Abstract: Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material (e.g., SiC—SiC composite), insulation layer of porous refractory ceramic material (e.g., zirconium carbide with open-cell foam structure or fibrous zirconium carbide), and interior structural member of refractory ceramic-graphite composite material (e.g., zirconium carbide-graphite or niobium carbide-graphite). Spacer structures between various layers provide a defined and controlled spacing relationship. A fuel element bundle positioned between support meshes includes a plurality of distributively arranged fuel elements or a solid, unitary fuel element with coolant channels, each having a fuel composition including high assay, low enriched uranium (HALEU).

Abstract: CERMET fuel element includes a fuel meat of consolidated ceramic fuel particles (preferably refractory-metal coated HALEU fuel kernels) and an array of axially-oriented coolant flow channels. Formation and lateral positions of coolant flow channels in the fuel meat are controlled during manufacturing by spacer structures that include ceramic fuel particles. In one embodiment, a coating on a sacrificial rod (the rod being subsequently removed) forms the coolant channel and the spacer structures are affixed to the coating; in a second embodiment, a metal tube forms the coolant channel and the spacer structures are affixed to the metal tube. The spacer structures laterally position the coolant channels in spaced-apart relation and are consolidated with the ceramic fuel particles to form CERMET fuel meat of a fuel element, which are subsequently incorporated into fuel assemblies that are distributively arranged in a moderator block within a nuclear fission reactor, in particular for propulsion.

Abstract: Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material, the interior surface of which is lined in higher temperature regions with an insulation layer of porous refractory ceramic material. Continuous insulation layer extends the length of the fuel assembly or separate insulation layer sections have a thickness increasing step-wise along the length of the fuel assembly from upper (inlet) section towards bottom (outlet) section. A fuel element positioned inward of the insulation layer and between support meshes has a fuel composition including HALEU and the form of a plurality of individual elongated fuel bodies or one or more fuel monolith bodies containing coolant flow channels. Fuel assemblies are distributively arranged in a moderator block, with upper end of the outer structural member attached to an inlet for propellant and lower end of the outer structural member operatively interfaced with a nozzle forming a nuclear thermal propulsion reactor.

Abstract: Carbide-based fuel assembly includes outer structural member of ceramic matrix composite material (e.g., SiC—SiC composite), insulation layer of porous refractory ceramic material (e.g., zirconium carbide with open-cell foam structure or fibrous zirconium carbide), and interior structural member of refractory ceramic-graphite composite material (e.g., zirconium carbide-graphite or niobium carbide-graphite). Spacer structures between various layers provide a defined and controlled spacing relationship. A fuel element bundle positioned between support meshes includes a plurality of distributively arranged fuel elements or a solid, unitary fuel element with coolant channels, each having a fuel composition including high assay, low enriched uranium (HALEU).

Abstract: A pressurized water reactor (PWR) comprises a pressure vessel containing primary coolant water. A nuclear reactor core is disposed in the pressure vessel and includes a plurality of fuel assemblies. Each fuel assembly includes a plurality of fuel rods containing a fissile material. A control system includes a plurality of control rod assemblies (CRA's). Each CRA is guided by a corresponding CRA guide structure. A support element is disposed above the CRA guide structures and supports the CRA guide structures. The pressure vessel may be cylindrical, and the support element may comprise a support plate having a circular periphery supported by the cylindrical pressure vessel. The CRA guide structures suitably hang downward from the support plate. The lower end of each CRA guide structure may include alignment features that engage corresponding alignment features of the upper end of the corresponding fuel assembly.

Abstract: A pressurized water reactor (PWR) comprises a pressure vessel containing primary coolant water. A nuclear reactor core is disposed in the pressure vessel and includes a plurality of fuel assemblies. Each fuel assembly includes a plurality of fuel rods containing a fissile material. A control system includes a plurality of control rod assemblies (CRA's). Each CRA is guided by a corresponding CRA guide structure. A support element is disposed above the CRA guide structures and supports the CRA guide structures. The pressure vessel may be cylindrical, and the support element may comprise a support plate having a circular periphery supported by the cylindrical pressure vessel. The CRA guide structures suitably hang downward from the support plate. The lower end of each CRA guide structure may include alignment features that engage corresponding alignment features of the upper end of the corresponding fuel assembly.

Abstract: A pressurized water reactor (PWR) comprises a pressure vessel containing primary coolant water. A nuclear reactor core is disposed in the pressure vessel and includes a plurality of fuel assemblies. Each fuel assembly includes a plurality of fuel rods containing a fissile material. A control system includes a plurality of control rod assemblies (CRA's). Each CRA is guided by a corresponding CRA guide structure. A support element is disposed above the CRA guide structures and supports the CRA guide structures. The pressure vessel may be cylindrical, and the support element may comprise a support plate having a circular periphery supported by the cylindrical pressure vessel. The CRA guide structures suitably hang downward from the support plate. The lower end of each CRA guide structure may include alignment features that engage corresponding alignment features of the upper end of the corresponding fuel assembly.

Abstract: A method, apparatus and assembly related to solid oxide fuel cell interconnects is disclosed. In its broadest embodiment, the invention contemplates a multi-layered ceramic interconnect having integrated flow fields and electrical connections. The method of making this interconnect includes judicious selection of materials, formation of appropriate apertures for the flow fields and electrical connectors, and the joining of the layers through a firing and/or sealing process.

Abstract: A method, apparatus and assembly related to solid oxide fuel cell interconnects is disclosed. In its broadest embodiment, the invention contemplates a multi-layered ceramic interconnect having integrated flow fields and electrical connections. The method of making this interconnect includes judicious selection of materials, formation of appropriate apertures for the flow fields and electrical connectors, and the joining of the layers through a firing and/or sealing process.

