Alternative High-Level Waste Treatments at the Idaho National Engineering and Environmental Laboratory (1999) / Chapter Skim
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13 Summary of Conclusions and Recommendations
13 Summary of Conclusions and Recommendations
Pages 107-120
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From page 107... ...
WHAT SHOULD BE DONE: HLW CALCINE (CHA"ER 11) The committee could identify no significant present hazard to public health or to the environment due to the storage of solid calcine in the bins at INEEL, which have been designed to be secure for at least 500 years.
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From page 108... ...
However, the committee emphasizes that this course should be subject to continued review and updating of comparative risks as additional information may be developed in the decades to come with respect to site availability, acceptable waste forms for such a site, and available transportation to such a site. This recommendation does not challenge the general strategy of geologic c isposal for HLW, which is an issue outside the scope of this study, but emphasizes that decisions on the ultimate fate of the INEEL HLW should be postponed pending the resolution of waste management issues noted above and pending the results of adequate risk analyses.
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From page 109... ...
Consequently, the committee believes that a risk analysis for the actions recommended above for both HLW calcine and SBW should be conducted promptly, and should include a comparison of the risks associated with INEEL HLW calcine and SBW to the risks associated with site inventories of other radioactive wastes. A sufficiently rigorous analysis should be performed to establish the current risks and to assess the changes in risk due to treatment options.
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From page 110... ...
However, the risk is substantial that the program will fail to achieve the separations goals (especially Class A requirements) without a substantial and sustained test program using actual aged calcine.
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From page 111... ...
Critical process vulnerabilities to be investigated should include solvent extraction recycle and degradation, impurity buildup in the organic phase, temperature effects, and formation of precipitates and emulsion. In particular, the behavior of RCRA constituents such as Pb and Hg needs to be clarified in tests win a range of actual aged calcines, because of lmown difficulties in stripping Pb and Hg from the organic phase and the formation of interracial Pb precipitates.2 Additional process testing is needed to solve these difficulties in order to demonstrate He capability to meet Class A separations requirements, which are extraordinarily demanding and therefore likely to require significant resources.
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From page 112... ...
However, several of the nonradioactive chemical constituents of INEEL HLW calcines will complicate the successful extraction of the relatively small mass of TRU elements present. The chemical process design will depend on the chemical composition of a TRUEX feed solution and its inherent variability, as derived from the variations in calcine compositions upon retrieval and after any subsequent blending operations.
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From page 113... ...
A successful pilot-scale demonstration of the proposed chemical separations process should be conducted prior to the commitment of resources to a full-scale system. Since downstream unit operations can be negatively impacted as a result of even minor changes in upstream operations, the testing should use actual aged calcine, full sequencing of operations, and reasonable run duration.
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From page 114... ...
The limited data for these alternative waste forms indicates a lack of current support for exploring these possibilities, win several documents given to He committee dating back to 114 Alternative High-Level Waste Treatments at INTEL
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From page 115... ...
From these chapters, the committee concludes that in any waste forms and processes for their creation can be identified. For example, Chapters 6 and 7 cite cementation and SSF as probably less costly processes than direct vitrification for the HLW calcine, but they produce final waste forms that would require furler development and proper qualification for acceptance for disposal.
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From page 116... ...
However, clean closure of the tanks and bin sets is impractical, insofar as some residual radioactivity, and possibly hazardous chemical constituents, will remain in the facilities. The options for closure of the tank farm and bin sets that are proposed in DOE literature are all possible from a technical standpoint.
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From page 117... ...
Tested on lab scale, mostly with simulants; limited testing with actual aged calcine. The application on INEEL HLW calcine poses problems (e.g., with constituents that interfere with separations processes)
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From page 118... ...
The INEEL HLW could be relegated to this second repository program, insofar as the Yucca Mountain repository, if built, is slated to be filled by 2035. The waste form performance and waste acceptance criteria for the second repository program are not yet known, and may differ from those of the first repository, if indeed a second repository is mandated.
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From page 119... ...
At this stage in the process, acquiring data to replace or validate key assumptions is a more informative and useful activity than conducting design studies and cost estimates that are based on assumptions yet to be validated. ~ addition to addressing uncertainties, other important features of a waste management plan, in the committee's view, are to adopt approaches that achieve risk and cost reductions and that support the thoughtful use of science and engineering in developing disposal strategies and waste forms.
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From page 120... ...
0ior~s are notfollowed, then the recommendations below apply. Characterization Calcine Dissolution Solid-Liquid Separations Cs, Sr, and TRU Separations Solidification Options for HLW Calcine: Vitrification Cementation Other Immobilization Options Disposal Requirements Adequately sample and characterize the calcine and SEW to reduce uncertainties in retrieval, dissolution, SLS, and other downstream proc esses.
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