Abstract: Fuel, heat exchangers, and instrumentation for nuclear reactors are disclosed. A nuclear power system includes a plurality of nuclear fuel elements, each of the nuclear fuel elements including an annulus; and a plurality of heat pipes, each of the plurality of heat pipes configured to pass through the annulus of a respective one of the nuclear fuel elements in conductive thermal contact with the respective nuclear fuel element. A nuclear instrumentation module includes an assembly of optical fibers, each optical fiber comprising one or more sensors and configured for removable installation at one of the plurality of heat pipes. A heat exchanger includes a heat pipe including an evaporating region and a condensing region; and a tube bundle configured to wrap around the condensing region of the heat pipe and including one or more adjacent, parallel tubes, each tube forming a helix that is coaxial to the heat pipe.

Abstract: Fuel, heat exchangers, and instrumentation for nuclear reactors are disclosed. A nuclear power system includes a plurality of nuclear fuel elements, each of the nuclear fuel elements including an annulus; and a plurality of heat pipes, each of the plurality of heat pipes configured to pass through the annulus of a respective one of the nuclear fuel elements in conductive thermal contact with the respective nuclear fuel element. A nuclear instrumentation module includes an assembly of optical fibers, each optical fiber comprising one or more sensors and configured for removable installation at one of the plurality of heat pipes. A heat exchanger includes a heat pipe including an evaporating region and a condensing region; and a tube bundle configured to wrap around the condensing region of the heat pipe and including one or more adjacent, parallel tubes, each tube forming a helix that is coaxial to the heat pipe.

Abstract: Fuel, heat exchangers, and instrumentation for nuclear reactors are disclosed. A nuclear power system includes a plurality of nuclear fuel elements, each of the nuclear fuel elements including an annulus; and a plurality of heat pipes, each of the plurality of heat pipes configured to pass through the annulus of a respective one of the nuclear fuel elements in conductive thermal contact with the respective nuclear fuel element. A nuclear instrumentation module includes an assembly of optical fibers, each optical fiber comprising one or more sensors and configured for removable installation at one of the plurality of heat pipes. A heat exchanger includes a heat pipe including an evaporating region and a condensing region; and a tube bundle configured to wrap around the condensing region of the heat pipe and including one or more adjacent, parallel tubes, each tube forming a helix that is coaxial to the heat pipe.

Abstract: Radiation shielding and methods of manufacture are disclosed. A radiation shielding apparatus includes a matrix including matrix material; and a mixture positioned in the matrix, the mixture including: a neutron thermalizing material; and a neutron absorbing material mixed with the neutron thermalizing material. A reactivity control system includes a container rotatable around an axis; a divider positioned inside the container to define two or more compartments within the container; at least one neutron absorber positioned in at least one of the two or more compartments; and at least one neutron reflector positioned in another of the two or more compartments that is fluidly isolated from the at least one of the two or more compartments. A method of manufacturing radiation shielding material includes: fabricating a matrix; generating a mixture by mixing a neutron absorbing material, a neutron thermalizing material, and additive materials; and loading the mixture into the matrix.

Abstract: Reactor buildings and vessel systems are disclosed. A nuclear power system includes: a building structure that comprises at least two exterior side walls and two end walls, at least one of the exterior walls angled non-orthogonally relative to a floor of the building structure, the at least two exterior walls and two end walls defining an interior volume of the building structure; one or more nuclear reactor systems mounted at least partially in the interior volume of the building structure; and one or more heat exchanger systems mounted at least partially to at least one of the exterior walls. A nuclear reactor vessel system includes: a nuclear fission reactor; an inner vessel that defines an inner volume sized to at least partially enclose the nuclear fission reactor; and an outer vessel sized to wholly or substantially enclose the inner vessel, the inner vessel being removable from the outer vessel.

Abstract: System and methods are disclosed for controlling a nuclear reactor that uses fuel having plutonium-239. The nuclear reactor includes a neutron moderator, such as ZrH1.6, which behaves as an Einstein oscillator and increases the energy of thermal neutrons into the Pu-239 neutron absorption resonance as the temperature of the nuclear reactor increases. A neutron absorbing element with neutron absorption around 0.3 eV is added to the nuclear reactor to suppress any reactivity gain that can occur due to the increase in temperature. The amount of the neutron absorbing element to be added to the nuclear reactor is calculated such that the reactivity gain that may occur at any time during the life of the fuel is suppressed.

Abstract: A nuclear reactor may comprise: fuel comprising or breeding plutonium-239; a neutron moderator, such as ZrHx, where x is about 1.6, YH2, TiH2 and/or ThH2, which behaves as an Einstein oscillator and as the temperature of the reactor increases the moderator increases the energy of thermal neutrons into the Pu-239 neutron absorption resonance; and a neutron absorbing element with strong neutron absorption around 0.3 eV added to one or more components of a reactor core of the nuclear reactor, wherein the neutron absorbing element is provided in an amount calculated to suppress, at any time during the life of the fuel, a reactivity gain with temperature due to the neutron moderator increasing the energy of thermal neutrons into the Pu-239 neutron absorption resonance.