Abstract: Nuclear fuel for use in nuclear reactors is provided in the form of a nuclear fuel element with an interior barrier layer interposed between the sheath and the fuel. The barrier layer incorporates particles of copper in finely divided form to provide by combination with cadmium, which is released during irradiation of the fuel, a stabilized copper-cadmium compound localized intermediate the fuel and the sheath, thus impeding attack on the sheath by the released cadmium. There is further provided a simple, low cost method for applying the barrier layer in a nuclear fuel element.

Abstract: A fuel assembly for a nuclear reactor including a plurality of fuel rods held in spaced, parallel position between upper and lower tie plates and retained in lateral position by intermediate spacers and having a water tube in lieu of a fuel element in one or more of the rod positions, the water tubes having an outside diameter greater than that of the fuel rods and the spacer springs in the spacer cells of the water tubes being modified to accommodate the larger diameter of the water tubes.

Abstract: In a system, such as a water-cooled nuclear reactor, water level sensors provide signals to a control channel for control of feedwater flow and hence the water level in the pressure vessel. Rapid and fine level control is provided by comparing fluid outflow and inflow. Means are provided to block automatically the flow comparison signal from the control circuit in response to a signal characteristic of a faulted flow comparison signal. At least one redundant control channel is provided and level control is transferred thereto automatically upon excusion of the water level beyond predetermined normal upper and lower limits or in response to a rapid change in the water level control signal to avoid unnecessary shutdown in the event of a faulted channel.

Abstract: Fixed ammonia in an aqueous stream is converted to free ammonia in solution by mixing the stream with a lime slurry in a mixing zone. The resulting liquid mixture is heated by contact with steam-containing gas to a temperature of at least about 95.degree. C. to form a heated liquid mixture containing free ammonia in solution and an ammonia-rich product vapor. A portion of the heated liquid mixture is withdrawn and is contacted with steam in a packed stripping zone to produce liquid waste and vapor containing free ammonia and steam. At least a portion of the vapor from the stripper is used as steam-containing gas for heating the liquid mixture. Ammonia is recovered from ammonia-rich product vapor withdrawn from the mixing zone.

Abstract: An apparatus incorporating a microprocessor control is provided for automatically loading nuclear fuel pellets into fuel rods commonly used in nuclear reactor cores. The apparatus comprises first and second elongated members having "V" troughs for alternately receiving a plurality of fuel pellets to be loaded alternately in first and second fuel rods. The pellets are weighed while in the "V" trough of each elongated member and each elongated member is alternately relocated in axial alignment with a cooperating fuel rod. A guide bushing assembly is provided to assist the transfer of the pellets from each of the elongated members into awaiting fuel rods. A rod handling assembly incorporating rod handling means, a thumper assembly to facilitate the loading of fuel pellets into the fuel rods, an adjustable fuel rod backstop and a rod carousel carrying a plurality of fuel rods, presents two fuel rods to the guide bushing assembly at the appropriate stage in the loading sequence.

Abstract: A method and arrangement for operating a boiling water nuclear reactor and fuel assembly designs for such reactor wherein the reactor is operated with uniquely located control rods that serve the primary functions of power shaping and reactivity control. A second and separate distinct group of control rods is withdrawn when the reactor is at power and the control rods of this group serve the primary function of reactor shutdown. The design of the fuel assemblies and the selected patterns of fuel assemblies and control rods make the separation of control functions feasible. The power shaping and reactivity control control rods are located in low power regions of the core designated control cells. The design of the fuel is such that the control rods of the control cells may remain in fixed positions in these cells during the operating cycle until withdrawal for burnup reactivity compensation.

Abstract: In a jet pump for a nuclear reactor a slip joint is provided between the mixer and diffuser sections thereof to facilitate jet pump maintenance and to allow thermal expansion. To limit leakage flow through the slip joint to a rate below that which causes unacceptable flow induced vibration of the pump, there is provided a labyrinth seal for the slip joint in the form of a series of flow expansion chambers formed by a series of spaced grooves in the annulus of the slip joint.

Abstract: A method is disclosed for preventing stress corrosion cracking or metal embrittlement of a zirconium or zirconium alloy container that is to be coated on the inside surface with a layer of a metal such as copper, a copper alloy, nickel, or iron and used for holding nuclear fuel material as a nuclear fuel element. The zirconium material is etched in an etchant solution, desmutted mechanically or ultrasonically, oxidized to form an oxide coating on the zirconium, cleaned in an aqueous alkaline cleaning solution, activated for electroless deposition of a metal layer and contacted with an electroless metal plating solution. This method provides a boundary layer of zirconium oxide between the zirconium container and the metal layer.

Abstract: A method is disclosed for controlling the release of radioiodine produced by the fission of uranium 235 during the process for the production of molybdenum 99. In the process for producing molybdenum 99, an aluminum-uranium alloyed target is irradiated with a neutron flux to bring about fission of the Uranium 235 producing molybdenum 99, radioiodine and other fission by-products. The method herein comprises reacting the irradiated target with a caustic solution. A reactive silver is then mixed with the caustic solution in an amount sufficient to react with substantially all of the radioiodine present in the caustic solution thereupon forming a silver precipitate of radioiodine. The precipitate formed is then separated from the caustic solution resulting in a substantially radioiodine-free caustic solution containing molybdenum 99.

