Debris-resistant fuel assembly

This patent describes an improvement in a fuel assembly. It comprises an upper tie plate and a lower tie plate, a plurality of fuel rods extending therebetween and a plurality of tie tubes extending therebetween and secured to the upper and lower tie plates, a plurality of grid spacers positioned between the tie plates and comprising intersecting strips forming cells through which the fuel rods and the tie tubes extend, the tie plates comprising relatively large, substantially circular openings through which water flows into the assembly. The improvement comprising: a grid spacer positioned substantially on the lower tie plate and positioned with the intersections of the strips approximately centered on the openings so as to subdivide the openings to trap debris and prevent it from entering spaces between the fuel rods. The last named grid spacer being formed of double strips. The double strips being deformed adjacent the intersections of the strips to form channels for cooling water, whereby the walls of the channels subdivide the openings