A methodology is disclosed for compaction of a ceramic matrix of certain nuclear fuels incorporating neutron poisons, whereby those poisons aid in reactor control while aiding in fuel fabrication. Neutronic poisons are rare-earth oxides that readily form eutectics suppressing fuel fabrication temperature, of particular importance to the fully ceramic microencapsulated fuel form and fuel forms with volatile species.

A method for producing microencapsulated fuel pebble fuel more rapidly and with a matrix that engenders added safety attributes. The method includes coating fuel particles with ceramic powder; placing the coated fuel particles in a first die; applying a first current and a first pressure to the first die so as to form a fuel pebble by direct current sintering. The method may further include removing the fuel pebble from the first die and placing the fuel pebble within a bed of non-fueled matrix ceramic in a second die; and applying a second current and a second pressure to the second die so as to form a composite fuel pebble.

A method for producing microencapsulated fuel pebble fuel more rapidly and with a matrix that engenders added safety attributes. The method includes coating fuel particles with ceramic powder; placing the coated fuel particles in a first die; applying a first current and a first pressure to the first die so as to form a fuel pebble by direct current sintering. The method may further include removing the fuel pebble from the first die and placing the fuel pebble within a bed of non-fueled matrix ceramic in a second die; and applying a second current and a second pressure to the second die so as to form a composite fuel pebble.

A nuclear fission reactor fuel assembly adapted to permit expansion of the nuclear fuel contained therein. The fuel assembly comprises an enclosure having enclosure walls to sealingly enclose a nuclear fuel foam defining a plurality of interconnected open-cell voids or a plurality of closed-cell voids. The voids permit expansion of the foam toward the voids, which expansion may be due to heat generation and/or fission gas release. The voids shrink or reduce in volume as the foam expands. Pressure on the enclosure walls is substantially reduced because the foam expands toward and even into the voids rather than against the enclosure walls. Thus, the voids provide space into which the foam can expand.

A nuclear fission reactor fuel assembly adapted to permit expansion of the nuclear fuel contained therein. The fuel assembly comprises an enclosure having enclosure walls to sealingly enclose a nuclear fuel foam defining a plurality of interconnected open-cell voids or a plurality of closed-cell voids. The voids permit expansion of the foam toward the voids, which expansion may be due to heat generation and/or fission gas release. The voids shrink or reduce in volume as the foam expands. Pressure on the enclosure walls is substantially reduced because the foam expands toward and even into the voids rather than against the enclosure walls. Thus, the voids provide space into which the foam can expand.

A method of manufacturing nuclear fuel elements may include: forming a base portion of the fuel element by depositing a powdered matrix material including a mixture of a graphite material and a fibrous material; depositing particles on the base portion in a predetermined pattern to form a first particle layer, by controlling the position of each particle in the first particle layer; depositing the matrix material on the first particle layer to form a first matrix layer; depositing particles on the first matrix layer in a predetermined pattern to form a second particle layer by controlling positions of each particle in the second particle layer; depositing the matrix material on the second particle layer to form a second matrix layer; and forming a cap portion of the fuel pebble by depositing the matrix material. The particles in the first particle layer and the second particle layer include nuclear fuel particles.

A nuclear fuel, the nuclear fuel comprising uranium aluminide grains, wherein the uranium aluminide grain properties are selected for good isotope extraction after irradiation and chemical digestion.

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.

Provided is a fuel design configured to have a thickness that is equal to or less than a mean-free path of electrons emitted by a radioactive energy source to prevent electrons produced thereby from being stopped within the fuel design and thus decreasing the intensity of bremsstrahlung radiation generated within the fuel design. Additionally provided is a two-phase shielding system including a first shield formed of a first material having a thickness exceeding a mean-free path of an electron emitted from a radioactive source material so as to prevent the electron from passing through the first shield, and a second shield formed of a second material configured to prevent bremsstrahlung radiation generated by the electron from passing through the second shield.

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.