Abstract: The method includes forming an inner monolithic layer from crystals of beta phase stoichiometric silicon carbide on a carbon substrate in the form of a rod by chemical methylsilane vapor deposition in a sealed tubular hot-wall CVD reactor. The method further includes forming a central composite layer over the inner monolithic layer by twisting continuous beta phase stoichiometric silicon carbide fibers into tows, transporting the tows to a braiding machine, and forming a reinforcing thread framework. A pyrocarbon interface coating is built up by chemical methane vapor deposition in a sealed tubular hot-wall CVD reactor. Then, a matrix is formed by chemical methylsilane vapor deposition in the reactor. A protective outer monolithic layer is formed from crystals of beta phase stoichiometric silicon carbide over the central composite layer by chemical methylsilane vapor deposition in a CVD reactor. And then the carbon substrate is removed from the fabricated semi-finished product.

Abstract: The method for producing non-core beta silicon carbide fibers includes four steps. The first step is spinning of multifilament polymeric fiber by melt-extrusion of polycarbosilane. The second step is thermooxidative cross-linking for which the produced spun polymeric fibers are cured in an oxidation furnace at a temperature of 175-250 degrees C. at a heating rate of 3-10 degrees C./h until their weight is increased by 6-15%. The third step is carbonization of the produced cured polymeric fibers with the conversion into the ceramic phase. The fourth step is finishing of the produced beta silicon carbide fiber. The effect of the invention is producing non-core silicon carbide fibers, improving their strength performance, improving resistance to high temperatures and their high creep resistance, stable fiber properties, optimal average diameter of fibers, absence of foreign impurities in the fiber composition.

Abstract: The invention relates to the nuclear industry and can be used for producing fuel pellets from uranium-molybdenum metal powders enriched to 7% uranium 235 for nuclear reactor fuel elements. The pellets are sintered in an inert atmosphere of argon at a temperature ranging from 1100° C. to 1155° C., and the initial powder is a uranium-molybdenum powder having a fraction size of 160 µm and a molybdenum con¬tent of 9.0 to 10.5 wt%. The powder is pre-heated at a temperature of 500° C. for 10-20 hours (in an atmosphere of argon) and is subsequently cold pressed into pellets in a die under a force of up to 950 MPa. In an alternative emb¬odiment for producing uranium-molybdenum pellets with a binder (plasticizer), the step of sintering is preceded by heating the pellets in an atmosphere of argon at 300° C. to 450° C. for 2-4 hours to remove the binder.

Abstract: The method for producing non-core beta silicon carbide fibers includes four steps. The first step is spinning of multifilament polymeric fiber by melt-extrusion of polycarbosilane. The second step is thermooxidative cross-linking for which the produced spun polymeric fibers are cured in an oxidation furnace at a temperature of 175-250 degrees C. at a heating rate of 3-10 degrees C./h until their weight is increased by 6-15%. The third step is carbonization of the produced cured polymeric fibers with the conversion into the ceramic phase. The fourth step is finishing of the produced beta silicon carbide fiber. The effect of the invention is producing non-core silicon carbide fibers, improving their strength performance, improving resistance to high temperatures and their high creep resistance, stable fiber properties, optimal average diameter of fibers, absence of foreign impurities in the fiber composition.

Abstract: The end plug includes two parts in the form of coaxial cylinders having different diameters, the diameter of the part configured to be arranged inside the cladding is less than the cladding inner diameter by 0.06-0.08 and 2-3 mm, respectively, for interposing brazes of different types. An end plug according to the third variant is composed of three parts in the form of three successively arranged coaxial cylinders having different diameters, the diameter of the two parts configured to be arranged inside the cladding being less than the cladding inner diameter by 0.06-0.08 and 2-3 mm, respectively, for interposing brazes of two types simultaneously. The effects of the invention are safety for the environment, possibility of using the developed end plugs as an alternative for replacing plugs used in various reactors, proposal of a simplified method for manufacturing an end plug, improvements in mechanical and thermophysical properties of end plugs.

Abstract: The method includes forming an inner monolithic layer from crystals of beta phase stoichiometric silicon carbide on a carbon substrate in the form of a rod by chemical methylsilane vapor deposition in a sealed tubular hot-wall CVD reactor. The method further includes forming a central composite layer over the inner monolithic layer by twisting continuous beta phase stoichiometric silicon carbide fibers into tows, transporting the tows to a braiding machine, and forming a reinforcing thread framework. A pyrocarbon interface coating is built up by chemical methane vapor deposition in a sealed tubular hot-wall CVD reactor. Then, a matrix is formed by chemical methylsilane vapor deposition in the reactor. A protective outer monolithic layer is formed from crystals of beta phase stoichiometric silicon carbide over the central composite layer by chemical methylsilane vapor deposition in a CVD reactor. And then the carbon substrate is removed from the fabricated semi-finished product.