Abstract: A lifting fixture for removing the upper internals from a nuclear reactor to provide access to the core during a refueling that does not require flooding of a refueling canal. A shield plate is integral to a lifting rig used to remove the upper internals. The shield plate is sized to be supported on the reactor vessel upper flange and to cover the reactor vessel opening with the closure head removed. The shield plate has openings that are in-line with the control rod assembly drive rod travel housings. Control rod assembly drive rods can be accessed through the openings. The lifting rig allows personnel to decouple the drive rods from the rod cluster control assemblies. The lifting fixture enables the decoupled drive rods to be lifted from the core with the upper internals, while shielding maintenance personnel without flooding the area above the reactor.

Abstract: A protective coating for a graphite (Gr) containing fuel element used in a nuclear thermal propulsion system includes a first layer that is configured to resist hot hydrogen attacks. The first layer has a coefficient of thermal expansion that is higher than a coefficient of thermal expansion of the Gr containing substrate. The coating also includes a plurality of second layers located between the first layer and the substrate. The second layers are configured to mitigate the differences in coefficients of thermal expansion between the first layer and the substrate to minimize debonding and exposure of the substrate to hydrogen attack. Preferably, the protective coating can comprise an outermost first layer including zirconium carbide (ZrC), a second layer including niobium (Nb), a third layer including molybdenum (Mo), and a fourth layer including molybdenum carbide (Mo2C) located adjacent to the substrate.

Abstract: An apparatus and method is described for transmuting higher actinides, plutonium and selected fission products in a liquid-fuel subcritical assembly. Uranium may also be enriched, thereby providing new fuel for use in conventional nuclear power plants. An accelerator provides the additional neutrons required to perform the processes. The size of the accelerator needed to complete fuel cycle closure depends on the neutron efficiency of the supported reactors and on the neutron spectrum of the actinide transmutation apparatus. Treatment of spent fuel from light water reactors (LWRs) using uranium-based fuel will require the largest accelerator power, whereas neutron-efficient high temperature gas reactors (HTGRs) or CANDU reactors will require the smallest accelerator power, especially if thorium is introduced into the newly generated fuel according to the teachings of the present invention.

Abstract: An apparatus for reinforcing weakened portions of the top guide assembly in a boiling water reactor. The repair apparatus includes a cruciform lattice segment which reinforces the damaged or weakened region of the top guide beam lattice. This cruciform lattice segment is held in place atop the existing top guide with specially designed straps. The cruciform lattice segment and associated straps are arranged so that a beam segment of the cruciform lattice segment bridges the weakened region in the cracked top guide. Thus, the bridging beam segment transmits loads across the weakened region of the top guide. The straps are designed to avoid interference with removal and installation of the fuel assemblies and the control rod blade which is inserted between the fuel assemblies.

Abstract: The present invention provides a process for the production of antihydrogen, comprising the steps of: (i) exciting alkali atoms to a Rydberg state; (ii) charge-exchanging the excited alkali atoms with positrons to produce Rydberg-state positronium; and (iii) charge exchanging the Rydberg-state positronium with antiprotons to produce Rydberg-state antihydrogen. Preferably, the Rydberg-state antihydrogen is permitted to decay to ground-state antihydrogen which can be trapped in a magnetic trap.

Abstract: A support grid for laterally maintaining the relative position of elongated fuel elements within a fuel assembly for use within a core of a nuclear reactor. The grid is formed in the shape of a lattice with the intersecting lattice members defining a plurality of cells, most of which respectively support the nuclear fuel elements. The remaining cells support nuclear control rod guide tubes and instrumentation thimbles. The cells supporting the nuclear fuel elements are provided with diagonally positioned springs on two adjacent walls. The springs support the fuel elements against dimples which protrude from the opposite cell walls. The adjacent, diagonal springs in each fuel element cell are inclined in opposite directions. The springs are formed from narrow, parallel slits in the cell wall that terminate along a line parallel to the line of intersection with the adjacent wall. The spring slits continue along that parallel line in a direction away from the spring to increase its flexure.

