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.

Micro encapsulated fuel particles enhance safety in high-temperature gas cooled reactors by employing multiple barriers to fission product release. Microencapsulated fuel particles also have the potential to do the same in other reactor platforms. The present disclosure provides a method for enhancing the ability of microencapsulated fuel particles to retain radionuclides and thereby further enhance safety in nuclear reactors. Specifically, a nuclear fuel particle including a fuel kernel; a buffer graphitic carbon layer; an inner pyrolytic carbon layer; a multilayer pressure vessel; and an outer pyrolytic carbon layer is disclosed. The multilayer pressure vessel includes alternating layers of silicon carbide and pyrolytic carbon.

A modular nuclear reactor comprises a plurality of sections arranged in a pattern and a side reflector material surrounding the plurality of sections. Each section includes a tank comprising a front plate, a back plate, side plates, a top plate, and a bottom plate. A plurality of grid plates are located within the tank. Each grid plate comprises a plurality of apertures and is vertically separated from an adjacent grid plate. The tank further includes a plurality of fuel elements extending through each grid plate. A plurality of heat pipes extend through each grid plate, the top plate, and an upper reflector. Methods of forming the modular nuclear reactor are also disclosed.

The invention relates generally to uranium fuel in a nuclear reactor and, more particularly, the inclusion of a fuel additive component to the bulk fuel material. The fuel additive component is selected and provided in an amount such that it is effective to improve one or more properties of the bulk fuel material. The fuel additive component has a grain size that is less than the grain size of the bulk fuel material. The granular fuel additive component coats or covers the granular bulk fuel material.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

An improved, accident tolerant fuel for use in light water and lead fast reactors is described. The fuel includes a ceramic cladding, such as a multi-layered silicon carbide cladding, and fuel pellets formed from U.sup.15N and from 100 to 10000 ppm of a boron-containing integral fuel burnable absorber, such as UB.sub.2 or ZrB.sub.2.

A customizable thin plate fuel form and reactor core therefor are disclosed. The thin plate fuel will comprise a fuel material embedded within a matrix material, with the entire unit having a coating. The thin plate fuel may be flat or curved and will have flow channels formed within at least the top surface of the fuel plate. The structure of the thin plate fuel will make it easier for coating with Tungsten or any other suitable material that will help contain any byproducts, prevent reactions with the working fluid, and potentially provide structural support to the thin plate fuel.

A TRISO architecture including an improved buffer layer is provided. The improved buffer layer contains sacrificial silicon in low density carbon to react with palladium released from the kernel and thereby limit the palladium available to react with the existing SiC layer. The introduction of silicon in the buffer layer allows for longer fuel lifetimes and/or higher operating temperatures. Higher achievable burnups and operational temperatures can reduce fuel costs and achieve higher efficient power production. In addition, the silicon-containing buffer layer mitigates fuel failure from palladium corrosion, thereby increasing the safety of the TRISO fuel particle.

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.

A nuclear fuel system (210), nuclear fuel particle (100), and method for operating a nuclear fuel system are disclosed. A nuclear fuel system includes a matrix (130) material and a plurality of fuel particles (100) disposed in the matrix material, each fuel particle comprising a fuel kernel (110) and a fuel coating (120) that covers a surface of the fuel kernel. The fuel kernel comprises a fissile material including one or more of uranium-233, uranium-235, or plutonium-239. The fuel coating is functionally graded in density. A density of the fuel coating increases along an outward radial direction referenced to the center of the fuel kernel. The fuel coating comprises a neutron moderating material. A volume fraction of fuel particles is thirty-five percent or more of a volume of a nuclear fuel compact.