Evaluation of special safety issues associated with handling the Three Mile Island Unit 2 core debris

This document reports the results of recent tests and analyses evaluating safety concerns relating to Three Mile Island Unit 2 (TMI-2) core debris pyrophoricity, radiolytic hydrogen and oxygen, and the potential for steam generation in shipping canisters during a fire. Recommendations drawn from these results include the following: (1) hydrogen-oxygen recombiners should be installed in each core debris canister, (2) water should be removed from each canister by drip drying (no vacuum pumping is required), (3) the maximum weight of the loaded, dewatered canisters and the minimum volume of gas/vapor in each canister should be controlled and measured by weighting before and after dewatering, (4) a cover gas of approximately two atmospheres of argon should be added to each canister, (5) each canister should be weighed and pressure checked prior to shipping, (6) the shipping cask should be designed to limit the temperature of the canister contents after the standard hypothetical accident (fire) such that the design pressure of the canister/cask will not be exceeded, (7) provisions should be made for canister venting during long-term storage and for cask venting in the event of an overpressure condition resulting from an ''extended'' fire, and (8) some pyrophoricity testing of samples taken during defueling should be conducted to assure adequate safety-related information during canister opening.