on the mixed waste focus area

About the focus areas

The U.S. Department of Energy's Office of Environmental Management has established an integrated approach for addressing waste issues based on problem, or focus areas. The focus areas are subsurface contaminants; mixed waste characterization, treatment, and disposal; radioactive tank waste remediation; decontamination and decommissioning; and plutonium stabilization. Three crosscutting technology areas support the focus areas: characterization, monitoring, and sensor technology; efficient separations and processing; and robotics.

Mixed waste contains both hazardous chemical components, subject to the requirements of the Resource Conservation and Recovery Act, and radioactive components, subject to the requirements of the Atomic Energy Act. The U.S. Department of Energy's inventory of mixed waste consists of over 2,000 different mixed waste streams at 36 sites in 19 states. Faced with multibillion dollar estimates for treating and disposing of mixed low-level and mixed transuranic waste, DOE established the mixed waste focus area in 1995 to pursue technology leading to better and less expensive characterization, retrieval, handling, treatment, and disposal of mixed waste. MWFA's goals are to reduce the volume of stored mixed waste and meet regulatory requirements for safe, permanent disposal.

Zeroing in on deficiencies

Under the leadership of the Idaho Operations Office and with the support of Lockheed Martin Idaho Technologies Co. and the Waste Policy Institute at the Idaho National Engineering and Environmental Laboratory in Idaho Falls, the focus area "zeroed in on the processes or unit operations that were inadequate to support treatment of mixed waste," according to MWFA Deputy Manager Bill Owca. "We defined those things that prevented implementation as deficiencies, and we will focus on them until we have them all resolved." When finished, the program will have demonstrated improvements to 55 proposed mixed waste treatment systems at 22 DOE sites. These technology enhancements not only will make treating mixed waste better and safer, but are expected to shave millions of taxpayer dollars off the DOE "mortgage" to clean up its weapons complex facilities.

Beginning with customer site visits and analysis of needs from Site Technology Coordination Groups, as well as data from site treatment plans and mixed waste inventory reports, focus area staff used a systems engineering approach to develop a prioritized list of technology deficiencies, which constitutes the MWFA technical baseline. Technical performance requirements necessary to resolve each deficiency were then described. The final step in resolving a deficiency is comparison of the technology development and demonstration results against requirements to ensure their fulfillment. The integrated technical baseline currently has 24 deficiencies, the highest priorities being characterization; mercury, ash, and salt stabilization; waste form performance; material handling; mercury separation; TRU waste transportation; and continuous emission monitors.

To facilitate development of appropriate technologies, MWFA uses product lines that reflect the major mixed waste problem categories: wastewaters and slurries; combustible organics; inorganic homogeneous solids and soils; solids, debris, and soils; and unique wastes. These waste-type product lines are managed by waste-type managers, who are members of MWFA's customer organizations--Office of Waste Management (EM-30), Office of Environmental Restoration (EM-40), and Office of Nuclear Material and Facility Stabilization (EM-60). Waste-type teams for each product line provide technical and regulatory support and tribal and stakeholder interface to principal investigators.

Wrapping up technology systems

At the same time they were overseeing resolution of technology deficiencies, MWFA staff worked toward completing by the end of fiscal year 1997 the development of three technology systems it will endorse as being cumulatively capable of treating at least 90 percent of DOE's mixed waste inventory. Some of the candidates for standard bearers are melter technologies, macroencapsulation and other stabilization processes for waste streams for which vitrification is problematic, and alternative technologies for organic destruction.

High-temperature melter technologies--MWFA's melter strategy is aimed at development activities to support the Plasma Hearth Process (see Initiatives, February 1996) and the Direct Current Arc melter because these technologies have the potential to treat a wide variety of stored and buried mixed waste in a single process. In support of melter development, MWFA has involved Russian scientists, who have been researching the behavior of radionuclides in high-temperature processes. MWFA has also provided implementation support to the Transportable Vitrification System at the Oak Ridge National Laboratory (see Initiatives, December 1996), supported the Vortec melter demonstration at the Paducah Gaseous Diffusion Plant (see Initiatives, October 1996), and supported the Western Environmental Technology Office's work on enhancing the service life of plasma torches. (Mississippi State University's Diagnostic Instrumentation and Analysis Laboratory is also involved in research to extend the life of plasma torches. See page 4.)

For the continuous detection of hazardous emissions in the off-gas of melter systems, MWFA participates in seeking improvements to continuous emissions monitors. MWFA joined a working group designed to coordinate CEM technology development between government agencies and private industry. The Interagency Continuous Emission Monitors Coordinating Committee/Working Group seeks to eliminate duplicative R&D efforts and speed up schedules. MWFA expects to leverage CEM funding with other agencies.

Polymer macroencapsulation and other stabilization technologies--Polymer macroencapsulation, developed at Brookhaven National Laboratory, surrounds mixed low-level wastes with a layer of clean polyethylene to isolate the contaminants from the environment. The U.S. Environmental Protection Agency has defined polymer macroencapsulation as the Best Demonstrated Available Technology for radioactive lead soils and mixed waste debris, defined as materials exceeding 60 mm in particle size.
MWFA was instrumental in the transfer of polymer macroencapsulation to the private sector. Through an August 1995 cooperative agreement between DOE and Envirocare of Utah, Envirocare uses macroencapsulation to treat wastes it receives from DOE sites. The transfer of polymer macroencapsulation to Envirocare is one of MWFA's major successes, and it serves as a model for other transfers of DOE-developed technologies to the private sector to solve DOE environmental problems (see Initiatives, February 1996). MWFA has coordinated shipments of radioactive lead from DOE sites to the low-level nuclear waste disposal facility 75 miles west of Salt Lake City. Envirocare has received shipments from 23 DOE sites. The focus area also renegotiated the cooperative agreement to allow Los Alamos National Laboratory in New Mexico to ship 60,000 pounds of radioactive lead, the site's entire inventory.

