Critical power enhancement system for a pressurized fuel channel type nuclear reactor using alignment of fuel bundle pairs

A fuel channel assembly for use in a pressurized fuel-channel-type nuclear reactor of the type adapted to be refueled on-line by the insertion and removal of fuel bundles into and from a plurality of fuel channel assemblies, each of said fuel channel assemblies comprising an elongated pressure tube and a plurality of fuel bundles longitudinally disposed in said pressure tube in end-to-end relation, each of said fuel bundles comprising a plurality of elongated fuel elements retained in parallel spaced relation uniformly about a longitudinal axis between transversely disposed end-plates, said end plates having apertures there through to permit coolant flow through said fuel channels in contact with said fuel elements, the fuel channel assembly further comprising at least one fuel bundle pair assembly, said fuel bundle pair assembly comprising a pair of fuel bundles in end-to-end relation and interconnecting means for interconnecting the adjacent facing end-plates of said pair of fuel bundles, said adjacent facing end-plates of said pair of fuel bundles being interconnected by said interconnecting means for maintaining said fuel elements in a predetermined position of relative rotational alignment about said longitudinal axis and preventing axial separation of said pair of fuel bundles in the pressure tube, the non-facing end-plates at opposite ends of said fuel bundle pair assembly permitting said fuel bundle pair assembly to be axially separable from adjacent bundles in the pressure tube to permit independent loading or unloading of said fuel bundle pair assembly.