Abstract: A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U3Si2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U3Si2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U3Si2.

Abstract: A method of manufacturing nuclear fuel elements may include: forming a base portion of the fuel element by depositing a powdered matrix material including a mixture of a graphite material and a fibrous material; depositing particles on the base portion in a predetermined pattern to form a first particle layer, by controlling the position of each particle in the first particle layer; depositing the matrix material on the first particle layer to form a first matrix layer; depositing particles on the first matrix layer in a predetermined pattern to form a second particle layer by controlling positions of each particle in the second particle layer; depositing the matrix material on the second particle layer to form a second matrix layer; and forming a cap portion of the fuel pebble by depositing the matrix material. The particles in the first particle layer and the second particle layer include nuclear fuel particles.

Abstract: The invention relates to the use of Dispersion Ceramic Micro-Encapsulated (DCM) nuclear fuel as a meltdown-proof, accident-tolerant fuel to replace uranium dioxide fuel in existing light water reactors (LWRs). The safety qualities of the DCM fuel are obtained by the combination of three strong barriers to fission product release (ceramic coatings around the fuel kernels), highly dense inert ceramic matrix around the coated fuel particles and metallic or ceramic cladding around the fuel pellets.

Abstract: A method of manufacturing nuclear fuel elements may include: forming a graphite base portion of the fuel element; depositing a first layer of graphite spheres on the base portion; depositing a first layer of fuel, burnable poison and/or breeder particles on the first layer of graphite spheres; forming a second layer of graphite spheres on the first layer of particles; depositing a second layer of fuel, burnable poison and/or breeder particles on the second layer of graphite spheres; and forming a graphite cap portion of the fuel element. Fuel, burnable poison and/or breeder particles of the first layer may be are spaced apart by substantially the same distance, and fuel, burnable poison and/or breeder particles of the second layer may be spaced apart by substantially the same distance. The fuel element may be a spherical fuel pebble. The fuel particles may be tri-structural-isotropic (TRISO) particles without an overcoat.

Abstract: The invention relates to the use of Dispersion Ceramic Micro-Encapsulated (DCM) nuclear fuel as a meltdown-proof, accident-tolerant fuel to replace uranium dioxide fuel in existing light water reactors (LWRs). The safety qualities of the DCM fuel are obtained by the combination of three strong barriers to fission product release (ceramic coatings around the fuel kernels), highly dense inert ceramic matrix around the coated fuel particles and metallic or ceramic cladding around the fuel pellets.

Abstract: A high-temperature gas-cooled reactor steam generating system comprises a plurality of nuclear steam supply systems, a high-pressure cylinder (21), a low-pressure cylinder (22), a condenser (23), a condensate pump (24), a low-pressure heater (25), a deaerator (26), a water supply pump (27), and a high-pressure heater (28) which are sequentially connected end to end to form a close steam loop. On one hand, the inherent safety of the reactor is guaranteed and the generating system is simplified with the inherent safety. On the other hand, the scale economy of the steam engine system and other systems of a whole power station is guaranteed through batch copy, a shared auxiliary system and a scale effect.

Abstract: A method of fabricating a nuclear fuel comprising a fissile material, one or more hollow microballoons, a phenolic resin, and metal matrix. The fissile material, phenolic resin and the one or more hollow microballoons are combined. The combined fissile material, phenolic resin and the hollow microballoons are heated sufficiently to form at least some fissile material carbides creating a nuclear fuel particle. The resulting nuclear fuel particle comprises one or more fission product collection spaces. In a preferred embodiment, the fissile material, phenolic resin and the one or more hollow microballoons are combined by forming the fissile material into microspheres. The fissile material microspheres are then overcoated with the phenolic resin and microballoon. In another preferred embodiment, the fissile material, phenolic resin and the one or more hollow microballoons are combined by overcoating the microballoon with the fissile material, and phenolic resin.

Abstract: The invention relates to a new and unique light water reactor (LWR) nuclear fuel pellet configuration formed using tri-isotropic (TRISO) fuel particles suspended in a metal, metal alloy, or ceramic matrix. The new TRISO LWR pellet would have the same dimensions as those of the standard uranium oxide pellet allowing its use without any change to the physical configuration of the reactor vessel, core internals or fuel assemblies. TRISO type fuels have a proven capability for retaining fission products within the confinement boundary created by the coating material. This robustness is expected to reduce or eliminate fuel failure risk and cost. Replacing standard pellets with TRISO LWR fuel pellets with the same, or higher, energy density can potentially extend the operating cycles of LWRs, reduce the number of fuel assemblies replaced in each refueling, reduce the quantity of spent fuel discharged from reactors, lower operating costs, and reduce radioactive waste.

