A honeycomb-shaped fuel assembly cooled by liquid chloride salt adopts a honeycomb-shaped structure. A fuel coolant is a mixture of liquid three-phase chloride salt NaClKClMgCl.sub.2. Fuel is U.sub.3Si.sub.2 with an enrichment of 19.75% or 16.0%. The fuel assembly includes: fuel coolant channel pipelines which vertically penetrate and laterally merge, a fuel coolant contained in the fuel coolant channel pipelines, a fuel zone, upper and lower endcap, a top gas plenum, and upper and lower endcap. A reflector assembly adopts a honeycomb-shaped structure, including: reflector coolant pipes which are vertically penetrating; a reflector coolant contained in the reflector coolant pipes; a titanium reflector; and upper and lower endcaps. A control assembly and a safety assembly adopt a rod bundle structure using B.sub.4C with a natural enrichment of .sup.10B as absorbers.

A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic (e.g., silicon carbide, zirconium carbide, or graphite) or a refractory metal (e.g., molybdenum or tungsten). In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.

A thermal bridge for improving thermal transfer between a fuel element to a fuel block wherein there is provided a high temperature gas cooled nuclear reactor fuel block comprising a fuel channel and a coolant channel wherein the fuel channel comprises a fuel element, the fuel channel further comprising a thermal bridge thermally linking the fuel element and the fuel channel, wherein the thermal bridge comprises a melting point greater than the working temperature of the fuel block, thereby improving thermal transfer from the fuel element to the fuel block, thereby improving thermal transfer to the coolant channel.

A commercial nuclear fuel system includes: a vessel that defines an inner volume; a reactor core positioned within the inner volume; and a plurality of fuel pins disposed in the reactor core, each of the plurality of fuel pins comprising at least one hydride fuel element positioned in a cladding. The at least one hydride fuel element is enriched to twenty percent or less of fissile material. The fissile material comprises one or more of uranium-233, uranium-235, or plutonium-239. The fuel pins are positioned in a lattice within the reactor core. The vessel comprises a first vessel, and a second vessel is positioned within the first vessel and surrounds the plurality of fuel pins. At least one reflector is positioned within the first vessel and surrounds the plurality of fuel pins. A shielding assembly is positioned between the reflector and the first vessel.

A method is described that includes the steps of making a thin walled Zr alloy tube, loading nuclear fuel pellets into the tube, compressing the tube onto the fuel pellets to substantially reduce free space around the fuel pellets, positioning end plugs at each of two ends of the tube, filling the tube with a heat transferring gas, and coating the compressed tube with a corrosion resistant material using a thermal deposition process, such as cold spray, before inserting the tube into a pre-formed SiC composite cover having at least one closed end.

Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arm contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.

Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arms contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.