Tank Wastes Planned for On-Site Disposal at Three Department of Energy Sites: The Savannah River Site: Interim Report (2005)

The committee’s full task is to review and evaluate DOE’s plans to manage radioactive waste streams from reprocessed spent fuel that:

1. exceed the concentration limits for Class C low-level waste as set out in Section 61.55 of Title 10, Code of Federal Regulations;

2. DOE plans to dispose of on the sites specified below rather than in a repository for spent nuclear fuel and high-level waste; and

3. are stored in tanks at the Savannah River Site, South Carolina; Idaho National Engineering and Environmental Laboratory, Idaho; and the Hanford Reservation, Washington.

Congress asked the National Academies to assess the following:

1. DOE’s knowledge of the physical, chemical, and radiological characteristics of the waste in the tanks;

2. actions that DOE should consider to ensure that management plans comply with the performance objectives for land disposal facilities;

3. DOE’s monitoring plans to verify compliance with the aforementioned performance objectives;

4. existing technology alternatives for waste management;

5. technology gaps for waste retrieval and management; and

6. any other matters that the committee considers appropriate and directly related to the subject matter of the study.

For its interim report, the committee was charged to examine whether DOE’s plans to manage its radioactive waste streams at the Savannah River Site will comply with the performance objectives of 10 CFR 61.

Compliance with the performance objectives depends upon the amount of radioactive material left onsite, the manner in which it is immobilized, its interaction with the environment and its interaction with ecological and human receptors. As noted above, some critical data, analyses and plans were not available when this report was written: the performance assessment for closed tanks; plans for residual waste characterization; plans for tank annuli and tank-system piping; support for assumptions, estimated levels of conservatisms, and sensitivity analyses for performance assessment calculations; and long-term monitoring plans are examples of the missing information. In this interim report, the

committee has fulfilled the charge to the extent possible by focusing mainly on the amount of waste left in the tanks and in the Saltstone Vaults at the Savannah River Site. The committee has made findings and recommendations on four major issues:

1. near-term and long-term risks in the context of tank waste removal and the schedule for tank closure;

2. the tank space crisis and options to alleviate the crisis;

3. the roles of the Class C limits and the performance objectives in determining whether on-site disposal is acceptable; and

4. research and development needs, particularly in-tank and downstream processing consequences of chemical cleaning options, technologies to assist in tank waste removal, including robotic devices, and studies of the projected near- and long-term performance of tank fill materials, such as grout.

The committee is still examining the interactions of the tanks and the saltstone with the surrounding environment; the role of environmental monitoring; the role of the point of compliance in meeting the performance objectives; and the role of modeling in the performance assessment. These topics are relevant to all three sites and will be addressed in the final report, along with the rest of the statement of task. For a substantive analysis, the information described above will be needed at all sites. In addition, because the wastes and the site conditions differ, the topics investigated in this report will also be examined at the Hanford and Idaho sites. These investigations will have an impact on the committee’s views on the Savannah River Site. Hanford will likely offer the committee the greatest challenge because it is the oldest site, has many tanks that have leaked, and has the most complicated wastes because of the various management practices and several chemical processes that generated the wastes, including the earliest processing technologies. The committee may also extend the comments on the Savannah River Site found in this report, as additional information on this site becomes available during the period of this study.