Framatome Gmbh

Compagnie Generale Des Matieres Nucleaires

Cogema, Inc.

Areva Np Gmbh

Frametome & Compagnie Generale Des Matieres Nucleaires

Michel Verdier

Eric Labarriere

Regis Mortgat

Alain Brosset

This bottom end-piece includes nozzles for directing the flow of water of the reactor along the lower ends of the fuel rods, the nozzles being arranged at nodes of the substantially regular network of the fuel rods, and an anti-debris device which delimits water flow channels. At least some of the water flow channels are arranged at nodes of the substantially regular network. Direction nozzles are arranged at least partially in the channels in order to delimit water passages therewith, and at least one water passage includes a first section and a second section which are mutually offset radially relative to the corresponding node of the network in order to form a baffle.

Bottom end-piece having an anti-debris device with a baffle for a nuclear assembly and corresponding assembly

A control rod guide tube for a nuclear reactor fuel assembly consists of several mutually portions of zirconium-based alloy. They define a passage that is narrow in a bottom portion of the tube. The guide includes a top length extending over at least 70% of its total length, and a bottom length of thickness greater than that of the top length. The top of the bottom length is engaged in the top length and is welded to the top length along the terminal edge of the top length.

Guide tube for a nuclear fuel assembly

A method of manufacturing a guide tube for a nuclear fuel assembly, in which a tubular blank of constant thickness is prepared, the thickness of the blank is reduced over a fraction of its length in the range 70% to 90% while maintaining a constant inner diameter, and then that section of the blank which has retained its original thickness is forced inwardly by an amount such that a tube is formed which has a constant outside diameter and a variable thickness.

Guide tube for a nuclear fuel assembly, and a method of manufacturing

The adaptor plate (11) comprises ribs (12) which are substantially perpendicular to its faces, projecting from its lower face, delimiting between them cells and zones (15) into each of which emerges a plurality of through-openings (16) of substantially square cross-section which are arranged in a predetermined pattern.

Bottom nozzle of a fuel assembly for a water-cooled nuclear reactor

A nuclear fuel assembly comprises a skeleton that constitutes the structure of the assembly and that holds a bundle of fuel elements at nodes in a regular array. The skeleton comprises two end pieces interconnected by guide tubes. The connection between each guide tube and the lower end piece comprises a peg formed with a coolant flow hole having a top portion fixed in the guide tube and a projecting bottom portion, which has a downwardly facing shoulder for bearing on the lower end piece, which passes through a passage formed in the lower end piece, and which is divided into a plurality of resilient fingers each having an upwardly facing shoulder for catching on the lower end piece.

Nuclear fuel assembly skeleton

The nozzle (8) comprises a transverse element consisting of a cross-braced structure (14) comprising wall elements (15) delimiting cells (16) of large dimensions. Ends of a plurality of mutually parallel leaves (18) are fixed to the inside walls of each of the cells (16) so that their faces are substantially parallel to the direction of circulation of the cooling water through the nozzle (8). The leaves (18) provide between them spaces of a width which is less than the size of the particles likely to be entrained in the cooling fluid and to lodge in the fuel assembly.

Filtering bottom nozzle for a fuel assembly of a lightwater-cooled

There is provided a method of manufacturing a grid for a nuclear fuel assembly, the grid having at least two crossed sets of mutually parallel plates which define cells, some of which receive guide tubes and others receive fuel rods, the plates being provided with boss means for limiting the amount of movement available to the rods relative to the nodes of a regular array. The plates are formed with bosses projecting radially inwardly into each cell for receiving a fuel rod by such an amount that they define a passage having a size at least equal to a minimum diameter of the fuel rods. Then the bosses are deformed radially outwardly for imparting to each passage a predetermined radial size, slightly higher than that of one fuel rod and determined by a gauge.

Method of manufacturing a grid having calibrated cells for a nuclear

A mixing grid for use in a pressurized reactor comprises at least two sets of crossed fixed together at their cross-points, delimiting cells, some for receiving fuel rods and the others for receiving guide tubes, the plates being provided with coolant stirring fins extending the plates downstream and disposed to deflect the coolant transversely to its general flow direction, each plate being provided with abutment means projecting inwardly from each of the faces of the cells for receiving fuel rods, thereby delimiting a passage that is larger than the size of the rods but small enough to prevent a rod contained in the cell coming into contact with the fins. In each wall the abutment means comprise two portions of plate that are cut out and deformed into a scoop-shape, and that are offset relative to each other in the coolant flow direction, with the scoops projecting in opposite directions and tending to cause coolant to pass from one cell to another.

Grid having mixing fins for a nuclear fuel assembly

The lower connector comprises an adaptor plate of square shape, traversed by water passage orifices, and a filtration plate pierced with holes of small dimensions and abutting against the adaptor plate. The water passage orifices of the adaptor plate are arranged completely symmetrically in relation to the medians and to the diagonals of the adaptor plate. The set of orifices in each of the zones of the adaptor plate limited by a diagonal and a median comprises orifices have an oblong cross-section and, if appropriate, water passage orifices of a different shape. The filtration plate comprises sets of holes of small dimensions arranged in the zones of the plate which come into alignment with the oblong orifices of the adaptor plate.

Lower connector for a fuel assembly of a nuclear reactor, comprising an

A spacer grid for a nuclear fuel assembly comprises a plurality of sets of plates which are interleaved and mutually interconnected to define cells each for receiving a fuel rod and further comprising a plurality of hairpin springs each carried by and retained on a respective one of the plates and each projecting into at least one respective cell when in released condition. Each spring is provided with one or two retention spurs arranged for retaining it temporarily in a retracted condition with respect to the respective plate. The retention spurs are releasable by a force of predetermined direction applied on the spring.

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Villeurbanne, France

Michel Verdier