A control assembly for a nuclear reactor includes a first reactivity control assembly having a first neutron modifying material, a second reactivity control assembly having a second neutron modifying material, and at least one drive mechanism coupled to the first neutron modifying material and the second neutron modifying material. The first neutron modifying material and the second neutron modifying material are selectively repositionable relative to a fuel region of the nuclear reactor. The at least one drive mechanism is configured to provide the first neutron modifying material and the second neutron modifying material in different directions through the fuel region thereby shifting a flux distribution within the fuel region away from the second neutron modifying material.

A nuclear power reactor may include a plurality of power modules, each including a nuclear fuel and a power conversion system configured to convert heat generated from the nuclear fuel to electricity, where the nuclear fuel of the plurality of power modules collectively forms a reactor core. The nuclear power reactor may also include a sleeve being disposed between the plurality of power modules, where the sleeve has a first end and a second end opposite to the first end. The nuclear power reactor may further include a reactivity booster having a neutron source and a reactivity quencher having a neutron absorber. The reactivity booster may be movable between a first location adjacent the first end of the sleeve and a second location adjacent the reactor core, and the reactivity quencher may be movable between a third location adjacent the second end and the second location adjacent the reactor core.

A nuclear power reactor may include a plurality of power modules, each including a nuclear fuel and a power conversion system configured to convert heat generated from the nuclear fuel to electricity, where the nuclear fuel of the plurality of power modules collectively forms a reactor core. The nuclear power reactor may also include a sleeve being disposed between the plurality of power modules, where the sleeve has a first end and a second end opposite to the first end. The nuclear power reactor may further include a reactivity booster having a neutron source and a reactivity quencher having a neutron absorber. The reactivity booster may be movable between a first location adjacent the first end of the sleeve and a second location adjacent the reactor core, and the reactivity quencher may be movable between a third location adjacent the second end and the second location adjacent the reactor core.

An electrochemically modulated molten salt reactor (EMMSR) that contains a vessel and a power source. The vessel houses a fuel salt, at least a portion of a neutron moderator, and at least a portion of an insulator. The fuel salt includes enough dissolved fissile isotopes to cause continued self-sustaining fission reactions during the operation of the EMMSR. The neutron moderator is configured to slow down fast neutrons produced by the dissolved fissile isotopes. The insulator is configured to electrically isolate the neutron moderator from the vessel. The power source has a positive potential and a negative potential. The positive potential is received by the neutron moderator and the negative potential is received by the vessel.

Nuclear propulsion fission reactor structure has an active core region including fuel element structures, a reflector with rotatable neutron absorber structures (such as drum absorbers), and a core former conformal mating the outer surface of the fuel element structures to the reflector. Fuel element structures are arranged abutting nearest neighbor fuel element structures in a tri-pitch design. Cladding bodies defining coolant channels are inserted into and joined to upper and lower core plates to from a continuous structure that is a first portion of the containment structure. The nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

The invention provides a core of a fast reactor including a sodium plenum installed above a core fuel, which is capable of reliably reducing a void reactivity, and an operation method thereof. The core of a fast reactor including the sodium plenum installed above the core fuel is characterized in that a tip of a primary control rod is inserted into a core fuel region, and a tip of a backup control rod is arranged above an upper end of the core fuel region for operation.

Various example embodiments are directed towards an improved control drum, as well as systems, apparatuses, and/or methods for operating a nuclear reactor with a plurality of improved control drums. The control drum includes an outer shell, an inner shell, a plurality of tubes, the plurality of tubes including at least one neutron absorbing tube and at least one neutron scattering tube, and at least one baffle plate arranged between the outer shell and the inner shell, the at least one baffle plate including a plurality of perforations, and at least one perforation of the plurality of perforations configured to support a tube of the plurality of tubes.

Various example embodiments are directed towards an improved control drum, as well as systems, apparatuses, and/or methods for operating a nuclear reactor with a plurality of improved control drums. The control drum includes an outer shell, an inner shell, a plurality of tubes, the plurality of tubes including at least one neutron absorbing tube and at least one neutron scattering tube, and at least one baffle plate arranged between the outer shell and the inner shell, the at least one baffle plate including a plurality of perforations, and at least one perforation of the plurality of perforations configured to support a tube of the plurality of tubes.

A system for use in shutting down a nuclear reactor includes a housing that defines a region therein sealed from an ambient environment and a gate member disposed within the region in a manner such that the gate member segregates the region into a first compartment and a second compartment isolated from the first compartment. The gate member is formed from a material having a predetermined melting point. The system further includes a neutron absorbing material disposed within the first compartment and a dispersion mechanism disposed within the region. The dispersion mechanism structured to encourage the neutron absorbing material from the first compartment into the second compartment.

A system for use in shutting down a nuclear reactor includes a housing that defines a region therein sealed from an ambient environment and a gate member disposed within the region in a manner such that the gate member segregates the region into a first compartment and a second compartment isolated from the first compartment. The gate member is formed from a material having a predetermined melting point. The system further includes a neutron absorbing material disposed within the first compartment and a dispersion mechanism disposed within the region. The dispersion mechanism structured to encourage the neutron absorbing material from the first compartment into the second compartment.