Spacer grid for nuclear reactor fuel assemblies with grid springs maintaining conformal contact with fuel rods and enlarged elastic range

Abstract

A spacer grid used for placing and supporting fuel rods in nuclear reactor fuel assemblies is disclosed. The spacer grid of this invention has a plurality of grid springs designed to have an optimal shape of their vertical support parts, thus reducing fretting wear of the fuel rods caused by contact of the fuel rods with the grid springs. The grid spring has a vertical support part and a fuel rod support part. The vertical support part includes upper and lower base parts extending downward and upward from the central portions of the top and bottom edges of an opening formed at the central portion of a unit strip, and two bridge parts branched from the upper base part and extending symmetrically downward until they are united at the lower base part. The fuel rod support part includes a conformal support part brought into surface contact with the external surface of a fuel rod. Two transverse connection parts extend outward from the opposite outside edges of the conformal support part while being specifically bent, and are integrated with the central portions of the inside edges of the two bridge parts into a single structure, thus connecting the fuel rod support part to the vertical support part.