SMALL-SCALE MELTER TESTING WITH LAW SIMULANTS TO ASSESS THE IMPACT OF HIGHER TEMPERATURE MELTER OPERATIONS - Final Report, VSL-04R49801-1, Rev. 0, 2/13/03, Vitreous State Laboratory, The Catholic University of America, Washington, D.C.

About 50 million gallons of high-level mixed waste is currently in storage in underground tanks at The United States Department of Energy's (DOE's) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE's Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed of in an engineered facility on the Hanford site while the IHL W product will be directed to the national deep geological disposal facility for high-level nuclear waste. The ILAW and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. The Office of River Protection is currently examining options to optimize the Low Activity Waste (LAW) facility and the LAW glass waste form. One option under evaluation is to enhance the waste processing rate of the vitrification plant currently under construction. It is likely that the capacity of the LAW vitrification plant can be increased incrementally by implementation of a variety of low-risk, high-probability changes, either separately or in combination. These changes include: (1) Operating at the higher processing rates demonstrated at the LAW Pilot Melter; (2) Increasing the glass pool surface area within the existing external melter envelope; (3) Increasing plant availability; (4) Increasing the glass waste loading; (5) Removing sulfate from the LAW stream; (6) Operating the melter at slightly higher temperature; (7) Installing the third LAW melter into the WTP plant; and (8) Other smaller impact changes. The tests describes in this report utilized blended feed (glass formers plus waste simulant) prepared by Optima Chemicals according to VSL specifications. Sufficient feed was prepared to produce nearly two metric tons of glass. Sugar was added (at VSL) to the feed at a ratio of 0.5 (1 mole sucrose per 16 mole NOx). The DM100-WV melter was used in order to provide a direct comparison with the LAW tests previously conducted on the same melter. Two 75-hour melter tests were conducted at two elevated temperatures, 1175 and 1225 C. These tests were preceded by the production of sufficient glass to turn over the melt pool to the target composition. Key operating parameters were held constant to investigate the effects of the operating temperature on processing characteristics, particularly melting rate. At each operating temperature, the feed rate was adjusted to provide a near-complete cold cap 99-100% of melt surface covered with feed. Quantitative measurements of glass production rates, melter operating conditions (temperatures, pressures, power, flows, etc.), and off-gas characteristics (NOx, SO{sub 2}, CO, particulate load and composition, and acid gases) were made for each test