Abstract: A fuel rod for a nuclear reactor includes a metal cladding tube being filled with nuclear fuel and having ends, an outer surface, and a longitudinal axis. A metal seal plug is welded to one of the ends of the cladding tube at a transition point, defining an annular bead disposed on the outer surface of the cladding tube at the transition point. The annular bead has a cylindrical outer jacket surface extending substantially parallel to the longitudinal axis of the cladding tube. The annular bead has material being formed of the metal of the cladding tube and the metal of the seal plug. A welding apparatus for producing the fuel rod includes an electrode having a through bore formed therein for receiving one end of a cladding tube. A counter electrode is displaceable relative to the electrode for holding a seal plug to be welded to the one end of the cladding tube. The electrode has a cylindrical step formed therein at an end of the through bore facing toward the counter electrode.

Abstract: A nuclear reactor vessel has a baffle-barrel assembly for supporting the fuel assemblies in its core region and guiding coolant flowing through the core region when the reactor vessel is in service. The baffle assembly includes a baffle plate fastened to a former plate by a bolt. The baffle plate has a countersunk hole extending to a smaller diameter baffle plate hole. The former plate has a bolt hole aligned with the baffle plate hole. The bolt has a head portion disposed in the countersunk hole and a shank extending from the undersurface of the head portion into the aligned bolt holes and threadedly engaged with the former plate.

Abstract: A multi-lift tool and method for moving control rod assemblies in a nuclear reactor. The multi-lift tool comprises a frame having an upper end and a lower end. A control rod grapple is supported by the frame for engaging a lifting handle of a control rod. The control rod grapple is movable along a length of the frame for raising and lowering the control rod relative to the frame. A fuel support piece grapple is secured to the lower end of the frame for engaging and lifting a fuel support piece together with the control rod. A blade guide grapple is secured to the upper end of the frame for engaging and lifting a blade guide together with the fuel support piece and the control rod. An unlatching grapple is supported near the lower end of the frame for engaging and lifting an unlatching handle of the control rod. The unlatching grapple is movable along a length of a lower portion of the frame for raising the unlatching handle of the control rod relative to the frame.

Abstract: A plant operation apparatus for satisfying a separation criteria includes an operation panel, an operation display screen control device for controlling a display on the operation panel and a touch operation and for selecting a train in a software selection function based on the operation signal from the operation panel, a selection device having momentary push buttons and for resetting other push buttons in a hardware train selection function when an operator pushes one of the push buttons to select a train, and for outputting a control signal to select the train corresponding to the button pushed by the operator. The plant operation apparatus realizes the train selection system having multiplicity, diversity, and independence for satisfying the separation criteria.

Abstract: A control rod guide tube mounting pin for engaging a hole in an upper core plate of a nuclear reactor pressure vessel has a resilient tubular portion with one or more axial crimps which flex allowing for resiliently fitting into a hole in an upper core plate without needing to enlarge or other machine the existing holes or drilling additional holes. Stainless steel mounting pins may be backfit into existing two pin mounting systems of control rod guide tubes adjacent to the outlet nozzles of the pressure vessels by removing the pins mounting the guide tubes adjacent the outlet nozzles to the upper core support plate; and then replacing the removed pins with stainless steel replacement pins.

Abstract: Methods and assemblies for cleaning a control rod guide tube in a nuclear reactor are described. An assembly, in accordance with one embodiment, includes a support housing and a flush tube. The support housing includes a bore extending between its first and second ends. The flush tube also includes a bore extending between its first and second ends. The flush tube extends through the support housing bore and is movably coupled to the support housing adjacent the first end of the support housing. The second end of the flush tube extends from the support housing and includes a flush nozzle which is movable between a first, or latched, position and a second, or open, position.

Abstract: A fuel rod for a light water reactor comprises a cladding tube which comprises a zirconium alloy having a composition including 0.6 to 2.0% by weight of Nb, 0.5 to 1.5% by weight of Sn, 0.05 to 0.3% by weight of Fe, and the balance being Zr and incidental impurities; uranium oxide fuel pellets packed in the cladding tube; and end plugs comprising a zirconium alloy and closing both ends of the cladding tube. The cladding tube is sealed by TIG welding with the end plugs. Grain boundaries in each heat affected zone of the cladding tube, which are adjacent to a bead formed by TIG welding, have structural compositions including 4 to 30% by weight of Nb, and 0.9 to 20% by weight of Fe.

