A nuclear fuel element comprises a core comprising a fissile element and an additional element, a first material surrounding the nuclear fuel, the first material comprising the fissile element and the additional element, the first material comprising a greater than stoichiometric amount of the additional element, and a metal around an outer portion of the nuclear fuel element. Related nuclear fuel elements, and related methods are disclosed.

The present invention relates to a method for preparing a fully ceramic capsulated nuclear fuel material containing three-layer-structured isotropic nuclear fuel particles coated with a ceramic having a composition which has a higher shrinkage than a matrix in order to prevent cracking of ceramic nuclear fuel, wherein the three-layer-structured nuclear fuel particles before coating is included in the range of between 5 and 40 fractions by volume based on after sintering. More specifically, the present invention provides a composition for preparing a fully ceramic capsulated nuclear fuel containing three-layer-structured isotropic particles coated with the substance which includes, as a main ingredient, a silicon carbine derived from a precursor of the silicon carbide wherein a condition of ΔL.sub.c>ΔL.sub.m at normal pressure sintering is created, where the sintering shrinkage of the coating layer of the three-layer-structured isotropic nuclear fuel particles is ΔL.sub.c and the sintering shrinkage of the silicon carbide matrix is ΔL.sub.m; material produced therefrom; and a method for manufacturing the material. The residual porosity of the fully ceramic capsulated nuclear fuel material is 4% or less.

A multi-inlet gas distributor for a fluidized bed chemical vapor deposition reactor that may include a distributor body having an inlet surface, an exit surface opposed to the inlet surface, and a side perimeter surface. The distributor body may also include multiple-inlets evenly spaced from each other, wherein the multiple-inlets penetrate the distributor body from the inlet surface to a first depth. The distributor body may additionally include cone-shaped apertures connecting to corresponding ones of the multiple-inlets at the first depth and extend from the first depth toward the exit surface. An apex may be formed on the exit surface at the intersection of the cone-shaped apertures.

Disclosed herein is a method comprising coating a fissile, uranium-containing ceramic material with a water-resistant layer, the layer being non-reactive with the fissile, uranium-containing ceramic material. The coating is applied to a surface of the fissile, uranium-containing ceramic material. Also disclosed is a fuel for use in a nuclear reactor.

The known fully ceramic microencapsulated fuel (FCM) entrains fission products within a primary encapsulation that is the consolidated within a secondary ultra-high-temperature-ceramic of Silicon Carbide (SiC). In this way the potential for fission product release to the environment is significantly limited. In order to extend the performance of this fuel to higher temperature and more aggressive coolant environments, such as the hot-hydrogen of proposed nuclear rockets, a zirconium carbide matrix version of the FCM fuel has been invented. In addition to the novel nature to this very high temperature fuel, the ability to form these fragile TRISO microencapsulations within fully dense ZrC represent a significant achievement.

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 coating the fissile material, such as a pellet of U.sub.3Si.sub.2 and/or the grain boundaries, to a desired thickness with a suitable coating material, such as atomic layer deposition or a thermal spray process. The coating material may be any non-reactive material with a solubility at least as low as that of UO.sub.2. Exemplary coating materials include ZrSiO.sub.4, FeCrAl, Cr, Zr, AlCr, CrAl, ZrO.sub.2, CeO.sub.2, TiO.sub.2, SiO.sub.2, UO.sub.2, ZrB.sub.2, Na.sub.2OB.sub.2O.sub.3SiO.sub.2Al.sub.2O.sub.3 glass, Al.sub.2O.sub.3, Cr.sub.2O.sub.3, carbon, and SiC, and combinations thereof. The water resistant layer may be overlayed with a burnable absorber layer, such as ZrB.sub.2 or B.sub.2O.sub.3SiO.sub.2 glass.

A method of forming one or more structures by additive manufacturing comprises introducing a first layer of a powder mixture comprising graphite and a fuel on a surface of a substrate. The first layer is at least partially compacted and then exposed to laser radiation to form a first layer of material comprising the fuel dispersed within a graphite matrix material. At least a second layer of the powder mixture is provided over the first layer of material and exposed to laser radiation to form inter-granular bonds between the second layer and the first layer. Related structures and methods of forming one or more structures are also disclosed.

Disclosed are a sintered nuclear fuel pellet, a fuel rod, a fuel assembly and a method of manufacturing the nuclear fuel pellet. The pellet comprises a matrix of UO.sub.2 and particles dispersed in the matrix. The particles comprises a uranium-containing material. Each of the particles is encapsulated by a metallic coating. The uranium-containing material has a uranium density that is higher than the uranium density of UO.sub.2. The metallic coating consists of at least one metal chosen from the group of Mo, W, Cr, V and Nb.

The application discloses a preparation method of monocrystal uranium dioxide nuclear fuel pellets, comprising: granulating and pelleting UO.sub.2 powder to obtain UO.sub.2 pellets; then coating surfaces of the UO.sub.2 pellets with monocrystal growth additive micro powder to form core-shell structure particles; and activated-sintering the core-shell structure particles at high temperature, liquefying the monocrystal growth additive on the surface of the core-shell structure particle at high temperature and then diffusing into UO.sub.2 pellets, dissolving the UO.sub.3 in the liquid monocrystal growth additive, and recrystallizing the UO.sub.2 to form the monocrystal UO.sub.2 nuclear fuel pellets.

An improved nuclear fuel that has enhanced oxidation resistance and a process for making it are disclosed. The fuel comprises a composite of U235 enriched U.sub.3Si.sub.2 particles and an amount less than 30% by weight of UO.sub.2 particles positioned along the surface of the U.sub.3Si.sub.2 particles. The composite may be compressed into a pellet form. The process comprises forming a layer of UO.sub.2 on the surface of U.sub.3Si.sub.2 particles, either by exposing U.sub.3Si.sub.2 particles to an atmosphere of up to 15% oxygen by volume dispersed in an inert gas for a period of time and at a temperature sufficient to form UO.sub.2 at the U.sub.3Si.sub.2 particle surface, or by mixing U.sub.3Si.sub.2 particles with an amount up to 30% by weight of UO.sub.2 particles.