Method of surface treatment for structure and facility in reactor

Surfaces of weld zones, in contact with liquid, of structures and equipments in a reactor made of austenite stainless steels disposed in the reactor water of a reactor pressure vessel are melted by laser. Then, heat affected zones and grain boundary segregation portions, etc. with low corrosion resistance formed under irradiation are melted by laser beams and the molten surfaces are quenched by the surrounding reactor water. In this case, ferrites are formed to provide a two-phase structure. This can improve the corrosion resistance. Further, plasma technology can be used instead of the laser method. (I.S.)