Aiming at the upper Ω seal weld of control rod drive mechanism（CRDM）in a nuclear power plant in China

primary investigation and overlaying repair technology have been carried out. Welding experiment is based on the representative test piece of 1:1 material

structure and restriction

and adopts automatic TIG welding machine. The overlaying parameters

key know-how and process flow have been achieved;by thin slice-radiographic examination

chemical analysis

metallographic examination and XRD phase analysis

the performance comparison between test piece and international typical witness piece has been done

the technical project and inspection item for overlaying piece performance examination has been established

the overlaying parameters and performance data of the upper Ω seal weld of CRDM has been obtained

so that a complete set of technology with performances equivalent to international typical witness piece’s performances has been achieved.