Nuclear Waste

Highly radioactive waste is leaking from underground storage tanks at the Energy Department's (DOE) Hanford Site in Washington state and has migrated through layers of rock and soil, known as the vadose zone, to groundwater. DOE, which assumed that the vadose zone would prevent waste from ever reaching groundwater, has no strategy to investigate the zone and does not know what information is needed to make key cleanup decisions. For example, the lack of information about the vadose zone has major implications for how to retrieve the remaining wastes from tanks that have leaked because at least one retrieval option would cause more liquid wastes to leak into the ground.

GAO noted that: (1) DOE's own reviews conclude what outside experts have been saying for some time; (2) DOE's understanding of how wastes move through the vadose zone to the groundwater is inadequate to make key technical decisions on how to clean up the wastes at the Hanford Site in an environmentally sound and cost-effective manner; (3) for many years, DOE assumed that wastes would move slowly, if at all, through the vadose zone; (4) therefore, DOE never issued a comprehensive plan to assess vadose zone conditions and funded few studies of the vadose zone; (5) outside experts have pointed out, however, that DOE cannot credibly estimate the site's long-term risk to the public or select the most efficient cleanup strategies unless it understands conditions in the vadose zone; (6) for example, the lack of knowledge about the vadose zone has major implications for how to go about retrieving the remaining wastes from tanks that have leaked or are leaking because at least one retrieval option would cause more liquid wastes to leak into the ground; (7) DOE has no strategy in place for investigating the vadose zone; (8) DOE assigned low funding priority to most proposed studies of it, responded slowly to experts' recommendations for improving ongoing studies, did not integrate the information needs of the three organizational units responsible for cleanup activities, and does not know what information is needed to make key cleanup decisions; and (9) with the emerging evidence of waste migration from leaking tanks to the groundwater, DOE has begun to develop a strategy to investigate the vadose zone.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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