Investigation of Rheological Impacts on the Defense Waste Processing Facility's Sludge Slurry Feed as Insoluble Solids and Wash Endpoints are Adjusted
- Savannah River National Laboratory, Westinghouse Savannah River Company, Aiken, SC 29808 (United States)
The Savannah River Site (SRS) is currently pursuing an aggressive program to empty its High Level Waste (HLW) tanks and immobilize its radioactive waste into a durable borosilicate glass in the Defense Waste Processing Facility (DWPF). To create a batch of feed for the DWPF, several tanks of radioactive sludge slurry are combined into one of the million gallon (i.e. 3.79 E06 liters) feed tanks for DWPF. Once these sludge slurries are combined, the soluble sodium and weight percent total solids are adjusted by a 'washing' process. The 'washing' process involves diluting the soluble sodium of the sludge slurry with inhibited water (0.015 M NaOH and 0.015 M NaNO{sub 2}) and allowing the sludge slurry to settle into two layers. The two layers in the tank consist of a clear supernate on top and a layer of settled sludge solids on the bottom. The clear supernate layer is then decanted to another hold tank. This 'washing' process is repeated until the desired wash endpoint (i.e. sodium concentration in the supernate) and weight percent total solids are achieved. A final washed batch of feed consists of approximately 500,000 gallons (i.e. 1.89 E06 liters). DWPF has already processed three batches of feed and is currently processing a fourth. Prior to processing a batch of feed in the DWPF, it must be well characterized. Samples of the prepared feed batch are sent to the Savannah River National Laboratory (SRNL) for this characterization. As a part of the SRNL characterization for the fourth batch, rheology measurements were performed. Measurements were performed at different weight percent insoluble solids loadings to mimic potential facility processing scenarios (i.e. mixing/pumping of concentrated sludge slurry). In order to determine the influence of the soluble Na on the rheological properties of the sample, the supernate of the 'as received' sample was adjusted from 1 M soluble Na to 0.5 M soluble Na by using a lab scale version of the 'washing' process. Rheology measurements were also completed for the 'washed' sample at different weight percent insoluble solids loadings. The flow curves (shear rate vs. shear stress) generated from the 'as received' and 'washed' samples were modeled to obtain the yield stresses and consistencies. These results were then compared to each other to determine the differences. The results of the SRNL studies showed that increasing the insoluble solids loading typically increased both the plastic viscosity and yield stress for the 'as received' and 'washed' samples. The studies also showed that the 'washed' sample had slightly different physical and rheological properties (i.e. yield stress and plastic viscosity), when compared to the 'as received' sample. These differences appear to be a function of sodium concentration and another physical property change. It is assumed that the physical property change was related to an actual shift in the particle size of the insoluble solids of the sample. However, this measurement was not completed as a part of this study due to the radioactivity of the sample. A method is currently being developed for determining particle sizes of radioactive samples. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
- OSTI ID:
- 21208729
- Report Number(s):
- INIS-US-09-WM-06274; TRN: US09V1040079516
- 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; 2 refs
- Country of Publication:
- United States
- Language:
- English
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