A nuclear reactor system includes a nuclear reactor core disposed in a pressure vessel. Nuclear reactor system further includes control drums disposed longitudinally within the pressure vessel and laterally surrounding fuel elements and at least one moderator element of the nuclear reactor core to control reactivity. Each of the control drums includes a reflector material and an absorber material. Nuclear reactor system further includes an automatic shutdown controller and an electrical drive mechanism coupled to rotatably control the control drum. Automatic shutdown controller includes a counterweight to impart a bias and an actuator. To automatically shut down the nuclear reactor core during a loss or interruption of electrical power from a power source to the electrical drive mechanism, the actuator is coupled to the counterweight and responsive to the bias to align the absorber material of one or more control drums to face inwards towards the nuclear reactor core.

In the present invention, in producing a SiC single crystal in accordance with a solution method, a crucible containing SiC as a main component and having an oxygen content of 100 ppm or less is used as the crucible to be used as a container for a Si—C solution. In another embodiment, a sintered body containing SiC as a main component and having an oxygen content of 100 ppm or less is placed in the crucible to be used as a container for a Si—C solution. The SiC crucible and SiC sintered body are obtained by molding and baking a SiC raw-material powder having an oxygen content of 2000 ppm or less. SiC, which is the main component of these, serves as a source for Si and C and allows Si and C to elute into the Si—C solution by heating.

A cutting element comprises a supporting substrate, and a cutting table attached to an end of the supporting substrate. The cutting table comprises inter-bonded diamond particles, and a thermally stable material within interstitial spaces between the inter-bonded diamond particles. The thermally stable material comprises a carbide precipitate having the general chemical formula, A.sub.3XZ.sub.n-1, where A comprises one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U; X comprises one or more of Al, Ga, Sn, Be, Bi, Te, Sb, Se, As, Ge, Si, B, and P; Z comprises C; and n is greater than or equal to 0 and less than or equal to 0.75. A method of forming a cutting element, an earth-boring tool, a supporting substrate, and a method of forming a supporting substrate are also described.

A cutting element comprises a supporting substrate, and a cutting table attached to an end of the supporting substrate. The cutting table comprises inter-bonded diamond particles, and a thermally stable material within interstitial spaces between the inter-bonded diamond particles. The thermally stable material comprises a carbide precipitate having the general chemical formula, A.sub.3XZ.sub.n-1, where A comprises one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U; X comprises one or more of Al, Ga, Sn, Be, Bi, Te, Sb, Se, As, Ge, Si, B, and P; Z comprises C; and n is greater than or equal to 0 and less than or equal to 0.75. A method of forming a cutting element, an earth-boring tool, a supporting substrate, and a method of forming a supporting substrate are also described.

An enhanced architecture for a nuclear reactor core includes several technologies: (1) nuclear fuel tiles (S-Block); and (2) a high-temperature thermal insulator and tube liners with a low-temperature solid-phase moderator (U-Mod) to improve safety, reliability, heat transfer, efficiency, and compactness. In S-Block, nuclear fuel tiles include a fuel shape designed with an interlocking geometry pattern to optimize heat transfer between nuclear fuel tiles and into a fuel coolant and bring the fuel coolant in direct contact with the nuclear fuel tiles. Nuclear fuel tiles can be shaped with discontinuous nuclear fuel lateral facets and have fuel coolant passages formed therein to provide direct contact between the fuel coolant and the nuclear fuel tiles. In U-Mod, tube liners with low hydrogen diffusivity retain hydrogen in the low-temperature solid-phase moderator even at elevated temperatures and the high-temperature thermal insulator insulates the solid-phase moderator from the nuclear fuel tiles.

Thermally-conductive ceramic and ceramic composite components suitable for high temperature applications, systems having such components, and methods of manufacturing such components. The thermally-conductive components are formed by a displacive compensation of porosity (DCP) process and are suitable for use at operating temperatures above 600° C. without a significant reduction in thermal and mechanical properties.

Disclosed is a method for preparing a carbon-reinforced metal-ceramic composite material, including: mixing raw materials of carbon, copper, zinc, titanium, copper oxide, calcium oxide and titanium dioxide, ball-milling the raw materials with a medium of ethanol to obtain a mixture, drying and milling the mixture to obtain a powder, sintering the powder with a laser having an irradiation power ranging from 100 to 600 W and an irradiation period of 3 min to 10 min to obtain a product, and rapidly cooling the product to allow a temperature of the product to be decreased to the room temperature within 5 min to obtain the carbon-reinforced metal-ceramic composite material.

Provided is a method for preparing a graphene-copper calcium titanate CCTO based ceramic composite dielectric material, which includes: dissolving metal ion sources in respective solvents to obtain respective solutions, and mixing the solutions evenly to obtain a precursor collosol of the CCTO based ceramic; allowing the precursor collosol of the CCTO based ceramic to stand for aging, followed by adding a graphene oxide dispersion to mix with the precursor collosol evenly, drying the resulting mixture to obtain dry precursor powders of the graphene-CCTO based ceramic, which are then grinded into fine powders, followed by irradiating by a low-power laser to obtain graphene-CCTO based ceramic composite powders; and compacting and molding the graphene-CCTO based ceramic composite powders, followed by catalytic synthesis with a high-power laser to obtain the graphene-CCTO based ceramic composite dielectric material.

Various embodiments of the disclosure provide methods using spark plasma sintering (SPS) at moderate temperatures and moderate pressures to fabricate high-density graphite material. The moderate temperatures may be temperatures not exceeding about 1200° C. The moderate pressures may be pressures not exceeding about 300 MPa. The high density exhibited by the resulting, sintered, high-density graphite material may be greater than about 1.75 g/cm.sup.3 (e.g., greater than about 2.0 g/cm.sup.3).

Provided is a dielectric composition exhibiting a high specific dielectric constant and a high resistivity even when fired in a reducing atmosphere. The dielectric composition contains a composite oxide having a composition represented by (Sr.sub.xBa.sub.1-x).sub.yNb.sub.2O.sub.5+y, the crystal system of the composite oxide is tetragonal, and y in the composition formula is smaller than 1.