Alternatives for High-Level Waste Salt Processing at the Savannah River Site (2000) / Chapter Skim
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Introduction
Introduction
Pages 5-19
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From page 5... ...
Under the statement of task for this study, the committee reviewed the DOE work to identify alternatives for separating cesium from high-level waste at the Savannah River site. This review addressed the following four charges from DOE: · Was an appropriately comprehensive set of cesium partitioning alternatives identified and are there other alternatives that should be explored?
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From page 6... ...
. The SRS is host to an extensive complex of facilities that included fuel and target fabrication plants, nuclear reactors, chemical processing plants, underground storage tanks, and waste processing and immobilization SAVANNAH RIVER SITE N Scale (Kilometers)
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From page 7... ...
3 There are 51 tanks in the F and H Tank Farms; of those, four are process tanks not being used for storage, two have been filled with grout, and one is empty. The data used to prepare these tables are from the Savannah River Waste Characterization System database and were provided to the committee by representatives at Westinghouse Savannah River Company in a specially prepared document (Fowler, 2000~.
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From page 8... ...
sludge separation strontium and actinide removal ceslum removal * / | cesium | | sludge | 1 1 strontium and actinides · strontium · cesium O actinides DWPF Glass - ~ | Saltstone | FIGURE 1.2 Schematic processing flow sheet for radionuclide removal from high-level waste at Savannah River.
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From page 9... ...
The saltcake, producecl by crystallization after the alkaline waste was processed through evaporators to remove excess water, will dissolve when additional water is addecl during waste processing. The saltcake ancl sludge contain substantial quantities of supernate within their mass; this interstitial supernate corresponds to about half of the total supernate in the tanks.
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From page 10... ...
10 Altematives for High-Level Waste Salt Processing at the Savannah River Site TABLE 1.2 Waste Volumes and Principal Radionuclide Contents of HighLevel Waste Tanks at the Savannah River Site Tank Waste Volumes (106 L) Soluble Radionuclides Sludge Number - Total Sludge Saltcake Free Alpha 90sr 137Cs 137Cs Waste Supernate (103 Ci)
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From page 11... ...
Salt Disposal A variety of secondary waste streams are formed during the processing operations described above. Some of these waste streams are recycled back to the tanks, some are recycled within the various processing operations, and yet other wastes are treated and stabilized for burial.
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From page 12... ...
The product of this reaction could be removed from the salt solutions by filtration for subsequent processing and immobilization. Subsequently, the removal of cesium from the salt solutions would be accomplished by a yet-to-be-chosen process from among precipitation, ion exchange, or solvent extraction processes.
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From page 13... ...
In 1996, the Defense Nuclear Facility Safety Board (DFNSB) issued Recommendation 96-1, urging DOE to hall all further testing and to begin an investigative effort to understand the mechanisms of benzene formation and release with the following recommendation (Defense Nuclear Faci~ities Safety Board, 1996; see Appendix F)
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From page 14... ...
Some technical uncertainties remain to be resolved, of which the major ones are the kinetics of sorption on MST and the amount of titanate acceptable for proper quality of the vitrified waste form. Work to address these concerns and consideration of alternative processes are discussed in Chapter 3.
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From page 15... ...
This history includes long periods of time in which solvents of various organic species have been exposed to high-radiation fields without experiencing catastrophic degradation rates. Solvent extraction operations usually consist of selectively transferring components from an aqueous, acidic stream into the organic stream.
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From page 16... ...
Direct Disposal in Grout Direct disposal of the tank waste following removal of strontium and actinides is very similar to the saltstone process that was to have been used to dispose of the salt solutions from ITP operations as low-level incidental waste. Although it is a rather mature technology and has already been demonstrated at the site for less radioactive salt solutions, the degree of retention of cesium may not satisfy regulatory requirements.
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From page 17... ...
For Task 3, regarding identification of any significant barriers to the implementation of the final four options selected for cesium processing, the committee concluded that any of these four alternative processes probably could be made to work if enough time and funding were devoted to overcoming the remaining scientific, technical, and regulatory hurdles. In response to Task 4, to comment on the adequacy of the planned research and development activities for the final four alternative processes, the committee observed that "R&D resource allocations for the four alternative processing options have been markedly inequitable." This funding disparity explains in part the different levels of technical maturities of the four processing options, independent of their likelihood of success.
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From page 18... ...
Different concerns are associated with the different alternatives; that is, grout faces the most formidable regulatory barriers but is the most mature technically, while solvent extraction has fewer regulatory barriers but is the least mature technically. The TPB and front end strontium and actinide removal MST processes have no particular regulatory barriers.
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From page 19... ...
Whereas SRS schedules may be undergoing change at any point in time, it is necessary that proposed evaluation, R&D, and demonstration schedules correspond as well as possible with the time requirements imposed by SRS for implementation of the waste treatment.
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