Abstract: A ceramic fiber composite structure particularly suitable for use as a hot gas cleanup ceramic fiber composite filter and method of making same from ceramic composite material has a structure which provides for increased strength and toughness in high temperature environments. The ceramic fiber composite structure or filter is made by a process in which a continuous ceramic fiber is intimately surrounded by discontinuous chopped ceramic fibers during manufacture to produce a ceramic fiber composite preform which is then bonded using various ceramic binders. The ceramic fiber composite preform is then fired to create a bond phase at the fiber contact points.

Abstract: A ceramic element for a sootblower element is disclosed in which the element is manufactured by winding a ceramic fiber around a mandrel and subsequently densifying the composite using a sol-gel process. Separate elements are coupled together using a ceramic coupling member. Ceramic nozzle bodies are inserted into the elements. The sootblower tubes disclosed herein can withstand greater temperatures and more corrosive environments than currently used metallic lance tubes, thus enabling the sootblower element to be permanently installed within a boiler and eliminating the need for a retracting element type sootblower.

Abstract: Metallization, applied by the thick film screening technique, utilized herein has glass-ceramic bonding agents designed to promote adhesion yet maintain the desired electrical properties and post-processing characteristics.

Abstract: Bonding additives for refractory metallization compositions allow for circuit traces having good resistivities and adhesion values in excess of 6 kpsi, generally between about 10 and 20 kpsi. The inks are provided in formulations devoid of a glass component, and are suitable for co-sintering circuit traces and vias with 96% alumina substrates, and especially for 99% alumina substrates. Suitable bonding additives are the oxides of molybdenum, tungsten, niobium, manganese, yttrium, and titanium, or mixtures of such oxides.

Abstract: Glass-ceramic packages for integrated circuits containing multi-layer, interconnected thick film wiring patterns are obtained by co-sintering a glass-ceramic composite and copper, silver, palladium, gold, based conductors at temperatures not exceeding about 1000.degree. C. The dielectric systems include composites of borosilicate glasses and crystalline fillers which are fabricated by either mixing glass frit and the filler or by a sol-gel coating process. The package is fabricated using a tape specifically designed for clean binder burnout in a reducing atmosphere at low temperatures and also for superior mechanical and thermal properties. Metallization, applied by the thick film screening technique, utilized herein has glass-ceramic bonding agents designed to promote adhesion yet maintain the desired electrical properties and post-processing characteristics.

Abstract: A tungsten paste suitable for co-sintering with 98+% alumina substrate can be produced by adding selected compositions of glass to the paste. Circuit packages produced in accordance with the present invention exhibit superior thermal conductivity, low shrinkage variability, and smoother and more homogeneous surface finish. A preferred embodiment of the invention utilizes a substrate comprising narrow size range alumina powder, thus yielding lower sintering temperature and further improvements in shrinkage variability and surface finish.

Abstract: This invention relates to glass-ceramic packages for integrated circuits containing multi-layer, interconnected thick film wiring patterns obtained by co-sintering a glass-ceramic composite and copper, silver, palladium or gold based conductors at temperatures not exceeding about 1000.degree. C. The dielectric systems disclosed herein contains composites of borosilicate glasses and crystalline fillers which are fabricated by either mixing glass frit and the filler or by a sol-gel coating process.

Abstract: Substrates consisting of at least 98% narrow size distribution ceramic particles are co-sinterable with metallized paste to which selected compositions of glass have been added. Substrates produced in accordance with the present invention exhibit superior thermal conductivity, low shrinkage variability, and smoother and more homogeneous surface finish.

Abstract: A welding flux binder and welding flux comprising the reaction product of a hydrolyzed and polymerized organometallic compound selected from the group consisting of metal alkoxides including tetraalkylorthosilicate, tetraalkylorthotitanate, tetraalkylorthozirconate and trialkylaluminate, metal esters, and metal oxalates. The organometallic compound is hydrolyzed and then polymerized to form a gel glass phase. Alkali and alkaline earth salts are added to stabilize and reduce the viscosity of the gel. The resulting welding flux binder and flux are non-hygroscopic and have a high fired strength.

Abstract: A welding flux binder is provided which comprises an alkali-alkaline earth silicate hydrolyzed and polymerized from tetraalkylorthosilicate, Si(OR).sub.4, wherein R is --CH.sub.3, --C.sub.2 H.sub.5, or --C.sub.3 H.sub.7, and alkali and alkaline earth salts. The reaction product of the tetraalkylorthosilicate and metal salts, M.sub.2 O.M'O.SiO.sub.2, where M is potassium, sodium or lithium, and M' is magnesium, calcium or barium, has several advantages as a welding flux binder. For example, it is not hygroscopic and can be prepared at low temperatures since the alkali ions lower the melting point for viscous sintering of the gel phase. Because of the low temperature processing, a wide variety of solid additives with low thermal stability, such as some metals, carbonates, and fluorides, can be incorporated into the flux. Other dopants may also be readily incorporated into the binder during the gel phase.

Abstract: Uniform-size, high-purity, spherical oxide powders are formed by hydrolysis of alkoxide precursors in dilute alcoholic solutions. Under controlled conditions (concentrations of 0.03 to 0.2 M alkoxide and 0.2 to 1.5 M water, for example) oxide particles on the order of about 0.05 to 0.7 micron can be produced. Methods of doping such powders and forming sinterable compacts are also disclosed.