Patent Number: 
Section: claims

1. A container for confining spent nuclear fuel, comprising:a sleeve of longitudinal axis comprising a first longitudinal end closed by a base and a second longitudinal free end via which the container is configured to be loaded;a plug configured to close the second longitudinal free end tightly by a weld made at a level of a welding zone, the welding zone being offset radially towards an interior of the container, relative to an inner face of the sleeve; anda flange projecting from the inner face of the sleeve to a side of the second longitudinal free end, the plug having at least one external diameter substantially equal to at least one internal diameter of the flange, the plug configured to be welded on the flange. 2. The container as claimed in claim 1, in which the flange is welded on the inner face of the sleeve. 3. The container as claimed in claim 2, in which the flange comprises a first section of larger internal diameter and a second section of smaller internal diameter connected by an annular surface forming a shoulder substantially orthogonal to the longitudinal axis, the plug comprising an external profile corresponding to the internal profile of the flange, such that the plug rests on the shoulder. 4. The container as claimed in claim 2, further comprising a handling device of the container distinct from the plug, the handling device being fixed to the sleeve at a level of the longitudinal free end of the sleeve, the flange being fixed in the sleeve back from the longitudinal free end of the sleeve. 5. The container as claimed in claim 4, in which the handling device includes a cover fitted in its center with a gripping element. 6. The container as claimed in claim 5, in which the cover comprises a rim of thickness close to the thickness of the longitudinal free end of the sleeve so as to enable welding of the cover on the sleeve without adding wire. 7. The container as claimed in claim 1, further comprising a wedging device of loading, the wedging device being mounted in the container. 8. The container as claimed in claim 7, the container being circular in cross-section, the wedging device comprising a casing whereof a length is substantially equal to that of the interior of the container and whereof transversal cross-section is a square, length of diagonals of the square being substantially equal to the internal diameter of the container. 9. The container as claimed in claim 8, in which the casing comprises a heat sink of heat emitted by loading. 10. The container as claimed in claim 9, in which the heat sink comprises fins extending longitudinally at least on one part of outer faces of the casing in a direction of largest dimension. 11. The container as claimed in claim 1, in which the plug comprises a first and a second connector for draining the container, sweeping with air of the interior of the container and its pressurizing. 12. The container as claimed in claim 11, further comprising a discharge pipe arranged inside the container, the pipe comprising a first free end arranged in the base of the container and a second end connected to one of connectors for suctioning water contained in the container. 13. A process for loading and closing a container for confining spent nuclear fuel including:a sleeve of longitudinal axis including a first longitudinal end closed by a base and a second longitudinal free end via which the container is configured to be loaded,a plug configured to close the second longitudinal free end tightly by a weld made at a level of a welding zone, the welding zone being offset radially towards an interior of the container, relative to an inner face of the sleeve,a flange projecting from the inner face of the sleeve to a side of the second longitudinal free end, the plug having at least one external diameter substantially equal to at least one internal diameter of the flange, the plug configured to be welded on the flange,the process comprising:placing the loading inside the container;placing the plug in the flange;welding the plug on the flange without adding material. 14. A process for loading and closing, as claimed in claim 13, further comprising a subsequent placing a handling device on the longitudinal free end of the sleeve and welding the handling device on the sleeve.