Abstract: The present invention relates to tubular elements, such as fuel assembly tubes, which are designed to be used in high pressure and high temperature water in nuclear reactors, such as pressurized water nuclear reactors. In particular, the present invention relates to a method of improving wear resistance and corrosion resistance by depositing a protective coating having a depth of from about 5 to about 25 ?m on the surface of the tubular elements. The coating is provided by nitriding the tubular element at a temperature of from about 400° C. to about 440° C. The nitridation of the tubular element can be carried out for a duration of from about 12 hours to about 40 hours.

Abstract: A spacer grid for nuclear fuel rods includes a plurality of unit spacer grids stacked one on top of another. Each unit spacer grid includes a plurality of unit spacer grid straps disposed at regular intervals in a row, and a plurality of fixing grid straps connected to respective opposite ends of the unit spacer grid straps so as to fix the unit spacer grid straps. Each unit spacer grid strap has convexities alternating with each other on opposite sides thereof at regular intervals, and at least one of the convexities has a diameter greater than the others. The unit spacer grids are rotated in one direction by a 90 or 180 degree angle when being stacked.

Abstract: The invention relates to a method of determining at least one technological uncertainty factor in respect of nuclear fuel elements (23) as a function of variations in the production parameters of the elements (23) in relation to nominal values. The inventive method comprises a step involving the use, for at least one production parameter, of a collective variation in said parameter in relation to the nominal value within a batch of produced elements (23). The invention can be used, for example, to design, produce and check pellets for light water reactors.

Abstract: A fuel assembly for a nuclear reactor that employs dissimilar materials for the fuel assembly grid and the control rod guide thimbles. The guide thimbles are secured to the grid employing a through grid cell sleeve that is welded to the grid and spot weld rings that are secured over the sleeve and welded directly to the guide tube through windows in the sleeve.

Abstract: An article made by applying a burnable poison onto the cladding of a nuclear fuel rod, which involves providing a nuclear fuel rod and at least one application device, rotating the nuclear fuel rod, optionally removing one or more oxides and/or surface deposits on the outer surface of the nuclear fuel rod by spraying an abrasive material onto the nuclear fuel rod via the application device while adjusting the position of the application device in relation to the nuclear fuel rod, and applying burnable poison particles onto the outer surface of the nuclear fuel rod by spraying the burnable poison onto the nuclear fuel rod via the application device while adjusting the position of the application device in relation to the nuclear fuel rod, where the burnable poison particles are applied at a velocity sufficient to cause adhesion to the outer surface of the cladding.

Abstract: Fuel elements are supported by fuel assemblies configured for use in land-based nuclear reactors such as the VVER-1000. The fuel elements include a kernel having a multi-lobed profile that forms spiral ribs that include fissionable material (e.g., uranium or plutonium), a central metal displacer extending along a longitudinal axis of the kernel, and a metal cladding (e.g., zirconium and/or other refractory metals) enclosing the kernel. The fuel element may be fabricated by joint extrusion of the displacer, kernel, and cladding through a die to metallurgically bond the kernel and cladding.

Abstract: A spacer grid for a nuclear fuel assembly for a light water reactor delimits a substantially regular array of cells housing nuclear fuel rods. The spacer grid further including supporting members which project into the cells from the peripheral belt of walls. The inner surface of at least one supporting member has before irradiation a concave shape in a plane transverse to the longitudinal direction. The inner surface of the contact part of the supporting member also has a convex shape in a longitudinal plane orientated radially with respect to the central axis of the corresponding cell before irradiation.

Abstract: A neutron source rodlet assembly having a separate source capsule assembly that is not encapsulated within the neutron source rodlet assembly. The neutron source rodlet assembly is made up, at least in part, of a neutron source positioning rodlet assembly and the source capsule assembly configured such that assembly together is feasible at a remote site and they can be shipped separately. The source capsule assembly has outer and inner capsules with the outer capsule having a threaded stud at one end that mates with a complimentary threaded recess on the neutron source positioning rodlet assembly. The inner capsule contains a neutron source. The neutron source positioning rodlet assembly and the source capsule assembly are locked together at their interface when the threaded joint is completely tightened. A secondary neutron source material may also be encapsulated within a hollow portion of the neutron source positioning rodlet assembly.

