Abstract: An energy production device may include a core and a heat exchanger positioned over the core. The core may include one or more fuel rods. The core may further include a heat transmission fluid configured to flow through natural convection upwards through the one or more fuel rods and collect heat therefrom. The core may also include a reaction control device including a neutron-absorbing material. The heat exchanger may be configured to receive the heat transmission fluid and transfer the heat to an energy harnessing device positioned on an opposite side of the heat exchanger from the core.

Abstract: A sensor assembly for determining an operating characteristic of a nuclear reactor. The sensor assembly includes a solid-state lasing media doped with a fissile species and disposable within a core of the nuclear reactor and an optical fiber operably coupled to the solid-state lasing media and configured to extend out of the core of the nuclear reactor and to control system of reactor. The fissile species include one or more of uranium, plutonium, americium, or californium. A method of determining an operating characteristic of a nuclear reactor includes during operation of the nuclear reactor; receiving from the optical fiber a laser light, analyzing the laser light, and based on the analysis of the laser light, determining the operating characteristic of the nuclear reactor.

Abstract: Methods and systems for producing feedstock powders, suitable for use in laser-based additive manufacturing, use laser ablation to vaporize a source material, which may be in bulk solid or solid coarse grain form. The source material is vaporized by a laser (or other focused energy source) in a vaporization chamber that is temperature controlled to provide a vertical thermal gradient. The vertical thermal gradient may be controlled to, in turn, control the nucleation, coagulation, and agglomeration of the vaporized molecules, enabling formation of microparticles that may then be used as feedstock powders in laser-based additive manufacturing. The produced feedstock powder particles may be of uniform composition, of uniform shape (e.g., substantially spherical), and of uniform phase or homogeneously-mixed phases.

Abstract: A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.

Abstract: A nuclear fuel element for a nuclear reactor comprises a body having a first region and a second region surrounded by the first region. The first segment comprises a poison material, and the second region comprises a nuclear fuel material and is substantially free of the poison material. A nuclear fuel element for use in a nuclear reactor comprises the body and a cladding material at least partially surrounding the body. Related methods of forming the nuclear fuel pellet include additive manufacturing processes to form first and second segments.

Abstract: A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.

Abstract: A method of forming silicon carbide by spark plasma sintering comprises loading a powder comprising silicon carbide into a die and exposing the powder to a pulsed current to heat the powder at a rate of between about 50° C./min and about 200° C./min to a peak temperature while applying a pressure to the powder. The powder is exposed to the peak temperature for between about 30 seconds and about 5 minutes to form a sintered silicon carbide material and the sintered silicon carbide material is cooled. Related structures and methods are disclosed.

Abstract: A method of forming silicon carbide by spark plasma sintering comprises loading a powder comprising silicon carbide into a die and exposing the powder to a pulsed current to heat the powder at a rate of between about 50° C./min and about 200° C./min to a peak temperature while applying a pressure to the powder. The powder is exposed to the peak temperature for between about 30 seconds and about 5 minutes to form a sintered silicon carbide material and the sintered silicon carbide material is cooled. Related structures and methods are disclosed.

Abstract: A method of forming silicon carbide by spark plasma sintering comprises loading a powder comprising silicon carbide into a die and exposing the powder to a pulsed current to heat the powder at a rate of between about 50° C./min and about 200° C./min to a peak temperature while applying a pressure to the powder. The powder is exposed to the peak temperature for between about 30 seconds and about 5 minutes to form a sintered silicon carbide material and the sintered silicon carbide material is cooled. Related structures and methods are disclosed.

Abstract: A method of forming silicon carbide by spark plasma sintering comprises loading a powder comprising silicon carbide into a die and exposing the powder to a pulsed current to heat the powder at a rate of between about 50° C./min and about 200° C./min to a peak temperature while applying a pressure to the powder. The powder is exposed to the peak temperature for between about 30 seconds and about 5 minutes to form a sintered silicon carbide material and the sintered silicon carbide material is cooled. Related structures and methods are disclosed.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: Implantable electrical lead wires, such as cobalt-chromium-molybdenum alloy wires, are coated with a metal, ceramic, or carbon to a thickness of about 100 nm or less to provide a non-reactive interface to polyurethane sheathing materials. Preferred is sputter coating an amorphous carbon intermediate the alloy wire and the polyurethane sheath.

Abstract: High reliability electrical connections between a helical strand and flat electrodes, such us strip electrodes found in implantable neurostimulator system, are described. The connection consists of a crimp joint in which an inside diameter mandrel is used to provided the coil with sufficient radial rigidity to ensure structural integrity of the crimp. The mandrel is made of a relatively soft biocompatible material that deforms rather than damages the fine wires of the helical strand during crimping. The crimping is accomplished by radial deformation of an annular or semi-annular crimping member that receives the helical strand/mandrel assembly.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Abstract: High reliability electrical connections between a helical strand and flat electrodes, such as strip electrodes found in implantable neurostimulator system, are described. The connection consists of a crimp joint in which an inside diameter mandrel is used to provide the coil with sufficient radial rigidity to ensure structural integrity of the crimp. The mandrel is made of a relatively soft biocompatible material that deforms rather than damages the fine wires of the helical strand during crimping. The crimp is accomplished by radial deformation of an annular or semi-annular crimping member that receives the helical strand/mandrel assembly.

Abstract: A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent's wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.