Abstract: The present invention relates to the control of grain structure in unalloyed zirconium metal and, more particularly, to the control of grain structure in zirconium metals containing less than 300 parts per million Fe.

Abstract: Zirconium-based corrosion resistant alloys for use primarily as a cladding material for fuel rods in a boiling water nuclear reactor consist essentially of by weight percent about 0.5 to 2.0 percent tin, about 0.24 to 0.40 percent of a solute composed of copper, nickel and iron, wherein the copper is at least 0.05 percent, and the balance zirconium. Nuclear fuel elements for use in the core of a nuclear reactor have improved corrosion resistant cladding made from these zirconium alloys or composite claddings have a surface layer of the corrosion resistant zirconium alloys metallurgically bonded to the outside surface of a Zircaloy alloy tube. The claddings may contain an inner barrier layer of moderate purity zirconium metallurgically bonded on the inside surface of the cladding to provide protection from fission products and gaseous impurities generated by the enclosed nuclear fuel.

Abstract: A fuel assembly for a nuclear reactor includes a number of fuel rods filled with a fuel material. A plurality of fuel rods have a partial effective fuel area filled with a fuel material and has a portion in which enrichment of a fissile nuclide is significantly reduced or the fissile nuclide does not exist at all on an axial level including a reactor shut-down zone at which subcriticality becomes small during a reactor operation period. The other fuel rods are filled with the fuel material throughout the entire axial length thereof. The first mentioned fuel rod may be provided with a partially interposed zone or may be constructed by a fuel rod having a length shorter than that of the other fuel rod. The tube means may be arranged in the fuel assembly so as to pass the moderator therethrough.

Abstract: A nuclear fuel element for use in the core of a nuclear reactor is disclosed having an improved corrosion resistant cladding. The cladding is comprised of zirconium alloys containing in weight percent 0.5 to 2.0 percent tin, or 0.5 to 2.5 percent bismuth, or 0.5 to 2.5 percent bismuth and tin, and about 0.5 to 1.0 percent of a solute composed of a member selected from the group consisting of molybdenum, niobium, tellurium and mixtures thereof, and the balance zirconium. Composite claddings are disclosed having a surface layer of one of the corrosion resistant zirconium alloys metallurgically bonded to a Zircaloy alloy tube. Claddings may contain an inner barrier layer of a moderate purity zirconium metallurgically bonded on the inside surface of the cladding to provide protection from fission products and gaseous impurities generated by the enclosed nuclear fuel.

Abstract: A nuclear fuel element for use in the core of a nuclear reactor is disclosed having an improved corrosion resistant cladding. The cladding is comprised of zirconium alloys containing in weight percent 0.5 to 2.0 percent tin, or 0.5 to 2.5 percent bismuth, or 0.5 to 2.5 percent bismuth and tin, and about 0.5 to 1.0 percent of a solute composed of a member selected from the group consisting of molybdenum, niobium, tellurium and mixtures thereof, and the balance zirconium. Composite claddings are disclosed having a surface layer of one of the corrosion resistant zirconium alloys metallurgically bonded to a Zircaloy alloy tube. Claddings may contain an inner barrier layer of a moderate purity zirconium metallurgically bonded on the inside surface of the cladding to provide protection from fission products and gaseous impurities generated by the enclosed nuclear fuel.

Abstract: Zirconium-based corrosion resistant alloys for use primarily as a cladding material for fuel rods in a boiling water nuclear reactor consist essentially of by weight percent about 0.5 to 2.0 percent thin, about 0.24 to 0.40 percent of a solute composed of copper, nickel and iron, wherein the copper is at least 0.05 percent, and the balance zirconium. Nuclear fuel elements for use in the core of a nuclear reactor have improved corrosion resistant cladding made from these zirconium alloys or composite claddings have a surface layer of the corrosion resistant zirconium alloys metallurgically bonded to the outside surface of a Zircaloy alloy tube. The claddings may contain an inner barrier layer of moderate purity zirconium metallurigcally bonded on the inside surface of the cladding to procide protection from fission products and gaseous impurities generated by the enclosed nuclear fuel.

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: Nuclear fuel elements for use in the core of a nuclear reactor include an improved composite cladding having a zirconium barrier layer metallurgically bonded on the inside surface of a zirconium alloy tube, wherein the inside surface of the barrier is alloyed with preselected elemental impurities to improve oxidation resistance. The zirconium barrier layer forms a shield between the zirconium alloy tube and a core of nuclear fuel material enclosed in the composite cladding. The alloy layer formed on the barrier surface acts to inhibit cracking during the tube production fabrication step and limits oxidation in the event that the cladding is breached during operation of the reactor, allowing the entrance of water or steam into the fuel element.

