Patent Number: 052590097
Section: summary

BACKGROUND OF THE INVENTION The invention relates to nuclear fuel rod assemblies for water reactors, and more particularly to a fuel rod spacer arrangement for boiling water reactors wherein the fuel rods are supported within an outer channel in a spaced and aligned fashion relative to one another. OBJECTS OF THE INVENTION It is an object of the invention to provide a nuclear fuel rod assembly for a boiling water reactor wherein a spacer assembly is provided which is of simple construction, yet provides a secure retention, alignment, and spacing for the nuclear fuel rods. It is another object of the invention to provide a spacer system wherein the fuel rods can be easily loaded. It is another object of the invention to provide a spacer system wherein moderator can flow freely therethrough. It is a further object of the invention to create a turbulent flow so that coolant contact with the fuel rods is maximized and steam bubble contact with the fuel rods is minimized. It is a further object of the invention to provide a spacer system which can be easily assembled. It is another object of the invention to provide a spacer system which will not be substantially affected by irradiation. SUMMARY OF THE INVENTION According to the invention, a boiling water reactor fuel rod assembly is provided wherein a spacer system is formed of a plurality of spaced apart and parallel spacer strips. Each of the spacer strips has a plurality of corrugations. Corrugations of adjacent spacer strips are reversed relative to one another so as to create support cells for receiving fuel rods between the opposed corrugations. The spacer strips are constructed of a spring-action or resilient material such that prior to loading of the fuel rods, there is an unloaded displaced position of at least some of the corrugations. When a fuel rod is loaded into a cell, the fuel rod forces the portions of the spacer strip which are in their unloaded displaced position into a loaded position. Preferably, pairs of spacer strips are provided having their corrugations abutting each other back-to-back, with every other corrugation along the spacer strips being welded to one another. The unwelded corrugations can then attain by spring action the unloaded displaced position, with the corrugations then being spaced apart from one another. Preferably the spacer strips are arranged to form a lattice or grid, with two of such lattices being positioned one above the other to form a rod spacer. A plurality of the rod spacers are provided at desired spaced intervals from top to bottom along the fuel rod assembly.