Integrity of Cast-iron Cask Against Free Drop Test — Verification of Brittle Failure Design Criterion

As a cask material, ductile cast iron may be susceptible to failure in a brittle manner under certain temperature and load conditions. A design criterion for ductile cast iron casks against brittle failure due to drop tests, has been proposed by Central Research Institute of Electric Power Industries (CRIEPI). In order to verify the proposed design criterion, a series of drop tests using a full scale cask with an artificial flaw located at the most critical location was carried out at a low temperature. In the test results, no crack propagation from the artificial flaw was observed under severe conditions where the safety factor calculated from the design criterion was below the proposed value of the criterion. These results, together with those of other workers, confirm that the proposed brittle failure design criteria described in the IAEA TECDOC-717 are applicable to evaluate the integrity of ductile cast iron casks against brittle failure due to drop tests.