Abstract: A boiling water reactor has a core disposed in the reactor pressure vessel and loaded with a plurality of fuel assemblies including transuranic nuclides. A ratio of Pu-239 in all of the transuranic nuclides included in the fuel assembly, which is loaded in the core, with a burnup of 0 is 3% or more but 45% or less. In the fuel assembly having a channel box and a plurality of fuel rods disposed in the channel box, a transverse cross section of a fuel pellet in the fuel rod occupies 30% or more but 55% or less of a transverse cross section of a unit fuel rod lattice in the channel box.

Abstract: In various embodiments, a spacer grid for a nuclear reactor fuel bundle is provided. The grid includes a plurality of interstitial dividers that form an array of cells. Each cell is structured to retain a respective one of a plurality of fuel rods to thereby form an array of equally spaced fuel rods. The grid additionally includes a perimeter band that peripherally surrounds the dividers and is connected to opposing ends of each divider. The perimeter band includes a plurality of spring tabs formed along and extending from an edge of the perimeter band. The spring tabs extend from the edge at an angle away from the dividers such that a distal end of each spring tab will contact an interior surface of a respective one of a plurality of walls of a channel in which the arrayed fuel rods can be inserted to form the fuel bundle.

Abstract: A fuel compact formed by integrally molding coated fuel particles by a press into a cylindrical body and comprising a chamfer having plane or curved surface at its corner to thereby prevent the coated fuel particles from being damaged due to stress on press molding whereby the strength thereof is improved against mechanical contact with a fuel sleeve and a graphite block.

Abstract: A method for design of a fuel assembly for nuclear reactors, including structural components made from zirconium alloy: the mean uniaxial tensile or compressive stress to which the components are subjected during the assembly life is calculated, the zirconium alloy of which the components are made is selected according to the following criteria: those components subjected to an axial or transverse compressive stress of between ?10 et ?20 MPa are made from an alloy with a content of Sn between Sn=(=0.025??0.25)% and Sn=?0.05?%: those components subjected to such a stress of between 0 et ?10 MPa are made from an alloy the Sn content of which is between Sn=traces and Sn=(0.05?+1)%: those components subjected to such a stress of between 0 and +10 MPa are made from an alloy the Sn content of which is between Sn=0.05% and Sn=(0.07?+1)%: and those components subjected to such a stress of between +10 and +20 MPa are made from an alloy the content of SN of which is between 0.05% and 1.70%.

Abstract: A metal particulate fuel system is described. The metal fuel system may include particulate metal fuel for use in nuclear reactors. The particulate metal fuel may include a plurality of particles of at least one enriched alloy where the particles are compacted into a fuel column. The metal particulate fuel system may also include a cladding and/or a gas-filled plenum.

Abstract: A core of a light water reactor having a plurality of fuel assemblies, which are loaded in said core, having nuclear fuel material containing a plurality of isotopes of transuranium nuclides, an upper blanket zone, a lower blanket zone, and a fissile zone, in which the transuranium nuclides are contained, disposed between the upper blanket zone and the lower blanket zone, wherein a ratio of Pu-239 in all the transuranium nuclides contained in the loaded fuel assembly is in a range of 40 to 60% when burnup of the fuel assembly is 0, sum of a height of the lower blanket zone and a height of the upper blanket zone is in a range of 250 to 600 mm, and the height of said lower blanket zone is in a range of 1.6 to 12 times the height of the upper blanket zone.

Abstract: A fuel assembly for a light water reactor contains a fuel rod cluster and a spacer that has a number of cells, bounded by webs for laterally holding fuel rods. A damaged region including at least one damaged cell is present in an edge region of a spacer. There being fastened above or below the damaged region on the spacer with the aid of at least one connecting part is a replacement assembly that contains at least a number of cells that corresponds to the number of the damaged cells, at least a portion of the cells being traversed by fuel rods. A method for repairing the light water reactor fuel assembly in the case of which fixed above or below the damaged region on the spacer is a replacement assembly that takes over the holding function at least of one defective cell.

Abstract: Example embodiments are directed to fuel assembly components and nuclear fuel bundles including the fuel assembly components. Example embodiments of a fuel assembly component may include a cylindrical device having first and second ends and a mounting assembly on the first end of the cylindrical device configured to attach to and detach from a partial length fuel rod. Example embodiments of a nuclear fuel bundle may include an upper tie plate, a lower tie plate, at least one full-length fuel rod, at least one partial length fuel rod, and a fuel assembly component.

Abstract: Example embodiments are directed to upper tie plates for debris mitigation and fuel bundles that use the upper tie plates. Example embodiment tie plates may include a plurality of debris capture elements that overlap each other so as to create debris traps for particulate debris that would fall onto the fuel bundle. Example embodiment fuel bundles may use the upper tie plates for debris mitigation.