Abstract: This invention relates to a method of preparing nuclear fuel including the step of depositing at least two adjacent series of layers (16, 18) around a kernel (12) of fissile material, each series comprising a layer of pyrolytic carbon (16) contiguous with a layer of silicon carbide (18) and each layer (16, 18) having a thickness of at most (10) micrometers, such that alternate layers of (16, 18) of pyrolytic carbon and silicon carbide are deposited around the kernel (12). The invention extends to a nuclear fuel element (10).

Abstract: Methods, processes, and systems of transportable nuclear batteries are provided. In one embodiment, the battery may comprise a sealed reactor shell, a reactor core, and a generator. In further embodiments, the transportable nuclear battery may comprise a nuclear fuel in the reactor core wherein the fuel comprises plutonium, carbon, hydrogen, zirconium and, thorium. In some embodiments, the fuel may comprise hydrogen-containing glass microspheres, wherein the glass microspheres, may be coated with a burnable poison, and other coating materials that may aid in keeping the hydrogen within the microsphere glass at relatively high temperature. The disclosed methods, processes and systems may aid in providing energy to remote areas.

Abstract: A nuclear fuel according to one embodiment includes an assembly of nuclear fuel particles; and continuous open channels defined between at least some of the nuclear fuel particles, wherein the channels are characterized as allowing fission gasses produced in an interior of the assembly to escape from the interior of the assembly to an exterior thereof without causing significant swelling of the assembly. Additional embodiments, including methods, are also presented.

Abstract: Disclosed is a breeding nuclear fuel mixture including metallic thorium useable in a nuclear power plant, prepared by mixing uranium dioxide (UO2) or plutonium dioxide (PuO2) having ceramic properties with metallic thorium (Th), in order to enable thorium breeding by neutrons released during nuclear fission of U or Pu and conversion of the bred thorium into a novel nuclear fissile material, i.e., U-233, thereby ensuring continuous nuclear fission. The foregoing nuclear fuel mixture may be burned at a reactor core of a nuclear power plant through thorium breeding over a long period of time. Therefore, when the inventive breeding nuclear fuel mixture is employed in a nuclear power plant, utilization of the nuclear power plant may be increased while maximizing conservation of limited uranium resources.

Abstract: The present invention provides a nuclear fuel assembly, where a boron-containing compound is used as a burnable poison and is distributed in a majority of the rods in the assembly. The assembly comprises a plurality of fuel rods, each fuel rod containing a plurality of nuclear fuel pellets, wherein at least one fuel pellet in more than 50% of the fuel rods in the fuel assembly comprises a sintered admixture of a metal oxide, metal carbide or metal nitride and a boron-containing compound.

Abstract: A high-temperature nuclear reactor, cooled by a liquid fluoride salt, is described. The reactor uses an annular fuel pebble comprised of an inert graphite center kernel, a TRISO fuel particles region, and a graphite outer shell, with an average pebble density lower than the density of the liquid salt so the pebbles float. The pebbles are introduced into a coolant entering the reactor and are carried into the bottom of the reactor core, where they form a pebble bed inside a plurality of vertical channels inside one or more replaceable Pebble Channel Assemblies (PCAs). Pebbles are removed through defueling chutes located at the top of each PCA. Each PCA also includes channels for insertion of neutron control and shutdown elements, and channels for insertion of core flux mapping and other instrumentation.

Abstract: A method of manufacturing nuclear fuel elements comprising the steps of placing nuclear fuel balls in the container made from ultra-porous material, applying a CVI to the container and removing the container. The container for manufacturing fuel elements comprising balls, and is produced from at least one ultra-porous material, for example carbon foam.

Abstract: The invention relates to a novel design and production of fuel element pebbles which satisfy the requirements of high temperature pebble bed nuclear reactors of the next generation. The invention uses a shell of the fuel element pebbles that is devoid of fuel and consists of silicon carbide (SiC) and/or zircon carbide (ZrC), in addition to natural graphite and graphitized petroleum coke, said shell having a maximum average nominal thickness of 5 mm and preferably only 3 mm.