Abstract: A stabilized alpha metal matrix provides an improved ductility after irradation without loss of corrosion resistance in a "Zircaloy" alloy modified with measurable amounts of up to 0.6 percent by weight of niobium or 0.1 percent by weight of molybdenum. Tin is present in the Zircaloy in the range of 1.2 to 1.70 percent by weight and the oxygen level is in the range of from 1000 to 1600 ppm. Iron and chromium alloying element levels are those of typical Zircaloys. The average intermetallic precipitates' particle sizes are in the range of from 1200 to 1800 angstroms, thereby providing optimum corrosion resistance of the improved alloy in both boiling water and pressurized water reactors.

Abstract: Disclosed are a cladding tube for a nuclear fuel and a nuclear fuel element incorporating the cladding tube. The cladding tube consists of an inner zirconium liner layer and an outer zirconium alloy layer. The cladding tube has at least one of the following features: (I) the ratio a/b of the oxygen content a to iron content b in the zirconium liner layer is greater than 1.0, (II) the zirconium liner layer is made of a zirconium into the matrix of which impurities are dissolved, and (III) the second phase particles having microscopic sizes and dispersed in the inner surface of the zirconium liner layer and/or the outer surface of the zirconium alloy layer have been removed substantially. Owing to these features, undesirable stress corrosion cracking and local corrosion are remarkably suppressed in the cladding tube and the nuclear fuel element of the invention.

Abstract: Nuclear fuel elements are provided that are resistant to pellet-clad interaction. The closed end nuclear fuel elements comprise a zirconium or zirconium alloy tube that has a layer of lubricant, preferably graphite, on the inner surface thereof, and enriched uranium dioxide pellets that have a coating on the outer surface thereof of a thickness sufficient to absorb fission products. The coating on the pellets may be a burnable absorber or a material that has a relatively low neutron absorption compared to a burnable absorber. The combination of the layer on the tube and the coating on the pellets reduces both the stress level and the concentration of damaging fission products that would contact and react with the layer of lubricant about the inside surface of the tubular cladding and thus reduces conditions for pellet-clad interaction.

Abstract: Fuel rod cladding tube having an inner tubular layer of a zirconium alloy with alloying components of 1.2 to 1.7% tin, 0.07 to 0.2% iron, 0.05 to 0.15% chromium, 0.03 to 0.08% nickel, 0.07 to 0.15% oxygen, with the sum of percentages of iron, chromium and nickel in the range of 0.18 to 0.38%; or with the alloying components 1.2 to 1.7% tin, 0.18 to 0.24% iron, 0.07 to 0.13% chromium, 0.10 to 0.16% oxygen, with the sum of percentages of iron and chromium in the range of 0.28 to 0.37%; and with the inner tubular layer having an outside surface layer of another zirconium alloy with a layer thickness of 5 to 20% of the cladding tube as well as with 0 to 1% iron as an alloying component and with at least one alloying component from the group of: vanadium with 0.1 to 1% by weight, platinum with 0.1 to 1% by weight, and copper with 1 to 3% by weight.

Abstract: A nuclear fuel rod cladding having a burnable absorber integrally incorporated therein has an outer tubular layer of a zirconium alloy; an intermediate layer, of a thickness less than the outer tubular layer, of a zirconium alloy containing a boron-containing burnable absorber; and an inner layer, of a thickness less than the intermediate layer, of zirconium metal. The layers are bonded together to form a cladding for the containment of nuclear fuel.

Abstract: An improved cesium getter 28 is provided in a breeder reactor fuel element or pin in the form of an extended surface area, low density element formed in one embodiment as a helically wound foil 30 located with silicon carbide, and located at the upper end of the fertile material upper blanket 20.

Abstract: A cadmium oxide glazed nuclear fuel pellet and glazing composition therefor is disclosed which controls the reactivity and extends the operating life cycle of a nuclear reactor while increasing the rate of burnout of the burnable absorber and reducing the amount of undersirable gases produced therefrom. The glaze forming composition comprises at least about 0.5 percent by weight cadmium oxide as a burnable absorber, i.e., cadmium-113 isotope, and at least one glaze forming oxide. The glaze constituents are formed into a slurry and a nuclear fuel pellet is dipped into the slurry to produce a hard refractory glaze upon firing and cooling.

Abstract: Described herein is a composite nuclear fuel rod cladding tube which includes two concentric layers of zirconium base alloys metallurgically bonded to each other. The outer layer is composed of a conventional zirconium base alloy having high strength and excellent aqueous corrosion resistance. The inner layer is composed of a second zirconium base alloy containing about 0.2 to 0.6 wt. % tin, about 0.03 to 0.11 wt. % iron and up to about 350 ppm oxygen. This second alloy while also having excellent aqueous corrosion resistance, is further characterized by the ability to prevent the propagation of cracks initiated during reactor operation due to pellet-cladding interaction.

