THE EFFECTS OF MELTING REACTIONS ON LABORATORY-SCALE WASTE VITRIFICATION

At the U.S. Department of Energy's Hanford Site, processes are being d eveloped to vitrify waste generated during nuclear materials processin g. One of the wastes slated for vitrification is known as neutralized current acid waste (NCAW). The batch chemistry of simulated NCAW was v aried with oxidants and reductants. Untreated, formated, nitrated, or sugar-added samples were combined with frit to produce melter feed. Of fgas measurements of the formated melter feed showed that formates dec omposed at temperatures too low for participation in melt redox reacti ons. Sugar pyrolyzed and produced CO and H-2 at temperatures exceeding 665 degrees C. For the sugar-added samples, the glass quenched from 1 200 degrees C produced an Fe2+/Sigma Fe of 0.79. The measured iron red ox ratios from the glasses made from untreated, formated, and nitrated wastes were essentially indistinguishable (0.0024 at 1000 degrees C a nd 0.032 at 1200 degrees C). However, the batch chemistry affected vol ume expansion and the reaction paths.