Nuclear reactor systems and associated devices and methods are described herein. A representative nuclear reactor system includes a heat pipe network having an evaporator region, an adiabatic region, and a condenser region. The heat pipe network can define a plurality of flow paths having an increasing cross-sectional flow area in a direction from the evaporator region toward the condenser region. The system can further include nuclear fuel thermally coupled to at least a portion of the evaporator region. The heat pipe network is positioned to transfer heat received from the fuel at the evaporator region, to the condenser region. The system can further include one or more heat exchangers thermally coupled to the evaporator region for transporting the heat out of the system for use in one or more processes, such as generating electricity.

A molten fuel salt nuclear reactor core assembly including a fluid neutron reflecting material defining a fast spectrum fuel volume configured to breed fissile fuel from fertile fuel, a first inlet channel, and a first outlet channel through which cooled molten fuel salt can enter and heated molten fuel salt can exit the fast spectrum fuel volume. The core assembly also includes a set of neutron absorbing members sized to fit within the fast spectrum fuel volume. The set of neutron absorbing members define a thermal spectrum fuel volume for a fission reaction of the fissile fuel, a second inlet channel, and a second outlet channel through which cooled molten fuel salt can enter and heated molten fuel salt can exit the thermal spectrum fuel volume.

A travelling wave reactor for a space exploration. A reactor core of the travelling wave reactor is dispersed into several modules in a travelling wave direction; a new reactor is sequentially provided with a starting source module and a plurality of new fuel modules at zero burnup; all the modules are coaxially assembled in the travelling wave direction by means of an assembling parts, and each module further includes a heat pipe; the heat pipe in each module positioned at a front part sequentially passes through all the modules positioned at a rear portion thereof and extends out of the module at a rear end; and after a period of time of burn-up, the reactor core of the travelling wave reactor is provided with the starting source module, a spent fuel module, a critical fuel module and the new fuel module sequentially in the travelling wave direction.

A nuclear reactor includes a passive reactivity control nuclear fuel device located in a nuclear reactor core. The passive reactivity control nuclear fuel device includes a multiple-walled fuel chamber having an outer wall chamber and an inner wall chamber contained within the outer wall chamber. The inner wall chamber is positioned within the outer wall chamber to hold nuclear fuel in a molten fuel state within a high neutron importance region. The inner wall chamber allows at least a portion of the nuclear fuel to move in a molten fuel state to a lower neutron importance region while the molten nuclear fuel remains within the inner wall chamber as the temperature of the nuclear fuel satisfies a negative reactivity feedback expansion temperature condition. A duct contains the multiple-walled fuel chamber and flows a heat conducting fluid through the duct and in thermal communication with the outer wall chamber.

A fuel assembly for use in a nuclear reactor comprising a fuel bundle, a plenum header connection positioned on the fuel bundle, a mast extending from the fuel bundle, and a common fission gas plenum extending from the mast is disclosed. The reactor includes a vessel and coolant situated within the vessel. The fuel bundle comprises a plurality of fuel elements including nuclear fuel material positioned therein. The plenum header connection comprises a plurality of passageways defined therein that are in fluid communication with the nuclear fuel material. The elongate mast comprises an internal passage connecting the common fission gas plenum to the plurality of passageways of the plenum header connection such that the common fission gas plenum is configured to receive an amount of fission gas generated by the nuclear fuel material during operation. The common fission gas plenum is positioned in an otherwise unused portion of the vessel.

The present invention relates to a travelling wave reactor for a space exploration. A reactor core of the travelling wave reactor is dispersed into several modules in a travelling wave direction; a new reactor is sequentially provided with a starting source module and a plurality of new fuel modules at zero burnup; all the modules are coaxially assembled in the travelling wave direction by means of an assembling parts, and each module further includes a heat pipe; during assembly, the heat pipe in each module positioned at a front part sequentially passes through all the modules positioned at a rear portion thereof and extends out of the module at a rear end; and after a period of time of burn-up, the reactor core of the travelling wave reactor is provided with the starting source module, a spent fuel module, a critical fuel module and the new fuel module sequentially in the travelling wave direction.

An anti-proliferation technique is disclosed to reduce the likelihood of nuclear proliferation due to the use fissionable fuel salts. The technique includes doping the fuel salt with one or more elements (referred to herein as activation dopants) that, upon exposure to neutrons such as would occur in the fuel salt when a reactor is in operation, undergo a nuclear reaction to, directly or indirectly, form highly active “protecting isotopes” (of the same element as the activation dopant or a different element). A sufficient mass of activation dopants is used so that the Figure of Merit (FOM) of the fuel salt is decreased to below 1.0 within some target number of days of fission. This allows the FOM of the fuel salt to be controlled so that the fuel becomes too dangerous to handle before to the creation of a significant amount of weaponizable isotopes.

A fuel element has a ratio of area of fissionable nuclear fuel in a cross-section of the tubular fuel element perpendicular to the longitudinal axis to total area of the interior volume in the cross-section of the tubular fuel element that varies with position along the longitudinal axis. The ratio can vary with position along the longitudinal axis between a minimum of 0.30 and a maximum of 1.0. Increasing the ratio above and below the peak burn-up location associated with conventional systems reduces the peak burn-up and flattens and shifts the burn-up distribution, which is preferably Gaussian. The longitudinal variation can be implemented in fuel assemblies using fuel bodies, such as pellets, rods or annuli, or fuel in the form of metal sponge and meaningfully increases efficiency of fuel utilization.

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.

Nuclear reactor systems and associated devices and methods are described herein. A representative nuclear reactor system includes a heat pipe network having an evaporator region, an adiabatic region, and a condenser region. The heat pipe network can define a plurality of flow paths having an increasing cross-sectional flow area in a direction from the evaporator region toward the condenser region. The system can further include nuclear fuel thermally coupled to at least a portion of the evaporator region. The heat pipe network is positioned to transfer heat received from the fuel at the evaporator region, to the condenser region. The system can further include one or more heat exchangers thermally coupled to the evaporator region for transporting the heat out of the system for use in one or more processes, such as generating electricity.