A fission based nuclear thermal propulsion rocket engine. An embodiment provides a source of fissionable material such as plutonium in a carrier fluid having neutron moderating constituents, such as hydrogen and/or carbon, therein. In various embodiments, the carrier fluid may be methane, or ethane, or a combination thereof. A neutron source is provided, such as from a neutron beam generator. By way of engine design geometry, various embodiments may provide for intersection of neutrons with the fissionable material injected by way of the carrier fluid, while in a reactor provided in the form of a reaction chamber. Impact of neutrons on fissionable material results in a nuclear fission in sub-critical mass reaction conditions in the reactor, resulting in release of heat energy to the materials within the reactor. The reactor is sized and shaped to receive the reactants and an expandable fluids such as hydrogen, and to confine heated and pressurized gases for discharge out through a throat, into a rocket engine expansion nozzle for propulsive discharge. The design provides a rocket engine with a specific impulse in the range of from about eight hundred (800) seconds to about twenty five hundred (2500) seconds.

A fission based nuclear thermal propulsion rocket engine. An embodiment provides a source of fissionable material such as plutonium in a carrier fluid having neutron moderating constituents, such as hydrogen and/or carbon, therein. In various embodiments, the carrier fluid may be methane, or ethane, or a combination thereof. A neutron source is provided, such as from a neutron beam generator. By way of engine design geometry, various embodiments may provide for intersection of neutrons with the fissionable material injected by way of the carrier fluid, while in a reactor provided in the form of a reaction chamber. Impact of neutrons on fissionable material results in a nuclear fission in sub-critical mass reaction conditions in the reactor, resulting in release of heat energy to the materials within the reactor. The reactor is sized and shaped to receive the reactants and an expandable fluids such as hydrogen, and to confine heated and pressurized gases for discharge out through a throat, into a rocket engine expansion nozzle for propulsive discharge. The design provides a rocket engine with a specific impulse in the range of from about eight hundred (800) seconds to about twenty five hundred (2500) seconds.

Engineering safety systems always have insufficiencies in terms of safety, and construction of a complete safety system causes installation costs for the safety system to become very high. Provided is a small nuclear reactor HAVING a load following control system in which a nuclear reaction in the nuclear reactor is naturally controlled by the generated heat, the small nuclear reactor being provided with: a reactor core provided with a plurality of fuel assemblies of metallic fuels containing uranium (U) 235, 238 and/or plutonium (Pu) 239; a primary coolant comprising a liquid metal; a neutron reflector which serves to control the nuclear reaction in the reactor core and is disposed to enclose the periphery of the reactor core; and a mechanism which contains a liquid or a gas having an expansion coefficient greater than that of the neutron reflector, converts the coefficient of volumetric expansion into an amount of linear thermal expansion, and, by using same, moves the neutron reflector or adjusts the spacing between the plurality of fuel assemblies.

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 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 green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

A green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

A method of fabricating metallic fuel from surplus plutonium may include combining plutonium oxide powder and uranium oxide powder to obtain a mixed powder with reduced proliferation potential. The mixed powder may be electroreduced in a bath of molten salt so as to convert the mixed powder to a first alloy. The first alloy may be pressed to remove a majority of the molten salt adhered to the first alloy to form a pressed alloy-salt mixture. The first alloy may be isolated from the salt by melting the pressed alloy-salt mixture. The first alloy may be further processed to fabricate a fuel rod. Accordingly, the metallic fuel produced may be used in a fast reactor system, such as a Power Reactor Innovative Small Module (PRISM).

A method of fabricating metallic fuel from surplus plutonium may include combining plutonium oxide powder and uranium oxide powder to obtain a mixed powder with reduced proliferation potential. The mixed powder may be electroreduced in a bath of molten salt so as to convert the mixed powder to a first alloy. The first alloy may be pressed to remove a majority of the molten salt adhered to the first alloy to form a pressed alloy-salt mixture. The first alloy may be isolated from the salt by melting the pressed alloy-salt mixture. The first alloy may be further processed to fabricate a fuel rod. Accordingly, the metallic fuel produced may be used in a fast reactor system, such as a Power Reactor Innovative Small Module (PRISM).

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.