Abstract: The "Purex" solvent extraction and separation process for recovering uranium from scrap material or spent fuel containing gadolinia is modified by treating uranium containing scrap or spent fuel with nitric acid to convert uranium oxide to soluble uranyl nitrate in an aqueous medium, separating the uranyl nitrate from the aqueous media with an organic medium containing tri-butyl phosphate, and then releasing the separated uranium from the organic medium with water. The improvement comprises monitoring the density of the organic medium and controlling the feed rate of the uranium in the aqueous medium in response to the density measurements.

Abstract: A combination of flow trippers with spacer deflectors in the two phase steam/water region of a fuel bundle in a boiling water reactor is disclosed. Spacers with deflectors are placed immediately above the flow trippers. The flow trippers are located on either an inside channel wall surrounding the fuel bundle or the outside of water chambers within the fuel bundle. Additional flow trippers may be located adjacent to the spacers, above the flow trippers that are below the spacers. The spacers are provided with deflector skirts overlying the flow trippers. In operation of the fuel bundle, excess water flows in the two phase region in a film on the unheated inside walls of the fuel channel or the outside walls of the water chambers. The film flow is perturbed by the flow trippers and is deflected toward the fuel rods. The overlying deflector skirts or tabs on the spacers further deflect the liquid toward the fuel rods to improve cooling and to increase the power generation capability of the fuel bundle.

Abstract: A suppression chamber in a nuclear reactor containment includes a heat exchanger disposed in a gas space above water in the suppression chamber. A gravity-driven pool contains a supply of make-up water that is gravity fed to the heat exchanger through a conventional level-maintaining valve such as a float valve. A top header in the heat exchanger includes a free surface area for permitting separation of steam from water, thereby permitting venting of vapor only, while retaining the liquid coolant in the heat exchanger. A downcomer tube permits return of excess water to a lower location for further use in the heat exchanger. The heat exchanger is normally sealed, whereby internal surfaces in the heat exchanger require only a small amount of low-volatility corrosion inhibitors to prevent corrosion on internal surfaces thereof. Locating the heat exchanger in the gas space in the suppression chamber reduces the amount of corrosion on its external surfaces.

Abstract: An improved lower tie plate having increased fluid flow resistance is disclosed for use in a boiling water nuclear reactor. The fuel bundle includes the lower tie plate, an upper tie plate, and a plurality of fuel rods supported therebetween in vertical upstanding relation, with the fuel rods surrounded by a square sectioned channel. In the preferred embodiment, some of the upper fuel rods are of partial length. The surrounding channel confines the fluid flow through the fuel bundles between the tie plates for the extraction of heat from the fuel rods undergoing a fission reaction. The lower tie plate includes a first group of apertures for the support of the fuel rods to selected positions in the 9x9 matrix; appropriate numbers of these apertures are threaded for tying the upper and lower tie plates together with tie rods. The matrix is interrupted at larger apertures for the support of moderator containing water rods.

Abstract: The disclosed invention consists of a ceramic form of fuel for a nuclear reactor comprising an oxide of a fissionable element and containing therein a consumable neutron absorbing agent. The ceramic fissionable fuel product provides longer fuel performance in nuclear reactor service.

Abstract: A lanthanide oxide selected from the group consisting of dysprosium oxide, erbium oxide, europium oxide, gadolium oxide and samarium oxide is formed into a compact and sintered to produce a body useful as a control rod material in a water cooled nuclear reactor. The lanthanide oxide is preferably combined with a corrosion stabilizing group 4A metal oxide such as hafnium oxide.

Abstract: An improved method and means for sizing metal configuration through the application of thermal expansion and contraction of a shaping mandrel. The thermally induced changes in the shaping mandrel are produced from within the body at the mandrel.

Abstract: In a steam generator utilized with a liquid sodium cooled nuclear reactor, provision is made to vent the violent sodium water reaction emanating from a tube rupture casualty. The steam generator includes a sodium plenum at the bottom thereof containing a conventional rupture disk for venting sodium, steam, and reaction products including hydrogen immediately upon a tube rupture casualty. The invention includes providing an alternate concentric flow path interior to the steam generator and parallel to the tube bundle. This alternate concentric flow path extends from the upper portion of the steam generator down into the lower head or plenum adjacent to the pressure relief diaphragm. This alternate path is partially filled with sodium during normal reactor operation.

Abstract: An apparatus and process for the construction of a cruciformed section control rod is disclosed. The control rod is characterized by having square exterior sectioned tubes with central cylindrical volumes for the containment of neutron absorbing poisons. In the process, these tubes are welded together at the corners of the square sections to form the planar members of the cruciformed shaped rods. An apparatus and process is disclosed in which the rods are all held by a jig in the same configuration as is ultimately fabricated. Thereafter, the jig is drawn through fixtures, which fixtures accurately guide the rods to be joined by welding past paired and opposed laser welding heads. By the expedient of positioning the laser and rapidly drawing the braced together tubes by the laser, control rod fabrication occurs. There results a solid, integral control rod constituting a suitable pressure vessel for neutron absorbers for control of nuclear reactions.

Abstract: Pellet trays bearing rows of fuel pellets of known enrichment concentrations are retrieved from selected storage elevators and successively conveyed to a zone makeup machine. Parallel rows of pellets are raked from each tray and advanced over a longitudinally elongated, grooved loading surface into abutment with a selectively longitudinally positioned stop. A zone makeup carriage makes up the pellet rows to a prescribed, common zone length, which are then weighted and advanced in parallel by a vibratory loader into a plurality of cladding tubes arranged in parallel loading positions by tube handling apparatus. Overall operation is coordinated by a system controller to concurrently load the cladding tubes with multiple pellet zones of varying enrichments and lengths in automated fashion.

