Nuclear reactor with fuel assembly support means

A nuclear reactor including a core having a plurality of fuel assemblies, each of generally polygonal transverse cross section, each of said assemblies being mutually nested side-by-side in an array, each of said fuel assemblies including a plurality of pins, each pin extending downwardly from a region near a corner of the bottom of said each fuel assembly, the pins extending from near the corners of a plurality of fuel assemblies whose corners converge in the region where said corners converge forming a group of adjacent pins, the pins of said group being positioned with their outer surfaces contiguous so that said outer surfaces together form a continuous surface, said reactor including a core support plate having holes, each of said holes being generally coaxial with a said continuous surface, and the boundary of each hole having the contour generally of at least a portion of said continuous surface, each group of pins extending into a hole with which their continuous surface is generally coaxial with the last-named continuous surface substantially being a snug, slidable fit in the boundary of the corresponding hole, whereby the said fuel assemblies are supported and aligned by said support plate.