Abstract: A thermal transfer unit may include one or more modules having a surface to volume ratio of greater than four hundred square meters per cubic meter. One or more of said modules may include a fluid inlet portion. Said fluid inlet portion may include a fluid inlet surface. One or more of said modules may include a thermal interface portion configured to interface with and thermally couple to an object for temperature regulation of the object. Said thermal interface portion may include a fluid return surface. Said module may include a matrix of pores configured to effect fluid flow. Said module may include a plurality of fluid return channels extending from said fluid return surface to an outlet. Said module may include a matrix of pores on or proximate said fluid inlet surface. Said module may include a matrix of pores on or proximate said fluid return surface.

Abstract: In some embodiments, a power generation system may include a first nuclear reactor, which may include a vessel having a wall defining a cavity. The nuclear reactor may include a core disposed within said cavity. Said core may include a solid matrix material defining one or more channels. A fuel material may be disposed in said one or more channels. Said solid matrix material may be a primary heat transfer medium. The power generation system may include an electric generating system having a secondary heat transfer medium. The power generation system may include one or more heat exchangers thermally coupled to said vessel wall. Said primary heat transfer medium may transfer heat generated by the fuel material to the one or more heat exchangers. Said secondary heat transfer medium may draw heat from said one or more heat exchangers.

Abstract: A thermal transfer unit may include one or more modules. One or more of said modules may include a fluid inlet portion, said fluid inlet portion may include a fluid inlet surface. One or more of said modules may include a thermal interface portion configured to interface with and thermally couple to an object for temperature regulation of the object. Said thermal interface portion may include a fluid return surface. Said module may define a plurality of micro-channels. Said module may define a plurality of fluid return channels extending from said fluid return surface to an outlet. Said module may define a plurality of lateral fluid supply channels on said fluid inlet surface interconnecting at least a subset of said micro-channels. Said module may define a plurality of lateral fluid return channels on said fluid return surface interconnecting at least a subset of said micro-channels and said fluid return channels.

Abstract: A nuclear reactor may include a vessel having a wall defining an interior cavity. The nuclear reactor may include a spherical core disposed within the cavity. The spherical core may include a plurality of fuel elements. Each fuel element may extend from an outer periphery of the core along a radius to a central portion of the core. Each fuel element may include a solid matrix material that defines a plurality of fuel channels. The core may include a fuel material disposed in the plurality of fuel channels. The core may include one or more control rod channels, each extending from the outer periphery of the core along a radius to the central portion of the core. The nuclear reactor may include a reactivity control system that may have one or more control rods comprising a neutron absorbing material for insertion into the one or more control rod channels.

Abstract: A method of welding aluminum alloy steel, and oxide dispersion strengthened aluminum alloy steel. The method includes heating at least one aluminum alloy steel work piece to a predetermined temperature, cleaning the weld surface, providing an Aluchrom Y filler to the weld site, welding the work piece and filler under an argon atmosphere to form a welded article, and post-weld heat treating the welded article. The method may also be used to join aluminum alloy steels to austenitic steels. A welded article joined by the method is also described.