Abstract: The present invention related to a novel process for accelerating the breeding and conversion of fissile fuel in various types of nuclear reactors. In said process a movable nuclear fuel ball bed filled with a coolant creeps through the reactor core. The said process could provide higher specific power per unit fuel volume inside the reactor core and proceed on-line refueling, thus requires much less initial fissile fuel inventory per unit power output as compared with the traditional breeding or conversion reactors. The said process has full inherent safety characteristics and could follow the external power demand with the inherent negative temperature coefficient of reactivity. The said process, therefore, is a more efficient and economic approach to meeting the enormous demand of fissile fuel for the forthcoming “second nuclear era”.

Abstract: This invention relates to a method of preparing nuclear fuel including the step of depositing at least two adjacent series of layers (16, 18) around a kernel (12) of fissile material, each series comprising a layer of pyrolytic carbon (16) contiguous with a layer of silicon carbide (18) and each layer (16, 18) having a thickness of at most (10) ricrometres, such that alternate layers of (16, 18) of pyrolytic carbon and silicon carbide are deposited around the kernel (12). The invention extends to a nuclear fuel element (10).

Abstract: Microstructured nuclear fuel adapted for nuclear power system use includes fissile material structures of micrometer-scale dimension dispersed in a matrix material. In one method of production, fissile material particles are processed in a chemical vapor deposition (CVD) fluidized-bed reactor including a gas inlet for providing controlled gas flow into a particle coating chamber, a lower bed hot zone region to contain powder, and an upper bed region to enable powder expansion. At least one pneumatic or electric vibrator is operationally coupled to the particle coating chamber for causing vibration of the particle coater to promote uniform powder coating within the particle coater during fuel processing. An exhaust associated with the particle coating chamber and can provide a port for placement and removal of particles and powder. During use of the fuel in a nuclear power reactor, fission products escape from the fissile material structures and come to rest in the matrix material.

Abstract: In the method, a reference core design is generated based on a defined set of limits. The set of limits may include a target hot excess reactivity constraint to be satisfied over a given core energy cycle and a given desired control blade definition that is set for the cycle. A reference core design is generated based on the defined limits. A unique subset of fresh fuel bundles is subject to an iterative improvement process including replacing, at each fuel location, at least one of the current fresh fuel bundles with at least one of the selected fresh fuel bundles, and simulating reactor operation on the reference core design to obtain a plurality of outputs to be ranked based on the defined set of limits. The highest ranked output may represent an accepted core design with set control blade definition that satisfies the target hot excess reactivity constraint.

Abstract: In the method, a set of limits applicable to a core may be defined, and a test core loading pattern design, to be used for loading the core, may be determined based on the limits. Reactor operation on at least a subset of the core may be simulated to produce a plurality of simulated results. The simulated results may be compared against the limits, and data from the comparison may indicate whether any of the limits were violated by the core during the simulation. A designer or engineer may use the data to modify the test core loading pattern, creating one or more derivative core loading pattern design(s) for simulation and eventual perfection as an acceptable core loading pattern design for the core.

Abstract: In the method, a set of limits are defined and a reference core design is generated based on the limits, and includes an initial loading pattern of current fresh fuel bundles arranged in a plurality of fuel locations. A unique subset of fresh fuel bundles is selected for evaluation as the reference core design is subjected to an iterative improvement process. The iterative process includes replacing, at each fuel location, at least one of the current fresh fuel bundles with at least one of the selected fresh fuel bundles, and simulating reactor operation on the reference core design to obtain a plurality of outputs. The outputs may be ranked based on the defined set of limits, and the highest ranked output may be selected as an accepted core design for the nuclear reactor.

Abstract: The nuclear fuel is made up of at least one bed (11) of substantially spherical particles (1′) having a diameter of between 0.5 and 5 mm. The structure for holding the fuel assembly (10) comprises a casing (8) of prismatic shape and at least one cage (9) placed inside the casing (8) and containing at least one bed (11) of nuclear fuel particles. The end nozzles (12, 13) of the casing are each traversed by at least one opening for the passage of water, the cage or cages comprising porous walls traversed by openings of a size smaller than the diameter of the fuel particles (1′) and placed such that the bed or beds of fuel particles (11) are traversed by cooling water from the nuclear reactor entering into the fuel assembly casing (8) via the first end nozzle (12) and leaving the fuel assembly via the second end nozzle (13).

Abstract: A process for producing high sinter density UO2 powder from UO2-containing scrap powder material, wherein the scrap material is oxidized at low temperature and the resulting U3O8 powder is reduced at a higher temperature which is than about to 800° C. to produce UO2 having high sinter density and high surface area.

