PURPOSE: To extinguish a zone depleted in the solid soln. components of alloy elements in the core equipment and to provide it with nodular corrosion resistance, in a final manufacturing stage for core equipment constituted of a Zr alloy, by irradiating the surface or whole body of the alloy with corpuscular beans.

CONSTITUTION: A Zr-base alloy to which Sn, Fe, Ni, etc., are added is subjected to soln. treatment and is then subjected to hot working, annealing, cold working, recrystallization annealing or the like. As a final stage, the whole body or the neighborhood of the surface in the alloy is irradiated with corpuscular beans such as electron beams, ions or the like to extinguish a zone depleted in the solid soln. components of alloy elements in the Zr alloy. In this way, nodular corrosion which has been generated caused by a zone depleted in the solid soln. components of alloy elements can be suppressed, by which core structure materials made of a Zr-base alloy having excellent safety and reliability such as fuel cladding tubes, spacers and channel boxes can be obtd.