Abstract: A nuclear reactor power system includes: a reactor core comprising a plurality of nuclear fuel elements, each nuclear fuel element comprising: a first cooling channel passing through the nuclear fuel element; and a second cooling channel passing through the nuclear fuel element and fluidly isolated from the first cooling channel; a first cooling system configured to transport a first fluid coolant through the reactor core, the first cooling system fluidly connected to the first cooling channel of each nuclear fuel element; and a second cooling system configured to transport a second fluid coolant through the reactor core, the second cooling system fluidly connected to the second cooling channel of each nuclear fuel element. A direction of first fluid coolant flow through the first cooling channel is the same as a direction of second fluid coolant flow through the second cooling channel.

Abstract: A nuclear reactor power system includes: a reactor core comprising a plurality of nuclear fuel elements, each nuclear fuel element comprising: a first cooling channel passing through the nuclear fuel element; and a second cooling channel passing through the nuclear fuel element and fluidly isolated from the first cooling channel; a first cooling system configured to transport a first fluid coolant through the reactor core, the first cooling system fluidly connected to the first cooling channel of each nuclear fuel element; and a second cooling system configured to transport a second fluid coolant through the reactor core, the second cooling system fluidly connected to the second cooling channel of each nuclear fuel element. A direction of first fluid coolant flow through the first cooling channel is the same as a direction of second fluid coolant flow through the second cooling channel.

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.

Abstract: In some aspects, deicer systems to distribute a deicing fluid along a roof of a building to limit ice dam formation can include: a pre-pressurized water source that provides pressurized water; a deicer solution source containing a deicer solution; a passive mixing system in fluid communication with the pre-pressurized water source and the deicer solution source, the passive mixing system being configured to combine the pressurized water and the deicer solution to form a deicer fluid; and one or more emitters configured to be disposed along the roof, the emitters being in fluid communication with the passive mixing system to receive the deicer fluid and dispense the deicer fluid along the roof. In addition, certain systems described herein can be run with an electric pump.

Abstract: Semi-submersible floating decanters and methods of use are provided. The decanters are moveable between a non-decant position and a decant position, and include a float forming an internal cavity, the float having a central annulus, a weir having an inlet opening and positioned within the center of the annulus and fixedly connected to the float forming a passage between the float and the weir, and a discharge conduit connected to the weir for discharging a supernatant fluid therefrom. A depth adjusting mechanism is provided for moving the decanter within a liquid between a non-decant position wherein the inlet opening is above the surface of the liquid and a decant position wherein the inlet opening is positioned within the supernatant to allow the supernatant to be withdrawn, the depth adjusting mechanism including a pumping mechanism for moving a fluid relative to the internal cavity.