Devices for transversely holding the fuel rods of a nuclear reactor assembly

A device for transversely holding the fuel rods of a bundle of fuel rods for a nuclear reactor assembly, which rods are arranged parallel to one another, in a uniform arrangement, having a plurality of support means for exerting forces on the rods in transverse directions to restrict vibrations thereof, while permitting axial lengthening of the rods, each of said support means comprising three sub-units comprising grids arranged adjacent one another in the longitudinal direction of the assembly, said sub-units comprising:

• two end grids each formed by small metal plates which are assembled in a uniform network delimiting cells inside which the rods pass, and whose side walls, parallel to the longitudinal axis of the assembly, are formed by said small metal plates arranged transversely, relative to the assembly, so that their width constitutes the thickness of said grid in the longitudinal direction, said end grids being identical and each grid having the same network as the other, each wall of each cell of one grid being located in the same longitudinal plane as the corresponding wall of the other grid, said grids being made integral with one another with a longitudinal spacing along the fuel rods, and
• an intermediate grid comprising small, elastic metal plates, the width of which is less than the width of said plates of said end grids, and which are assembled in a uniform network delimiting cells inside which the rods pass and arranged between said end grids in said longitudinal space provided therebetween, in a staggered manner in a transverse direction relative to said end grids, so that two adjacent elastic walls of the cells of said intermediate grid exert on each fuel rods transverse forces which press the rods against two walls of said cells of each end grid, said intermediate grid resting on at least one of said end grids.