A method of obtaining transuranic elements for nanofuel including: receiving spent nuclear fuel (SNF); separating elements from SNF, including a stream of elements with Z>92, fissile fuel, passive agent, fertile fuel, or fission products; and providing elements. A method of using transuranic elements to create nanofuel, including: receiving, converting, and mixing the transuranic elements with a moderator to obtain nanofuel.

A nanofuel engine including receiving nanofuel (including a molecular mixture, where the molecular mixture includes at least one molecule with dimensions on a nanometer scale) internally in an internal engine that releases nuclear energy, is set forth. A nanofuel chemical composition of fissile fuel, passive agent, and moderator. A method of operating a nanofuel engine loaded with nanofuel in spark or compression ignition mode. A method of cycling a nanofuel engine, including compressing nanofuel; igniting nanofuel; capturing energy released in nanofuel, which is also the working fluid; and using the working fluid to perform mechanical work or generate heat.

Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material (e.g., SiC—SiC composite), insulation layer of porous refractory ceramic material (e.g., zirconium carbide with open-cell foam structure or fibrous zirconium carbide), and interior structural member of refractory ceramic-graphite composite material (e.g., zirconium carbide-graphite or niobium carbide-graphite). Spacer structures between various layers provide a defined and controlled spacing relationship. A fuel element bundle positioned between support meshes includes a plurality of distributively arranged fuel elements or a solid, unitary fuel element with coolant channels, each having a fuel composition including high assay, low enriched uranium (HALEU). Fuel assemblies are distributively arranged in a moderator block and the upper end of the outer structural member is attached to a metallic inlet tube for hydrogen propellant and the lower end of the outer structural member is interfaced with a support plate, forming a nuclear thermal propulsion reactor.

A nuclear reactor system includes a nuclear reactor core disposed in a pressure vessel. Nuclear reactor system further includes control drums disposed longitudinally within the pressure vessel and laterally surrounding fuel elements and at least one moderator element of the nuclear reactor core to control reactivity. Each of the control drums includes a reflector material and an absorber material. Nuclear reactor system further includes a control drum controller with a counterweight to impart a reverse torque on the control drum. Control drum controller includes a driven pulley coupled to the counterweight, a tension member coupled to the driven pulley to rotatably control the driven pulley and apply torque to the driven pulley, and an actuator to apply a tension force to the tension member. The actuator counteracts the reverse torque with the applied tension force, and the tension member applies the torque in response to the tension force.

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.

The disclosure describes various aspects of a space-based radioisotope production system and methods use. In one aspect, a propellant is accelerated by decay energy to yield thrust. The decay energy is provided by activating a target material. In one aspect, a radioisotope rocket thruster may be recharged or “reactivated” in a space-borne charging station. The activated isotopes may also be used generate electricity. The space-borne charging station may also be used for irradiating other items in space for any number of purposes.

An aft plenum assembly for use with a nuclear thermal reactor including a pressure vessel and a nozzle assembly having a top plenum plate disposed within the pressure vessel, the top plenum plate defining a first plurality of fuel flow apertures, a bottom plenum plate disposed within the pressure vessel, the bottom plenum plate being parallel to the top plenum plate thereby defining a plenum space therebetween, the bottom plenum plate defining a second plurality of fuel flow apertures, and a plurality of tubular connections extending between the first plurality of fuel flow apertures of the top plenum plate and the second plurality of fuel flow apertures of the bottom plenum plate, wherein the aft plenum assembly is disposed between the pressure vessel and the nozzle assembly.

A fusion drive magnetically confining a plasma in a stable plectonemic minimum-energy Taylor states formed from the merging of a plurality of plectonemic Taylor states. Magnetic reconnection converts magnetic energy into ion heating to attain high temperatures before compression. The plasma configuration is then compressed to net gain in a peristaltic magnetic nozzle arrangement. The fusion drive supports generation of electrical power with inductive direct electric or thermal conversion methods.

A control rod assembly for a nuclear reactor having a reactor core and a pressurized fluid source, including a control rod disposed within a control rod sleeve, a lead screw that is selectively secured to the control rod, a trip latch that is secured to a bottom end of the lead screw, the trip latch being selectively securable to a top end of the control rod, a control rod drive motor that is operably connected to the lead screw, and a valve that is in fluid communication with the pressurized fluid source of the nuclear reactor and is movable between a first position and a second position, wherein in the second position of the gas valve the trip latch is in an open position.

A method for generating a fissile material is described. The method includes positioning a fertile, non-fissile material within outer space, the position within an area of proton or other high energy particle radiation, rather naturally or artificially occurring, allowing the high energy particle radiation to impinge the fertile but non-fissile material over a time, the time based on amount of high energy particle radiation at the position, such that the non-fissile material gradually transmutes into a fissile material due to the impingement, and deploying the fissile material within a spacecraft.