Abstract: An accurately formed straight edge member serves as a track for a carriage movable along the length of an elongated component. Distance measuring devices supported by the carriage engage the adjacent surface of the component by which flatness, bow and twist of the component can be determined.

Abstract: A hydrogen ion sensor comprising in combination a gas impervious membrane sheath of an oxygen ion conducting ceramic, an electrochemical system partially contained therein, a terminal external to the ceramic sheath electrically connected to the electrochemical system and means for sealing the interior of the ceramic sheath from the ambient, the electrochemical system providing a fixed steady electrical potential that varies only with temperature between the inner surface of the ceramic sheath and the terminal.

Abstract: A method of nitriding ferrous alloys for improving the quality and integrity of the resultant case or hardened surface portion formed thereby, comprising the application of a specific combination of sequenced temperature and nitrogen conditions.

Abstract: A pulse conversion circuit which converts input voltage pulses to current pulses, compares the resulting current pulses to a threshold current and produces an output voltage proportional to the integrated difference between the current pulses and the threshold current.

Abstract: This describes a fuel assembly for utilizing plutonium fuel in combination with other nuclear fuel in a nuclear reactor core. The plutonium fuel is placed in a separate zone in the fuel assembly to take advantage of the characteristics of the plutonium fuel. Fuel costs may be reduced by mixing the plutonium fuel with natural or depleted uranium. Fabrication costs can be minimized by placing the plutonium in less than all of the fuel elements of the assembly.

Abstract: This disclosure relates to a distinctive construction and method of operating a furnace or oven for controlled atmosphere service whereby substantial savings in heating power or energy are realized. The furnace or oven includes a combination of refractory and insulating materials arranged in a given sequence with respect to their relative gas permeabilities, and at least two gases of discernably different weights are strategically supplied to the furnace or oven at particular locations therein.

Abstract: Method and apparatus for the nondestructive determination of the amount and quantitative distribution of a paramagnetic additive such as gadolinia in nuclear fuel elements. Changes in paramagnetic susceptibility of the material in the element are detected as the element is passed through a constant magnetic field and compared to the changes in susceptibility produced by a standard element of known additive content.

Abstract: An apparatus incorporating a microprocessor control is provided for automatically loading nuclear fuel pellets into fuel rods commonly used in nuclear reactor cores. The apparatus comprises a split "V" trough for assembling segments of fuel pellets in rows and a shuttle to receive the fuel pellets from the split "V" trough when the two sides of the split "V" trough are opened. The pellets are weighed while in the shuttle, and the shuttle then moves the pellets into alignment with a fuel rod. A guide bushing is provided to assist the transfer of the pellets into the fuel rod. A rod carousel which holds a plurality of fuel rods presents the proper rod to the guide bushing at the appropriate stage in the loading sequence. The bushing advances to engage the fuel rod, and the shuttle advances to engage the guide bushing. The pellets are then loaded into the fuel rod by a motor operated push rod.

Abstract: A process for treating a particulate uranium oxide composition containing ammonium diuranate precursors such as uranyl fluoride and uranyl nitrate, along with possible impurities, is disclosed. The process comprises the steps of (a) contacting the composition with a sufficient amount of an ammonium hydroxide solution to convert the ammonium diuranate precursors to ammonium diuranate, and (b) heating the composition under a controlled atmosphere at a temperature sufficient to dry the composition, sublime any ammonium fluoride present, and convert the ammonium diuranate to uranium dioxide. In a first modification of the invention, there is practiced the additional step of moving the composition, preferably by mechanically agitating the composition, prior to the heating step, or during the heating step, or both prior to and during the heating step, for a sufficient time to produce rounded agglomerates in the form of a readily flowable powder.

Abstract: Process for recovering compounds of enriched nuclear fuel from scrap materials is disclosed. The process yields an acid solution with the nuclear fuel dissolved therein. Except for spent filter media, the scrap materials are calcined to produce an oxidized material, which is reduced to a particulate material and leached in an acid bath that contains some recycled acid to yield an acid solution of the nuclear fuel material. The scrap materials comprised of spent filter media are mulched and contacted with the acid solution. The insoluble materials are separated from the acid solution, and at least a portion of the acid solution is recycled to the leaching step, while the remainder of the acid solution is collected for subsequent treatment to recover the dissolved nuclear fuel material. Apparatus for performing the foregoing process is also disclosed.

Abstract: The amount of fissile material such as U-235 in each portion of a fuel element, some of which portions may also contain burnable poison such as gadolinium, is determined by detecting the gamma ray emission due to the natural radioactive decay of the fuel material, analyzing the gamma ray signals from each portion to provide a first count of gamma rays primarily due to the U-235 and a second count of gamma rays primarily due to the U-238 daughter products. These first and second counts are corrected for the cladding wall thickness, the density of the fuel material and the burnable poison content in each portion. The first (U-235) count is then corrected by the second (U-238 daughter) count and the thus corrected U-235 count is converted to an indication of the fuel enrichment in each portion. From the enrichment, the burnable poison content, the density of the fuel material and the volumes of each portion, the weight of U-235 in each portion can be determined.