Abstract: Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Abstract: An intermediate end plug assembly for a segmented fuel rod can stably support the fuel rod to the end of its cycle even if an interval between the fuel rods becomes narrow due to application of a dual-cooled fuel rod, and reduce excess vibration induced by flows of interior and exterior channels of the dual-cooled fuel rod for obtaining high burnup and output. To this end, the fuel rod has a segmented structure so as to make its length short. A lower intermediate end plug includes at least one channel hole, through which a coolant flows into an internal channel of the fuel rod, so that a possibility of causing departure from nuclear boiling ratio (DNBR) of the dual-cooled fuel rod is reduced.

Abstract: Method including: inducing, with antiprotons, nuclear fission in a material, such as depleted uranium; measuring leakage of radioactive byproduct produced by the fission; and producing, responsive to the measuring, a design for the nuclear fuel element. Apparatus, manufactures, and products produced by the method can be encompassed.

Abstract: Example embodiment fuel bundles use multiple types of spacers within the same fuel bundle. The type for each spacer location may be determined based on the axial position of the spacer, the characteristics of the spacer type, and the location and coolant characteristics for the particular example fuel bundle including the spacers. Historic performance data for the particular bundle location, predictive modeling, etc. may be used to determine what spacer types at which locations result in the best operating conditions and margins for example fuel bundles.

Abstract: A fuel element for a nuclear reactor has a fuel rod bundle, at least one spacer with cells defined by at least one web section made from a first material and several guide tubes each running through a cell and axially fixed thereto made from a second material. The first and second materials have differing thermal expansion coefficients. The connection between the guide tube and the spacer is embodied as follows: first and second projections are directly or indirectly fixed to the guide tube. The first projections are disposed in a first axial position and the second projections are arranged at a second axial position and the projections each engage in an opening through the web section to give an axially-acting undercut.

Abstract: Illustrative embodiments provide a nuclear fission reactor, a vented nuclear fission fuel module, methods therefor and a vented nuclear fission fuel module system.

Abstract: A method for fabricating porous UO2 sintered pellets to be fed into the electrolytic reduction process for the purpose of metallic nuclear fuel recovery is provided, which includes forming a powder containing U3O8 by oxidizing spent nuclear fuel containing uranium dioxide (UO2) (step 1), fabricating green pellets by compacting the powder formed in step 1 (step 2), fabricating UO2+x sintered pellets by sintering the porous U3O8 green pellets fabricated in step 2 at 1200 to 1600° C., in an atmospheric gas (step 3), and forming UO2 sintered pellets by cooling the UO2+x sintered pellets to room temperature, and reduction the same at 1000 to 1400° C., in a reducing atmosphere (step 4).

Abstract: An apparatus for generating medical isotopes provides an annular fissile solution vessel surrounding a neutron generator. The annular fissile solution vessel provides for good capture of the emitted neutrons and a geometry that provides enhanced stability in an aqueous reactor. A neutron multiplier and/or a neutron moderator may be used to improve the efficiency and control the criticality of the reaction in the annular fissile solution vessel.

Abstract: The nuclear fuel assembly means a group of nuclear fuel rods disposed in a substantially regular array together with a support skeleton (5), the assembly having: two nozzles; guide tubes interconnecting the nozzles; and spacer grids secured to the guide tubes for holding the rods. The assembly includes at least one support skeleton reinforcing device disposed between two successive spacer grids and secured to guide tubes. The reinforcing device is disposed inside the group of rods and presents a transverse extent that is smaller than the transverse extent of the array of nuclear fuel rods.

Abstract: Among other things, an apparatus includes a combination of a fissionable material, a molten salt, and a moderator material including one or more hydrides, one or more deuterides, or a combination of two or more of them.

Abstract: A method for the surface tribological decontamination of nuclear fuel rods automates surface wiping by one or more bands of fabric. The band is distant from the axis of the rod, the rod is placed facing the band, and then the band is tensioned around the surface of the rod and moved. The rod may be immobile, moved in pure translation along its axis or with a wide-step helical movement. Preferably, the decontamination is carried by two bands simultaneously, so as to cover the total surface in one pass of the rod.

Abstract: A nuclear fuel assembly support grid formed from an array of a plurality of orthogonally arranged straps in an egg-crate configuration with angled trailing and/or leading edges that are designed to break the correlation of vortices shed from the edges of the grid straps by varying the phase of the vortices to avoid resonant vibration of the straps.

