Overhead Vertical Strike Analysis for the MCO in the CSB

Abstract

The purpose of this calculation is to document the structural adequacy of Multi-Canister Overpacks (MCOs) in two separate normal configurations for the 40-year interim period in the storage tubes at the Canister Storage Building (CSB). The two configurations apply when the lower MCO is arranged with (1) just a shield plug mechanical closure or (2) with the canister cover welded over the shield plug. Multiple analyses have been conducted to show the MCO design is adequate for drop events involving a lower, passive MCO being struck by an overhead drop load MCO both in vertical position. Minimal plastic deformations are experienced for either the MCO with shield plug or the MCO with cover cap. This survivability at 35 g's demonstrates the package's worthiness for 40 years of storage. The force between the two MCOs created by a drop event far exceed that resulting from stacking two loaded MCOs. The stacking load condition is not a structural concern and is, therefore, acceptable for the design duration of 40 years of storage. Both mechanical and welded cap models have the lifting ring and associated flat plate for the top unit to rest on and, therefore, easily fit together. Both designs were analyzed for the top unit to be dropped onto the lower unit. The mechanical seal unit only has high localized stress. The capped unit has a tendency to buckle but is still acceptable. Both designs will still be adequate for leakage and pressure during passive storage and are acceptable for the design duration of 40 years.