Modeling of Pilot-Scale Salt-cake Dissolution
- Diagnostic Instrumentation and Analysis Laboratory, Mississippi State University, 205 Research Blvd, Starkville, MS, 39759 (United States)
- Applied Research Center, Florida International University, 10555 West Flagler St, EC 2100, Miami, FL, 33174 (United States)
Large portions of the high-level waste present at the Hanford Site and Savannah River Site are comprised of porous salts with associated interstitial liquors. Various processes have been proposed wherein the aqueous phase is removed followed by dissolution of the salt with further mixing or blending of the resulting stream in a receiver tank. This leads to a large reduction in the radioactivity for the dissolved salt-cake; however, the interstitial retrieval process is hindered by capillary forces within the salt-cake pores and large aqueous phase fractions may remain. Thus, the interim stabilized or low-curie salt processes may have less separation effectiveness than desired. In addition, based on the initial extent of pretreatment of the waste, the salt-cake may be either unsaturated or hydraulically saturated. Different interactions are expected based on the contact of the diluent with the salt and/or on mixing the diluent with the salt and some fraction of interstitial liquid. The initial approximation is that the dissolution is governed by the associated thermodynamics of the system. This may be correct assuming sufficient time for contact between the salt and diluent has occurred. Pilot-scale simulant salt-cake dissolution experiments have been conducted by the Applied Research Center (ARC) at Florida International University. As part of a companion program, these experiments have been modeled at the Diagnostic Instrumentation and Analysis Laboratory (DIAL, Mississippi State University) using the Environmental Simulation Program (ESP, OLI Systems, Inc.). Hanford simulant compositions were examined under unsaturated and saturated conditions. To account for channeling that occurred during the unsaturated experiment, additional operations were required for the process flowsheet. Direct modeling of the saturated bed was possible without this consideration. The results have impacts on the salt-cake retrieval process. First, depending on the extent of interstitial liquid contained in the waste, recycling may be necessary; removal of the resulting aqueous stream at the largest specific gravity consistent with the operating safety basis ensures productive use of water. Secondly, direct modeling of a given waste dissolution must consider variations in the extent of channeling such that limits can be established on anticipated concentrations expected during the course of the retrieval. Finally, the ability to account for heterogeneous dissolution has been accounted for. Details regarding the development of the modeling strategy as well as knowledge gained regarding flowsheet development are provided. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
- OSTI ID:
- 21208750
- Report Number(s):
- INIS-US-09-WM-06300; TRN: US09V1061079537
- Resource Relation:
- Conference: Waste Management 2006 Symposium - WM'06 - Global Accomplishments in Environmental and Radioactive Waste Management: Education and Opportunity for the Next Generation of Waste Management Professionals, Tucson, AZ (United States), 26 Feb - 2 Mar 2006; Other Information: Country of input: France; 14 refs
- Country of Publication:
- United States
- Language:
- English
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