Abstract: Remotely assemblable and disassemblable fuel assembly comprising a mechanical structure constituted by an upper plate, a lower plate and a plurality of brace rods extending between the said plates, and a plurality of elongated fuel elements fixed to the brace rods by gratings, one of the ends of each brace rod being irremovably fixed in the upper plate, the other end of each brace rod being fixed to the lower plate by a system of remotely assemblable and disassemblable assemblies, wherein the said system of assemblies comprises a thread made at the end of each brace rod, a screwing member having a thread able to cooperate with the thread on the brace rod and a head having a plug hole and on its periphery at least one chamfer, as well as machining in the lower plate, constituted by a bore having a larger diameter portion issuing into the outer face of said plate, said larger diameter portion being surrounded by a flange shaped by cutting in the plate and which is separated from the remainder of the plate by an

Abstract: In an assembly of two parts having flat assembly faces, the upper part has a bore provided with an ovalized orifice and the lower part has an internally-threaded bore, the two bores being coaxial when the parts are in the assembly position. A first connecting member has a threaded end in cooperating relation with the internally-threaded bore and a second connecting member has a portion in contact with one face of the upper part. One member has an ovalized portion which cooperates with the ovalized orifice and has a deformable portion which cooperates with the other member after crimping in order to secure the two members at least against rotational motion.

Abstract: In a pressurized water reactor, the pressure vessel contains a plurality of fuel wrappers of parallelepipedal section supported on a lower grid which carries projecting sleeves equal in number to the wrappers. Each sleeve penetrates into a bore of a wrapper base plate and has a higher coefficient of thermal expansion than the base plate so that its external diameter is smaller than that of the bore in the cold state and equal thereto at the operating temperature of the reactor. The bore is thus clamped against the sleeve as a result of thermal expansion, the fuel assemblies being secured within the wrappers by means of spring-type elastic devices.

Abstract: A nuclear fuel assembly comprises a cluster of elongated fuel, retained parallel and at the nodal points of a square network by a bottom supporting plate and by spacing grids. The supporting plate is connected to a top end plate via tie-rods which replace fuel pins at certain of the nodal points of the netword. The diameter of the tie-rods is equal to that of the pins and both are slidably received in the grids.