The review of welding process and weldability for Inconel-690 used in steam generator tubesheet cladding

On the ground that the welded areas of tubesheet of steam generator for pressurized water reactors (PWR) are required to play an absolute part in the existence of radioactive materials and the difference of fluid pressure between primary and secondary system, it is required that the tubes to tubesheet welding should be assured of high quality. Hitherto, Inconel-600 has been used for tubes and tubesheet, but, as tube failures have been occurred due to a problem of corrosion mechanisms (IGA, SCC etc.), the continued development of materials with microstructures and compositions designed to withstand the environments met in water reactor operation has increased the reliability of steam generator. This paper reports on the weldability for each welding process for the applications in tubesheet cladding by using Inconel-690 welding material currently being developed. 6 tabs., 16 figs