Tank Wastes Planned for On-Site Disposal at Three Department of Energy Sites The Savannah River Site: Interim Report (2005) / Chapter Skim
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III Findings and Recommendations
III Findings and Recommendations
Pages 37-52
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From page 37... ...
. Management, treatment, and eventual disposal of tank wastes at DOE sites involve a complex and interdependent set of decisions, characterized by uncertainties in the consequences of each decision element.
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From page 38... ...
The tank heels that remain after bulk removal contain a smaller quantity of waste that is less mobile and constitutes a much lower near-term probability of release. Finding 1b: The Savannah River Site Federal Facility Agreement has schedules for waste removal from and closure of the noncompliant tanks.
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From page 39... ...
, will also reduce risks although it is more difficult to achieve. The committee agrees with DOE's and South Carolina's overall approach to tank waste removal at the Savannah River Site: bulk removal and immobilization of the waste is the highest priority to reduce the probability of release of radioactive materials to the environment in the near term.
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From page 40... ...
As previously noted, the long-term performance of the tank fill materials, especially Smart Grout, has not been adequately established. To lend confidence to the assumptions used in the performance assessment, a delay in tank closure would give DOE more time to evaluate grout formulation and techniques further and to conduct studies of projected long-term performance by laboratory and field testing of tank fill materials (see Recommendation 4)
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From page 41... ...
Finally, as DOE considers delaying closure for some tanks, it has to evaluate advantages and disadvantages from both a risk and a cost perspective. If DOE can relax other constraints on tank waste removal, such as the tank space problem, then delaying tank closure could free up funds planned for closure activities, and those funds could be devoted to enhancing waste removal, waste processing, and confidence in the near- and long-term performance of the waste immobilization and tank fill materials.
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From page 42... ...
DOE plans to address the tank space problem in the near term by implementing the interim salt waste DDA process. The DDA process would alleviate some of the space problem.
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From page 43... ...
DOE's analyses indicate that both the nonradioactive and the radioactive compositions of samples taken from the off-gas condensate tank, and subsequently the recycle concentrate tank, which collects all DWPF recycle stream, reflect the composition of the waste sludge that is being vitrified. According to the same analyses, the total radioactivity in the recycle stream amounts to about 0.001 Ci/liter with about two thirds of the radioactivity coming from cesium-137 and one third from alpha-emitting 56 Several Govemment Accountability Office reports have commented on the challenges of bringing online and operating large-scale waste processing facilities (GAO, 1997a, 1997b, 1999, 2003,2004)
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From page 44... ...
DOE is currently sending the DWPF recycle stream to the tank farm because of future potential use in waste processing (e.g., batch preparation) ; however, this waste stream currency does not appear to be used for any purpose and the near-term benefits of more tank space may outweigh the long-term detriment of introducing additional water into the system.
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From page 45... ...
Nuclear Regulatory Commission has not been defined in the NDAA and is now being applied for the first time. TABLE 5 Management Standards for Wastes Stored Site and the Idaho National Laboratory Non-HLW Class C or Less HLW Default classification of all highly radioactive wastes from reprocessing of spent nuclear fuel DOE, in consultation with the USNRC, may decide that the wastes do not require deep geologic disposal High-activity radionuclides removed to the maximum extent practical Disposal must meet performance objectives of 10 CFR 61, subject to USNRC monitoring and reporting to congressional committees Disposal must be approved by host state Must be disposed of Need not be disposed of in in deep geologic deep geologic repository repository NOTE: Standards established in Section 3116 of the Ronald Reagan National Defense Authorization Act of 2005.
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From page 46... ...
Indeed, if the Class C limits alone were the criteria for acceptance of waste in the Saltstone Disposal Vaults, all of the cesium-137 in the high-level waste tanks at the Savannah River Site could potentially go into the saltstone. Congress recognized the importance of the performance objectives for evaluating site-specific near-surface disposal of waste in Section 3116 of the NDAA by explicitly including these objectives as the basis for management standards to be applied to waste in high-level waste tanks at the Savannah River Site and Idaho.
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From page 47... ...
. Research and Development Needs Finding 4: Focused research and development could help DOE reduce the amount, improve the immobilization, and test some of the assumptions used in performance assessment of tank waste to be disposed of at the Savannah River Site.
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From page 48... ...
These research and development activities would be carried out either in parallel with the current baseline approach to tank waste removal and closure or until a specific technology becomes ready to be deployed. These technologies will likely require pilot-scale tests with tank mockups and with surrogate heels to test their effectiveness before full-scale deployment.
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From page 49... ...
The efficacy of bulk retrieval in tanks with coils is uncertain: good cleaning of tank surfaces appears to have been achieved in zones beneath the risers but the amount of residual waste remaining in the 'dead zones' between risers and in the tank periphery is unknown. However, the use of remotely controlled and robotic devices to retrieve residual tank waste also faces challenges as a result of the jungle of piping and other obstructions that severely limit the size and mobility of retrieval devices.
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From page 50... ...
In the interim, reseanch and development investments in residual waste retrieval technologies suitable for tanks containing cooling coils or other obstructions appears pnudent. Near-Tern' and Long-Tern' Performance Studies for Tank Fill Material As previously mentioned, DOE's assumptions about the long-term performance of the tank fill materials, especially Smart Grout, have not been verified with empirical tests or SIDEBAR 2 USE OF TEST BEDS FOR THE STUDY OF RETRIEVAL TECHNIQUES Waste retrieval (bulk or heel)
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From page 51... ...
Many of these research and development needs were identified by Westinghouse Savannah River Company at the committee's meetings; the committee is not aware of any active research on tank fill materials performance for the Savannah River Site. Ongoing research on building materials, mainly for civil engineering purposes, could also provide a valuable insights for applications involving waste immobilization.
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From page 52... ...
An updated, albeit partial, environmental impact statement for the Saltstone Vaults was provided to the committee. The environmental impact statement for all tank closures is not yet available (see Appendix B)
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