Patent Number: 
Section: claims

1. Nuclear fuel element comprising a first plate, a first network having a plurality of walls integral with the first plate for forming a plurality of individual cells separated from one another and defined by said walls, and at least one nuclear fuel pellet having opposite sides confined within a corresponding cell such that a circumferential gap is formed between said opposite sides of said pellet and the walls of the cell, with the nuclear fuel pellet extending along an axis aligned in a direction approximately parallel to the walls of the cell; a second plate disposed in parallel alignment with said first plate on a side of said network opposite to the first plate in order to close the cells; said second plate is integral with a second network, substantially the same as the first network; and an axial gap formed between the at least one fuel pellet and the first and second plates. 2. Element according to claim 1, wherein the walls of the networks have the same thickness, taken in a direction parallel to the first and second plates. 3. Element according to claim 1, wherein the first and second networks are manufactured in a unitary manner with the first and second plates, respectively. 4. Element according to claim 1, wherein each closed cell is filled with helium. 5. Element according to claim 4, wherein the fissile phase of the fuel pellets accounts for more than 20% of the volume of the element. 6. Element according to claim 1, wherein the gaps formed in the cell create a residual volume in such cell, which accounts for at least 40% of the volume of the pellet located in such cell. 7. Element according to claim 1, wherein at least one of the opposite sides of the pellet is curved outwards to minimize comparative stress levels in the plate facing said opposite side of the pellet. 8. Element according to claim 1, wherein the first and second networks are a honeycomb structure of hexagonal cells. 9. Element according to claim 1, wherein the plates and the networks are made from the same refractory material, metal or ceramic. 10. Element according to claim 9, wherein the plates and the networks are composed of a ceramic. 11. Element according to claim 10, wherein said ceramic is SiC. 12. Element according to claim 11, wherein each pellet is cylindrical in geometry. 13. Element according to claim 10, wherein said ceramic is fibrous. 14. Element according to claim 10, further comprising a metallic layer plated on to the walls of each cell.