Alternatives for High-Level Waste Salt Processing at the Savannah River Site (2000) / Chapter Skim
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Strontium and Actinide Removal
Strontium and Actinide Removal
Pages 35-42
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From page 35... ...
Although the process details differ for some of the cesium removal options, in its simplest form, the process combines MST with the high-level waste salt solutions in a reaction vessel, mixing (typically for 24 to 48 hours) to promote the sorption of strontium and actinides with the MST solids, and then filtering to separate the MST solids from the "decontaminated" salt solutions.
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From page 36... ...
To this end, MST sorption kinetics for strontium and actinides, MST solids filtering, and MST solicis washing must be rapid enough to support the required process cycle times. The MST solids feed to the DWPF must have a composition that is compatible with the DWPF glass.
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From page 37... ...
As discussed elsewhere in this chapter, these MST concentrations may be too high to meet DWPF glass limits. Work on MST kinetics following 1995 startup operations has employed both real and simulated salt solutions using lower concentrations of MST (0.2 to 0.4 gram MST per liter of salt solution)
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From page 38... ...
The process for removal of MST solids from the tank waste has been described by SRS as having a potentially significant impact on the success of the strontium and actinide removal step, especially for the ion exchange, solvent extraction, and direct grout options. The baseline technology for MST solids removal is crossbow filtration, in which the MST-sludge slurry is streamed tangentially across the face of a microporous filter.
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From page 39... ...
. Site personnel acknowledged, however, that a complete variability study would need to be done to ascertain the effects of increased TiO2 loacling on glass clurability, homogeneity, liquiclus temperature, and viscosity, and that DWPF glass formulation models would need to be upclated to reflect this information before any of the processing options could be implemented.
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From page 40... ...
. Alternate methods to remove MST solids from the decontaminated salt solutions involving the testing of a small number of removal technologies identified in a recent Tank Focus Area report (U.S.
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From page 41... ...
SRS must demonstrate that strontium and actinide removal can be accomplished within saltstone limits and at the throughput rates required by the DWPF; and 2) SRS must demonstrate that the MST concentrations used to remove the strontium and actinides will not exceed compatibility limits for DWPF glass.
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From page 42... ...
1) SRS should resolve the technical uncertainties with the MST processing step as soon as possible by implementing an R&D program focused on the technical uncertainties noted above, and others that are consistent with a systems engineering approach to salt processing.
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