Abstract: A fuel assembly for a pressurized water nuclear reactor contains a multiplicity of fuel rods which are guided in a plurality of axially spaced spacers which in each case form a square grid, composed of grid webs, with a multiplicity of cells arranged in rows and columns. In each case one control rod guide tube is guided through a number of these cells. At least one spacer is configured to be mechanically stronger in a first partial region than in a second partial region. In this second partial region, the spacer is provided with at least one resisting element which protrudes into a flow sub-channel formed between the fuel rods and increases the flow resistance. The resisting element counteracts a reduction associated with the mechanically weaker configuration, in the flow resistance in the second partial region and in this manner effects a homogenization of the hydraulic behavior of a spacer which is mechanically inhomogeneous on account of the varying mechanical configuration.

Abstract: A metal matrix, microencapsulated nuclear fuel component includes an integral metal matrix having an outer buffer region and an inner fuel containing region; a multiplicity of nuclear fuel capsules embedded in the fuel containing region of the matrix for encapsulating a nuclear fuel particle and products resulting from nuclear and chemical reactions; and a nuclear fuel particle encapsulated in each of the nuclear capsules.

Abstract: A debris filter for reactor coolant includes a plurality of adjacent plates defining a plurality of channels therebetween, each of said channels being at an angle to the flow path of the coolant into the filter.

Abstract: A water reactor fuel cladding tube (4) is described. The tube (4) comprises an outer layer (6) of a first zirconium based alloy and has metallurgically bonded thereto an inner layer (7) of a second zirconium based alloy. The inner layer protects (7) the cladding tube (4) against stress corrosion cracking. The second zirconium based alloy comprises tin as an alloying material, and each one of the zirconium based alloys comprises at least 96 percent by weight zirconium. The first zirconium based alloy comprises at least 0.1 percent by weight niobium. A method of manufacturing the cladding tube (4) is also described and comprises the step of co-extruding two tubes of different zirconium based alloys to produce the cladding tube (4).

Abstract: A compressed powder composite (CPC) material for absorbing neutrons emitted from spent nuclear fuel thereby preventing the initiation of a chain reaction. The CPC material is typically provided as a substantially insoluble cylindrical pellet that is highly resistant to corrosion and is not subject to the failure modes associated with the alloy materials typically used in neutron absorption materials. The pellet preferably includes a dendritic nickel powder substantially uniformly mixed with a neutron absorber powder material, preferably boron carbide. Tubes filled with CPC materials, such tubes for replacing control roads so that a spent nuclear fuel assembly may be disposed of substantially indefinitely.

Abstract: The present invention relates to nuclear fuel compositions including triuranium disilicide. The triuranium disilicide includes a uranium component which includes uranium-235. The uranium-235 is present in an amount such that it constitutes from about 0.7% to about 5% by weight based on the total weight of the uranium component of the triuranium disilicide. The nuclear fuel compositions of the present invention are particularly useful in light water reactors.

Abstract: A nuclear fuel pellet design that is a cylindrical axial profile with either a larger radius or conical shaped ends such that the as built diameter at the ends of the pellet are slightly smaller than at the middle and at normal operating conditions, the diameter at the ends is nearly the same as at the middle. Preferably, there are short chamfers at the axial ends of the pellet.

Abstract: A nuclear fuel includes a volume of a nuclear fuel material defined by a surface, the nuclear fuel material including a plurality of grains, some of the plurality of grains having a characteristic length along at least one dimension that is smaller than or equal to a selected distance, wherein the selected distance is suitable for maintaining adequate diffusion of a fission product from a grain interior to a grain boundary in some of the grains, the nuclear fuel material including a boundary network configured to transport the fission product from at least one grain boundary of some of the grains to the surface of the volume of the nuclear fuel material.

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: 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: A composite nuclear fuel pellet comprises a composite body including a UO2 matrix and a plurality of high aspect ratio particies dispersed therein, where the high aspect ratio particies have a thermal conductivity higher than that of the UO2 matrix. A method of making a composite nuclear fuel pellet includes combining UO2 powder with a predetermined amount of high aspect ratio particles to form a combined powder, the high aspect ratio particles having a thermal conductivity higher than that of the UO2 powder; mixing the combined powder in a solvent to disperse the high aspect ratio particles in the UO2 powder; evaporating the solvent to form a dry mixture comprising the high aspect ratio particles dispersed in the UO2 powder; pressing the dry mixture to form a green body; and sintering the green body to form the composite fuel pellet.

