Coolant mixing vanes

Claim 1

In a liquid-cooled nuclear reactor core having a plurality of adjacent fuel assemblies which are polygonal in cross-section and have adjacent corners defining an intersection of said fuel assemblies, each of said fuel assemblies having a plurality of elongated fuel elements in parallel array held in position by upper and lower securing means and by fuel element spacers, each of said spacers having intersecting straps forming openings through which the elements longitudinally extend and coolant can flow in a longitudinal direction, and adjacent ones of said fuel elements at the intersections of said straps forming subchannels for the flow of coolant therethrough, wherein the improvement comprises: each of said fuel assemblies including a plurality of coolant flow deflecting means mounted on at least some of the intersections of said straps of said spacers, a first plurality of said flow deflecting means arranged concentrically relative to said intersection of said adjacent corners of said adjacent fuel assemblies and oriented in the same circumferential direction for deflecting at least a portion of the longitudinal coolant flow transversely within each fuel assembly for producing a first concentric uNidirectional substantially unrestricted vortex flow pattern of the coolant relative to the intersection of said adjacent corners of said adjacent fuel assemblies which transfers substantially all of the coolant deflected by said first plurality of flow deflecting means in one of said fuel assemblies to a single adjacent one of said fuel assemblies and a second plurality of flow deflecting means arranged concentrically relative to the center of each of said fuel assemblies and oriented in the same circumferential direction for producing therein a second unidirectional substantially unrestricted vortex flow pattern of coolant relative to said center for effecting temperature averaging between high and low temperature regions of said adjacent fuel assemblies and within each assembly, the orientation of said first and second plurality of flow deflecting means being such that adjacent ones of the coolant flow vortices cooperate with each other to maintain established flow patterns.