Importance

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Abstract

A BWR fuel assembly having an array of spaced fuel rods, an outer hollow tubular flow channel surrounding the fuel rods so as to direct flow of coolant/moderator fluid therealong, and a hollow central water cross extending through the channel and composed of radially extending members dividing the fuel rods into separate fuel rod mini-bundle subassemblies which each has fuel rod spacers being displaced from one another along the length of the subassembly, includes features on at least one of the spacers of each subassembly which minimize degradation of CHF performance. These features are coolant flow diverting scoops mounted on the outer peripheral strap of the spacer. The scoops are disposed in spaced apart relation along an upstream side of the outer strap so as to extend inwardly along and in spaced relation from an upstream side of respective ones of the terminal end portions of the interleaved inner straps of the spacer which with the outer strap form a ring of perimeter cell openings in the spacer. The scoops also extend within the respective spaces between those of the fuel rods received through the perimeter cell openings and terminate at inner ends being disposed above a border defined by the inner straps which surrounds and separates a group of inner cell openings defined by the interleaved inner straps from the perimeter cell openings. The scoops have flow deflecting portions disposed in inclined relationships across portions of the coolant flow paths to the perimeter cell openings for causing redistribution of flow to the inner cell openings.

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First Claim