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 sludge slurry are combined into one of the million gallon, i.e. 3.79E06 liters, feed tanks for DWPF. A batch of feed nominally consists of 500,000 gallons, i.e. 1.89E06 liters. After a batch of feed is prepared, a portion of the batch, 26,500 liters, is transferred to DWPF. This batch is then chemically adjusted in the Chemical Processing Cell, CPC, prior to being fed to the melter to make the final product; canisters filled with glass. During the processing of the third batch, or Sludge Batch 2, of feed through the DWPF CPC, pumping and transfer problems were noted. These problems hindered the processing of the feed through the CPC, and thus impacted canister production in DWPF. In order to investigate the root cause of these problems, data were collected and evaluated for possible trends. One trend noted was the relationship between the pH, solids loading concentration, and temperature of the feed. As any one of these three variables changed, the rheological properties of the feed appeared to change. To determine the dependency of the rheological property, samples were obtained and shipped to Savannah River National Laboratory's, SRNL, Shielded Cells Facility. The samples were processed under two sets of conditions and rheological measurements obtained. The results of the SRNL studies showed that the ending pH of the samples impacted the rheological properties of the sample. Lowering the pH of the sludge slurry resulted in lower plastic viscosity and yield stress values,thus alleviating the processing problems. Increasing the solids loading typically increased both the plastic viscosity and yield stress. There was minimal or no dependency on temperature.
PDF
download
878987797
028-85220240
