Abstract: 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 lower and upper core plates to from a continuous structure that is a first portion of the containment structure. The body of the fuel element has a structure with a shape corresponding to a mathematically-based periodic solid, such as a triply periodic minimal surface (TPMS) in a gyroid structure. The nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

Abstract: 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 lower and upper core plates to from a continuous structure that is a first portion of the containment structure. The body of the fuel element has a structure with a shape corresponding to a mathematically-based periodic solid, such as a triply periodic minimal surface (TPMS) in a gyroid structure. The nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

Abstract: A light-water reactor nuclear fuel rod loading apparatus, which comprises a spacer grid holder and a loading power device installed with a traction module configured to reciprocally move toward the spacer grid holder. The loading apparatus further comprises a hollow cladding tube sample and a pulling bar comprising one end part and an opposite end part. The one end part passing in use through a cell of a spacer grid held by the spacer grid holder and configured to couple to the hollow cladding tube sample. The opposite end part is coupled to the traction module. The loading apparatus further comprises: a measuring device installed on the pulling bar and configured to measure loading force of the traction module loading the pulling bar; a holder cap; and a holder comprising an end part configured to in use pass through the cladding tube sample and couple to the holder cap.

Abstract: A PWR includes a secondary circuit that is normally fluidly isolated from the primary circuit. The secondary circuit includes secondary fluid in a steam generator. In response to detection of a core melt, the secondary circuit is placed in fluidic communication with the primary circuit, so that secondary fluid from the steam generator can flow into the primary circuit and then into the reactor vessel.

Abstract: A magnetic confinement fusion reactor includes a host hall, and a host including a Dewar system, a cold shield system, a superconducting magnet system, a vacuum chamber system, a divertor system, a blanket system, a remote operation system, and a maintenance system. The superconducting magnet system includes a central solenoid magnet, a poloidal field magnet, and a toroidal field magnet. The central solenoid magnet is configured to provide necessary volt-seconds. The poloidal field magnet is configured to generate a poloidal magnetic field. The toroidal field magnet is configured to generate a toroidal magnetic field. The plasma is confined by the toroidal magnetic field and the poloidal magnetic field. The vacuum chamber system is provided with a neutron shielding block to protect the superconducting magnets from being damaged by fusion neutrons.

Abstract: A nuclear reactor main heat and waste heat integrated thermal exchanger has a first coolant zone for a first main heat loop, a second coolant zone for a second main heat loop and a third coolant zone for a waste heat removal loop. The first coolant for the first main heat loop passes through the first coolant inlet, and then reaches the orifice plate, and finally flows out from the first coolant outlet. The second coolant for the second main heat loop passes through the second coolant inlet, and then reaches the lower tube sheet, and finally flows out from the second coolant outlet. The third coolant for the waste heat removal loop enters the entrance sleeve through the third coolant inlet, and then enters multiple tubes of the tube bundle, and then enters the exit sleeve, and finally flows out from the third coolant outlet.

Abstract: A tube grid cell (2) for a fuel bundle (8) of a nuclear reactor. The tube grid cell (2) having the length (L), comprises a cell housing (10) which has, along the longitudinal axis A, a lower section (16), an upper section (18) and a middle section (20). The middle section (20) is provided with two pairs of support members (22) and a resilient member (24) configured to generate a resilient force in an inward radial direction, the resilient member is arranged at essentially equal distance from the support members (22), and positioned approximately (120) degrees apart from the support members seen along axis A. The upper section (18) and the lower section (16) have respectively a length L1 and L2 along axis A that is larger than 0.1 L and smaller than 0.3 L, and is provided with a solid housing wall, having an even thickness and no openings, indentations or protrusions.

Abstract: A modular nuclear reactor system includes a lift-out, replaceable nuclear reactor core configured for replacement as a singular unit during a single lift-out event, such as rather than lifting and replacing individual fuel assemblies and/or fuel elements. The system includes a reactor vessel and a power generation system configured to convert thermal energy in a high temperature working fluid received from the reactor vessel into electrical energy. The reactor vessel includes: a vessel inlet and an adjacent vessel outlet arranged near a bottom on the vessel; a vessel receptacle configured to receive a unified core assembly; locating datums in the base of the vessel receptacle and configured to constrain a core assembly in multiple degrees of freedom; and an interstitial zone surrounding the vessel receptacle and housing a set of control or moderating drums.

Abstract: A nuclear component handling arrangement is disclosed including a storage overpack including an inner envelope, an inner canister including an outer envelope, and a vent and duct system. The inner canister is positionable within the storage overpack. The vent and duct system includes an inlet vent, an outlet vent, and a passageway defined between the inner envelope of the storage overpack and the outer envelope of the inner canister. The passageway extends between the inlet vent and the outlet vent. The inlet vent includes an inlet entrance, an inlet exit, and a curved transition surface extending between the inlet entrance and the inlet exit.

Abstract: Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arm contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.

Abstract: An automatically adjusting seismic restraint system for nuclear fuel storage in one embodiment comprises a free-standing first fuel storage component (FSC) configured to contain nuclear fuel, and a stationary second FSC configured to receive the first fuel storage component. An inter-body gap formed between the FSCs includes at least one seismic restraint assembly. The assembly includes a stationary wedge member fixedly coupled to the second FSC and a movable loose wedge member engaged with and supported in place by the stationary wedge member. The stationary wedge member defines an inclined load bearing surface slideably engaged with a mating inclined load bearing surface of the loose wedge member. During a seismic event or thermal expansion of the first FSC, the first FSC moves towards the second FSC which shrinks the inter-body gap and the loose wedge member is vertically displaced relative to the stationary wedge member while maintaining engagement therewith.

