Processing simulated oxalated high-level waste through a vitrification feed preparation flowsheet

Following an initial vitrification phase at the West Valley Demonstration Project (WVDP), residual tank waste, consisting of cesium-loaded zeolite in Tank 8D-1 and a mixture of neutralized plutonium-uranium extraction (PUREX) sludge and thorium extraction (THOREX) waste in Tank 8D-2, may require additional processing. A proposed treatment process involves adding oxalic acid to Tanks 8D-1 and 8D-2 to remove the residual activity. The oxalic acid will dissolve solids and increase the mobility of the radioactivity components. One option is to process the oxalated waste directly through the vitrification process. Laboratory-scale tests at the Pacific Northwest National Laboratory (PNNL) with simulated oxalated waste have evaluated the effect of oxalated waste in the melter feed flowsheet, for comparison to the baseline WVDP flowsheet. Comparisons were made on the basis of rheology, pH, and glass redox potential.