plants.