Assessment of retrieval alternatives for the geologic disposal of nuclear waste. Final report

Currently, the most feasible alternative for permanent disposal of high-level nuclear waste is storage in deep underground repositories in geologic media. Uncertainties in investigation, design and construction necessitate maintaining the retrieval option until the isolation is proven likely. Investigations were limited to concepts in geologic media (tuff, salt, and basalt) currently being investigated by DOE. Retrieval in most concepts is not a simple reversal of waste emplacement. This study identified several concerns. Technological concerns are associated with remining and monitoring radioactivity in backfilled storage rooms and retrieval of breached canisters. Retrieval systems currently incorporated into DOE designs were found inadequate for handling breached canisters or those bound in the storage holes. Short holes containing single canisters could be overcored, but equipment must be developed to overcore large diameter holes. Safety concerns common to all repository concepts are protection of personnel from heat, traffic congestion, and deterioration of ground support. Concerns on radionuclide release were the radiation and radionuclides which would be released into the air and water present in a storage room if there were a canister breach. The confinement ventilation circuit air-flows provided in the DOE conceptual designs are just adequate for retrieval and are inadequate for retrieval from backfilled rooms