Abstract: A process for the electrolytic deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electrolytic plating solution containing the metal to be deposited on the article in the presence of an electrode receiving current.

Abstract: The invention is directed to an axially alignable nuclear fuel pellet of the type stacked in end-to-end relationship within a tubular cladding. Experience has shown that fuel cladding failures can occur at pellet interface locations due to mechanical interaction between misaligned fuel pellets and the cladding. Mechanical interaction between the cladding and the fuel pellets loads the cladding and causes increased cladding stresses. Nuclear fuel pellets constructed according to the invention are provided with an end structure that increases plastic deformation of the pellets at the interface between pellets so that lower alignment forces are required to straighten axially misaligned pellets. Plastic deformation of the pellet ends results in less interaction between the cladding and the fuel pellets and significantly lowers cladding stresses. The geometry of pellets constructed according to the invention also reduces alignment forces required to straighten fuel pellets that are tilted within the cladding.

Abstract: A process for the separation and collection of molybdenum-99 from an irradiated uranium-containing target material utilizes thermal chromatographic separation. The irradiated target material containing the molybdenum-99 is heated in an oxidizing atmosphere to form an oxidized target material and gaseous molybdenum-99 trioxide. The gaseous molybdenum-99 trioxide is carried by the oxidizing atmosphere along with other vaporized materials to a cooling zone for progressive condensation and collection of the molybdenum-99 trioxide and the other materials in the form of separate deposits.

Abstract: An ion chamber type neutron detector is disclosed which has a greatly extended lifespan. The detector includes a fission chamber containing a mixture of active and breeding material and a neutron shielding material. The breeding and shielding materials are selected to have similar or substantially matching neutron capture cross-sections so that their individual effects on increased detector life are mutually enhanced.

Abstract: A method and apparatus for separating a mixture of cation and anion resins is disclosed. The separation involves introducing the mixture of cation and anion resins to a treatment zone in countercurrent flow with a carrier fluid to achieve hydroclassification of the resins. The method and apparatus may be employed to separate cation and anion resins on either a batch or continuous basis.

Abstract: An electrical penetration assembly is disclosed for providing a vapor and pressure seal between a conductor passing through two freestanding walls of a nuclear reactor containment which are subject to relative movement due to a seismic event. Penetration nozzles or tubes are placed through the walls of the containment when it is constructed. The penetration assembly is inserted into the nozzles and comprises a first subassembly fixed and sealed to a first penetration nozzle in the first wall and a second penetration subassembly in sliding or rolling engagement and sealed to a second penetration nozzle in the second wall. The sliding or rolling seal in the second nozzle allows the unrestrained reaction of the conductor to relative movement between the two freestanding walls during a seismic event without damage to the conductor or the penetration assembly. The penetration assembly also prevents the possibility of damage to either the conductor or the penetration assembly due to thermally induced stresses.

Abstract: A method and apparatus for monitoring the output of an ion chamber type in-core neutron detector is disclosed. Neutron detectors of this type are known to produce both alternating current and direct current signals which are used as measures of the neutron flux in the chamber. The monitor employs a ratio of the alternating current and direct current signals to detect ion chamber leaks, to correct the output of the detector after a leak, to predict the end-of-life of the detector and to determine the non-linearity of the detector at different power levels.

Abstract: In a moderated nuclear reactor core, an in-core neutron detector assembly with means for fixing the location of the detectors and for displacing the moderator in the vicinity of the detectors to thereby flatten and reduce the thermal neutron flux to which the neutron detectors are exposed.

Abstract: A fixed bed adsorption gas separation system wherein the use of a combination of temperature and pressure swing cycles together with a chromatographic separation step provides separation of gases with a minimum number of stages.

Abstract: A process for the electroless deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electroless plating solution containing the metal to be deposited on the article upon sufficient contact with the article.

Abstract: A system for indicating radiation from a radioactive fluid such as a gas wherein simultaneous indications of the activity concentration of radioactivity of the gas, the radiation dose rate and average energy of the radiation are provided.

Abstract: Conversion of gaseous uranium hexafluoride to a uranium dioxide rich composition in the presence of an active flame in a reactor defining a reaction zone is achieved by separately introducing a first gaseous reactant comprising a mixture of uranium hexafluoride and a reducing carrier gas, and a second gaseous reactant comprising an oxygen-containing gas, the reactants being separated by a shielding gas as introduced to the reaction zone. The shielding gas temporarily separates the gaseous reactants and temporarily prevents substantial mixing and reacting of the gaseous reactants. The flame occurring in the reaction zone is maintained away from contact with the inlet introducing the mixture to the reaction zone. After suitable treatment, the uranium dioxide rich composition is capable of being fabricated into bodies of desired configuration for loading into nuclear fuel rods.