Abstract: A pyrolytic carbon coated nuclear fuel particle and method of making it. The fuel particle has a core composed of a refractory compound of an actinide metal. The pyrolytic carbon coating surrounds the core so as to provide a void volume therebetween. The coating has an initial density of no greater than 1.45 grams/cm.sup.3 and an anisotropy factor than 3.0 and a final density upon heat treatment above about 2000.degree. C. of greater than 1.7 grams/cm.sup.3 and an anisotropy factor greater than 5.

Abstract: The invention is directed to a high-density dispersion nuclear fuel having spherical particles of an uranium alloy dispersed in a nonfissionable matrix. The alloy includes uranium and 4-9 wt % Q, wherein Q is selected from the group consisting of Mo, Nb, and Zr. A process of manufacturing the spherical particles is also disclosed.

Abstract: A method and an apparatus for producing microspherical ceramic particles such as particulate ceramic fuels for use in nuclear reactors. To produce gel particles by performing microwave heating on the small droplets of a stock solution or sol that contains uranium and other elements for nuclear reactor fuels, the small droplets are allowed to fall down through a cavity resonator using microwaves having an engineering frequency of 2.45 GHz and a quartz rod is inserted into or withdrawn out of the resonator to adjust the resonant frequency so that it will lie within the spectrum width of the microwave frequency.

Abstract: Provided is a method for making high-temperature high-performance fuel particles wherein fertile or fissile metal carbides are dispersed in spherical graphite skeletons. That is, a fissile metal salt, such as uranyl nitrate, is added to an aqua-mesophase in alkaline solution, to form a fuel solution. The fuel solution is added to an oil bath to form an emulsion of aqueous pitch-derrived spheres in oil. The emulsion is heated and stirred to drive water from the spheres to dry them into solid spheres which contain the above metal salts. The solid spheres are then heated to between 700-1100 C. to carbonize them and convert the metal salts to metal oxides and then the spheres are further heated to between 2000.degree.-3000.degree. C., to carburize the metal oxides to metal carbides and graphitize the carbon. The resulting fuel spheres are then preferably coated by deposition thereon, of a carbon or carbide coating to contain the future reaction products thereof.

Abstract: Nuclear fuel compacts, containing thousands of individually coated fuel particles in a carbonaceous matrix, are provided with an overcoating of silicon carbide which can be readily inspected for defects. This overcoating helps retain fission products within the compact should any of the fuel particles have damaged or defective coatings, and provides an outer secondary barrier that can be 100% inspected.

Abstract: Particulates from a source fall into a tundish which discharges to a collection chamber. The build-up of particulates in the chamber is sensed, and a valve opened at the bottom of the chamber when a pre-determined level of the particulates is sensed in the chamber. A valve at the top of the chamber may be closed at the same time so that pressurized air can be injected into the chamber to expel the particulates through the bottom of the chamber through the valve. A filter circuit may be connected to the tundish to assist in removing particulates from the tundish.

Abstract: Methods for making nuclear fuel compacts exhibiting low heavy metal contamination and fewer defective coatings following compact fabrication from a mixture of hardenable binder, such as petroleum pitch, and nuclear fuel particles having multiple layer fission-product-retentive coatings, with the dense outermost layer of the fission-product-retentive coating being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.3 g/cm.sup.3. Such particles can be pre-compacted in molds under relatively high pressures and then combined with a fluid binder which is ultimately carbonized to produce carbonaceous nuclear fuel compacts having relatively high fuel loadings.

Abstract: Nuclear fuel particles having fission-product-retentive characteristics are disclosed which are particularly adapted for the production of nuclear fuel compacts or nuclear fuel elements by combination with a matrix material having an acceptable nuclear properties and good thermal conductivity. Preferably, the outermost shell of the fission-product-retentive layer is formed of a refractory carbide, such as silicon carbide or zirconium carbide, and a thin overcoating material is applied thereto. When aluminum is employed as the matrix material, an overcoating of elemental silicon or elemental zirconium is used which is wet by the aluminum matrix. Silicon also forms a low melting eutectic alloy with the aluminum of the matrix that provides good lubricating properties--a particularly valuable feature when high pressure extrusion is used to form fuel elements.

Abstract: An energy producing system employing nuclear fission of fuel in pellets disposed in a boiling liquid to produce superheated vapors.