Abstract: A fuel pellet for a nuclear core fuel rod for use in a nuclear reactor fuel assembly having a predetermined radial distribution of burnable poison, fertile, and fissile nuclear material to provide the desired control of reactivity of the fuel pellet with the minimum amount of burnable poison material and to provide control of the nuclear reactivity of the fuel assembly.

Abstract: The present invention pertains to zirconium base alloys containing about 0.1 to 0.6 weight percent tin; about 0.07 to 0.24 weight percent iron; about 0.05 to 0.15 weight percent chromium; and up to about 0.05 weight percent nickel. The balance of the alloy is zirconium with incidental impurities. The levels of the incidental impurity, oxygen, is controlled to a level of less than about 350 ppm. These alloys have been designed to minimize the adverse effects of pellet-clad interaction, when they are used as a liner bonded to the inside surface of water reactor nuclear fuel cladding. Specific cladding and fuel element designs according to the present invention are described.

Abstract: A hydride blister-resistant nuclear fuel rod cladding has a tubular cladding formed from a zirconium-based alloy which has a thin nickel base film, of a thickness of about 0.01 to 5 microns distributed over between 1-40 percent of the area of the internal surface of the tubular cladding. The dispersed nickel base film provides multiple sites for hydride transport from the interior of the nuclear fuel rod and prevents localized hydride transport and resulting hydride blistering.

Abstract: An improved method for producing nuclear fuel containers of a composite construction having components providing therein a barrier system for resisting destructive action by volatile fission products or impurities and also interdiffusion of metal constituents, and the product thereof. The composite nuclear fuel containers of the method comprise a casing of zirconium or alloy thereof with a layer of copper overlying an oxidized surface portion of the zirconium or alloy thereof.

Abstract: A graphite-coated tube, especially a cladding for nuclear fuel pellets, comprising a matrix tube of zircalloy, an oxide layer of not more than about 5,000 .ANG. laid on an inside surface of the matrix tube, and a graphite layer of at least 5 .mu.m laid on the oxide layer has a good resistance to peeling of the graphite layer.

Abstract: A fuel rod for a nuclear reactor comprises a cladding tube of a zirconium-based alloy, on the internal surface of which there is arranged a layer of zirconium containing 0.1-1 per cent by weight tin. The fuel rod contains a nuclear fuel preferably of uranium dioxide.

Abstract: A nuclear reactor component such as a fuel rod, burnable absorber rod, or neutron absorber rod, comprising a hermetically sealed metallic tube containing a solid material such as a nuclear fuel, burnable absorber, or neutron absorber, within a helium atmosphere, which solid material will release tritium into the helium atmosphere, has added thereto about 2-3 percent by volume of a gas, selected from oxygen, carbon monoxide and carbon dioxide. The addition of this gas to the helium atmosphere is effective to form an oxide layer on the inner surface of the metallic tube and significantly reduce the permeation of tritium through the metallic tube, such that the tritium is retained within the reactor component.

Abstract: A burnable absorber coated nuclear fuel. A fissionable material nuclear fuel substrate is at least partially covered by a burnable absorber layer. A hydrophobic material overcoat layer generally covers the burnable absorber layer and is bonded directly to it.

Abstract: A method for coating a uranium dioxide nuclear fuel with a zirconium diboride burnable poison. First, a layer of niobium is bonded to the nuclear fuel. Then, a layer of zirconium diboride is deposited by chemical vapor deposition on the niobium layer. A zirconium diboride coated nuclear fuel having a layer of niobium between a uranium dioxide substrate and the zirconium diboride layer also is disclosed.

Abstract: An improved fuel pin cladding, particularly adapted for use in breeder reactors, consisting of composite tubing with austenitic steel on the outer portion of the thickness of the tube wall and with nickel and/or ferritic material on the inner portion of the thickness of the tube wall. The nickel forms a sacrificial barrier as it reacts with certain fission products thereby reducing fission product activity at the austenitic steel interface. The ferritic material forms a preventive barrier for the austenitic steel as it is immune to liquid metal embrittlement. The improved cladding permits the use of high density fuel which in turn leads to a better breeding ratio in breeder reactors, and will increase the threshold at which failure occurs during temperature transients.

Abstract: A getter-lubricant coating system between the nuclear fuel and the fuel cladding minimizes the pellet-clad stress concentration and renders fission gases and impurities unreactive to the cladding. The getters are matched to the lubricant matrix such that they are homogeneously dispersed in the matrix and are physically and/or chemically bound in place. A preferred form of the getter is a graphite or boron nitride intercalate of the getter material.