Abstract: A steam power station, in particular a nuclear power station, includes a steam conduit leading through a wall and forming a fixed point with the wall for the introduction of forces and moments. A main valve is connected to the steam conduit at the fixed point, without a high-pressure pipe being interposed. Satellite valves, which have smaller nominal widths than the main valve, are fastened to the housing of the main valve, without a high-pressure pipe being interposed. At least one additional valve has a housing fastened to the housing of a satellite valve, without a high-pressure pipe being interposed and without any support.

Abstract: A technique for assaying samples entails irradiating a sample with a beam of gamma rays of sufficient energy to excite the nuclei of the assay elements into their isomeric states, ceasing the irradiation, detecting the gamma rays resulting from the decay of the isomeric states to the ground state, and analyzing the detected gamma rays to determine the content of assay elements in the sample. In a preferred embodiment, the apparatus is configured such that the irradiated sample is rapidly moved to a shielded environment in which the gamma rays from the isomeric transitions are detected. The system is ideally suited for analyzing large samples of ore for gold, silver, barium and other assay elements, but can be embodied to detect any assay elements susceptible to photon activation analysis in any sample geometry.

Abstract: A mixture of metal ions is added to the primary cooling water of a water-cooled nuclear reactor to inhibit deposition of radioactive materials in the cooling water on the inner surfaces of pipes. The mixture of metal ions added to the cooling water introduced into the primary cooling system simultaneously comprises two to four of the metal ions, Mn ion, Mg ion, Ni ion and Zn ion, one of these ions being manganese ion.

Abstract: A shroud including an integral track for mounting inspection and cleaning tooling is described. In one embodiment, the shroud includes substantially cylindrical first and second shroud sections having a main body with a first end and a second end. One shroud first end has a weld prepared surface. Each shroud section includes a ledge in an exterior surface adjacent the first end. A weld is formed between the weld prepared surface and the first end of the second shroud section. At the weld, the shroud is substantially geometrically balanced with equal material on both sides of the weld. A geometrically balanced weld provides the same heat sink characteristics on both sides of the weld, and allows for a more uniform distribution of weld residual stresses.

Abstract: A restraint assembly which is a bolted lattice structure for preventing the in-core guide tubes from experiencing excessive flow induced vibrations is described. In one embodiment, the restraint assembly includes upper and lower restraint brackets secured to an in-core housing and in-core guide tube assembly. The restraint brackets are located approximately equal distance from the end supports of the in-core guide tube and in-core housing assembly. The upper restraint bracket is welded between sections of the in-core guide tube, and the lower restraint bracket is welded between the in-core guide tube and the in-core housing. Each bracket includes four flanges, and each flange has tapped, or threaded, openings therein. Each bracket also includes cylindrical sections extending from the flanges, and in one embodiment, the cylindrical sections have inner and outer diameters which match the inner and outer diameters of the in-core housing and the in-core guide tube.

Abstract: A method for integrating liquid metal magnetohydrodynamic power generation with fusion blanket technology to produce electrical power from a thermonuclear fusion reactor located within a confining magnetic field and within a toroidal structure. A hot liquid metal flows from a liquid metal blanket region into a pump duct of an electromagnetic pump which moves the liquid metal to a mixer where a gas of predetermined pressure is mixed with the pressurized liquid metal to form a Froth mixture. Electrical power is generated by flowing the Froth mixture between electrodes in a generator duct. When the Froth mixture exits the generator the gas is separated from the liquid metal and both are recycled.

Abstract: A core barrel for a reactor pressure vessel of a nuclear reactor plant has a carrying structure that is supported on an inner surface of the shroud of the barrel. The carrying structure receives a tension rod that extends parallel to the longitudinal axis of the barrel and braces the shroud in the axial direction.