Abstract: A system for detecting a leak in a cladding tube in a nuclear reactor that has a plurality of cladding tubes housed in a plurality of horizontally arranged channels. A plurality of tubes are positioned adjacent to the channels. A plurality of solid state radiation detectors are in each of the tubes. The detectors are spaced from each other along the length of each tube. The detectors can detect the presence of radiation from a selected fission product within a channel. A processor calculates a leak location by receiving signals above a base line level from the detectors, determining differences in signal strength from the detectors over a period of time, and identifying location of the detector emitting the strongest signal.

Abstract: A storage device for storing and/or transporting nuclear fuel assemblies. The storage device includes a number N of adjacent recesses. Some of the recesses created by means of notched, intersecting and stacked plates. In at least one transverse plane, at least one of the adjacent recesses has an inner surface which defines the recess. The adjacent recess being formed in part by a first surface of a first notched plate made with boron and a first surface of a second notched plate made without boron.

Abstract: A fuel rack for storing nuclear fuel in a fuel pool in one embodiment comprises a baseplate configured for placement in a fuel pool, and a cellular body coupled to the baseplate. The body comprises tightly-packed upwardly open cells which each hold a nuclear fuel assembly. In one embodiment, each cell may have a hexagonal cross-sectional configuration. The cells are each formed by angled cell walls and corners formed between adjoining cell walls. Adjacent cells are arranged to meet in corner-to-corner alignment. This produces triangular-shaped flux traps interspersed between the cells for reactivity control. In some embodiments, at least one peripheral side of the fuel rack has an undulating configuration defining a series of alternating peaks and valleys which nests with a complementary configured peripheral side of an adjacent fuel rack. This provides higher packing density of fuel racks and fuel assemblies in the fuel pool.

Abstract: A detector for generating an electrical current that is proportional to a flux of neutrons includes a neutron sensitive emitter, a conductive collector, an insulator between the neutron-sensitive emitter and the collector, an electrical connection to the neutron sensitive emitter, and an electrical connection to the conductive collector. The neutron sensitive emitter includes an emitter material with no more than 2 stable isotopes, and which upon impact by a neutron having an energy of from 100 keV to 1000 keV will generate electrons in proportion to the flux of neutrons in less than 10 minutes, and any generated electrons not generated in less than 10 minutes will be generated in no less than 30 days. A method of detecting neutrons generated by a nuclear reactor is also disclosed.

Abstract: A closed-vessel molten salt reactor (cvMSR) is described herein. A cvMSR may comprise a suspended container, such as a metallic container, within a trench surrounded by a concrete enclosure and a concrete cover having a number of channels. The container is rotatable between different orientations. The container may be hollow and a solution of fissile materials and salt materials may be provided within the container. The solution may be capable of undergoing a chain reaction nuclear fission process once a threshold temperature is reached. Heat generated by the solution may heat a fluid surrounding the container. The heated fluid may be transported, through the number of channels of the concrete cover, to an external location where the heated fluid may be used in distributing heat and/or electricity generation.

Abstract: A power conversion system for converting thermal energy from a heat source to electricity is provided. The system includes a chamber including an inner shroud having an inlet and an outlet and defining an internal passageway between the inlet and the outlet through which a working fluid passes. The chamber also includes an outer shroud substantially surrounding the inner shroud. The chamber includes a source heat exchanger disposed in the internal passageway, the source heat exchanger being configured to receive a heat transmitting element associated with the heat source external to the chamber, and to transfer heat energy from the heat transmitting element to the working fluid. The system also includes a compressor disposed adjacent the inlet of the inner shroud and configured to transfer energy from the compressor to the working fluid, and an expander disposed adjacent the outlet of the inner shroud.

Abstract: An underground nuclear power reactor system has a hollow blast tunnel which extends from one end of a containment member. The system includes a nuclear reactor vessel and other components that may be positioned on a movable support member or on a bottom wall of the containment member. A blast tunnel, which defines a blast chamber, has a plurality of spaced-apart debris deflectors positioned therein. The blast chamber has an upper wall with a roof opening formed therein which is selectively closed by a roof portion. If the reactor needs to be repaired or replaced, the roof portion is opened so that the reactor vessel can pass through the roof opening. If the reactor vessel explodes, a blast therefrom drives debris therefrom through a blast door and into the blast chamber where the deflectors reduce blast force as the debris passes through the blast chamber.

Abstract: Thorium-based fuel bundles according to one or more embodiments of the present invention provide a fresh fuel bundle comprising a first ring of fuel pins and a second ring of fuel pins. Each ring fuel pin has a fuel composition comprising uranium and thorium. The first ring fuel pins differ from the second ring fuel pins in each of the thorium wt %, uranium wt %, and 235U enrichment.

Abstract: A target well of a target delivery assembly for use in an irradiation system operative to allow irradiation of a radioisotope target via a vessel penetration of a fission reactor. The target well includes an outer tube and an inner tube disposed therein so that an annulus is formed therebetween. The target is positioned in the inner tube during irradiation. At least one flow channel extends between a bottom end of the outer tube and a bottom end of the inner tube. An elevation piston is slidably disposed within the inner tube to elevate the target, the elevation piston including a one-way check valve allowing flow in a downward direction and preventing flow in an upward direction.