Analysis Of The Behaviors Of The TS-69B Cask For Transport And Storage Of Spent Nuclear Fuel In Drop Tests

In Japan, spent nuclear fuel is stored on an interim basis until it is being reprocessed. Thus, it is mandatory that metal casks maintain safety functions as they are placed in the interim storage as well as in a process of transport. At Toshiba Energy Systems & Solutions Corp. (ESS), design of the TS-69B type, a dry metal cask for dual purposes of transport and storage, is in progress in recent years. As part of the design efforts, Toshiba ESS verified the integrity of the cask under the specific conditions for the 9-meter drop tests, which are required by the government regulations for transport casks. During the evaluation of the 9-meter drop tests, cask behaviors for each section were analyzed with the use of non-linear analysis in LS-DYNA. In the event of a vertical drop on the cask’s lid-side, the impact load may become larger due to the delayed impact resulting from the gap (i.e. space) between the primary lid and the contents. This study focused on the delayed impact load and the cask contents in the event of a vertical drop on the lid-side for further evaluations of seal integrity of the TS-69B. During the study, data for content movement were obtained as the gap between the primary lid and the contents, and the various fuel assembly models were used as parameters. As a result, accelerations become the largest when the largest value is assumed for the gap between the primary lid and the cask contents. Impact behaviors on cask contents and other sections vary depending on the parameters for fuel assembly models. Accordingly, acceleration values obtained from this study also verified the seal integrity of TS-69B.