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SummaryThe U. S. Department of Energy (DOE) Richland Operations Office has initiated a twophased approach to privatizing the processing of hazardous and radioactive waste at Hanford. In support of this effort, Pacific Northwest National. Laboratories (PNNL,) was directed to conduct Research-Scale Melter (RSM) experiments to determine feed processing characteristics of two potential privatization Phase 1 high-level waste (HLW) glass formulations and to determine if increased amounts of silver, tellurium, and noble metals would have adverse effects on waste processing.. Feed processing characteristics were evaluated by examining the effects of feed compositions and process conditions on processing rate, cold cap behavior, off-gas characteristics, and glass properties. Two glass formulations developed by PNNL were used for the study: 1) NOM-2 was formulated so that the adjusted waste loading (defined as the waste loading of all components except silica and soda) was 25 wt % and 2) NOM-3 was a maximum waste loaded glass that had an adjusted waste loading of 30 wt %. The 25 wt % adjusted waste loading is the minimum requirement in the privatization Request For Proposal (IWP). -The RSM operated for 19 days divided into five run segments. A total of 1010 kg of feed was processed, producing 362 kg of glass. Test s e b e n t 1 provided a shakedown test and confirmed operations of the melter and feed systems. Test segments 2 and 3 established nominal conditions to provide a baseline for NOM-2 and NOM-3 respectively. Portions of test segment 2 i d 3 were run at 10 to 30°C above the nominal temperature of 1150°C.Processing rates were significantly increased with the effect most pronounced in test segment 3.Processing observations lead to the choice of NOM-3 for noble metal testing in segments 4 and 5. During noble metal testing, processing rates fell 50% fiom the baseline rates measured in segment 3. After completion of the noble metal test segments, destructive analysis of the melter'showed that a layer of noble metals and noble metal oxides settled on the floor of the melter. This layer lead to current "channeling" which allowed the top section of the melter to cool reducing production rates.Acknowledgments.
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