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: Methods and systems for in-vessel natural circulation alkali metal reactor systems, purification systems, and associated methods are disclosed. A nuclear reactor vessel system includes an inner vessel that defines an inner volume sized to at least partially enclose a reactor. The reactor includes a plurality of nuclear fuel elements at least partially enclosed within a cladding, the reactor being cooled by a liquid metal coolant in a primary coolant loop. A pool of immersing fluid occupies a volume inside the inner vessel. The reactor vessel system includes an outer vessel sized to wholly or substantially enclose the inner vessel. A nuclear reactor power system includes a reactor core including an active fuel region; and a rotatable drum including at least one of a neutron absorbing material, a neutron leakage enhancing material, or a neutron reflecting material, the rotatable drum positioned external to the active fuel region of the reactor core.

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.