SPRING MEMBER FOR USE IN IRRADIATION ENVIRONMENT

摘要

PURPOSE: To reduce stress by composing a spring member of first and second sheet springs having different irradiation growth rate bonded each other. CONSTITUTION: A spacer 18 is entirely made of a zircaloy sheet metal and has peripheral band plates 20, 22 in which square grid members 24, 26 are secured. A spring element 28 is fixed in the opening of the members 24, 26 with four leaf springs 30 of the element 28 facing four adjacent openings. The spring 30 has inner and outer layers 34, 32 disposed oppositely to the opening on the recessed and projecting surface sides thereof, respectively. The outer layer 32 is made of a first zircaloy alloy having a first irradiation growth rate while the inner layer 34 is made of a zircaloy alloy having a second irradiation growth rate lower than the first irradiation growth rate. Both alloys are made of a single zirconium alloy in which the content of tin and oxygen is varied so that the recrystallization temperature of one layer is higher than that of the other layer.