Abstract: A nuclear fuel element consisting of a zirconium or zirconium alloy container and nuclear fuel pellets is provided for use in the core of a nuclear reactor. The zirconium or zirconium alloy container has an inner coating of copper in proximity to the nuclear fuel, and is separated from the zirconium or zirconium alloy by an intermediate zirconium oxide diffusion barrier layer. The copper layer and the intermediate zirconium oxide diffusion barrier of the composite cladding reduce perforations or failure in the zirconium or zirconium alloy cladding substrate caused by stress corrosion cracking or metal embrittlement. Good bonding of the copper to the oxide zirconium and zirconium alloy prevents scaling of copper from the composite cladding during the loading of the fuel element with fuel pellets.

Abstract: An improved method for producing nuclear fuel containers of a composite construction having components providing therein a barrier system for resisting destructive action by volatile fission products or impurities and also interdiffusion of metal constituents, and the product thereof. The composite nuclear fuel containers of the method comprise a casing of zirconium or alloy thereof with a layer of copper overlying an oxidized surface portion of the zirconium or alloy thereof.

Abstract: Method of protecting a zirconium-alloy cladding tube of a nuclear-reactor fuel rod against attack by radioactive fission products, such as iodine especially, which includes applying an internal pressure to the cladding tube at a temperature of from 300.degree. to 500.degree. C. so as to deform the cladding tube, depending upon the geometric dimensioning thereof, in the elastic range and up to nearly the yield point thereof and, while this condition exists, reacting a medium previously introduced into the interior of the cladding tube, with the inner surface of the cladding tube to form a protective layer.

Abstract: The pressure P.sub.R in the reactor pressure vessel, the flow rate W.sub.c of the cooling water flowing through the core in the reactor pressure vessel, and the flow rate W.sub.STM of the steam supplied from the reactor pressure vessel to the turbine are detected. The enthalpy H.sub.f of the saturated cooling water is determined on the basis of the pressure P.sub.R. The values of the cooling water flow rate W.sub.c, the steam flow rate W.sub.STM, the enthalpy H.sub.f of the saturated cooling water and a predetermined enthalpy H.sub.IN of the cooling water at the core inlet are substituted into the equation below thereby to obtain the enthalpy H.sub.fw of the feed water. ##EQU1## An error is determined between the feed-water enthalpy H.sub.fw thus obtained and the enthalpy T.sub.

Abstract: Cladding for nuclear fuel elements which is formed with a zirconium metal barrier layer bonded to the inside surface of a zirconium alloy tube and which is sized by a cold working tube reduction process and is heat treated after final reduction at a temperature and for a time period which allows substantially complete recrystallization of the zirconium metal barrier layer and provides a fine-grained microstructure therein and which stress-relieves but does not fully recrystallize the zirconium alloy tube. The crystallographic structure of the zirconium metal barrier layer may be improved by compressive deformation such as shot-peening.

Abstract: The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

Abstract: A nuclear fuel element for use in the core of a nuclear reactor is disclosed and has a composite cladding having a substrate and a metal barrier metallurgically bonded on the inside surface of the substrate so that the metal barrier forms a shield between the substrate and the nuclear fuel material held within the cladding. The metal barrier forms about 1 to about 30 percent of the thickness of the cladding and is comprised of a low neutron absorption metal of substantially pure zirconium. The metal barrier serves as a preferential reaction site for gaseous impurities and fission products and protects the substrate from contact and reaction with such impurities and fission products. The substrate of the composite cladding is selected from conventional cladding materials and preferably is a zirconium alloy. Methods of manufacturing the composite cladding are also disclosed.

Abstract: An aluminide coating for a fuel cladding tube for LMFBRs (liquid metal fast breeder reactors) such as those using liquid sodium as a heat transfer agent. The coating comprises a mixture of nickel-aluminum intermetallic phases and presents good corrosion resistance to liquid sodium at temperatures up to 700.degree. C. while additionally presenting a barrier to outward diffusion of .sup.54 Mn.

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: Rupture of boiling water reactor nuclear fuel cladding resulting from embrittlement by fission product cadmium is prevented by adding the stoichiometrically equivalent amount of V.sub.2 O.sub.4 or V.sub.2 O.sub.5 to the fuel.

Abstract: Rupture of boiling water reactor nuclear fuel cladding resulting from embrittlement caused by fission product cadmium is prevented by adding the stoichiometrically equivalent amount of CuFe.sub.2 O.sub.4 or CuTiO.sub.3 to the fuel.