Abstract

A nuclear engine system includes: a pump configured to pump a propellant; a fuel element including a set of nuclear fuel particles; a moderator configured to surround the fuel element and defining a set of moderator coolant channels configured to cool the moderator; a reflector including a neutron-reflecting material and a reflector coolant channel arranged within the reflector to cool the reflector, the reflector configured to at a first time, operate in a closed configuration to reflect neutrons to the fuel element to increase an energy flux, and at a second time, operate in an open configured to leak neutrons out of the engine system to decrease the energy flux; and a thrust nozzle configured to outlet propellant from the fuel element to produce thrust including a nozzle coolant channel arranged within a wall of the thrust nozzle configured to cool the nozzle.

IPC Classes  ?

• G21D 5/02 - Reactor and engine structurally combined, e.g. portable
• B64G 1/40 - Arrangements or adaptations of propulsion systems
• B64G 1/42 - Arrangements or adaptations of power supply systems
• F02K 9/64 - Combustion or thrust chambers having cooling arrangements
• G21C 7/28 - Control of nuclear reaction by displacement of the reflector or parts thereof
• G21C 15/06 - Arrangement or disposition of passages in which heat is transferred to the coolant, e.g. for coolant circulation through the supports of the fuel elements from fissile or breeder material in fuel elements
• G21C 15/08 - Arrangement or disposition of passages in which heat is transferred to the coolant, e.g. for coolant circulation through the supports of the fuel elements from moderating material
• G21C 15/10 - Arrangement or disposition of passages in which heat is transferred to the coolant, e.g. for coolant circulation through the supports of the fuel elements from reflector or thermal shield
• G21C 1/06 - Heterogeneous reactors, i.e. in which fuel and moderator are separated

Abstract

One variation of a reactor assembly for a nuclear thermal propulsion system includes a set of fuel elements arranged within a moderator block. Each fuel element, in the set of fuel elements, includes: a cold shell; a compliance structure; a fuel bed; and a hot shell.

IPC Classes  ?

• B64G 1/40 - Arrangements or adaptations of propulsion systems
• G21C 1/07 - Pebble-bed reactorsReactors with granular fuel
• G21C 5/08 - Means for preventing undesired asymmetric expansion of the complete structure

Abstract

A method includes: during a first time period, pumping propellant: to a set of moderator coolant channels to cool the moderator; through a set of fuel elements to heat the propellant to a first outlet temperature; out of a thrust nozzle to produce a first thrust; and locating the reflector at a first closed position to reflect neutrons toward the set of fuel elements to maintain a fission rate of the set of fuel elements above a threshold fission rate. Additionally, during a second time period: locating the reflector at a second open position to reduce the fission rate of the set of fuel elements to below the threshold fission rate; and pumping the propellant through the fuel elements to heat the propellant to a second outlet temperature less than the first outlet temperature and out of the thrust nozzle to produce a second thrust less than the first thrust.

IPC Classes  ?

• F02K 9/42 - Rocket-engine plants, i.e. plants carrying both fuel and oxidant thereforControl thereof using liquid or gaseous propellants
• G21C 1/06 - Heterogeneous reactors, i.e. in which fuel and moderator are separated
• G21D 5/02 - Reactor and engine structurally combined, e.g. portable