Abstract: A spacer retaining element, which may be a fuel rod or water-containing rod, is provided with axially-spaced lugs, each adapted to be received in a slot in a fuel element spacer of a nuclear fuel assembly. When assembled, the lugs maintain proper axial spacing between the individual spacers and the lug-slot arrangement prevents the rod from rotating. Moreover, because the slot in the spacer can receive the lug from only one direction, the arrangement prevents the spacer from being inserted into the assembly upside down.

Abstract: Alloys reacting with water, water vapor and reactive gases at temperatures in the range of about 200.degree. to about 650.degree. C have essential components of nickel, titanium an zirconium. The alloys can be made by arc melting zirconium, nickel and titanium and can be formed into sheet or foil by inert-atmosphere hot rolling. The alloys can also be made by plating nickel on a sheet of zirconium-titanium alloy and then conduction a diffusion process by heating the plated alloy in vacuum.

Abstract: An electrochemical carbon meter is described which is especially useful for measuring the concentration of carbon in liquid sodium. The meter includes a carbon activity gas having a known ratio of carbon monoxide to carbon dioxide contained within a chamber as an intermediary between a diffusion membrane in contact with the sodium and an electrochemical cell. A calcium carbonate fixing compound is also located within the chamber for maintaining the concentration of carbon dioxide therein at a predetermined level. The chamber is fixed to the end of a probe tube which supports the same fully surrounded by liquid sodium to be maintained thereby at a uniform temperature.

Abstract: A process for fabricating a body of a nuclear fuel material has the steps of admixing the nuclear fuel material in powder form with a binder of a compound or its hydration products containing ammonium cations and anions selected from the group consisting of carbonate anions, bicarbonate anions, carbamate anions and mixtures of such anions, forming the resulting mixture into a green body such as by die pressing, heating the green body to decompose substantially all of the binder into gases, further heating the body to produce a sintered body, and cooling the sintered body in a controlled atmosphere. Preferred binders used in the practice of this invention include ammonium bicarbonate, ammonium carbonate, ammonium bicarbonate carbamate, ammonium sesquicarbonate, ammonium carbamate and mixtures thereof.

Abstract: A method of conditioning the fuel of a nuclear reactor core to minimize failure of the fuel cladding comprising increasing the fuel rod power to a desired maximum power level at a rate below a critical rate which would cause cladding damage. Such conditioning allows subsequent freedom of power changes below and up to said maximum power level with minimized danger of cladding damage.

Abstract: A nuclear fuel element for use in the core of a nuclear reactor is disclosed and has a composite cladding having a substrate, a metal barrier metallurgically bonded to the inside surface of the substrate and an inner layer metallurgically bonded to the inside surface of the metal barrier. In this composite cladding, the inner layer and the metal barrier shield the substrate from any impurities or fission products from the nuclear fuel material held within the composite cladding. The metal barrier forms about 1 to about 4 percent of the thickness of the cladding and is comprised of a metal selected from the group consisting of niobium, aluminum, copper, nickel, stainless steel, and iron. The inner layer and then the metal barrier serve as reaction sites for volatile impurities and fission products and protect the substrate from contact and reaction with such impurities and fission products.

Abstract: A method and apparatus for locating defective nuclear fuel elements is disclosed. Fuel elements that are to be tested are enclosed in a test chamber, filled with water. Air is pumped or pulled into the chamber, entering through a gas sparger at the bottom of the chamber and displacing a portion of the water above the fuel element. This reduces the pressure in the vessel, forms an air pocket above the fuel element and purges the water surrounding the fuel element of fission gases released from defective fuel elements. The activity of sample gas drawn from the chamber is continuously monitored to indicate fission gas content. In subsequent steps the pressure in the chamber is further reduced with a vacuum pump and gas drawn from the air pocket above the fuel for testing is recirculated and allowed to continuously purge the water surrounding the fuel elements of fission gases released from defective fuel elements.

Abstract: An improved means is provided to control coolant leakage between the flow channel and the lower tie plate of a nuclear fuel assembly. The means includes an opening in the lower tie plate and a movable element adjacent thereto. The coolant pressure within the tie plate biases the movable means toward the inner surface of the surrounding flow channel to compensate for any movement of the flow channel away from the lower tie plate to thereby control the leakage of coolant flow from the fuel assemblies to the spaces among the fuel assemblies of the core.