FUEL ASSEMBLY FOR LIGHT WATER REACTOR, PARTS USED THEREFOR AND MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To enable high anti-neutron damage and high anti-corrosion by making at least one of a cladding tube, a spacer and a channel box Zr-based alloy, and making the average crystal particle diameter a specific value or less. SOLUTION: A fuel assembly is provided with fuel uranium pellets containing plutonium, cladding tubes cladding the pellets, spacers holding the cladding tubes, and a channel box housing a plurality of the cladding tubes. At least one member of the cladding tube, the spacer and the channel box therein is made of Zr-based alloy containing Fe of about 0.5-30 wt.%, and the average particle diameter of Zr-based alloy is made of the fine crystal of about 100 nm or less. Crystalline Zr-based alloy powder is mechanically mixed and agitated, and made amorphous alloy powder. It is solidified under a static water pressure at temperature lower than the recrystallization temperature, a solidified block is hot-worked or cold-worked to be molded in a member shape, and heat treatment is performed to be crystallized in a metal structure.