Nuclear Waste:

DOE Lacks Critical Information Needed to Assess Its Tank Management Strategy at Hanford

GAO-08-793: Published: Jun 30, 2008. Publicly Released: Jun 30, 2008.

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The Department of Energy (DOE) manages more than 56 million gallons of radioactive and hazardous waste stored in 149 single-shell and 28 double-shell underground tanks at its Hanford Site in Washington State. Many of these aging tanks have already leaked waste into the soil. Meanwhile, DOE's planned process for emptying the tanks and treating the waste--mixing it with molten glass and solidifying it in canisters for storage--has experienced delays, lengthening the time the tanks will store waste and intensifying concerns about the tanks' viability during a long cleanup process. This report addresses (1) the condition, contents, and long-term viability of Hanford's underground tanks; (2) DOE's strategy for managing the tanks; and (3) the extent to which DOE has weighed the risks and benefits of its tank management strategy against the growing costs of that strategy. GAO analyzed numerous studies and reports on the tanks and interviewed DOE officials and other experts on relevant issues.

DOE lacks comprehensive information about the condition, contents, and long-term viability of Hanford's waste tanks. Although recent work indicates that the newer, double-shell tanks are generally sound structurally, the condition of the older, single-shell tanks is less certain. All the tanks contain a complex mix of radioactive elements and chemicals, making the proportions of constituents in any tank uncertain and emptying the tanks technically challenging. DOE officials acknowledged the lack of information about the condition of the single-shell tanks and are in early stages of a study to assess these tanks' structural integrity. The uncertainties over tank condition, especially as the time frames for emptying tanks are extended and the tanks age, raise serious questions about the tanks' long-term viability. DOE's tank management strategy involves continuing to use Hanford's aging tanks to store waste until they can be emptied, the waste treated, and the tanks closed. As work proceeds, however, DOE's time frames for completion are lengthening by decades, and the agency appears to be operating under more than one schedule. For example, DOE's internal milestone for emptying single-shell tanks is 19 years later than the date agreed to with its regulators. Although DOE and its regulators have been discussing new tank waste management milestones, as of May 2008, no decisions had been reached. Moreover, DOE's tank management strategy relies on assumptions that may be overly optimistic, such as assuming that emptying single-shell tanks will proceed significantly faster than it has to date. DOE lacks comprehensive risk information needed to weigh the benefits of pursuing its tank waste removal and closure strategy against growing costs. In particular, DOE has not assessed the risks posed by continuing to store waste in the aging tanks until the waste is removed and cannot demonstrate that benefits are commensurate with the costs of its tank management strategy. DOE is nevertheless moving forward with negotiating new tank waste milestones with its regulators.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: DOE gave priority to its efforts to gather key information about single-shell tank integrity. DOE assembled an expert panel--with subject matter experts from industry and academia--to study single-shell tank integrity at the Hanford Site. The panel met in January and May 2009 and ultimately issued a report in September 2009 (RPP-RPT-43116 Rev. 0) containing 33 recommendations for addressing single-shell tank integrity in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. The panel met again in January 2010 and issued a revised report in May 2010 (RPP-RPT-45921 Rev. 0). DOE has also taken actions to carry out recommendations of the panel including initiating an independent review to assess the integrity of tank components, including steel liners and concrete vaults; initiating an examination of previously-emptied single-shell tanks at Hanford to assess the potential condition of tanks which continue to store waste; and initiating a program to quantify the structural long-term viabiltiy of the tanks through the anticipated extended period of storage, retrieval, waste treatment, and tank closure. As a result of these actions, this recommendation is closed as implemented.

    Recommendation: To ensure that DOE has the fundamental information needed to make appropriate and cost-effective decisions about how to manage Hanford's tank waste, the Secretary of Energy should give priority to carrying out the department's assessment, in early planning stages as of 2008, of the structural integrity of Hanford's single-shell tanks--an effort we fully support--and ensure that this assessment includes examining the following key attributes: (1) corrosion of the tanks' inner steel shells; (2) the condition of concrete domes and outer shells, especially where waste has leaked; (3) the integrity of long-obscured parts of the tanks for tanks that have been emptied; and (4) the long-term viability of the tanks in light of their increasing age and DOE's extended schedule for waste retrieval, waste treatment, and tank closure.

    Agency Affected: Department of Energy

  2. Status: Closed - Implemented

    Comments: DOE took actions that addressed this recommendation. DOE assembled an expert panel to study single-shell tank integrity. A report was issued in September 2009 containing recommendations for addressing single-shell tank integrity in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. The panel met again and a revised report was issued in May 2010. This information was provided to the Washington State Department of Ecology and is being used by DOE to revise the Tank Closure and Waste Management Environmental Impact Statement to include an assessment of the risks posed by DOE's tank management strategy in light of the long-term use of the tanks to store waste. In addition, a modification to the Federal Facility Agreement and Consent Order, or Tri-Party Agreement, was finalized October 5, 2010, that establishes actions to improve the Tri-Parties' understanding of single-shell tank integrity, and includes an implementation plan for these actions. This recommendation is closed as implemented.

    Recommendation: To ensure that DOE has the fundamental information needed to make appropriate and cost-effective decisions about how to manage Hanford's tank waste, the Secretary of Energy should on a routine basis--such as every 3 to 5 years--specifically quantify the risks posed by the tank waste to workers, the public, and the environment and the risks posed by DOE's tank management strategy in light of the tanks' questionable viability.

    Agency Affected: Department of Energy

  3. Status: Closed - Implemented

    Comments: DOE took steps to address this recommendation. DOE assembled an expert panel to study single-shell tank integrity at the Hanford Site which issued two reports with recommendations (September 2009 and May 2010). The information was provided to the Washington State Department of Ecology and is being used by DOE to revise the Tank Closure and Waste Management Environmental Impact Statement. Although a draft settlement agreement and consent order with milestone changes was issued in August 2009, before the first panel report was issued, Ecology is still overseeing the revision of the draft EIS in order to inform decisions. This recommendation is closed as implemented.

    Recommendation: To ensure that DOE has the fundamental information needed to make appropriate and cost-effective decisions about how to manage Hanford's tank waste, the Secretary of Energy should work with the Washington State Department of Ecology and the Environmental Protection Agency to (1) reassess its tank management strategy, incorporating quantified risk information, and (2) develop and agree to realistic schedule and cost milestones.

    Agency Affected: Department of Energy

 

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