Patent Number: 
Section: claims

1. A cask for loading at least one nuclear fuel assembly in a transport container, including a body with a longitudinal axis configured to cover sealably an upper end of a container, at least one aperture for letting through a fuel assembly, and at least one means configured to maintain a plug for sealing a chamber of the container inside the cask and at a distance from one entrance of said chamber during loading, wherein the maintaining means includes a first arm rotationally mobile around a first axis and a second arm attached to the first arm and rotationally mobile relatively to the first arm, said cask also including external control device for controlling the arms, and wherein the second arm includes a housing for receiving the sealing plug. 2. The cask according to claim 1, including an aperture for letting through a pneumatic tool configured to be connected to the container, and a housing for receiving a plug when the pneumatic tool is connected, said plug configured to seal the aperture for connecting the pneumatic tool to the container. 3. The cask according to claim 1, the control device includes means for controlling the first arm and means for controlling the second arm, the second arm being displaceable independently of the first arm. 4. The cask according to claim 3, wherein the control device is manually actuated and includes assistance means for displacing the arms along predetermined trajectories. 5. The cask according to claim 4, wherein the control device are formed by first and second handwheels firmly attached to first and second connecting shafts, respectively, said first and second connecting shafts being mechanically connected to the first and second arms, respectively. 6. The cask according to claim 5, wherein the assistance means include a fixed flange and a rotationally mobile flange with a connecting arm, the flanges being superimposed, a flange including at least one imprint delimiting two extreme positions of the associated arm and an abutment borne by the other flange, so as to limit the angle of rotation between both flanges. 7. The cask according to claim 6, wherein the mobile flange associated with the second arm is formed by the handwheel. 8. The cask according to claim 6, wherein the mobile flange is distinct from the handwheel for controlling the first arm and jointly rotatable with the latter. 9. The cask according to claim 8, wherein the fixed flange for the first arm is attached onto the upper surface of the cask. 10. The cask according to claim 6, wherein the assistance means include an imprint so as to define two extreme positions adapted to each chamber of the container. 11. The cask according to claim 1, wherein the control device includes indexation means for the position of each arm. 12. The cask according to claim 1, wherein the housing is placed at a free end of the second arm and in that it includes a sealed bottom so as to collect dusts and/or debris borne by the sealing plug. 13. The cask according to claim 1, wherein the arm also includes the housing for the plug of the orifice for pneumatically connecting the container. 14. The cask according to claim 1, wherein the cask includes several apertures each placed opposite to a respective chamber of the container, for loading and unloading nuclear fuel assemblies. 15. The cask according to claim 1, including at its lower end configured to come into contact with the upper end of the container, first and second annular bearing faces, configured to respectively bear against first and a second supporting faces of the container, the second bearing face being positioned radially towards the inside of the cask relatively to the first bearing face, both bearing faces being connected through a cylinder extending along the longitudinal axis. 16. The cask according to claim 1, including a plug for the aperture. 17. The cask according to claim 1, including an aperture sealed by a plug for letting through a pneumatic tool configured to be connected to the container, and a housing for receiving a plug when the pneumatic tool is connected, said plug configured to seal the orifice for connecting the pneumatic tool to the container. 18. A device for loading at least one nuclear fuel assembly in a transport container, including a cask for loading at least one nuclear fuel assembly in a transport container, including a body with a longitudinal axis configured to cover sealably an upper end of a container, at least one aperture for letting through a fuel assembly, and at least one means configured to maintain a plug for sealing a chamber of the container inside the cask and at a distance from one entrance of said chamber during loading, wherein the maintaining means includes a first arm rotationally mobile around a first axis and a second arm attached to the first arm and rotationally mobile relatively to the first arm, said cask also including an external control device for controlling the arms, and wherein the second arm includes a housing for receiving the sealing plug, and dynamic confinement means configured to be connected with a channel communicating with the inside of the chambers and configured to cause a flow of air from the outside to the inside of the cask, and then to the inside of the chambers for the whole opening period of a chamber. 19. The device according to claim 18, wherein the dynamic confinement means include a pneumatic suction exhauster configured to be connected to collector (206) for collecting particles sucked up into the container. 20. A method for loading a container with a nuclear fuel assembly, including the following steps:a) placing a cask for loading at least one nuclear fuel assembly in a transport container, including a body with a longitudinal axis configured to cover sealably an upper end of a container, at least one aperture for letting through a fuel assembly, and at least one means configured to maintain a plug for sealing a chamber of the container inside the cask and at a distance from one entrance of said chamber during loading, wherein the maintaining means includes a first arm rotationally mobile around a first axis and a second arm attached to the first arm and rotationally mobile relatively to the first arm, said cask also including an external control device for controlling the arms, and wherein the second arm includes a housing for receiving the sealing plug, on the upper end of a container,b) connecting dynamic confinement means in a lower portion of the container in order to create an air flow towards the inside of the container,c) removing the plug for the pneumatic tool and placing the pneumatic tool,d) removing the plug from the first cell,e) placing an assembly in the first cell,f) replacing the plug of the first cell,g) repeating steps d) to f) if necessary, for loading other assemblies in the other cells,h) removing the pneumatic tool and replacing the plug for the pneumatic tool,i) disconnecting the dynamic confinement means, andj) removing the cask. 21. The method according to claim 20, wherein the dynamic confinement means are actuated prior to the removal of the plug of the first cell. 22. The method according to claim 20, wherein a step for removing a plug from an associated passage of the cask is carried out prior to the removal of the pneumatic plug of the container or of the plugs of the cells.