Tc-99 and Cs-137 Volatility from the DWPF Production Melter During Vitrification of the First Macrobatch of HLW Sludge a
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2 molten glass. The top surface area of the melt is 2.6m and is 95% covered by a cold cap while the wasteglass frit slurry (-60 wt% water) is being fed to the melter. The feed rate is nominally 2L/min. Note in Table I that there was approximately a 21 month period between the first two and the third glass sample. These samples were taken from the pour stream of the melter using a special removable sampler that fit into the top of a canister and collected -40 grams of glass. The glass samples were sent from the DWPF to the Savannah River Technology Center (SRTC) where they were analyzed. Samples of the HLW sludge slurry taken from the 3.7E06L DWPF feed-tank (Tank 51) to the DWPF were also analyzed at SRTC.
Table I. Properties of the Macrobatch One Campaign in the DWPF Volume of Sludge Slurry Vitrified Amount of Glass Produced Number of Canisters Filled First Glass Sample Taken During Pouring of Canister 50 Second Glass Sample Taken During Pouring of Canister 61 Third Glass Sample Taken During Pouring of Canister 409
-1.6 Million Liters -0.9 Million Kilograms 495 Taken on 9/2/96 Taken on 9/23/96 Taken on 6/30/98
EXPERIMENTAL The sludge slurry and glass samples had to be dissolved and analyzed in order to determine their composition. These dissolutions were performed remotely in the Shielded Cells of SRTC using procedures developed and tested at SRTC. The resulting solutions were diluted and removed from the Shielded Cells for analyses by various techniques. For the HLW sludge slurry, a large sample was thoroughly mixed and portion taken for dissolution. This sample was dried at I 15'C and four samples were taken from it for dissolution. Each of these samples was dissolved by two separate dissolution methods. These methods were an aqua regia method at 11 5'C in sealed Teflon vessels and a sodium peroxide fusion followed by a HNO3 dissolution. For the glass dissolutions, the three glass samples listed in Table I were crushed and sieved prior to dissolution. The portion passing through a 200 mesh sieve was used for dissolution of each glass. Quadruplicate samples of each were dissolved by two separate dissolution methods. The first used a mixture of HF/HNO3/HCI/H3BO3 solutions at 115'C in sealed Teflon vessels. The second was a sodium peroxide fusion. The solutions from the acid dissolutions in sealed Teflon vessels were used for the determination of Tc-99 or Cs-137, since no losses of these radionuclides could occur during these dissolution procedures. A standard glass with a composition similar to the DWPF glass, (Analytical Reference Glass-1)[4] was dissolved and analyzed each time a set of sludge slurry or glass samples were dissolved in order to check if the dissolutions were complete and the analytical procedures were performed correctly. For each set of dissolutions, the results confirmed that this was the case. The major nonradioactive waste elements (excluding oxygen) in the dissolved HLW sludge slurry and the glass samples were measured by analyzing the diluted solutions from the Shielded Cells by inductivel
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