Shock-absorbing device for fuel assembly and fuel assembly housing container

摘要

A fuel assembly 20 is constituted by combining a plurality of fuel rods 21, holding the fuel rods 21 by a plurality of support grids 22, and arranging a lower nozzle 24 and an upper nozzle 23 at opposite ends of the fuel rods 21. A shock-absorbing device 10 for a fuel assembly is fitted to the lower nozzle 24 and the upper nozzle 23. The shock-absorbing device 10 for a fuel assembly is constituted a nozzle support 12 fitted to a depression 24U of the lower nozzle 24 and a depression 23U of the upper nozzle 23, and a buffer 11 combined with the nozzle support 12, with stiffness thereof in a longitudinal direction of the fuel rods 21 being equal to or lower than that of the nozzle support 12.

主权项

1. A shock-absorbing device for a fuel assembly including a plurality of fuel rods, the shock-absorbing device comprising:
a first nozzle and a second nozzle including one surfaces, respectively, by which the plurality of fuel rods are sandwiched, the first and second nozzles including other surfaces having a plurality of legs for defining first and second depressions, respectively; a nozzle support fitted to a center portion of the first depression of the first nozzle, the nozzle support being comprised of iron, aluminum alloy containing boron)(B10), stainless steel, lead, or concrete so that radiation from the fuel assembly is shielded; and a buffer combined with the nozzle support, the buffer having stiffness in a longitudinal direction of the fuel rods being equal to or less than that of the nozzle support, wherein the nozzle support and the buffer are arranged in sequence along the longitudinal direction of the fuel rods as separating from the depressions and wherein the buffer is either one of the followings (a) to (g): (a) a buffer including a buffer member including a hydrogen-containing resin so as to shield neutron and a casing holding and surrounding the buffer member; (b) a buffer including a bottom plate and a plurality of plate materials fitted to the bottom plate; (c) a buffer including a bottom plate and a plurality of rod members arranged with an axial direction being parallel to the longitudinal direction of the fuel rods; (d) a buffer including a buffer member including a hydrogen-containing resin so as to shield neutron and a casing holding and surrounding the buffer member, the casing being coupled with a pipe for housing the plurality of fuel rods by a coupling member (33); (e) a buffer including a first buffer that is provided with a depression and contacts the plurality of legs and a second buffer that is provided on the depression and contacts the nozzle support; (f) a buffer including a first buffer that contacts the plurality of legs and a second buffer that is provided with a salient and contacts the nozzle support at the salient, the first buffer having stiffness in a compression direction lower than that of the second buffer in the compression direction; (g) a buffer that has a depression and contacts the nozzle support at the depression, the buffer contacting the plurality of legs.