Nuclear reactor systems and associated devices and methods are described herein. A representative nuclear reactor system includes a reactor vessel having a barrier separating a core region from a shield region. A plurality of fuel rods containing a liquid nuclear fuel are positioned in the core region. A liquid moderator material is also positioned in the core region at least partially around the fuel rods. A plurality of heat exchangers can be positioned in the shield region, and a plurality of heat pipes can extend through the barrier. The moderator material is positioned to transfer heat received from the liquid nuclear fuel to the heat pipes, and the heat pipes are positioned to transfer heat received from the moderator material to the heat exchangers. The heat exchangers can transport the heat out of the system for use in one or more processes, such as generating electricity.

A nuclear reactor core includes a plurality of fuel elements and a skewed-pin moderator block array of skewed-pin moderator blocks to form a nuclear reactor core inner portion and a nuclear reactor core outer portion. The nuclear reactor core inner portion includes an inner moderator matrix formed of a plurality of inner holes that include a plurality of inner fuel openings with one or more fuel elements disposed therein. The plurality of inner holes further include a plurality of inner coolant passages to flow a coolant. The nuclear reactor core outer portion includes an outer moderator matrix formed of a plurality of outer holes that include a plurality of outer fuel openings with one or more fuel elements disposed therein. The plurality of outer holes further include a plurality of outer coolant passages to flow the coolant. The inner holes are irregularly spaced with respect to the outer holes.

Combined moderator-propellant technologies allow a dual-purpose fluid to act as both a nuclear moderator as well as a propellant in a nuclear reactor system, such as a nuclear thermal propulsion (NTP) system. By increasing the mass efficiency of the NTP system and improving the overall performance during operation, the combined moderator-propellant technologies improve valuable payload efficiency in the NTP system. Advantageously, the combined moderator-propellant technologies require little to no dedicated storage space for the majority of NTP system operation. For example, the combined moderator-propellant is ammonia (NH.sub.3), which satisfies moderation requirements as well as propulsion requirements for the NTP system.

Combined moderator-propellant technologies allow a dual-purpose fluid to act as both a nuclear moderator as well as a propellant in a nuclear reactor system, such as a nuclear thermal propulsion (NTP) system. By increasing the mass efficiency of the NTP system and improving the overall performance during operation, the combined moderator-propellant technologies improve valuable payload efficiency in the NTP system. Advantageously, the combined moderator-propellant technologies require little to no dedicated storage space for the majority of NTP system operation. For example, the combined moderator-propellant is ammonia (NH.sub.3), which satisfies moderation requirements as well as propulsion requirements for the NTP system.

A method of generating power using a Thorium-containing molten salt fuel is disclosed. One example of the disclosed method includes the steps of providing a vessel containing a molten salt fuel, the molten salt fuel comprising Thorium and at least one salt containing a nucleus capable of interacting with a proton of sufficient energy to produce a (p, n) reaction resulting in the generation of a neutron at a first energy level and generating a proton beam externally to the vessel, where the externally generated proton beam being of an energy level sufficient to interact with the at least one salt in the vessel to produce a (p, n) reaction resulting in the generation of a neutron at the first energy level. In the example, the externally generated proton beam is directed into the vessel such that at least some protons forming the beam will interact with an atom forming a part of the at least one salt contained in the vessel to causing interaction between the externally generated proton beam and the at least one salt contained in the vessel to produce (p, n) reactions resulting in the generation of neutrons within the vessel and an absorption reaction involving the generated neutrons and Thorium within the vessel. Neutrons generated within the vessel through the (p, n) reactions caused by the externally generated proton’s interaction with the at least one salt are utilized to produce a fission reaction where the fission reaction increases. the heat content of the molten salt within the vessel. In the example, a heat exchanger is used to extract heat from the molten salt within the vessel and power is generated from the extracted heat.

A composite structure is disclosed comprising a neutron-absorbing metal hydride phase contained within a matrix having a density of greater than 95%. In various embodiments the metal hydride is a hydride of one or more of the following: Gadolinium, Hafnium, Europium, Samarium. The composite structure is utile as a shield for fusion or fission reactors.

A composite structure is disclosed comprising a neutron-absorbing metal hydride phase contained within a matrix having a density of greater than 95%. In various embodiments the metal hydride is a hydride of one or more of the following: Gadolinium, Hafnium, Europium, Samarium. The composite structure is utile as a shield for fusion or fission reactors.

The reactor core includes at least one module, a solid neutron moderator, and a liquid neutron moderators. Each module contains a casing, at least one heat pipe, one fuel element and thermal insulation. The heat pipe comprises a casing, a wick, and a coolant. The fuel element is made of nuclear fuel, arranged along an evaporation area of the heat pipe, around the heat pipe casing, in thermal contact with the heat pipe casing, and enclosed in a can. Liquid metals are used as the coolant of the heat pipe. Thermal insulation is arranged between the can and the module casing. At least one hole is made in the solid neutron moderator. Each module is arranged within a respective hole of the solid neutron moderator. The space between the module casing and the solid neutron moderator is filled with a liquid neutron moderator.

A nuclear reactor core includes at least one module, a solid neutron moderator, and liquid neutron moderator. Each module comprises a housing, at least one heat pipe, at least one fuel element, casing, and thermal insulation. The heat pipe comprises a housing, wick, and evaporating coolant. The fuel element includes a shell and nuclear fuel. An evaporation zone of the heat pipe and the fuel elements are enclosed by the casing. The casing is filled with a liquid coolant. Liquid metal, for example, lithium, calcium, lead, and/or silver, is used as the heat pipe coolant and the liquid coolant. The thermal insulation is arranged in a space between the casing and module housing. The solid neutron moderator has at least one hole, wherein at least one module is located. A space between the solid neutron moderator and module is filled with the liquid neutron moderator.

A reactor core block is disclosed including a fuel channel, a heat pipe, a primary moderator matrix configured to encompass the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix. The secondary moderator channel is comprised of metal hydride.