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: Additive manufacturing compositions include low-absorbing particles or non-absorbing particles that have an absorbance for wavelengths of 300 nm to 700 nm that is equal to or greater than 0 Au and is less 1.0 Au, such as 0.001 Au?absorbance?0.7 Au. Slurries including such particles and an uranium-containing particle and that are used in additive manufacturing processes have an increased penetration depth for curative radiation. Removal of low-absorbing particles or non-absorbing particles during post-processing of as-manufactured products results in pores that create porosity in the as-manufactured product that provide a volume accommodating fission gases and/or can enhance wicking of certain heat pipe coolant liquids.

Abstract: Methods to in-situ monitor production of additive manufacturing products collects images from the deposition process on a layer-by-layer basis, including a void image of the pattern left in a slurry layer after deposition of a layer and a displacement image formed by immersing the just-deposited layer in a renewed slurry layer. Image properties of the void image and displacement image are corrected and then compared to a binary expected image from a computer generated model to identify defects in the just-deposited layer on a layer-by-layer basis. Additional methods use the output from the comparison to form a 3D model corresponding to at least a portion of the additive manufacturing product. Components to control the additive manufacturing operation based on digital model data and to in-situ monitor successive layers for manufacturing defects can be embodied in a computer system or computer-aided machine, such as a computer controlled additive manufacturing machine.

Abstract: Fuel bundle has plurality of twisted ribbon fuel rodlets arranged hexagonal packing or circle packing arrangement in a reactor core encased in a multilayer casing. Arrangement of twisted ribbon fuel rodlets is facilitated by rodlet seating fixture with seating surface having a plurality of protrusions that form a receiving space for ends of the twisted ribbon fuel rodlets. Manufacture of the fuel bundle incorporates fiber manufacturing technologies and, optionally, infiltration of spaces in the reactor core by infiltrant. Twisted ribbon fuel rodlet manufacturing system has sub-systems that impart twist periodicity to extruded ribbons, inspect twisted extruded ribbons, and cut twisted extruded ribbons to length. Inspection sorts twisted ribbon fuel rodlets as well as provides feedback to adjust operation of sub-systems. The fuel bundle (and optional fuel bundle support) can be incorporated into a fuel assembly of nuclear propulsion fission reactor structure of, for example, a nuclear thermal propulsion engine.

Abstract: Fuel bundle has plurality of twisted ribbon fuel rodlets arranged in hexagonal packing or circle packing arrangement in a reactor core encased in a multilayer casing. Arrangement of twisted ribbon fuel rodlets is facilitated by rodlet seating fixture with seating surface having a plurality of protrusions that form a receiving space for ends of the twisted ribbon fuel rodlets. Manufacture of the fuel bundle incorporates fiber manufacturing technologies and, optionally, infiltration of spaces in the reactor core by infiltrant. Twisted ribbon fuel rodlet manufacturing system has sub-systems that impart twist periodicity to extruded ribbons, inspect twisted extruded ribbons, and cut twisted extruded ribbons to length. Inspection sorts twisted ribbon fuel rodlets as well as provides feedback to adjust operation of sub-systems.

Abstract: Fuel bundle has plurality of twisted ribbon fuel rodlets arranged hexagonal packing or circle packing arrangement in a reactor core encased in a multilayer casing. Arrangement of twisted ribbon fuel rodlets is facilitated by rodlet seating fixture with seating surface having a plurality of protrusions that form a receiving space for ends of the twisted ribbon fuel rodlets. Manufacture of the fuel bundle incorporates fiber manufacturing technologies and, optionally, infiltration of spaces in the reactor core by infiltrant. Twisted ribbon fuel rodlet manufacturing system has sub-systems that impart twist periodicity to extruded ribbons, inspect twisted extruded ribbons, and cut twisted extruded ribbons to length. Inspection sorts twisted ribbon fuel rodlets as well as provides feedback to adjust operation of sub-systems. The fuel bundle (and optional fuel bundle support) can be incorporated into a fuel assembly of nuclear propulsion fission reactor structure of, for example, a nuclear thermal propulsion engine.

Abstract: Additive manufacturing compositions include low-absorbing particles or non-absorbing particles that have an absorbance for wavelengths of 300 nm to 700 nm that is equal to or greater than 0 Au and is less 1.0 Au, such as 0.001 Au?absorbance?0.7 Au. Slurries including such particles and an uranium-containing particle and that are used in additive manufacturing processes have an increased penetration depth for curative radiation. Removal of low-absorbing particles or non-absorbing particles during post-processing of as-manufactured products results in pores that create porosity in the as-manufactured product that provide a volume accommodating fission gases and/or can enhance wicking of certain heat pipe coolant liquids.

Abstract: A vibration minimization towing hitch includes a shank attachable into the receiver tube the towing vehicle, and a separately formed head, such as for supporting a tow ball. The head is pivotable through a partial range of motion relative to the head, such as allowing the tow ball to pivot up to 7° downward or up to 3° upward. One or more compressible inserts are disposed in a pocket between the shank and the head, for resisting the limited pivotal motion of the head relative to the shank. A user performs a part of the assembly using two insertable pins or bolts, with insertion of the second pin compressing a compressible bumper which is separate from the insert(s).

