Patent Number: 
Section: claims

1. A nuclear fuel assembly comprising:a group of nuclear fuel rods and a support skeleton, the assembly comprising:two nozzles;guide tubes interconnecting the nozzles; andspacer grids secured to the guide tubes and serving to hold the rods;the nuclear fuels rods extending along a longitudinal direction and being disposed in a substantially regular array;the assembly including at least one support skeleton reinforcing device disposed between two successive spacer grids and secured to the guide tubes, and the reinforcing device being disposed inside the group of rods and presenting a transverse extent that is less than the transverse extent of the array of rods. 2. The assembly according to claim 1, wherein the reinforcing device does not extend into a peripheral layer of rods. 3. The assembly according to claim 2, wherein the reinforcing device does not extend between the peripheral layer of rods and an adjacent layer of rods. 4. The assembly according to claim 1, wherein the reinforcing device extends longitudinally substantially as far as a spacer grid immediately above the reinforcing device. 5. The assembly according to claim 1, wherein the reinforcing device defines at least one transverse flow passage above the spacer grid immediately beneath the reinforcing device, the passage serving to pass a cooling fluid for flowing through the assembly. 6. The assembly according to claim 5, wherein the reinforcing device extends longitudinally substantially as far as the spacer grid immediately below the reinforcing device, and wherein the passage is formed by an opening formed through a bottom end of the reinforcing device. 7. The assembly according to claim 5, wherein the bottom end of the reinforcing device is disposed at a distance from the spacer grid immediately beneath the reinforcing device so as to define the transverse flow passage for the cooling fluid. 8. The assembly according to claim 1, wherein the reinforcing device is secured to at least two guide tubes. 9. The assembly according to claim 1, wherein the reinforcing device is a substantially plane plate. 10. The assembly according to claim 9, wherein the reinforcing device is substantially parallel to one of faces of the group of nuclear fuel rods. 11. The assembly according to claim 1, wherein the reinforcing device is an angle member forming at least one L-shape. 12. The assembly according to claim 11, wherein the angle member is disposed in a corner of the group of nuclear fuel rods. 13. The assembly according to claim 1, wherein the reinforcing device does not have a mixer arrangement for mixing the cooling fluid that is to flow through the assembly. 14. The assembly according to claim 1, wherein the reinforcing device has cells for receiving the nuclear fuel rods, wherein the dimensions of each of the cells are greater than the diameters of the nuclear fuel rods.