Abstract: A device for collecting core melt from a reactor pressure vessel improves a flow of the core melt out of the reactor pressure vessel. A prechamber is disposed below the reactor pressure vessel and a spreading chamber for the core melt is disposed laterally next to the reactor pressure vessel. The spreading chamber is connected to the prechamber through a channel. A base unit forms a bottom region at least of the prechamber and is made of a material having high thermal conductivity.

Abstract: A storage framework for nuclear reactor fuel elements includes a baseplate on which a plurality of structural wells of essentially rectangular cross section are fastened. The structural wells stand upright on the baseplate and in each case are disposed approximately diagonally opposite one another in a checkered manner. Structural wells located diagonally opposite one another in each case span an interspace. A neutron-absorbing structure with boron-treated steel is disposed in the interspace and/or in the structural wells, is displaceable relative to the structural wells and has plates made from boron-treated steel. The plates form an essentially rectangular absorber well which does not take on any load-bearing functions of the storage framework. The absorber well is fixed in its position by spacers, in particular edge beads, on the plates.

Abstract: An apparatus for repairing a shroud in which one or more seam welds are cracked. The repair involves the attachment of a splice bracket to the shroud so that the bracket bridges the cracked weld seam and is applicable to both vertical and horizontal weld seams. The bracket is intended to structurally replace the shroud seam weld which is cracked. Multiple splice brackets can be placed along the length of a crack. Each splice bracket is attached to the shroud by a plurality of tapered fastener assemblies.

Abstract: The invention relates to a nuclear fuel element for pressurized-water reactors comprising a fuel cladding of a zirconium alloy composed of two parts. The inner part constitutes a supporting part of a conventional zirconium and the outer part a corrosion-resistant layer of zirconium with 0.65-0.95% Sn and 0.4-0.5% Fe. The difference in Sn content between the inner and outer parts must not exceed 0.7%. The cladding is finally heat-treated within the range 450 to 510.degree. C.

Abstract: The present invention relates to a method and a device for correction of the movements of a suspension device and positioning thereof in a fluid. The suspension device is provided with a first and a second end, and the first end is suspended from a point (S). A correction device is arranged at the second end of the suspension device and adapted to generate a force which provides an acceleration in the fluid so that the position of the second end of the suspension device is corrected.

Abstract: The invention relates to a steam blowing tube for nuclear power plants of the kind which has a lower end immersed in a water pool, the purpose of tube being to permit, if required, the blow down of steam into the water of the pool with the purpose of condensing the same so as to counteract the build-up of damaging steam overpressure in the containment of the reactor. A number of through holes are recessed in the wall (11) of the individual blow down tube (10) which each one is delimited by upper and lower edges (13, 14) of which at least one constitutes part of a portion (15) bent in relation to the tube wall (14). The lower hole edge (14) forms a steam flow cutting edge which, when the steam rushes down through the tube, divides a part flow from the main steam flow and brings said part flow out into the surrounding water of the pool before the main flow reaches the bottom opening (12) of the tube.

Abstract: A method and apparatus is disclosed for inspecting a wall to evaluate the remaining thickness of the wall as well as the extent to which the wall has been infiltrated by another material. The disclosure discusses directing photons of radiation and/or neutrons into the wall and measuring and analyzing the radiation emitted from the wall as a result of Compton scattering, pair production, photoelectric absorption and/or neutron absorption. The invention is particularly well suited for inspecting a carbon hearth-wall liner of an iron-smelting blast furnace.

Abstract: A power supply system for driving reactor coolant recirculation pumps within an advanced boiling water reactor is configured in such a manner that: at least one normal-operation busbar branches off from either a main on-site power line or from a power line for auxiliary power generation that branches off from the main on-site power line, with a house transformer therebetween; at least one MG set is connected to one of these normal-operation busbars; one static adjustable-frequency power supply device is connected to each MG set; and a plurality of recirculation pumps is connected to each static adjustable-frequency power supply device.

Abstract: The present invention is used in fuel handling for lifting of fuel assemblies and/or control rods out of/into a reactor vessel in a nuclear reactor. The reactor vessel comprises a reactor core with a plurality of fuel assemblies and control rods. A fuel pool is arranged adjacent the reactor vessel. A cassette comprising a plurality of storage positions for fuel assemblies and/or control rods is arranged near the reactor core, whereupon fuel assemblies and/or control rods are lifted out of the reactor core and arranged in the cassette. The cassette is then transported to the fuel pool for temporary storage.

Abstract: The present invention relates to a fuel assembly in or for a boiling water reactor, comprising a plurality of vertical fuel rods extending between a top and a bottom tie plate and surrounded by a sleeve-formed casing where the fuel rods are positioned with the aid of a plurality of axially separated spacers. The invention is characterized in that only one fuel rod is detachably arranged in the top tie plate and in the bottom tie plate and in that at least one of the other fuel rods is fixed to the bottom tie plate and adapted to extend above the top tie plate to obtain a tensile-force-transmitting connection with the bottom tie plate.

