The present invention relates to a lower end fitting for reducing flow resistance due to an in-core instrument in a nuclear fuel assembly, that is, a lower end fitting (100) having a plurality of flow holes for a nuclear fuel assembly, in which the flow holes (121) are formed under an assembly groove in which an instrumentation tube (131) for a nuclear fuel assembly is inserted, and at least two or more flow holes (121) are formed at a predetermined distance from the central axis (C) of the instrumentation tube (131).

A nuclear reactor fuel assembly includes a plurality of fuel rods, a plurality of guide channels, two nozzles, one of which has a bearing plate with openings, elements for the detachable connection of the nozzles to the guide channels, a detachable connection locking device and locking device fasteners. The elements for the detachable connection of the nozzles to the guide channels have a cross-section size greater than the size of openings in the nozzle bearing plate.

A lower nozzle for use in a nuclear fuel assembly provided. The lower nozzle is of the type having an axis and comprising a transverse lower tie plate for channeling the coolant through the lower tie plate and a tubular skirt extending axially from the periphery of the lower tie plate, the skirt delimiting an axial housing closed at one end by the lower tie plate and open at the opposite end, a debris filter configured for axial insertion in the housing and snap-fit springs for retaining the debris filter in the housing after insertion. The springs are configured to shift the debris filter axially towards the lower tie plate.

A modular water purification system for a nuclear power plant includes a plurality of modules that may be selectively connected together directly or through the use of intermediary adapters in a plurality of arrangements. The modules may include a pump module, a FOSAR module, a particulate filtration module, a cross-flow filtration module, a degasification module, and/or a demineralization module, among other possible modules. The modules may have common interfaces so that they can be interconnected (directly or through intermediary adapters) in a variety of configurations for different purposes within the context of the nuclear power plant (e.g., filtering pool water; collecting large objects via vacuuming). Various modules may have form factors and/or mounting structures that are similar enough to the fuel assemblies of the plant that (1) the plant's fuel assembly handling equipment can grab, move, and reposition the modules, and/or (2) the modules may be stored in the fuel pool's storage rack.

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 nuclear reactor has a core installed on a lower core plate and formed from multiple fuel assemblies, each fuel assembly including a structural cage assembly. The structural cage assembly has an upper end fitting, mid grids, and a lower end fitting (LEF). The LEF positions the fuel assembly using four locating pins located at each corner of the LEF. The pins position the fuel assembly laterally by mating with receiving holes in the lower core plate. The locating pins have a chamfered tip with a flat end. The chamfered tip allows for a greater positioning margin when installing the fuel assembly in the core by guiding the pins into holes in the lower core plate, and the flat tip provides strength and stability in case the assembly is inadvertently rested on the tip of the pin instead of the LEF pads.

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.

An apparatus including a lower end fitting having a top planar surface, a bottom planar surface, a counterbore defined therebetween, an opening extending from the counterbore to the top planar surface, and a lock recess that extends both radially outwardly from the counterbore and extends inwardly into the lower end fitting from the bottom planar surface. The apparatus includes a guide tube having a lower end and an end plug configured to connect with the lower end of the guide tube. The end plug has a threaded shaft sized to pass through the opening of the lower end fitting, and a female lock nut has a deformable side wall configured to be swaged into the recess of the lower end fitting. The lock recess remains visible as viewed from the bottom planar surface of the lower end fitting when the female lock nut is fully disposed in the counterbore.

Nuclear reactor fuel assembly comprising a bundle of fuel elements installed in a frame having guide channels and retention grids, a bottom nozzle, a removable head comprising collet tubes, an upper mantle, a support element, and springs. The collet tubes a comprise two movable coaxially arranged tubes with interacting stops on their side surfaces to select the length of the tubes. The tube passing through the hole in the plate of the operation mantle is rigidly fastened to the plate. The support element is a pipe with a rigidly fixed plate interacting with spring. The upper mantle is a pipe coaxial with the support element and having a gap at the bottom of bosses. A supporting element opposite each of the bosses has holes. The margin between a hole in the supporting element and the boss is not less than a gap between the upper mantle and support element.

An insertable flux thimble interface for use in a bottom nozzle of a fuel assembly in a nuclear reactor (i.e., a bottom nozzle insert) is disclosed herein. In various aspects, the bottom nozzle insert has properties that are different from traditional bottom nozzle flux thimble interfaces. The properties of the bottom nozzle insert may mitigate wear phenomena observed on the flux thimble. For example, the bottom nozzle insert may be constructed from material that is different from the material of the bottom nozzle. In some aspects, the bottom nozzle insert is constructed from material that has a hardness that is less than the hardness the bottom nozzle material. In other aspects, the bottom nozzle insert is constructed from a material that has a hardness that is less than the hardness of the flux thimble material.