As part of its investigation of alternatives for problematic waste streams, MWFA is planning an "Ash Bake-Off" scheduled for this fall or winter to compare and contrast three different ash stabilization technologies for treating fly ash. After passing through an off-gas system of an incineration process, fly ash is what remains. Ash stabilization is one of the focus area's 24 technology deficiencies in treating mixed waste. Phosphate-bonded ceramics, RocTec (a commercial process), and sintered ceramic stabilization will be tested at bench scale and later at drum scale, using ash from the Waste Experimental Reduction Facility at the Idaho National Engineering and Environmental Laboratory. Performance strengths--such as leachability, compressive strength, waste loading, volume reduction, operability, and cost--will be gathered on each technology for customers to evaluate. See article about chemically bonded phosphate ceramics in this issue.

Alternative organic destruction--MWFA is supporting three technologies that are chemical alternatives to high-temperature processes for combustible mixed low-level waste: DETOX^SM, acid digestion, and direct chemical oxidation.

DETOX is a chemical wet oxidation method, developed and patented by Delphi Research, Inc. of Albuquerque, New Mexico (see Initiatives, August 1996 and this issue). DETOX destroys hazardous organics and concentrates heavy metals and radionuclides in a process solution while controlling releases of hazardous air pollutants.

Acid digestion is another wet oxidation technology. Operating below 200^oC and at atmospheric pressure, the process treats heterogeneous waste with a nitric-phosphoric acid. Treated residues are immobilized readily using phosphate ceramic solidification. A license agreement has been negotiated between Westinghouse Savannah River Company and CeraChem, a private company. Initial testing with surrogate waste has begun in a 40-liter pilot unit, and plans are under way to design, construct, and test a 400-liter reactor.

MWFA is supporting the bench-scale demonstration of direct chemical oxidation as a unique omnivorous destruction process for organic solids and liquids. Using acidified ammonium peroxydisulfate solutions, the process does not require any toxic or expensive catalysts for bulk destruction. The process operates within the aqueous phase at low temperature and ambient pressure, and the reagent can be regenerated and recycled.

Quick wins

The Quick Win program is a strategy the focus area has successfully used to quickly clean up small unique quantities of mixed waste. Projects pegged as quick wins are those for which mature technologies can be demonstrated and deployed within a given fiscal year to reduce DOE's inventory of noncompliant mixed waste. Once treatability studies have proven successful, end users can permit the process and begin treating mixed waste. Quick wins generate data other sites can use to assess applicability to similar wastes at their facilities. The annual $2.4 million Quick Win program has helped 14 sites reduce their mixed waste inventories. By the end of FY97, a total of 653 cubic meters of mixed waste will have been treated under the program.

Quick Win projects are solicited from DOE sites through a call for proposals. For the FY97 program, 12 projects are being funded. One of the FY97 projects will use an electrochemical process to regenerate ion exchange resins at Oak Ridge National Laboratory, thereby reducing the generation of secondary waste and saving almost $700,000 a year in avoided costs. Another project at Argonne National Laboratory-West will use phosphate-bonded ceramics to stabilize two waste streams--lead-lined gloves and crushed mercury-contaminated light bulbs. The demonstration will be coordinated with other stabilization demonstrations to provide comparisons of stabilization technologies under identical testing conditions.

Among the quick wins of 1996 was a project using a full-scale, base hydrolysis nonthermal process to destroy explosives at the Pantex Plant in Amarillo, Texas. The technology was funded because customers were looking for an alternative to open burning of dismantled materials. The technology neutralized 500 pounds of contaminated explosives and generated data that are being used to obtain an operating permit for the technology.

Public involvement

MWFA's Regulatory and External Liaison Program facilitates regulator, tribal, and stakeholder involvement within the focus area to enhance the implementation of mixed waste treatment systems. Through its participation in the National Technical Workgroup and the Interstate Technology and Regulatory Cooperation Working Group (see Initiatives, April 1997), MWFA gains the perspectives of regulatory agencies, stakeholders, and tribes. NTW--composed of representatives from DOE, EPA, the Nuclear Regulatory Commission, regulating states, and citizen groups--supports the development of coordinated, consistent, and environmentally protective processes for permitting mixed waste thermal treatments. ITRC promotes cooperation among states in the common effort to test, demonstrate, evaluate, verify, and deploy innovative environmental technologies.

MWFA affords another opportunity for public involvement through development of its Technology Development Requirements Documents, which provide a guide for investigators when designing their technology development activities. TDRDs specify verifiable requirements for each project to ensure that development projects meet customer needs and can be implemented successfully. Tribal and stakeholder participants on the Technology Requirements Working Group develop and define requirements that reflect tribal and stakeholder social, political, and cultural values and economic concerns. TRWG has reviewed and submitted recommendations to MWFA on the following TDRDs: salt stabilization, polymer encapsulation, radionuclide partitioning, heavy-metal monitoring, dioxin/furan monitoring, controlled emissions demonstration, and mercury amalgamation.

For more information, see MWFA's homepage at http://wastenot.inel.gov/mwfa.