Patent Number: 047388196
Section: claims

1. In a fuel assembly having an array of spaced fuel rods, an outer tubular flow channel surrounding said fuel rods so as to direct flow of coolant/moderator fluid therealong, and a water cross extending through said channel and having a plurality of radially extending members dividing the array of fuel rods into a plurality of separate fuel rod mini-bundle subassemblies, each radial member being connected at multiple segments along its outer longitudinal edge to said channel so as to define a series of spaced apart openings between said member and channel which allow cross-flow of coolant/moderator between adjacent subassemblies for pressure equalization therebetween, each subassembly having a plurality of spacers being displaced from one another along the length of said subassembly between the bottom and top thereof and surrounding said fuel rods thereof so as to maintain them in side-by-side spaced relationship, the improvement which comprises: means interconnecting said each water cross radial member and said channel for closing predetermined ones of said openings adjacent the locations of upper ones of said spacers for blocking portions of said coolant/moderator cross-flow between said separate mini-bundles via said predetermined ones of said openings so as to minimize degradation of CHF performance and resulting penalities and uncertainties associated therewith, said blocking means being in the form of a solid continuous structure impervious to cross-flow and interconnecting said each radial member and said channel adjacent the locations of said upper ones of said spacers. 2. The fuel assembly as recited in claim 1, wherein said blocking means is a continuous rib formed in said channel and connected to a respective one of said water cross radial members, said rib extending along said channel through a distance which encompasses the regions of said adjacent subassemblies occupied by said upper ones of said spacers. 3. The fuel assembly as recited in claim 2, wherein said upper ones of said spacers are three in number. 4. The fuel assembly as recited in claim 1, wherein said blocking means is a continuous weld interconnecting said channel with a respective one of said water cross radial members, said weld extending along said channel through a distance which encompasses the regions of said adjacent subassemblies occupied by said upper ones of said spacers. 5. The fuel assembly as recited in claim 4, wherein said upper ones of said spacers are three in number. 6. The fuel assembly as recited in claim 1, wherein said blocking means is a continuous bar disposed between and interconnecting said channel and respective one of said water cross radial members, said bar extending along said channel through a distance which encompasses the regions of said adjacent subassemblies occupied by said upper ones of said spacers. 7. The fuel assembly as recited in claim 6, wherein said upper ones of said spacers are three in number.