After removal from the spent fuel storage bay of a candu reactor, irradiated nuclear fuel may be stored above-ground in dry storage containers (DSCS). DSCS are loaded with fuel underwater in the spent fuel bay, and then capped with a lid. Prior to transfer of the dscs to an area where they can be dried and have the lids permanently welded into place, a temporary lid clamp must be installed to ensure that the dsc contents will be safely retained during all required handling and transportation activities.
In addition to a range of Westinghouse High Integrity Dry Storage Containers developed for multiple CANDU reactor operators, Westinghouse has designed and built a custom DSCS lid clamp to secure the lid and contents during transportation and handling prior to permanent welding.
The High Integrity Lid Clamps are designed to perfectly fit a range of dsc sizes and weigh in at 4500 lbs secured at all times. To meet the stringent safety requirements, a novel actuation mechanism engages clamping dogs from each side of the clamp to engage the top flange of the dsc and hold its lid in place. In addition to basic structural analysis, Westinghouse undertook detailed non-linear analysis to ensure the ability of the clamp to retain the lid on the dsc under several postulated drop/impact scenarios.
In this extreme safety critical application, accurate mating tolerances must be met to ensure a tight fit between the dsc and its lid. as final machining after welding is not practical for a weldment of this size, Westinghouse had to develop an innovative and carefully sequenced custom welding procedure. This ensures that the tight tolerances required between the lid clamp and the dsc base are not compromised due to the warpage that typically occurs from large weld heat input during the process. Westinghouse has developed a range of dscs and lid clamps with various specifications customizable to meet the specific requirements of our customer’s applications.