Patent ID: 9646724
Date: 2017-05-09
CPC Classifications: G21C,Y02E

Claim:
1. A fuel assembly, comprising: a plurality of fuel rods containing a fissile material; a lower tie plate which supports each lower end portion of the fuel rods; an upper tie plate which holds each upper end portion of the fuel rods; a plurality of fuel spacers, each of which bundles the plurality of fuel rods; a channel box attached to the upper tie plate, extending toward the lower tie plate, and surrounding the plurality of fuel rods bundled by the fuel spacers; and flow resistance members, which are disposed in an inner side of an outermost layer region of an array of the plurality of fuel rods in a cross section in a direction perpendicular to a center axis of the channel box, and through which coolant paths are formed, and which the fuel rods penetrate, wherein Sa is smaller than Sb, in one of the flow resistance members, ferrules are arranged in a square grid of six rows and six columns in a square-shaped band, and two water rod disposition regions, each of which occupies a region capable of disposing four ferrules, are formed in a central portion, adjacent ferrules are joined to each other by welding, and each of the ferrules disposed in an outermost layer is joined to the square-shaped band by welding, in each of the ferrules, only two protrusions are formed in a circumferential direction, and only a single spring member is provided across adjacent pairs of ferrules and attached thereto, a bridge member is provided only at every two adjacent ferrules facing a water rod disposition region and is attached to a side surface of each ferrule, and a spring member is attached to only one bridge member among the four bridge members facing each of the water rod disposition region.