Abstract: The injector (B) designed specifically to supply a steam generator (G) with water at high pressure when necessary, is supplied by steam that may originate from the generator itself, and by pressurized water from an ejector (C) supplied during the start up phase by a water circuit (D) pressurized by steam, and during the steady state phase, by an extraction circuit (R) connected on the downstream side of the injector. This device entrains water originating from a tank at low pressure (73) into injector (B), to pressurize it at a pressure exceeding the steam pressure.Application to safety devices in nuclear power stations.

Abstract: A sintered nuclear fuel body includes (U, Pu)O.sub.2 mixed crystals having a mean particle size in a range from 7.5 .mu.m to 50 .mu.m. This sintered nuclear fuel body has a high retention capacity for fission gas in a power reactor. In order to produce the sintered nuclear fuel body by sintering a body in a hydrogen-containing sintering atmosphere, a powered substance selected from the group consisting of aluminum oxide, titanium oxide, niobium oxide, chromium oxide, aluminum stearate, aluminum distearate and aluminum tristearate is added to the starting powder for the body. As an alternative or in addition, the body made from the starting powder is sintered during a holding period of 10 minutes to 8 hours at a sintering temperature of 1400.degree. C. to 1800.degree. C. in a hydrogen-containing sintering atmosphere, initially with an oxygen partial pressure of 10.sup.-10 to 10.sup.-20 bar and then from 10.sup.-8 to 10.sup.

Abstract: A spacer for maintaining a pressure tube in spaced relation with a caland tube of a nuclear reactor. The spacer comprising a split ring adapted to be disposed about the outer surface of said pressure tube. The ring has a central annular body portion with a raised bearing surface thereon adapted to contact the inner surface of said calandria tube and prevent contact between said outer surface and said inner surface. An annular land projecting from each side of said central body portion is adapted to receive a collar thereon effective create an interference fit between said ring and said pressure tube and thereby constrain axial movement of said spacer on said pressure tube. The spacer of the present invention maintains its location on the pressure tube and does not suffer the axial movement which characterizes some conventional spacers. The bearing surface can have a coating to reduce wear and heat transfer.

Abstract: A fuel assembly for a pressurized water reactor having a fuel rod with a high strength cladding tube including an inner tubular layer of a zirconium alloy with alloying components of molybdenum and 3 to 6 weight percent bismuth, the balance zirconium.

Abstract: A capsule containing a tag gas in a zircaloy body portion having a hemispical top curved toward the bottom of the body portion. The hemispherical top has a rupturable portion upon exposure to elevated gas pressure and the capsule is positioned within a fuel element in a nuclear reactor.

Abstract: A nuclear power plant has a reactor core and a containment chamber for receiving core melt of the reactor core. A cooling system for cooling the containment chamber includes a flooding container to be filled with coolant fluid. A cooling pipe leads from the flooding container to the containment chamber. A passively opening closure element closes the cooling pipe in the flooding container and opens as a function of a level of the coolant fluid.

Abstract: A containment of a nuclear power station includes a device for igniting hydrogen contained in a hydrogen/air mixture. A central electrode for lightning flash generation is provided to ensure the maintenance of a particularly low hydrogen concentration in the entire interior of the containment. The central electrode is connected to a high-voltage source for generating a high voltage greater than the disruptive discharge voltage of air.

Abstract: A tube of zirconium-based alloy for constituting all or a portion of a cladding or guide tube for a nuclear fuel assembly. The tube is made of an alloy containing, by weight, 1.0-1.7% of tin, 0.55-0.80% of iron, 0.20-0.60% total of chromium and/or vanadium, and 0.10-0.18% of oxygen, with 50-200 ppm of carbon and 50-120 ppm of silicon. The alloy further contains only zirconium and unavoidable impurities, and it is completely recrystallized.

Abstract: A passive emergency water system for cooling the atmosphere inside containment in a water-cooled nuclear reactor comprises an elevated in-containment water reservoir connected to an in-containment heat exchanger. The heat exchanger promotes natural convection of containment atmosphere and heat transfer. Heat from containment atmosphere is transferred to the reservoir by a convective return flowpath. The heat exchanger is preferably an elevated tube bank Baffle walls can be used inside containment to promote circulation of containment atmosphere. In one embodiment, the reservoir tank is closed with respect to containment atmosphere and is vented through the containment wall to the external atmosphere. In an alternative embodiment, the reservoir tank can be of a sufficient volume to absorb heat from containment as sensible heat without boiling.

Abstract: A control rod includes four panels in cruciform section each containing a plurality of absorber tubes. The absorber tubes are mounted between upper and lower mounting structures having generally T-shaped slots opening toward one another. The absorber tubes have generally T-shaped end plugs for reception in the slots. The slots and end plugs are configured to permit limited axial movement of each absorber tube relative to the control rod and to adjacent tubes. The absorber tubes are maintained in tension during all nuclear operations including during a scram.