When the U.S. Department of Energy’s Office of Science and Technology was still called the Office of Technology Development, it funded a project called Minimum Additive Waste Stabilization (see Initiatives, June 1995). As demonstrated in July 1994 in a pilot-scale test at DOE’s Fernald Environmental Management Project in Fernald, Ohio, MAWS integrated soil washing, ion exchange, and its chief technology, vitrification. The MAWS project was a testing ground for GTS Duratek, an environmental technology and services firm in Columbia, Maryland, to prove to DOE the efficacy of its low-temperature, joule-heated melter. GTS Duratek successfully used its pilot-scale vitrifier, the DuraMelter 300, to melt and convert to glass approximately 7,000 gallons of Fernald mixed wastes. Although OST funding for the Minimum Additive Waste Stabilization project ended in 1994, the concept is still viable, and MAWS elements and principles have been incorporated into other technologies that are now being used to clean up DOE and commercial sites. Before radioactive waste is buried, it must be stabilized to prevent its escape into the environment. Vitrification traps radioactive elements in glass to provide a durable, leach-resistant waste form capable of withstanding years of storage. Vitrification combines radioactive and hazardous waste with glass-forming materials in a melter, or vitrifier. Heat from the vitrifier melts the feed materials. As the molten material cools into glass, waste elements become part of the molecular structure of the glass. The waste glass can be stored indefinitely until the radioactive elements have decayed. The advantages of vitrification over encapsulation of waste in concrete or epoxy are that waste volume is reduced and the glass waste form is more durable. The MAWS concept is that hazardous and radioactive waste streams can be judiciously combined and prepared for melting without adding large amounts of clean additives to promote glassmaking. The MAWS process depends on selecting waste streams that can provide the optimal combination of basic chemical building blocks—formers, fluxes, and intermediates—for making durable glass waste forms. MAWS promotes high waste loading, which means a large percentage of the glass is derived from the waste itself with addition of a minimal amount of expensive, nonwaste ingredients such as sand, soda ash, borax, lime, or alumina. MAWS is cost-effective because of reduced additive purchases, volume reduction, and smaller treatment facilities. In a broad sense, most plasma units being developed today can be seen as deriving from the MAWS concept because at their high operating temperatures they can use as feed material a variety of wastes to make the final waste form without adding clean materials. And in the same sense, any vitrification process using contaminated soils as part of the feed material can also be viewed as deriving from the MAWS concept, because soils are an excellent glass-making material. GTS Duratek benefits from MAWS funding But the most direct descendent of MAWS funding and the most commercially viable technology flowing from OST’s investment in MAWS is GTS Duratek’s low-temperature, joule-heated melter—one member of the DuraMelter family of melters. In November 1993, GTS Duratek and its research partner, Catholic University of America’s Vitreous State Laboratory, won the first contract DOE awarded for a commercial-scale, mixed waste stabilization project using vitrification. GTS Duratek designed, built, and was operating its Vendor Treatment Facility to stabilize radioactive sludges stored in tanks at Savannah River Site’s M-Area. GTS Duratek began radioactive operations using its DuraMelter 5000 on October 18, 1996. Since then, the company’s VTF operations staff has started to produce glass from the 660,000 gallons (90,000 cubic feet) of low-level mixed waste sludge stored in M-Area tanks and has filled drums with environmentally safe glass gems. The DuraMelter’s output is designed to reach 12 tons of glass a day at full-scale production. To date, GTS Duratek has processed 100,000 gallons of M-Area waste. On March 27, the company temporarily suspended vitrification operations when operators noticed hot spots, or spikes in operating temperatures. Company management decided to bring down and cool the unit so internal components could be examined. Accelerated wear on refractory bricks was determined to be the problem. The processing delay will affect the date set for completing processing, October 1997. During the final portion of the contract, GTS Duratek will clean the empty waste storage tanks. Since the waste processed at M-Area represents only 1 percent of the radioactive waste at SRS, GTS Duratek is negotiating with Westinghouse Savannah River Company, DOE’s managing and operations contractor at SRS, to send other waste streams to VTF once this project is completed. DOE’s management at the Savannah River Site remain committed to the long-term benefits of vitrification and commend GTS Duratek for dealing with the problem in a way that ensures the safety and reliability of the system. Bob Prince, GTS Duratek’s chief executive officer, views the M-Area experience as invaluable in learning melter operation lessons that will be applied to improve the quality of designs for future projects. GTS Duratek is also participating in two major contracts DOE recently awarded to privatize cleanups at DOE sites near Idaho Falls, Idaho (Idaho National Engineering and Environmental Laboratory) and Richland, Washington (Hanford Site). Both contracts have been awarded to teams led by BNFL Inc., the American subsidiary of British Nuclear Fuels plc. For the Tank Waste Remediation System project at DOE’s Hanford Site in Washington state, GTS Duratek will scale up its DuraMelter 5000, which was being used for the M-Area sludge cleanup at SRS, to convert to glass up to 6 million gallons of high-level radioactive waste stored in Hanford’s tanks. During Phase I, which could take up to 16 months to complete and cost $27 million, the facility will be designed and the permitting process begun. This contract represents the beginning phases of a massive undertaking—converting tank waste to glass at an estimated cost of $20 to 40 billion over a 20- to 30-year period. DOE will permit the BNFL-led team to continue working on succeeding phases based on the team’s success in meeting milestones. For the Advanced Mixed Waste Treatment Project at the Idaho National Engineering and Environmental Laboratory, GTS Duratek is an equity partner with BNFL and will supply technologies, including vitrification and thermal desorption, in the cleanup of 65,000 cubic meters of transuranic and mixed waste at INEEL. During Phase I, the team will seek an operating permit from the state of Idaho for its planned vitrification facility. For more information about GTS Duratek, call William Greenman at (410) 312-5100, or e-mail Greenman@GTSDuratek.com.