Patent Number: 
Section: claims

1. A method of manufacturing a core shroud for a nuclear power plant, the method comprising steps of:setting a narrow groove between abutting surfaces of first and second metal members adjacent to each other, each of the first and second metal members having a respective thickness not less than 30 mm, with a root face on each of the abutting surfaces, each root face having its length which is between 25% and 95% of a thickness of a thinner one of the first and second metal members; andlaser welding the abutting surfaces with a welding wire to construct the core shroud, the laser welding being performed in a shielding gas including nitrogen,wherein the welding wire comprises an austenitic stainless steel including a ferrite content of 14-20% calculated from the material composition of the welding wire, and a ratio between Cr in the austenitic stainless steel and Ni in the austenitic stainless steel is 1.9-2.2. 2. The method of manufacturing a core shroud for a nuclear power plant in claim 1, wherein:a curved surface is provided in an end portion of a groove bottom portion of said narrow groove, and a width of the groove bottom portion constructed by intersecting points of an extension line of a side surface in both sides of said narrow groove and an extension line of the groove bottom portion is set to 1 mm to 4 mm, andan angle of the groove formed by the side surfaces in both sides of said groove is between 1 degree and 7 degrees. 3. The method of manufacturing a core shroud for a nuclear power plant in claim 1, wherein:a step is formed between the abutting surfaces of the first and second members, ora concavity is formed in one of the metal members and a convexity is formed in the other metal member. 4. The method of manufacturing a core shroud for a nuclear power plant as claimed in claim 1, further comprising the steps of:forming a weld groove by butting the root faces;complete penetration welding the root faces from one side or both sides; anddeposition welding said narrow groove portion while adding the welding wire.