A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.

Annular metal fuel and fuel rods are described that have improved performance over uranium oxide fuel rods. The annular metal fuel can be made out of porous metal nuclear fuel and will generate more power and operate at a much lower temperature than uranium oxide fuel. The annular metal fuel rods may be used in traveling wave reactors and other fast reactors. Pressurized water reactors may also be retrofit with annular metal fuel rods to improve reactor performance.

Annular metal fuel and fuel rods are described that have improved performance over uranium oxide fuel rods. The annular metal fuel can be made out of porous metal nuclear fuel and will generate more power and operate at a much lower temperature than uranium oxide fuel. The annular metal fuel rods may be used in traveling wave reactors and other fast reactors. Pressurized water reactors may also be retrofit with annular metal fuel rods to improve reactor performance.

Disclosed are a nuclear fuel pellet having enhanced thermal conductivity and a method of manufacturing the same, the method including (a) a step of manufacturing a mixture including a nuclear fuel oxide powder and a thermally conductive plate-shaped metal powder; and (b) a step of molding and then heat-treating the thermally conductive plate-shaped metal powder to have an orientation in a horizontal direction in the mixture, thereby forming a pellet.

There is provided a core of a fast reactor including: a core fuel region in which core fuel assemblies loading a metal fuel are arranged on a central region in a radial direction of the core; an inner blanket fuel region in which blanket fuel assemblies loading another metal fuel are circumferentially arranged on an inner portion of the core fuel region; and an outer peripheral blanket fuel region in which the blanket fuel assemblies are circumferentially arranged on an outer periphery of the core fuel region, wherein the metal fuel is formed of a UPuZr alloy or an alloy of U, Pu, TRU other than Pu, and Zr, the other metal fuel is formed of an alloy of U and Zr, and the Zr content of the other metal fuel is lower than the Zr content of the metal fuel.

There is provided a core of a fast reactor including: a core fuel region in which core fuel assemblies loading a metal fuel are arranged on a central region in a radial direction of the core; an inner blanket fuel region in which blanket fuel assemblies loading another metal fuel are circumferentially arranged on an inner portion of the core fuel region; and an outer peripheral blanket fuel region in which the blanket fuel assemblies are circumferentially arranged on an outer periphery of the core fuel region, wherein the metal fuel is formed of a UPuZr alloy or an alloy of U, Pu, TRU other than Pu, and Zr, the other metal fuel is formed of an alloy of U and Zr, and the Zr content of the other metal fuel is lower than the Zr content of the metal fuel.

Thorium-based fuel bundles according to one or more embodiments of the present invention are used in existing PHWR reactors (e.g., Indian 220 MWe PHWR, Indian 540 MWe PHWR, Indian 700 MWe PHWR, CANDU 300/600/900) in place of conventional uranium-based fuel bundles, with little or no modifications to the reactor. The fuel composition of such bundles is 60+ wt % thorium, with the balance of fuel provided by low-enriched uranium (LEU), which has been enriched to 13-19.95% 235U. According to various embodiments, the use of such thorium-based fuel bundles provides (1) 100% of the nominal power over the entire life cycle of the core, (2) high burnup, and (3) non-proliferative spent fuel bundles having a total isotopic uranium concentration of less than 12 wt %. Reprocessing of spent fuel bundles is also avoided.

Nuclear fuel assemblies include fuel elements that are sintered or cast into billets and co-extruded into a spiral, multi-lobed shape. The fuel kernel may be a metal alloy of metal fuel material and a metal-non-fuel material, or ceramic fuel in a metal non-fuel matrix. The fuel elements may use more highly enriched fissile material while maintaining safe operating temperatures. Such fuel elements according to one or more embodiments may provide more power at a safer, lower temperature than possible with conventional uranium oxide fuel rods. The fuel assembly may also include a plurality of conventional UO2 fuel rods, which may help the fuel assembly to conform to the space requirements of conventional nuclear reactors.