Patent ID: 6400788
Filing Date: 2002-06-04
Classification: G21C,Y02E

Abstract:
A fuel assembly comprising:a plurality of fuel rods arranged in a square lattice array, said fuel rods including a plurality of short-length fuel rods each having a fuel active length shorter than that of said fuel rods which are non-short-length fuel rods; at least one water rod arranged in a region in which at least one of said fuel rods are arrangeable in said array; and a plurality of fuel spacers, provided at a plurality of positions in the axial direction, for holding said plurality of fuel rods and said at least one water rod with mutual radial intervals therebetween kept immovable; wherein said plurality of short-length fuel rods include at least one first short-length fuel rod arranged in the outermost peripheral region of said square lattice array, and at least one second short-length fuel rod arranged at a lattice position adjacent to said at least one water rod; each of said plurality of fuel spacers including a plurality of cylindrical members which are connected to each other and in which said fuel rods are to be inserted respectively, and first loop-shaped springs each of which is provided at a joined portion between a pair of adjacent cylindrical members for pressing two of said fuel rods inserted in said adjacent cylindrical members; said plurality of fuel spacers including first fuel spacers positioned above the upper ends of said first and second short-length fuel rods, and at least one of said first fuel spacers is configured such that cylindrical members are omitted at locations of first and second lattice positions associated with said first and second short-length fuel rods; each of said plurality of cylindrical members located at lattice positions adjacent to said second lattice position has on said second lattice position side a second loop-shaped spring for pressing said fuel rod in said cylindrical member; said plurality of second loop-shaped springs located at said lattice positions adjacent to said second lattice position are supported by a spring pressing member provided at said second lattice position, said spring pressing member having a transverse cross-section smaller than a transverse cross-section of said cylindrical member; and said spring pressing member in said at least one first fuel spacer includes a plurality of spring holding portions which are inserted in loops of said plurality of second loop-shaped springs for holding said plurality of second loop-shaped springs, respectively, and a plurality of spring pressing portions which are brought in contact with the loops of said plurality of second loop-shaped springs from an outer peripheral side for supporting said plurality of second loop-shaped springs such that said plurality of second loop-shaped springs generate pressing forces applied to associated fuel rods, respectively.