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.

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 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: 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 upper and lower core plates to from a continuous structure that is a first portion of the containment structure. The nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

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: A bolt repair platform includes a frame and a tool module. The tool module includes a tool having a first end configured to rotationally engage a bolt. The tool module also includes an actuator disposed between the tool and the frame so that actuation of the actuator moves the tool with respect to the frame. The frame is removably disposed on the structure, and the tool is movable with respect to the frame, so that, at each of a plurality of positions, the second end of the tool is capable of engagement with a respective bolt disposed in an internal support structure of a nuclear reactor vessel.

Abstract: A robot for heat exchanger inspection is provided including a mobility system configured to move the robot in reference to the heat exchanger, a camera configured to capture image data including at least a portion of the heat exchanger, and processing circuitry. The processing circuitry is configured to receive the image data from the camera, determine a plurality of heat exchanger characteristics in the image data, compare the heat exchanger characteristics to heat exchanger data, determine a current location and an orientation angle of the robot based on the comparison of the one or more heat exchanger characteristics to the heat exchanger data, identify the heat exchanger characteristic based on the current location, determine an orientation angle of the robot, and determine an end effector position based on the current location and the orientation angle.

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: 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 nuclear propulsion fission reactor structure can be incorporated into a nuclear thermal propulsion engine for propulsion applications, such as space propulsion.

Abstract: Additive manufacturing methods use a surrogate slurry to iteratively develop an additive manufacturing protocol and then substitutes a final slurry composition to then additively manufacture a final component using the developed additive manufacturing protocol. In the nuclear reactor component context, the final slurry composition is a nuclear fuel slurry having a composition: 30-45 vol. % monomer resin, 30-70 vol. % plurality of particles of uranium-containing material, >0-7 vol. % dispersant, photoactivated dye, photoabsorber, photoinitiator, and 0-18 vol. % (as a balance) diluent. The surrogate slurry has a similar composition, but a plurality of surrogate particles selected to represent a uranium-containing material are substituted for the particles of uranium-containing material. The method provides a means for in-situ monitoring of characteristics of the final component during manufacture as well as in-situ volumetric inspection.

Abstract: Pre-ceramic particle solutions can prepared by a Coordinated-PDC process, a Direct-PDC process or a Coordinated-Direct-PDC process. The pre-ceramic particle solution includes a polymer selected from the group consisting of (i) an organic polymer including a metal or metalloid cation, (ii) a first organometallic polymer and (iii) a second organometallic polymer including a metal or metalloid cation different from a metal in the second organometallic polymer, a plurality of particles selected from the group consisting of (a) a ceramic fuel particle and (b) a moderator particle, a dispersant, and a polymerization initiator. The pre-ceramic particle solution can be supplied to an additive manufacturing process, such as digital light projection, and made into a structure (which is pre-ceramic particle green body) that can then be debinded to form a polymer-derived ceramic sintered body. In some embodiments, the polymer-derived ceramic sintered body is a component or structure for fission reactors.

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.