Abstract: A boiling water reactor fuel rod assembly is provided having a plurality of fuel rod spacers which are slidably receivable within an outer channel. Each of the rod spacers is formed of at least one lattice which defines a plurality of fuel rod retaining cells. The lattice is constructed of a plurality of pairs of oppositely facing springy support strips, with each support strip having a plurality of spring-loaded indentations. In an unloaded condition, oppositely facing indentations of each pair of strips, which define each cell, are displaced closer to one another. In a loaded condition, the oppositely facing cell indentations are forced away from each other by the fuel rods so that the springloaded indentations support and retain the fuel rods.

Abstract: A fuel assembly for a boiling water nuclear reactor is provided comprising an elongated central water channel including wall members that define an enclosed fluid flow path therethrough, the channel includes a lower opening for receiving water and allowing water to flow through the fluid flow path and at least one outlet opening. At least one partial water rod is provided that is coupled to a partial fuel rod so as to be disposed axially above the partial fuel rod. The partial water rod includes an inlet opening in fluid communication with the outlet opening of the central water channel so as to allow water to flow from the water channel into an interior of the partial water rod.

Abstract: A grid spacer for a nuclear reactor fuel assembly is formed of two superposed combs. Each comb has a base strip which extends the width of the assembly. To it are attached parallel grid strips which are free at their other ends. The grid strips are perpendicular to the base strip and are formed for spring engagement with the fuel rods of the assembly. The combs can be inserted from the sides of the assembly, so that an additional or substitute spacer can be added to the assembly without disassembling the latter.

Abstract: A debris screen for a fuel assembly for a reactor to which coolant fluid is supplied comprises a substantially planar plate member having an array of coollant openings extending through the plate member dimensioned to trap at least a portion of debris particles carried by the coolant; and a skirt member enclosing the periphery of the plate member; each of the coolant flow openings having a coolant entry region at a lower surface, a coolant exit region at an upper surface and a coolant flow path extending between the entry and exit regions, the flow path including an intermediate segment laterally offset from the entry and exit regions to cause coolant to change direction of flow in the intermediate segment and thereby prevent at least a portion of the debris particles from passing through the plate members.

Abstract: An intermediate mixing grid for nuclear reactor fuel assemblies is made without the usual perimeter strip. The ends of the grid members are formed so that they hold the fuel rods at the edges of the assembly in place.