Initial SB4 Melt Rate Furnace Testing (U)

The Defense Waste Processing Facility (DWPF) is presently vitrifying Sludge Batch 3 (SB3) and preparing to process Sludge Batch 4 (SB4) in late 2006 or early 2007. The final composition of SB4 has not been finalized, as various blending and/or washing strategies are still being considered. SB4 will be comprised of the contents of Tanks 5, 6, 7, 8, and 11 (which will be transferred to Tank 51) along with plutonium and neptunium solutions from F and H Canyons, and possibly material from Tank 4. Tank 4 was originally included in projections, but plans have since changed (after completion of these tests) and Tank 4 is no longer part of SB4 due to problems with sludge removal. Even though the final SB4 composition was not finalized at the time of this study, there were 20 bounding options documented that could be used for preliminary melt rate tests. At the time of these tests, the SB4 compositions described as ''SB4 1200 canister baseline'' and ''SB4 1200 canister baseline (one less washed)'' documented elsewhere were chosen for these tests. The 1200 canister describes the number of equivalent canisters that would be produced from the beginning of the current contract period before SB3more » is blended with SB4. These compositions were chosen as they had the highest amount of SB4 in the blend and were therefore considered as worse case SB4 feeds with regards to melt rate. This is because SB4 has higher alumina levels of any sludge batch yet processed and alumina has a negative impact on the DWPF melt rate. This baseline sludge includes Tank 4 but does not include auxiliary waste streams such as the Actinide Removal Process (ARP) stream, which contains monosodium titanate (MST), entrained sludge, and various soluble sodium compounds as the result of filter cleaning and stream adjustment for transfer. These preliminary dry-fed Melt Rate Furnace (MRF) tests were needed to initially evaluate melt rate/waste throughput. This study addressed SB4 with Frits 418 and 320, the impact of waste loading, the impact of the higher amount of Al in SB4, the amount of sludge washing, the possible addition of the ARP stream, the possible need to use a new frit to increase sulfur solubility, and the impact of the use of low Li frits to minimize the formation of an Al-Li-silicate phase that may be an intermediate reaction phase that could possibly hinder melt rate for SB4. For the SB4 sludge tested in the MRF for this preliminary work, the melt rate for SB4 simulant was lower than SB3. The higher alumina content in SB4 is probably the reason for the lower SB4 melt rate. Because the actual SB4 composition has not yet been finalized and may be different enough from the simulant SB4 sludges tested for these tests, the actual difference in melt rate for the two sludge batches cannot be projected. Therefore, further melt rate testing, including slurry testing in the Slurry-Fed Melt Rate Furnace (SMRF) will be needed as the SB4 compositions are further refined. Tests were performed with non-radioactive, simulated SB4 material. Due to the small-scale of the test equipment and the design of the equipment, as well as the use of dry, non-radioactive simulant feed, the behavior of the actual radioactive SB4 feed in the DWPF melter cannot be fully proven. « less