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: A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod disposed within the torque tube and including an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, a lock cam assembly rotatably secured to a top end of the connecting rod and including a locking cam, and a holdout collar disposed non-rotatably within the torque tube, the holdout collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

Abstract: A method of manufacturing a nuclear fuel segment includes varying a parameter of a lattice structure of a first mathematically-based periodic solid to form a second mathematically-based periodic solid. The second mathematically-based periodic solid comprises a triply periodic minimal surface (TPMS). The varying includes varying periodicity, thickness, or bias of the first mathematically-based periodic solid. The second mathematically-based periodic solid is embodied in a gridded mesh. The gridded mesh is sectioned into a plurality of layers. An additive manufacturing process is used to deposit a fissionable fuel composition in creating a body having a structure with a shape corresponding to the second mathematically-based periodic solid. The plurality of layers are used in controlling the additive manufacturing process.

Abstract: A control rod assembly having a connecting rod, a spider, a plurality of control rods, a coupling sleeve secured to the connecting rod and including a body portion defining at least one cam pin, and a barrel cam defining a cam track, the barrel cam being rotatably secured to the spider. The cam track includes a first camming surface and a second camming surface that are configured so that the barrel cam rotates in a first direction as the at least one cam pin slides along the first and second camming surfaces. The barrel cam rod is rotatable between a first position in which the spider is connected to the connecting rod and a second position in which the spider is disconnected from the connecting rod.

Abstract: A method inspects weld quality in-situ. The method obtains a plurality of sequenced images of an in-progress welding process and generates a multi-dimensional data input based on the plurality of sequenced images and/or one or more weld process control parameters. The parameters may include: (i) shield gas flow rate, temperature, and pressure; (ii) voltage, amperage, wire feed rate and temperature (if applicable); (iii) part preheat/inter-pass temperature; and (iv) part and weld torch relative velocity). The method generates defect probability and analytics information by applying one or more computer vision techniques on the multi-dimensional data input. The analytics information includes predictive insights on quality features of the in-progress welding process. The method then generates a 3-D visualization of one or more as-welded regions, based on the analytics information, and the plurality of sequenced images.

Abstract: A method is provided for particle morphology classification. The method includes obtaining input imagery of a particle sample that includes powder particles that are sintered together. The method also includes generating an input dataset for clustering based on the input imagery, including (i) detecting and segmenting powder particles, (ii) extracting and standardizing powder particle images, and (iii) calculating morphology metrics of the powder particles. The method also includes identifying categories, based on geometry or morphology-based similarities between different particles, using K-means clustering on Hu invariant moments of the powder particle images. Some implementations include receiving labels for the categories from a user, and subsequently using the categories to analyze or quantify future batches of particulate based on those labels.

Abstract: Insulated fuel assembly core with plurality of fuel monoliths, exhaust support plate, exhaust shield assembly, and insulation layer in which the plurality of fuel monoliths are located axially along a longitudinal axis and each of the plurality of fuel monoliths has a shape of an eccentric cylinder and a composition including a fissionable fuel component. Channels in the exhaust support plate are oriented so that propellant gas flow through the exhaust support plate does not impinge the exhaust shield assembly. The insulated fuel assembly core is manufactured by forming a tensioned fuel monolith stack mandrel assembly using mandrels spacers and internal tensioning components and forming an insulation layer on an outer surface of the tensioned fuel monolith stack mandrel assembly by mandrel winding. The insulated fuel assembly core can be incorporated into a fuel assembly of nuclear propulsion fission reactor structure of, for example, a nuclear thermal propulsion engine.

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 method is provided for unsupervised 3D modeling and geometric measurement of additively manufactured parts. The method includes obtaining near-infrared (NIR) images for a welding process for a welded part. The welded part includes welded metal and agglomerated powder particles. The method also includes generating a multi-dimensional dataset based on the NIR images, including cropping the multi-dimensional dataset to a region of interest. The method also includes detecting melted regions in image layers of the multi-dimensional dataset to obtain an output volume. The method also includes detecting agglomerated powder in the output volume to obtain melt masks. Each melt mask indicates weld pixels for a respective image layer. The method also includes applying a multi-layer predictive model to account for multi-layer weld penetration, based on the melt masks, to obtain an output data mask that represents a 3D model and geometric measurements for the welded part.

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 control rod drive mechanism having a torque tube with an inner surface defining a central bore, a control rod assembly including a connecting rod including a cam extending radially-outwardly therefrom and an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, and a holdout collar disposed non-rotatably within the torque tube and defining a locking recess, wherein the connecting rod is axially-movable with respect to the torque tube between a first position in which the elongated key is disposed within the key slot so that the connecting rod is non-rotatable with respect to the torque tube, and a second position in which the elongated key is removed from the key slot and the connecting rod is rotatable with respect to the torque tube.

Abstract: A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod and a spider, a lock cam assembly rotatably secured to a bottom end of the connecting rod and including a locking cam, and a locking collar disposed non-rotatably within the spider, the locking collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

Abstract: Reactor core and thermal neutron fission reactor has fuel rods with a composite fuel composition (each having the same uniform cross-section along their axial length), end plates at first and second ends, and intermediate support plates located along a longitudinal length of the reactor core. In a radial cross-section, the fuel rods are arranged at nodes of a hexagonal pitch arrangement, in which the nodes are in a spaced-apart arrangement and interconnected by ligaments. Openings between the nodes form part of a coolant flow path through the thermal neutron reactor core. At least two of the nodes of the hexagonal pitch arrangement are sized to allow insertion, translation, removal, or a combination thereof of auxiliary equipment, such as a target delivery system (TDS) for isotopes. Thermal neutron flux (neutrons ?0.06 eV) is maximized for maximum neutron activation potential, which is applied to produce both commercial and research isotopes.

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: 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 method is provided for enhancing image resolution for sequences of 2-D images of additively manufactured products. For each of a plurality of additive manufacturing processes, the process obtains a respective plurality of sequenced low-resolution 2-D images of a respective product during the respective additive manufacturing process and obtains a respective high-resolution 3-D image of the respective product after completion of the respective additive manufacturing process. The process selects tiling maps that subdivide the low-resolution 2-D images and the high-resolution 3-D images into low-resolution tiles and high-resolution tiles, respectively. The process also builds an image enhancement generator iteratively in a generative adversarial network using training inputs that includes ordered pairs of low-resolution and high-resolution tiles.

Abstract: Insulated fuel assembly core with axially arranged fuel monoliths including channels and having a composition including a fissionable fuel component, exhaust support plate, exhaust shield assembly, and insulation layer. Fuel monoliths have an eccentric cylinder shape or a right circular cylinder shape with side surface keyway. The eccentric shape and/or a keyway (with associated alignment rod) provide alignment. Channels in the exhaust support plate are oriented so propellant gas flowing from the fuel monoliths through the exhaust support plate does not impinge the exhaust shield assembly. Insulated fuel assembly cores are manufactured by forming a tensioned fuel monolith stack mandrel assembly using mandrel spacers and internal tensioning components and mandrel winding an insulation layer on an outer surface of the tensioned fuel monolith stack mandrel assembly.

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 arms 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: A method is provided for tracking multiple beams in weld pools. The method includes obtaining an input video feed that includes a plurality of frames having a plurality of beams for weld pools. The method also includes, for each frame of the plurality of frames of the input video feed, creating a gradient mask that identifies one or more pixels in the respective frame for a weld pool. The method also includes detecting and filtering contiguous regions based on the gradient mask to obtain a pixel mask for each contour of a weld pool. The method also includes identifying one or more beam locations within the weld pool based on the pixel mask for each contour.

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.