The present invention provides a small nuclear power generation system being safe and easily controlled by load following, and allowing reductions in manufacturing costs and maintenance and management costs. The small nuclear power generation system has a small nuclear reactor employing a load following control method. The reactor includes: a fuel assembly reactor core 4 having metallic fuel containing one or both of uranium (235, 238) and plutonium-239; a reactor vessel 1 containing the fuel assembly reactor core 4; metallic sodium loaded into the reactor vessel 1 and heated by the fuel assembly reactor core 4; and a neutron reflector 2 for achieving criticality in the reactor core with effective multiplication factor of neutrons emitted from the fuel assembly reactor core 4 being maintained at or above about 1. The load following control method of the reactor allows a neutron effective multiplication factor to be controlled by coupling the neutron reflector to spring or spiral metallic members and utilizing heat deformation in the metallic members due to the temperature in coolant metallic sodium to control the fast neutron reflection efficiency of the neutron reflector

A block-type movable reflector/moderator (RM) for nuclear reactor control is disclosed. This reactor control system can be applied to all types of reactors regardless of design. This design for reactor control is used in addition to the necessary rod control system in accordance with the 10CFR50 design criteria. This allows for the requirements of the NRC to be met along with the ability for dual control on power control of any type reactor regardless of process output from the secondary plants.

A compact nuclear power generation system includes a reactor (3) comprising a core (2) which uses metal fuel containing either or both of uranium-235/238 and plutonium-239. A reactor vessel (1) houses the core (2). Metal sodium primary coolant (8) is heated by the core (2). A neutron reflector (9) maintains the effective multiplication factor of neutrons emitted from the core (2) at approximately one or more to bring the core into a critical state. The neutron reflector is movable from a lower part towards an upper part of the core. The heated metal sodium is supplied to a main heat exchanger (15) which is located outside the reactor. A secondary coolant of supercritical carbon dioxide, which circulates through the main heat exchanger, is in heat exchange with the heated metal sodium. The heated secondary coolant drives a turbine (20). A power generator (21) can be operated by the driven turbine.

A compact nuclear power generation system includes a reactor (3) comprising a core (2) which uses metal fuel containing either or both of uranium-235/238 and plutonium-239. A reactor vessel (1) houses the core (2). Metal sodium primary coolant (8) is heated by the core (2). A neutron reflector (9) maintains the effective multiplication factor of neutrons emitted from the core (2) at approximately one or more to bring the core into a critical state. The neutron reflector is movable from a lower part towards an upper part of the core. The heated metal sodium is supplied to a main heat exchanger (15) which is located outside the reactor. A secondary coolant of supercritical carbon dioxide, which circulates through the main heat exchanger, is in heat exchange with the heated metal sodium. The heated secondary coolant drives a turbine (20). A power generator (21) can be operated by the driven turbine.

A dynamic neutron reflector assembly for a breed-and-burn fast reactor incrementally adjusts neutron spectrum and reactivity in a reactor core. The composition of materials in the dynamic neutron reflector may be adjusted to change neutron reflectivity levels, or to introduce neutron moderating or absorption characteristics. The dynamic neutron reflector may contain a flowing reflecting liquid of adjustable volume and/or density. Submergible members may be selectively inserted into the flowing reflecting liquid to alter its volume and introduce other neutron modifying effects such as moderation or absorption. Selective insertion of the submergible members allows for concentration of the neutron modifying effects in a selected portion of the reactor core. The flowing reflecting liquid may also act as a secondary coolant circuit by exchanging heat with the molten fuel salt.

A dynamic neutron reflector assembly for a breed-and-burn fast reactor incrementally adjusts neutron spectrum and reactivity in a reactor core. The composition of materials in the dynamic neutron reflector may be adjusted to change neutron reflectivity levels, or to introduce neutron moderating or absorption characteristics. The dynamic neutron reflector may contain a flowing reflecting liquid of adjustable volume and/or density. Submergible members may be selectively inserted into the flowing reflecting liquid to alter its volume and introduce other neutron modifying effects such as moderation or absorption. Selective insertion of the submergible members allows for concentration of the neutron modifying effects in a selected portion of the reactor core. The flowing reflecting liquid may also act as a secondary coolant circuit by exchanging heat with the molten fuel salt.

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.

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.

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.

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.