Abstract: A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, including a target delivery assembly including a body defining a central bore, a basket that is slidably receivable within the central bore of the body, and a winch that is connected to the basket by a cable, the target delivery assembly being affixed to the vessel penetration of the reactor, and a target passage that is in fluid communication with the target delivery assembly, wherein the basket is configured to receive the radioisotope target therein via the target passage and be lowered into the vessel penetration of the reactor when irradiating the radioisotope target, and the target delivery system forms a portion of the pressure boundary of the reactor when in fluid communication with the reactor.

Abstract: A tri-ball trailer hitch coupler lock has three differently sized ball substitute members. A lanyard extends in two directions off a portion which adjoins the ball substitute members, with mating portions of a lock permanently attached to each free end of the lanyard. One portion of the lock terminates in a pin sized to fit in the latch pin opening of the coupler, and the other portion of the lock is matably lockable onto the pin after the pin has been extended through the coupler pin opening. The lanyard preferably passes through an opening in the adjoinment portion offset from the center.

Abstract: A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, includes a target delivery assembly with a body defining a central bore, a basket that is slidably receivable within the central bore of the body, and a winch that is connected to the basket by a cable. The target delivery assembly is affixed to the vessel penetration of the reactor; and a target passage is in fluid communication with the target delivery assembly. The basket is configured to receive a radioisotope target therein via the target passage and be lowered into the vessel penetration of the reactor when irradiating the radioisotope target. The target delivery system forms a portion of the pressure boundary of the reactor when in fluid communication with the reactor.

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: An irradiation target for the production of radioisotopes, comprising at least one plate defining a central opening and an elongated central member passing through the central opening of the at least one plate so that the at least one plate is retained thereon, wherein the at least one plate and the elongated central member are both formed of materials that produce molybdenum-99 (Mo-99) by way of neutron capture.

Abstract: A fuel bundle surrogate for the irradiation of a target material, having a plurality of tube sheaths, each tube sheath being parallel to a longitudinal center axis of the fuel bundle surrogate, a plurality of end caps, a pair of end plates, wherein the end plates are disposed at opposing ends of the plurality of tube sheaths, and a first target comprised of a first target material suitable for producing the isotope by way of a neutron capture event, wherein the first target is disposed in a first tube sheath, and wherein the first tube sheath of the plurality of tube sheaths comprises an elongated thickened wall portion and a pair of annular end portions, each annular end portion being disposed on a corresponding end of the thickened wall portion and having a wall thickness that is less than a wall thickness of the thickened wall portion.

Abstract: A target irradiation system including an irradiated target removal system having a body defining a central bore, an elevator received within the central bore, and a docking surface for placing the irradiated target removal system in fluid communication with a vessel penetration of a reactor. A target canister slidably receives the radioisotope target therein, and the elevator is configured to receive the target canister. The elevator is lowered into the reactor when irradiating the radioisotope target, and the irradiated target removal system forms a portion of a pressure boundary of the reactor during target irradiation.

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: An irradiation target for the production of radioisotopes, comprising at least one plate defining a central opening and an elongated central member passing through the central opening of the at least one plate so that the at least one plate is retained thereon, wherein the at least one plate and the elongated central member are both formed of materials that produce molybdenum-99 (Mo-99) by way of neutron capture.

Abstract: A fuel bundle surrogate for the irradiation of a target material, having a plurality of tube sheaths, each tube sheath being parallel to a longitudinal center axis of the fuel bundle surrogate, a plurality of end caps, a pair of end plates, wherein the end plates are disposed at opposing ends of the plurality of tube sheaths, and a first target comprised of a first target material suitable for producing the isotope by way of a neutron capture event, wherein the first target is disposed in a first tube sheath, and wherein the first tube sheath of the plurality of tube sheaths comprises an elongated thickened wall portion and a pair of annular end portions, each annular end portion being disposed on a corresponding end of the thickened wall portion and having a wall thickness that is less than a wall thickness of the thickened wall portion.

Abstract: Additive manufacturing compositions include low-absorbing particles or non-absorbing particles that have an absorbance for wavelengths of 300 nm to 700 nm that is equal to or greater than 0 Au and is less 1.0 Au, such as 0.001 Au?absorbance?0.7 Au. Slurries including such particles and an uranium-containing particle and that are used in additive manufacturing processes have an increased penetration depth for curative radiation. Removal of low-absorbing particles or non-absorbing particles during post-processing of as-manufactured products results in pores that create porosity in the as-manufactured product that provide a volume accommodating fission gases and/or can enhance wicking of certain heat pipe coolant liquids.

Abstract: A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, including a target elevator assembly including a body portion defining a central bore and an open bottom end, a center tube that is disposed within the central bore of the body portion, a target basket that is slidably receivable within the center tube, and a winch that is connected to the target basket by a cable, wherein the target basket is configured to receive the radioisotope target therein and be lowered into the vessel penetration of the reactor when irradiating the radioisotope target.