Abstract: A closure system for a storage cask containing spent nuclear fuel has redundant mechanical seals to temporarily close the cask during development, testing, and refinement thereof, when it is occasionally necessary to open the cask, and redundant welded seals to supplement the mechanical seals when development is completed and the cask is permanently sealed during long-term storage. The closure system includes a primary cover which cooperates with an O-ring to provide a mechanical seal and which includes a canopy element that can be welded to the cask base element if a permanent seal is desired. The closure system also includes a secondary cover which cooperates with an additional O-ring to provide an additional mechanical seal and which is configured to receive an additional canopy element in the event that an additional welded seal is desired. The closure system permits the cask to be developed, tested, and refined using the same closure system that will be installed during actual use.

Abstract: An overflow control valve for use in a liquid sodium coolant pump tank which valve can be extended to create a seal with the pump tank wall or retracted to break the seal thereby accommodating valve removal. An actuating shaft which controls valve disc position also has cams which bear on roller surfaces to force retraction of a sliding cylinder against spring tension to retract the cylinder from sealing contact with the pump tank.

Abstract: Orifices which are removably attached to individual tubes of a steam generator.