VERIFICATION OF THE DEFENSE WASTE PROCESSING FACILITY PROCESS DIGESTION METHOD FOR THE SLUDGE BATCH 6 QUALIFICATION SAMPLE [report]

D. Click, M. Jones, T. Edwards
2010 unpublished
digestions. The average Al concentration in the CC digestions is ~6.6% lower than the PF digestions, and the average Al concentration from the AR digestions is ~7.7% lower than the PF digestions indicating an aluminum species that is sparingly soluble in acid digestions.  A statistical difference of means at the 5% significance level is noted for Fe, Mn, Na, Ni, and Th (for the elements greater than 1.0 Wt% of total solids). As with the SRAT Receipt sample, Fe, Mn, Na, and Ni concentrations
more » ... i concentrations are lower in the CC digestions compared to the AR and PF digestions. The mean Th concentration is statistically different in the CC digestions compared to the AR digestions, but there is no statistically significant difference compared to the PF digestions. The results from a statistical and relative comparison of the data suggest that the DWPF CC method may not be completely solubilizing the following:  Fe, which is ~11-16% lower in the CC digestions relative to the PF and AR digestions.  Mn, which is ~5-7% lower in the CC digestions relative to the PF and AR digestions.  Ni , which is ~10-12% lower in the CC digestions relative to the PF and AR digestions.  Th, which is ~4-25% lower in the CC digestions relative to the PF and AR digestions.  The low results observed for Fe, Mn, and Ni in the CC digestions of the SB6 SRAT Receipt and SRAT Product are not mirrored in the ARG results indicating a potential problem with digestion of the sludge matrix. In addition, the mean Na concentration is ~4% lower in the CC digestions versus the aqua regia digestions. The results from Th analysis of SB6 SRAT Receipt and SRAT Product include the following:  Calcium thorium fluoride (Ca 0.5 Th 0.5 F 3 ) is a constituent of the precipitated solids in the SRAT Receipt CC digestions (from C-XRD analysis). Undisssolved solids in the SRAT Product have not been analyzed to date, but the C-XRD analysis is expected to yield a similar result.  ICP-AES measurements of Th in the CC digestions at 1.3 kW using the Th 374.118 nm and Th 401.913 nm emission lines in axial mode gave comparable results to ICP-MS measurements performed at 1.35 kW.  ICP-AES measurements of Th in the CC digestions at 1.1 kW in both radial and axial modes are ~40% lower than ICP-MS measurements obtained at 1.35 kW.  ICP-AES Th results from axial and radial modes at 1.1 kW (using the 318.019 nm emission line) of AR and PF digestions were comparable to ICP-MS measurements at 1.35 kW.  Th interferes with the U 367.007 nm emission line, and an inter-element correction (IEC) was applied to all U data (IEC factor of ~0.2 in radial mode and ~0.15 in axial mode).  No significant interference from U on Th emission lines utilized in this study was noted. Based on the comparison of digestion methods tested at SRNL for SB6, we present the following short and long-term recommendations:  A dissolution study should be performed on the SB6 WAPS sample by SRNL, which consists of the final composition of the sludge (the SB6 Blend), to determine if the Fe, Mn, Ni, and Th concentrations are consistently lower in the CC digestions versus the AR and PF methods for SB6.  Given the problems seen with measuring Al by the CC method for SB5 and that a SB5 heel remains in Tank 40, the DWPF lab should monitor the Al concentration in the first 10 SRAT
doi:10.2172/982222 fatcat:egomh3s7bvdodfgcugp6azc3tu