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 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.

The disclosure relates to a high temperature gas-cooled reactor core including a plurality of elongate fuel elements arranged in the form of a multi-lobed prism. Each prismatic fuel element includes an elongate prismatic body and a plurality of elongate fuel channels located within the prismatic body, wherein the cross-sectional area of each prismatic fuel element in a plane parallel to the bases of the prismatic fuel element is no more than 800 cm.sup.2 and wherein a ratio of the height of the prismatic body to its greatest width is greater than or equal to 3.0.

A nuclear fuel assembly for a nuclear reactor core, the fuel assembly having at least one fuel element including an elongated shell defining an interior volume, a lattice structure disposed within the interior volume, at least one flow channel extending through the lattice structure, at least one lattice site disposed in the lattice structure, and at least one fuel compact disposed within a corresponding one of the at least one lattice site, a first end cap including a boss having a first cross-sectional shape, the first end cap being affixed to a first end of the shell, and a second end cap including a first bore having a second cross-sectional shape, the second end cap being affixed to a second end of the shell, wherein the first cross-sectional shape of the boss is the same as the cross-sectional shape of the bore.

A nuclear fuel assembly for a nuclear reactor core, the fuel assembly having at least one fuel element including an elongated shell defining an interior volume, a lattice structure disposed within the interior volume, at least one flow channel extending through the lattice structure, at least one lattice site disposed in the lattice structure, and at least one fuel compact disposed within a corresponding one of the at least one lattice site, a first end cap including a boss having a first cross-sectional shape, the first end cap being affixed to a first end of the shell, and a second end cap including a first bore having a second cross-sectional shape, the second end cap being affixed to a second end of the shell, wherein the first cross-sectional shape of the boss is the same as the cross-sectional shape of the bore.

A fuel assembly for a nuclear reactor having an upstream minor portion defining an upstream end, a main portion, and a downstream minor portion defining a downstream end. Fuel rods extend in a flow interspace permitting a flow of coolant through the fuel assembly in contact with the fuel rods. Two elongated tubes form a respective internal passage extending in parallel with the fuel rods and enclosing a stream of the coolant. Each elongated tube having a bottom, an inlet at the upstream minor portion and an outlet at the downstream minor portion. Each elongated tube having an inlet pipe having an inlet end and an outlet end in the internal passage at a distance from the bottom, thereby forming a space in the internal passage between the outlet end and the bottom.

A fuel assembly for a nuclear reactor having an upstream minor portion defining an upstream end, a main portion, and a downstream minor portion defining a downstream end. Fuel rods extend in a flow interspace permitting a flow of coolant through the fuel assembly in contact with the fuel rods. Two elongated tubes form a respective internal passage extending in parallel with the fuel rods and enclosing a stream of the coolant. Each elongated tube having a bottom, an inlet at the upstream minor portion and an outlet at the downstream minor portion. Each elongated tube having an inlet pipe having an inlet end and an outlet end in the internal passage at a distance from the bottom, thereby forming a space in the internal passage between the outlet end and the bottom.

The fuel assembly includes at least one fuel rod and an outer channel with four sidewalls surrounding the fuel rod, the outer channel having a configuration based on a position of the fuel assembly within a core of the nuclear reactor, wherein at least a first select sidewall, of the four sidewalls of the outer channel, is a reinforced sidewall, the remaining sidewalls of the outer channel, other than the at least a first select sidewall, are non-reinforced sidewalls, the at least a first select sidewall being in a controlled location that faces and is directly adjacent to a control blade that is to be utilized in the nuclear reactor, wherein an entirety of the reinforced sidewall as a whole is at least one of thicker and made from a material that is more resistant to radiation-induced deformation as compared to an entirety of the non-reinforced sidewalls.

The fuel assembly includes at least one fuel rod and an outer channel with four sidewalls surrounding the fuel rod, the outer channel having a configuration based on a position of the fuel assembly within a core of the nuclear reactor, wherein at least a first select sidewall, of the four sidewalls of the outer channel, is a reinforced sidewall, the remaining sidewalls of the outer channel, other than the at least a first select sidewall, are non-reinforced sidewalls, the at least a first select sidewall being in a controlled location that faces and is directly adjacent to a control blade that is to be utilized in the nuclear reactor, wherein an entirety of the reinforced sidewall as a whole is at least one of thicker and made from a material that is more resistant to radiation-induced deformation as compared to an entirety of the non-reinforced sidewalls.

The disclosure relates to a high temperature gas-cooled reactor core including a plurality of elongate fuel elements arranged in the form of a multi-lobed prism. Each prismatic fuel element includes an elongate prismatic body and a plurality of elongate fuel channels located within the prismatic body, wherein the cross-sectional area of each prismatic fuel element in a plane parallel to the bases of the prismatic fuel element is no more than 800 cm.sup.2 and wherein a ratio of the height of the prismatic body to its greatest width is greater than or equal to 3.0.