FUEL ASSEMBLY LOADED IN BOILING WATER REACTOR, AND REACTOR CORE USING THE SAME

PROBLEM TO BE SOLVED: To improve fuel economic performance of a fuel assembly, with a water channel to be loaded in a boiling water reactor, while ensuring the thermal tolerance thereof. SOLUTION: The fuel assembly 81 comprises a plurality of fuel rods 51, 52 and 53, each having a nuclear fuel material stored in a cylindrical cladding tube, and aligned in a square-grid shape, with the lower end thereof being supported by a lower tie plate; and a water channel 38 extended in a square cylindrical shape in the same direction as the fuel rods 51, 52 and 53 to occupy a plurality of grid positions of the square grid, in which the fuel rods 51, 52 and 53 are aligned, and carrying a coolant in the inner part. The fuel rods 51, 52 and 53 include the standard fuel rod 51, the upper end of which is supported by an upper tie plate, and two or more kinds of partial length fuel rods 52, 53 which are smaller in length than the standard fuel rod 51 and differed in length to each other. At least one partial length fuel rod 52, 53 is disposed at a position adjacent to each side surface of the water channel 38. COPYRIGHT: (C)2010,JPO&INPIT