Framatome Gmbh

Cogema, Inc.

Other

Compagnie Generale Des Matieres Nucleaires

Bernard Petit

A nuclear fuel assembly grid has a plurality of mutually interleaved straps forming an array of fuel rod receiving cells. Each strap is formed with regularly distributed slots for interleaving with other straps of the grid. The strap has dimples located between some at least of the slots for maintaining fuel rods in the cells. An uptstream portion of the plate extending in transverse relation to a coolant flow direction has a double sided concave chamfer.

Grid strap for a nuclear fuel assembly, and a grid including such straps

Spacing grid of a fuel assembly for a nuclear reactor and fuel assembly

A spacer grid spring (6) consists of a single metal leaf including two end parts (6a, 6b) substantially in the same plane and a central part (6c) out of the plane of the end parts (6a, 6b). At least one of the end parts (6a, 6b) is laterally provided with two flanges (6d, 6e) folded out of the plane of the end part (6a, 6b), in the opposite direction from the central part (6c) of the spring (6). The call wall (5) intended to receive the spring (6) includes, in an arrangement adjacent to each of two dimples (7a, 7b) placed at the ends of the wall (5), a part (8a,8b) for holding an end (6a, 6b) of the spring, and an opening (10a, 10b) passing through the wall (5) adjacent to the holding part (8a, 8b).

Spacer grid of a fuel assembly for a nuclear reactor, including attached

A bracing grid suitable for use in a light water reactor has a plurality of mutually intersecting sets of plates defining cells which receive fuel rods. The plates carry springs for retaining the rods by friction. Each spring is formed has a U legs located each on one side of a plate, the branch being for contact on the elements in two mutually adjacent cells separated by the plate. The two legs are connected by a loop straddling the plate and are connected to each other by a weld at the base of the loop, through a window formed through the plate. The legs of each spring are also mutually connected by mechanical locking means which retain the two legs with respect to each other and with respect to the respective plate.

Grid with holding springs for a nuclear fuel assembly

Each of the zones of the ferrule (25) comprising a radially projecting deformed part (29) is deformed by inward bending, so as to extract the deformed part (29) from a corresponding cavity (22) of the end block. The locking sleeve (20) is then extracted by exerting a pulling force on this sleeve (20) in the axial direction (ZZ') of the guide tube (4). Preferably, the ferrule (25) consists of cylindrical segments separated by slits arranged along the generatrices of the ferrule (25). A tool (31) is used to fold the segments of the ferrule (25) and to grip these segments so as to extract the locking sleeve (20). Extraction is performed underwater in a fuel storage well.

Method for extracting a locking sleeve from a demountable guide tube of

The sleeve (20) for locking the guide tube has an outer surface comprising successivley a cylindrical and a frustoconical part in the axial direction, without any radially protruding part. The upper cylindrical part (25) of the sleeve constitutes a fastening shell of the sleeve (20) in the end fitting of the assembly and the lower frustoconical part (24) a ring for expanding the guide tube. The fastening shell (25) the thickness of which is substantially smaller than the thickness of the ring (24) can be distorted into cavities machined in the end fitting of the assembly. An annular interlocking groove (20) is machined in the upper part of the ring (24).

Device for demountable fastening of a guide tube into an end fitting of

The guide tube (4) is fixed inside the adapter plate (10) of the demountable end block by a locking sleeve (20). The locking sleeve (20) comprises a part (24) ensuring expansion of the tube (4) and a ferrule (25) for fixing in the adapter plate (10). The fixing ferrule (25) consists of cylindrical segments separated by slits arranged in the direction of the generatrices of the ferrule (25). The cylindrical segments have deformations (29) inside cavities (22) radially directed relative to the through-hole (11) of the adapter plate (10), for ensuring fixing of the sleeve (20). The cylindrical segments of the ferrule (25) can be folded inwards so as to disengage the deformations (29) from the cavities (22), before extraction of the sleeve (20), in order to carry out demounting of the connection of the guide tube (4) and the adapter plate (10).

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Brignais, France

Bernard Petit