Abstract: Disclosed is an electrode probe for employment in monitoring electrochemical potentials and which has a robust structure particularly suiting it for employment within the rigorous environment of the reactor core of a nuclear power facility. The electrode of the present invention is comprised of four major segments: a metal cap electrode, an alumina retainer, an annular metal sleeve, and a positioning and signal transfer assembly. The metal cap electrode has a tip portion and an annulus extending therefrom which defines a cavity having an interior surface. The alumina retainer has a base region with a sleeve attachment surface, an oppositely disposed cap securing portion nestably disposed within said cap electrode cavity and sealingly attached thereto. The retainer further has an axis channel penetrating therethrough from the base region to the cap securing portion.

Abstract: An apparatus and process for the accurate measurement and calibration of core flow in a boiling water reactor is disclosed. The reactor includes a pressure vessel having internal forced circulation through the core. An annular downcomer region establishes reactor coolant flow downwardly in the periphery of the reactor vessel and finally upwardly and centrally into the core across a core plate. A pressure sensor detecting the pressure differential across the core plate is utilized. This pressure sensor has its measurement enhanced by input from local power range monitors in the core to utilize both the sensed pressure differential and the power to predict more accurately flow in the reactor. An algorithm is developed for utilizing the pressure differential and the real time readings from the local power range monitor to accurately gauge overall reactor coolant flow. To ensure accurate calibration, two calibration standards are itilized at steady states of reactor power output and coolant flow.

Abstract: A method of inhibiting deleterious reactions between metallic fissionable fuel for nuclear reactors and stainless steel containers for housing such fuel comprising imposing an expendable body of alloying metal intermediate the fuel and container is disclosed. The disclosure also includes an improved nuclear fuel element comprising metal alloy fuel housed within stainless steel containers having a body of zirconium metal interposed between the fuel and containers.

Abstract: In operation, the device is lowered with paired lines attached to both housing lugs but suspended under tension only from one line to one lug so that the streamline housing is vertically disposed. With the housing vertically disposed during lowering, obstacles can be avoided such as the guide rod for the steam separator and dryer as well as the feedwater and core spray spargers. When lowered to the vicinity of the ledge and cover plate to be inspected, the slack line is fished around any obstacle and thereafter placed under tension. The streamline housing is then lowered using both lines in a horizontal position so as to expose downwardly the pedestal and rubber foot. Lowering is completed with remote camera assistance. Sample sweeps with the ultrasound transducer of spaced apart sections of the cover plate weld are used for precise centering of the pedestal and rubber base with respect to the center of the cover plate.

Abstract: In a nuclear fuel bundle, an improved lock washer is disclosed for permitting ease of remote removal of hex nuts on tie rods for the remote submerged disassembly of fuel bundles after use in a reactor. The improved lock washer includes two spaced apart and interconnected tie rods surrounding washer members, each of these tie rod washer members having radially inwardly extending keys. These keys register to corresponding keyways in the threaded ends of the tie rods to prevent tie rod rotation and threaded disengagement from the lower tie plate. Each washer member is manufactured from a spring material and includes at least one and preferably two radially protruding tangs T. These tangs are elongate and bent in an inverted U-shaped configuration. The inverted U-shaped configuration commences at the washer member and extends upwardly and outwardly away from the hex bolt to be locked. Reversal of the spring member occurs at the end of the U with the spring member returning angularly back towards the tie rod.

Abstract: A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

Abstract: A safety qualified interface device is interposed between an operator manned control position having an operator interface and qualified safety system logic monitoring and control devices. This microprocessor driven interface incorporates a memory carrying a library collection of valid safety directives as well as valid parameter inputs and permissible parameter deviation ranges. Control or parameter requests are asserted by the operator from non-safety related but conveniently positioned interface devices at the control position which are treated as trial inputs which are matched at the interface with memory retained valid directives and parameters. Where a match between memory retained data and the trial input signals occurs, then the operator is apprised through a qualified safety related display and a corresponding acknowledgement is made to the interface.

Abstract: In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus and method for the repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand.

Abstract: A suppresion chamber in a nuclear reactor containment includes a heat exchanger disposed in a gas space above water in the suppression chamber. A gravity-driven pool contains a supply of make-up water that is gravity fed to the heat exchanger through a conventional level-maintaining valve such as a float valve. A top header in the heat exchanger includes a free surface area for permitting separation of steam from water, thereby permitting venting of vapor only, while retaining the liquid coolant in the heat exchanger. A downcomer tube permits return of excess water to a lower location for further use in the heat exchanger. The heat exchanger is normally sealed, whereby internal surfaces in the heat exchanger require only a small amount of low-volatility corrosion inhibitors to prevent corrosion on internal surfaces thereof. Locating the heat exchanger in the gas space in the suppression chamber reduces the amount of corrosion on its external surfaces.

Abstract: An electrode probe suited for employment as a reference electrode in a high pressure, high temperature, and high radiation field environment such as adjacent the core of a nuclear reactor is described. The electrode is a brazed and welded assembly consisting of only ceramic and metal parts including a sapphire crucible which is brazed to a kovar/stainless steel housing, welded in turn, to a coaxial cable assembly for signal transfer. The crucible incorporates an integrally formed pedestal through which a conductor wire extends and over which is positioned a selectively coated cylindrically shaped sealing retainer. The device is particularly suited for employment with a silver/silver chloride electrode system.