While typically-collected diameter data contains information for detecting some garter springs, many garter springs may not be detected without processing the diameter data. Responsively, a method for processing the diameter data to detect the garter springs has been developed. In particular, the processing involves fitting of the diameter data to a shape, determining residual errors and using the residual errors to locate garter springs.

A method for decommissioning a heavy water reactor facility includes: removing the plurality of guide tubes from a plurality of through-holes; installing a plurality of shielding stoppers in the plurality of through-holes; removing the shielding stopper installed in one through-hole of the plurality of through-holes, and inserting a cutting device into a lower portion of the reactivity mechanism deck through the one through-hole to cut a connection portion between the reactivity mechanism deck and the calandria vault by using the cutting device; and separating the reactivity mechanism deck from the calandria vault.

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.

A cross-over fluid coupling includes a first coupling end and a second coupling end. A plurality of first conduits have inner ends disposed toward the first coupling end and outer ends spaced apart from the inner end toward the second coupling end and being outboard of the inner end. A plurality of second conduits have outer ends that are disposed toward the first coupling end and positioned laterally outboard of the inner end of at least one of the first conduits, and inner ends that are spaced apart from the outer end toward the second coupling end in the axial direction and is laterally inboard of the outer end of the at least one of the first conduits.

A gas-cooled pressure tube nuclear reactor is described that uses a room temperature and pressure gas as a primary coolant and a liquid moderator as a secondary coolant. The primary coolant, which may be maintained in a supercritical state, is circulated through fuel columns in a pool of the liquid moderator. The primary coolant removes the heat generated by fission from the nuclear fuel. The heated primary coolant is then passed to one or more turbines to generate power. The primary coolant is then repressurized by one or more compressors using some of the generated power from the turbines. Several modified Brayton cycle configurations are described that are uniquely suited to the operating conditions of the gas-cooled pressure tube reactor.

A fuel assembly for a pressure-tube nuclear reactor includes a fuel channel assembly. The fuel channel assembly has an outer conduit and an inner conduit received within the outer conduit. The conduits define an annular fuel bundle chamber for receiving a flow of a coolant in one direction. The inner conduit includes a central flow passage for receiving a flow of the coolant in an opposite direction. A fuel bundle positioned within the fuel bundle chamber consists of fuel elements arranged to form an inner ring surrounding the inner conduit, and an outer ring surrounding the inner ring. The coolant may be light water, and geometries of the fuel assembly may be selected so moderation by the volume of coolant promotes generally uniform power distribution in the fuel elements.

A fuel assembly for a pressure-tube nuclear reactor includes a fuel channel assembly. The fuel channel assembly has an outer conduit and an inner conduit received within the outer conduit. The conduits define an annular fuel bundle chamber for receiving a flow of a coolant in one direction. The inner conduit includes a central flow passage for receiving a flow of the coolant in an opposite direction. A fuel bundle positioned within the fuel bundle chamber consists of fuel elements arranged to form an inner ring surrounding the inner conduit, and an outer ring surrounding the inner ring. The coolant may be light water, and geometries of the fuel assembly may be selected so moderation by the volume of coolant promotes generally uniform power distribution in the fuel elements.

The invention relates to the field of nuclear energy, more particularly to low-power and particularly low-power reactors. A nuclear reactor contains a housing with a reflector which forms a reactor core. The core has arranged therein primary process tubes, which are intended for circulating a coolant, and secondary process tubes, which are intended for accommodating elements of a control and protection system. The reactor also contains an intake chamber for coolant of a primary loop, and a discharge chamber for coolant of the primary loop, which are separated by a partition. The primary process tubes are designed in the form of Field tubes, the outer tubes of which are secured on the bottom of the intake chamber for the coolant of the primary loop, and the inner tubes are secured on the partition. Fuel assemblies are mounted in the inner tubes of the Field tubes on suspensions, which are secured on an upper portion of the discharge chamber for the coolant of the primary loop. The secondary process tubes are sealed off from the intake and discharge chambers for the coolant of the primary loop, and the inter-tube space of the core is filled with a medium or material which is transparent to neutrons.

The invention relates to the field of nuclear energy, more particularly to low-power and particularly low-power reactors. A nuclear reactor contains a housing with a reflector which forms a reactor core. The core has arranged therein primary process tubes, which are intended for circulating a coolant, and secondary process tubes, which are intended for accommodating elements of a control and protection system. The reactor also contains an intake chamber for coolant of a primary loop, and a discharge chamber for coolant of the primary loop, which are separated by a partition. The primary process tubes are designed in the form of Field tubes, the outer tubes of which are secured on the bottom of the intake chamber for the coolant of the primary loop, and the inner tubes are secured on the partition. Fuel assemblies are mounted in the inner tubes of the Field tubes on suspensions, which are secured on an upper portion of the discharge chamber for the coolant of the primary loop. The secondary process tubes are sealed off from the intake and discharge chambers for the coolant of the primary loop, and the inter-tube space of the core is filled with a medium or material which is transparent to neutrons.