FUEL ASSEMBLY FOR BOILING WATER REACTOR AND BOILING WATER REACTOR LOADED WITH THE SAME

摘要

PROBLEM TO BE SOLVED: To improve the economical efficiency of a nuclear fuel by suppressing a deterioration in a neutron slowdown efficiency in an upper region of a fuel effective section while securing the strength of a channel box.SOLUTION: The fuel assembly for a boiling water reactor includes a plurality of fuel rods arranged in a shape of a lattice, an upper tie plate, a lower tie plate, and a channel box 7 formed so as to enclose the circumference of the plurality of fuel rods and connected respectively to the upper tie plate and the lower tie plate. A horizontal central part of a lateral face of the channel box 7 is provided with a channel box thin wall part 7b thinner than the thinness of the channel box corner part 7a, regarding a range in a longitudinal direction including the upper region, at least up to an upper edge of the fuel effective section of the fuel assembly. Opposite face dimensions inside the channel box 7 are constant at any place, and the channel box thin wall part 7b may have thinness that monotonously reduces upward.