Irradiation Effects on Phase-Separation Performance Using a Centrifugal Contactor in a Caustic-Side Solvent Extraction Process
A test program has been conducted to determine the extent to which irradiation of a calixarene-based cesium extractant affects-separation of the organic (solvent) phase from aqueous solutions with which it is contacted in a prototype extraction flowsheet. A caustic-side solvent extraction process, known as CSSX, has been developed for the selective removal of cesium from wastes generated by the processing of irradiated nuclear reactor fuels. This process consists of a cascade of mass transfer stages in which cesium is transferred from an aqueous feed into the CSSX extractant (BOBCalixC6), the extract is scrubbed with 0.05 M nitric acid to remove coextracted elements, and the solvated cesium is stripped (or back-extracted) into 0.001 M HNO{sub 3}. Removal of cesium from stored waste supernatants is desirable as a means of segregating high-activity cesium-137 ({sup 137}Cs) from the solution, thereby reducing the volume of material that must be processed and disposed of as high-level waste. The CSSX process is one of three cesium removal technologies currently being considered for deployment for treatment of wastes that are stored at the U. S. Department of Energy's (USDOE's) Savannah River Site (SRS). The irradiation tests described in this report were designed to simulate the effect of 2 years of continuous solvent irradiation under conditions present in the stripping and extraction sections of the CSSX cascade. Stated simply, the irradiation tests consisted of continuously mixing an aqueous process solution (either simulated SRS waste supernatant or dilute nitric acid) with the CSSX solvent. The aqueous solutions used in testing were spiked with {sup 137}Cs at known activity levels. Test durations were determined based on the activity levels in the experiment and the estimated solvent exposures to radionuclides in a full-scale CSSX facility.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 786763
- Report Number(s):
- ORNL/TM-2001/91; TRN: US0200485
- Resource Relation:
- Other Information: PBD: 12 Sep 2001
- Country of Publication:
- United States
- Language:
- English
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