Preventing failure in spent nuclear fuel canisters
A spent nuclear fuel canister has been developed with the goal of no containment failure even during accidental drop conditions. This canister was designed to be loaded with U.S. Department of Energy spent nuclear fuel and then used for interim storage, transportation to the nation’s repository, and final disposal at the repository. The design required a high degree of confidence against failure if the canister were subjected to loads (e.g., accidental drop events) resulting in large plastic deformations and high strains. Significant testing of the canister clearly demonstrates that it can safely achieve the intended design goals without failure. The canister skirt and its attachment to the containment boundary are the key engineered elements of the design that allow significant impact damage without failure of the containment.
A combination of analytical techniques and physical testing was used to develop and demonstrate the viability of the design. Finite element modeling coupled with scaled drop tests established the design prototype. To validate the design concept, nine full-scale test canisters were fabricated and dropped from various heights and orientations. The nine test canisters experienced varying degrees of damage to their skirts, lifting rings, and containment boundary components. However, all of the tested canisters maintained the containment boundary as evidenced through the results of pressure and selective helium leak testing. Pre- and post-drop finite element analyses were also performed. The analytical results provide accurate predictions of canister responses to the drop tests.
The results achieved for the canister can also be applicable to other well-designed containers (canisters, casks, cans, vessels, etc.) subjected to similar loads. Properly designed containers can maintain containment after experiencing dynamically induced high strains, and computer analyses can accurately predict the response of these containers to dynamic loads.
Keywordsaccidental drop containment impact plastic deformation spent fuel strain rate
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