Abstract: Methods for making nuclear fuel compacts containing precise amounts of nuclear fuel material which exhibit low heavy metal contamination and fewer defective coatings following compact fabrication using a hardenable binder including petroleum pitch or the like. Nuclear fuel particles having a multiple layer fission-product-retentive barrier, with a dense outer layer thereof being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.2 g/cm.sup.3, that is encapsulated within a thin shell of pyrocarbon from about 1.7 to about 2 g/cm.sup.3 in density, can be precisely metered to create charges containing very precise amounts of nuclear fuel material that can be pre-compacted in molds under relatively high pressures and then combined with the fluid binder which is ultimately carbonized to produce carbonaceous compacts containing very precise nuclear fuel loadings.

Abstract: A method of operating a gas-cooled nuclear reactor having graphite fuel elements in which, to reduce the reactor, a quenching element is introduced which takes a particle of a reaction-reducing substance in a sheath which will melt or release the substance in vapor form so that the substance can penetrate in gaseous form through the surrounding graphite body and deposit upon fuel elements.

Abstract: Fiber reinforced hollow film forming material microspheres 17 made from a fiber and film forming material composition are described. The fiber reinforced hollow microspheres 17 are used to make shaped and molded articles and to make insulation materials. The fibers can be made from ceramic materials, glass, metal, metal glass and plastic. The reinforcing fibers can be one-half to five microns in diameter and five to one hundred microns in length.

Abstract: Substantially isotropic spherical fuel and absorber elements for high temperature reactors are produced by molding corresponding fuel particles and graphite molding compositions. There is used as graphite molding powder a mixture of graphitized granules of coke and a hardenable resin binder. There are first produced in steel dies at 80.degree. to 120.degree. C. half shells and a nucleus with a pressed density of 1.0 to 1.4 g/cm.sup.3 followed by molding in a further steel die to the final format.

Abstract: To produce spherical fuel or absorber elements for high temperature reactors a mixture of coated nuclear fuel or absorber particles and graphite molding composition is molded into spheres, carbonized in a furnace having gas flushing and calcined in a vacuum. There are attained high throughputs without addition of transportation aides by employing as resin binders a thermosetting synthetic resin, hardening the resin at 110.degree. to 170.degree. C. and subsequently allowing the spheres to roll for 1 to 10 hours through an oven which is inclined around 2.degree. to 12.degree. to the horizontal. Thereby the oven must exhibit an increasing and decreasing temperature profile, the flushing gas introduced from both sides and be removed in a temperature zone of 400.degree. to 500.degree. C.

Abstract: To provide a lithium-containing neutron target particle for breeding tritium within the core of a nuclear reactor, including a central core formed of a stable lithium-containing compound, a surrounding buffer layer, and an outer tritium-impermeable silicon carbide coating, the core is initially sealed with an inner sealing layer of pyrolytic carbon and an outer sealing layer of stoichiometric zirconium carbide. The pyrocarbon seal protects the lithium within the core from attack from the zirconium carbide coating atmosphere, and the zirconium carbide layer prevents loss of lithium from the core when the silicon carbide coating is deposited at elevated temperatures.

Abstract: A method of applying a burnable absorber coating on a nuclear fuel pellet comprising the step of exposing the nuclear fuel pellet to a gas stream of boron trichloride and anhydrous ammonia at a temperature of from about 600.degree.-800.degree. C. A coating of boron nitride is formed as a reaction product of boron trichloride with anhydrous ammonia on the fuel pellet.

Abstract: For the production of plate shaped fuel elements for material testing and research reactors with highly enriched uranium recently there has been needed U.sub.3 O.sub.8 fuels which have a high density, high strength and a small open porosity. Such fuels are obtained if U.sub.3 O.sub.8 powder produced in known manner is first compressed mechanically to molded bodies of any shape, then processed to a granulate having a size of fuel grains below 200.mu. and subsequently sintered to high density particles, preferably at 1370.degree..+-.50.degree. C.

Abstract: A method for compressing gases in a contained volume consisting of hollow glass microspheres is described. The gases are compressed under high pressure and can be easily handled and stored. The gases to be compressed and contained in the microspheres are used as blowing gases to blow the microspheres.The metal vapor deposited coating can be reflective of or transparent to visible light.The hollow glass microspheres can be made to contain a thin transparent or reflective metal coating deposited on the inner wall surface of the microspheres by adding to the blowing gas small dispersed metal particles and/or gases of organo metal compounds and decomposing the organo metal compounds.The hollow glass microspheres can be made in the form of filamented glass microspheres with a thin glass filament connecting adjacent glass microspheres.

Abstract: A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.