Abstract: A nuclear power reactor has an active zone in which a plurality of fuel elements containing a large number of fuel rods are held between two grid plates. A tension device is disclosed which is provided for each fuel element and holds the same between the grid plates. The tension device includes a resilient pressure arrangement disposed between one of the grid plates and the end portion of the fuel element facing the one grid plate for holding the fuel element against the other one of the grid plates.

Abstract: For use in forming the core of a pressurized-water reactor, a fuel assembly supporting structure for holding a bundle of interspaced fuel rods, is formed by interspaced end pieces having holes in which the end portions of control rod guide tubes are inserted, fuel rod spacer grids being positioned by these guide tubes between the end pieces. The end pieces are fastened to the end portions of the guide tubes, to integrate the supporting structure, and in the case of at least one of the end pieces, this is done by means which releases that end piece from the guide tubes when the end pieces receive an abnormal thrust force directed towards each other and which would otherwise place the guide tubes under a compressive stress that would cause them to buckle. The spacer grids normally hold the fuel rods interspaced by distances determined by nuclear physics, and buckling of the control rod guide tubes can distort the fuel rod spacer grids with consequent dearrangement of the fuel rod interspacing.

Abstract: A boiling-water reactor has control rods operable from the top of the reactor pressure vessel and has control rod guide tubes structurally connected with upwardly removable water separators in a steam space above the reactor core.

Abstract: A nuclear reactor fuel element comprised of a plurality of fuel rods disposed in a plurality of spacers in which the tubular casing for each fuel rod is designed without regard to the mechanical stress produced by the spacers and has a reinforced wall thickness adjacent to the spacers which is thicker than the wall thickness of the tubular casing in other areas not adjacent to the spacers. The spacers are arranged in a circular mesh with a center support rod.