At Hanford, DOE’s planned cleanup process entails retrieving waste  from the tanks; mixing this waste with molten glass through a process  known as vitrification; and pouring the waste into steel canisters, where it  will cool and solidify. Uncertainties Raise Questions about Tanks’ Long-Term Viability

Neither DOE nor its contractors have comprehensive information about  the overall integrity or contents of Hanford’s underground waste tanks; as  a result, they cannot predict the tanks’ long-term viability with any degree  of certainty. Although recent studies indicate that the newer, double-shell  tanks are generally sound, the integrity of many single-shell tanks has been  compromised in the past, and the condition of the rest is difficult to  ascertain. DOE tank management officials acknowledge that the integrity of the  single-shell tanks is a continuing uncertainty—with potentially significant  effects on DOE’s tank management strategy—and have taken steps, such  as limited examination of the tanks’ external structure and in-tank  observations and analysis, to learn more about the condition of the single- shell tanks. The radioactive  elements, chemicals, and miscellaneous materials have been extensively  mixed and commingled over the years. Some of these tanks may be more than 80 years old by the  time they are emptied and the tank farms are closed (see app. DOE’s Tank Management Strategy Involves Continued Use of the Aging Tanks, Perhaps for Decades

DOE’s strategy for managing Hanford’s tanks involves transferring waste  from the single- to the double-shell tanks and using the latter to store the  waste until it can be treated and the tanks closed. 3). DOE Appears to Be Operating under More Than One Schedule

Within DOE’s general strategy for addressing the aging tanks, time frames  for completing specific actions, such as emptying the tanks and closing  them, remain in flux. Moreover, DOE has made limited progress in actually  emptying the tanks, and at its present rate of progress, it will not achieve  the milestones it agreed to. Emptying single-shell tanks will proceed two to three times faster than it  has to date. DOE Cannot Weigh the Benefits of Pursuing Its Tank Management Strategy against Growing Costs Because It Lacks Critical Information

Without a comprehensive analysis that quantifies the risks of tank waste  and the proposed strategies to address them, DOE lacks critical  information to weigh the benefits of pursuing its present strategy against  costs that continue to climb. Recommendations for Executive Action

To ensure that DOE has the fundamental information needed to make  appropriate and cost-effective decisions about how to manage Hanford’s  tank waste, we recommend that the Secretary of Energy take the following  three actions:    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: corrosion of the tanks’  inner steel shells; the condition of concrete domes and outer shells,  especially where waste has leaked; the integrity of long-obscured parts of  the tanks for tanks that have been emptied; and 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. Thus, in our view,  DOE’s current knowledge is not adequate, for the single-shell tanks in  particular, to assess the appropriateness of the department’s tank  management strategy—which involves continuing to store waste in aging  tanks until they can be emptied and closed—especially in light of  lengthening cleanup time frames.
Why GAO Did This Study

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.

What GAO Found

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.