Abstract: A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.

Abstract: The present invention concerns a fuel assembly for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods. At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235U. At least 20% of the fuel rods belong to a first set of fuel rods. The fuel rods in this first set comprise both U enriched in 235U and Th. The first set comprises a first and a second subset of fuel rods. The ratio, with regard to weight, between Th and U, in each fuel rod of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor.

Abstract: An embodiment of the present invention takes the form of a system that allows for simultaneously assembling or disassembling multiple segmented nuclear fuel rods (hereinafter “segmented rods”). An embodiment of the present invention, may receive, secure, and move the segmented rods into a position that allows for performing the tasks of either assembly or disassembly, allowing for an operator to use a tool to complete the aforementioned tasks.

Abstract: A device for supporting nuclear fuel plates (4) with a longitudinal axis (X) including a bottom (6) forming a lower longitudinal end of the supporting device and a lid (8) forming an upper longitudinal end of the supporting device, the bottom (6) and the lid (8) being rigidly connected to each other through a central connecting means and peripheral connecting means, a plurality of upper means (18) for supporting the plates (4) attached to the lid (8), and a plurality of lower means (16) for supporting the plates (4) attached to the bottom (6), ensuring elastic support of the longitudinal ends of the plates (4) in a direction of the width (R) of the plate (4) and allowing free deformation of said longitudinal ends in the direction of the thickness (T) of the plate.

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: Example embodiments and methods are directed to irradiation target retention devices that may be inserted into conventional nuclear fuel rods and assemblies. Example embodiment devices may hold several irradiation targets for irradiation during operation of a nuclear core containing the assemblies and fuel rods having example embodiment irradiation target retention devices. Irradiation targets may substantially convert to useful radioisotopes upon exposure to neutron flux in the operating nuclear core and be removed and harvested from fuel rods after operation.

Abstract: A rod assembly for a fuel bundle of a nuclear reactor may include an upper end piece, lower end piece and a plurality of rod segments attached between the upper and lower end pieces and to each other so as to form an axial length of the rod assembly. The rod assembly may include an adaptor subassembly provided at given connection points for connecting adjacent rod segments or a given rod segment with one of the upper and lower end pieces. The connection points along the axial length of the rod assembly may be located where the rod assembly contacts a spacer in the fuel bundle. One (or more) of the rod segments may include an irradiation target therein for producing a desired isotope when a fuel bundle containing one (or more) rod assemblies is irradiated in a core of the reactor.

Abstract: A fuel assembly for a boiling water reactor comprising a plurality of fuel units (3a, 3b, 3c, 3d), stacked on top of each other, each one comprising a top tie plate (5), a bottom tie plate (6) and a plurality of fuel rods (4a, 4b, 4c) arranged between the top tie plate and the bottom tie plate. The fuel units are surrounded by a fuel channel (9) with a substantially square cross section. At least some of the fuel units comprise fuel rods with different diameters and different fuel quantities. The fuel rods are adapted such that fuel quantity and lattice space are optimized laterally and axially in the fuel assembly.

Abstract: The present invention provides improved nuclear fuel pellets having high thermal conductivity for use in an LWR. This can be achieved by creating a continuous deposition phase of high-thermal conductivity substances in the grain boundaries in the pellets. As a result, the temperature in the center of the fuel rod can be significantly reduced, and the discharge amount of gases generated on the nuclear fission can be efficiently reduced.The present invention also provides a method of manufacturing the above-described nuclear fuel pellets.

Abstract: A boiling water nuclear reactor used for the production of electricity includes fuel rods and an assembly of these fuel rods that improve the reactor economics and safety. The fuel assemblies include hydride fuel pellets at selected axial and radial positions in addition to oxide fuel pellets. The hydride fuel functions simultaneously as a fuel and as a moderator. The hydride fuel can be made from different combinations of fissionable materials such as uranium, and hydrides such as zirconium hydride. The hydride fuel (such as U-ZrH.sub.1.6) is substituted for oxide fuel (UO.sub.2) in undermoderated regions of the core. Hydride fuel rods also replace water rods in the fuel assemblies.

Abstract: A fuel bundle is disclosed in which interspersed part length fuel rods define between the end of the fuel rods and the upper tie plate void regions which are not otherwise occupied. Full length fuel rods adjacent to these regions are provided with an expanded upper plenum region which effectively increases the fuel rod diameter at the end of the upper two phase region of the fuel bundle. Under normal circumstances and a fuel bundle with only full length fuel rods, such an expansion of the upper regions of the fuel rods would cause unacceptable pressure drop. Where such expansion occurs adjacent the vacated volumes created by the part length fuel rods, unacceptable pressure drop does not occur. Consequently, and with the expanded plenum volume, a longer length of active fuel pellets can be accommodated within the full length fuel rods.

Abstract: Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

Abstract: A fuel pellet for a nuclear reactor fuel rod is fabricated with smooth and gently sloping surfaces having no sharp edges or areas of high stress concentration. The bearing surfaces of the fuel pellets are contoured so that the pellets are easily stacked within a fuel rod and permit pivoting action between the fuel pellets. The fuel pellets are stacked end to end in a fuel rod which is incorporated into a fuel assembly for a nuclear reactor.

Abstract: A control rod for a nuclear fuel assembly has structures formed of boron carbide mounted inside it. The boron carbide structures are provided deformable members between them which will deform at operating temperatures to accommodate the dimensional increase of the boron carbide structures and reduce the level of deformable stress on the rod cladding.

Abstract: An electron and ion accelerator includes plural spaced electrodes which are apertured to define a gas discharge path and supported at their peripheries by insulative means. A gas supply provides low pressure gas capable of producing electrons and ions in the gas discharge path. A voltage applied between the at least two electrodes establishes an electrical potential between them such that a spark-like gas discharge occurs along the gas discharge path. The current density obtainable in the low pressure gas is substantially higher than the density of an electron or ion flow in a vacuum.