The present invention concerns a fuel assembly for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods. At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235U. At least 20% of the fuel rods belong to a first set of fuel rods. The fuel rods in this first set comprise both U enriched in 235U and Th. The first set comprises a first and a second subset of fuel rods. The ratio, with regard to weight, between Th and U, in each fuel rod of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor.

The present invention concerns a fuel assembly for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods. At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235U. At least 20% of the fuel rods belong to a first set of fuel rods. The fuel rods in this first set comprise both U enriched in 235U and Th. The first set comprises a first and a second subset of fuel rods. The ratio, with regard to weight, between Th and U, in each fuel rod of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor.

Nuclear fuel assemblies include non-symmetrical fuel elements with reduced lateral dimensions on their outer lateral sides that facilitate fitting the fuel assembly into the predefined envelope size and guide tube position and pattern of a conventional nuclear reactor. Nuclear fuel assemblies alternatively comprise a mixed grid pattern that positions generally similar fuel elements in a compact arrangement that facilitates fitting of the assembly into the conventional nuclear reactor.

A fuel assembly for use in a core of a nuclear power reactor. The assembly includes a plurality of helically twisted fuel elements supported by a frame in a fuel rod bundle. Each of the fuel elements includes fissile material. When viewed in a cross-section that is perpendicular to an axial direction of the fuel assembly, the outermost fuel elements of the fuel rod bundle define a substantially circular perimeter. The fuel elements are arranged in a mixed grid pattern that includes a first, rectangular grid pattern and a second, triangular grid pattern.

A green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

A green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

A method of forming a high purity ingot for wafer production, such as a silicon carbidewafer. Precursors are added to a reactor; at least part of a fiber is formed in the reactor from the precursors using chemical deposition interacting with the precursors; and granular material is then formed from the fiber. The method further includes forming the ingot from the granular material. In one aspect, the chemical deposition can include laser induced chemical vapor deposition. Further, the method can include separating one or more wafers from the ingot for use in semiconductor fabrication.

A method of forming a high purity ingot for wafer production, such as a silicon carbidewafer. Precursors are added to a reactor; at least part of a fiber is formed in the reactor from the precursors using chemical deposition interacting with the precursors; and granular material is then formed from the fiber. The method further includes forming the ingot from the granular material. In one aspect, the chemical deposition can include laser induced chemical vapor deposition. Further, the method can include separating one or more wafers from the ingot for use in semiconductor fabrication.

A fuel assembly includes full length fuel rods which contain a plutonium fissile (Puf) but do not contain a burnable poison, full length fuel rods which contain the fissile uranium and the burnable poison, and partial length fuel rods which contain Puf but do not contain the burnable poison in a channel box. The plutonium enrichment is decreased in an order of the full length fuel rods. The concentration of the burnable poison of the full length fuel rod is higher than the concentration of the full length fuel rod. In each side of a rectangular outermost periphery adjacent to the inner surface of the channel box in a horizontal cross-sectional view of the fuel assembly, two partial length fuel rods are adjacently disposed, and the full length fuel rod containing the burnable poison is disposed to be adjacent to each partial length fuel rod.

A fuel assembly includes full length fuel rods which contain a plutonium fissile (Puf) but do not contain a burnable poison, full length fuel rods which contain the fissile uranium and the burnable poison, and partial length fuel rods which contain Puf but do not contain the burnable poison in a channel box. The plutonium enrichment is decreased in an order of the full length fuel rods. The concentration of the burnable poison of the full length fuel rod is higher than the concentration of the full length fuel rod. In each side of a rectangular outermost periphery adjacent to the inner surface of the channel box in a horizontal cross-sectional view of the fuel assembly, two partial length fuel rods are adjacently disposed, and the full length fuel rod containing the burnable poison is disposed to be adjacent to each partial length fuel rod.