Saltcake Dissolution Studies in Single-Shell Tank Retrieval
Results of column dissolution experiments designed to evaluate the physical and chemical processes inherent to saltcake dissolution are presented along with model chemical equilibrium calculations. Two different compositions representing saltcakes in Hanford tanks were characterized, and porosities and permeabilities for a third composition based upon the saltcake waste in Tank 41H at the Savannah River Site (SRS) were also evaluated. Whereas the surrogates are all chemically similar, the presence of high phosphate loadings for the Hanford (HNF) simulants was noted as significantly affecting draining. The permeability was higher for the SRS saltcake, and the sodium nitrate loading in this saltcake was roughly 80% by weight compared to less than 60% by weight for the HNF compositions. Average values of the permeability and porosity were reduced for the surrogates based on Hanford Tanks S-112 and S-101. Here a secondary layer formed above the saltcake bed and was found to contain a large amount of gibbsite, Al(OH)3. Experiments with 3 molal (m) NaOH as a diluent, compared to water, did not result in additional layer formation that has been attributed to a change in local pH thereby altering the solid liquid equilibrium. Chemical analysis of the two HNF saltcakes indicated solids re-precipitation as a function of diluent added. The events were signified by large decreases in the nitrate and carbonate anion concentrations and were confined to low % dilution by weight values. Solids re-precipitation is noted as arising from the mixing of the dissolved saltcake stream with pockets of saturated interstitial liquor.
- Research Organization:
- Mississippi State University, Starkville, MS; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- FC26-98FT40395
- OSTI ID:
- 826285
- Resource Relation:
- Conference: Waste Management 2003 Symposium, Tucson, AZ (US), 02/23/2003--02/27/2003; Other Information: PBD: 26 Feb 2003
- Country of Publication:
- United States
- Language:
- English
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