Abstract: Anti-ejection device for nuclear reactor control rod.The reactor comprises a tight enclosure integral with the nuclear reactor vessel, the control rod being integral with the command bar. A system for manipulating the command bar comprises means for locking it. These means lock the command bar with respect to the tight enclosure for as long as the force exerted on this bar remains below a limit value. This limit value is at least equal to the force exerted on the command bar in the case of an accidental external cause urging the control rod to leave the reactor core. The device comprises means for obtaining a translation of the control rod, by exerting a force exceeding said limit value on the command bar.

Abstract: The frame consists of a base and a plurality of square tubes which are secured to the base in upstanding manner. The base consists of rows of intersecting, inter-fitted and inter-welded metal strips which are disposed in mutually perpendicular groups. The tubes are arranged on the strips in a checkerboard fashion with two walls of each tube substantially flush with two parallel strips. In addition, the rows of tubes are offset to one group of metal strips so that the strips are disposed in planes coincident with the longitudinal axes of the tubes in order to support nuclear fuel elements thereon.

Abstract: A nuclear fuel assembly includes and upper yoke, a base, an elongated, outer flow channel disposed substantially along the entire length of the fuel assembly and an elongated, internal, central water cross, formed by four, elongated metal angles, that divides the nuclear fuel assembly into four, separate, elongated fuel sections and that provides a centrally disposed path for the flow of subcooled neutron moderator along the length of the fuel assembly. A separate fuel bundle is located in each of the four fuel sections and includes an upper tie plate, a lower tie plate and a plurality of elongated fuel rods disposed therebetween. Preferably, each upper tie plate is formed from a plurality of interconnected thin metal bars and includes an elongated, axially extending pin that is received by the upper yoke of the fuel assembly for restraining lateral motion of the fuel bundle while permitting axial movement of the fuel bundle with respect to the outer flow channel.

Abstract: A spray device adapted to spray cooling water vertically to a reactor core in the event of a coolant accident and located in a space between the reactor core surrounded by a shroud and a shroud head mounted on the shroud. The spray device comprises a duct assembly disposed along an inner periphery of the shroud, a plurality of pipes pivotably connected to the duct assembly so as to be movable between horizontal and vertical positions, and nozzles provided for the respective pipes for downwardly ejecting the cooling water to the reactor core.

Abstract: In a nuclear fuel assembly spacer providing passages for fuel rods or other elongated elements, a spring component of H-shape including a pair of spaced spring members of hairpin-like configuration connected by a retaining strap wherein an arched side of one of the spring members projects into one of the passages and the arched side of the other of the spring members projects into an adjacent one of the passages for resilient engagement with the fuel rods or other elongated elements extending through the passages.

Abstract: End fitting for the fuel assembly of a nuclear reactor comprising in per se known manner a device for holding the fuel assembly against an upper or lower plate of the reactor core, wherein the maintaining device is constituted by a plurality of rigid levers, having a first end and a second end, each lever being articulated on an axis A, a closed recess provided in the sides of a frame of the end fitting for each lever and elastic means contained in the recesses and exerting a restoring torque on the corresponding lever.

Abstract: The multiple fuel rod gripper comprises a plurality of split tube collets arranged to be inserted into corresponding tapered holes in a locking plate. When the gripper has been positioned to have a plurality of fuel rods disposed in the holes of locking plate, an actuating mechanism causes the collets to be inserted into the tapered holes thereby causing the fuel rods to be inserted in the collets. The taper of the holes forces the collets into locking engagement with the fuel rods so that the fuel rods may be extracted from the fuel assembly.

Abstract: A fuel pin transfer tool has a latching device of the collet type attached to a first member movable vertically through a long work stroke enabling a fuel pin in an under water assembly to be engaged and withdrawn therefrom or placed therein and released. The latching device has a collet provided with a plurality of resilient fingers having cam portions normally spaced apart to receive the upper end of a fuel pin between them and a second member, movable vertically through a short stroke relative to the first member is provided with cam portions engageable with those of the fingers and is yieldably and resiliently held in a raised position in which its cam portions engage those of the fingers and force the fingers into their pin-gripping positions.

Abstract: Installation for cooling a water-filled fuel element storage well, including a plurality of cooling circuits having drain lines with connections to the well, pumps connected to the drain lines, heat exchangers connected to the pumps and feed lines being connected to the heat exchangers and having connections to the well, one of the connections of the drain lines to the well being disposed at a level which is at least as high as the other of the drain line and feed line connections, and a downwardly directed pipe disposed in the storage well being connected to the one of the drain line connections and having a lower opening formed therein at a lower level than the drain line and feed line connections.

Abstract: A nuclear fuel assembly is described for producing tritium in a light water moderated reactor. The assembly consists of two intermeshing arrays of subassemblies. The first subassemblies comprise concentric annular elements of an outer containment tube, an annular target element, an annular fuel element, and an inner neutron spectrums shifting rod. The second subassemblies comprise an outer containment tube and an inner rod of either fuel, target, or neutron spectrum shifting neutral.