Abstract: A method for treating or preparing a fuel rod cladding tube in such a way that an influence of iron oxide deposits on its surface can be studied and assessed precisely under virtually operational conditions with as little risk as possible, includes at least partially coating the fuel rod cladding tube with an iron oxide layer by immersing it in an aqueous electrolyte medium which contains iron oxide particles. The iron oxide particles are produced by anodic oxidation of an iron-containing working electrode. A test body and a device for pretreating a fuel rod cladding tube with an electrochemical three-electrode configuration, are also provided.

Abstract: Disclosed herein are a nuclear fuel rod for fast reactors, which includes an oxide coating layer formed on the inner surface of a cladding, and a manufacturing method thereof. The nuclear fuel rod for fast reactors, which includes the oxide coating layer formed on the inner surface of the cladding, can increase the maximum permissible burnup and maximum permissible temperature of the metallic fuel slug for fast reactors so as to prolong the its lifecycle in the fast reactors, thus increasing economic efficiency. Also, the fuel rod is manufactured in a simpler manner compared to the existing method, in which a metal liner is formed, and the disclosed method enables the cladding of the fuel rod to be manufactured in an easy and cost-effective way.

Abstract: A new nuclear fuel element has been developed to be used in particular in fourth generation gaseous heat exchanger reactors working with a fast neutron flow. With a composite plate structure, the element (1) according to the invention comprises a network of cells (8), more preferably of honeycomb shape, in each of which is placed a nuclear fuel pellet (10). Radial and axial gaps are provided in each cell (8) to compensate for the differential expansion between fissile materials and structural materials inherent in the operation of the plate (1).

Abstract: A tool to slide a channel on a nuclear reactor fuel bundle assembly, the tool includes: a plate having a slot to receive a handle of the fuel bundle and a lower surface that engages an upper edge of the channel; at least one post extends up from the plate, and an arm is attached to a pivot on the post and includes a first end to receive a downward force and a second end adapted to engage the handle of the fuel bundle to apply an upward force to the handle and push down on the channel.

Abstract: Fused neutron particles from a multi-neutron particle generator are injected into atomic nuclei that have a core with groups of fused neutron pairs. Nuclear fusion reactions between injected multi-neutron particles and atomic core neutron particle pairs produce binding energy which causes atomic nuclei to fission. Consequently, more binding energy is released and fused neutron particle pairs are ejected from the nucleus. The ejected fused neutron particle pairs then enter nuclei of other atoms to cause nuclear fusion and nuclear fission reactions. More binding energy and more fused neutron particle pairs are released from the nuclei. This is a chain reaction process that can produce nuclear binding energy from almost any element as fuel.

Abstract: The nuclear reactor comprises a lower stopper sealingly fixed to a lower end of a tubular casing of the pencil that comprises a part which is internal to the casing successively comprising a first cylindrical section having a diameter which is substantially equal to the inner diameter of the tubular casing; a second cylindrical section whose diameter is smaller than the inner diameter of the tubular casing and a third cylindrical section whose inner diameter is smaller than the inner diameter of the tubular casing and greater than the diameter of the second cylindrical section such that 1-2 tenths of a millimetre radial play is created in the gas passable between the outer surface of the third section and the inner surface of the casing.

Abstract: Fuel assemblies include an outer channel having a physical configuration optimized for a position of the fuel assembly within a core of a nuclear reactor. The position of the fuel assembly with respect to an employed control blade in the nuclear reactor determines if the outer channel may be thickened, reinforced, and/or fabricated of Zircaloy-4 or similar distortion-resistant material, so as to reduce or prevent distortion of the channel against the control blade, or thinned so as to increase water volume and enhance reactivity in the assembly. Reactor cores having configured fuel assemblies include fuel assemblies having different outer channels. Methods include determining operational characteristics of the fuel assembly, including likelihood of being placed directly adjacent to an employed control blade, and physically selecting or modifying the outer channel of the fuel assembly based thereon.

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 embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.

Abstract: Disclosed are a fuel rod and a fuel bundle using the fuel rod. The fuel rod may include first enriched uranium in a boost zone of the fuel rod, wherein the boost zone may be arranged directly at a bottom of the fuel rod. The fuel rod may also include second enriched uranium in a second zone of the fuel rod, wherein the second zone is arranged over the boost zone. The fuel rod may also include natural uranium in a third zone of the fuel rod, wherein the third zone is arranged over the second zone. In this fuel rod, a percent of enrichment of the enriched uranium in the boost zone is at least one percent.