Tritiated Mixed Waste: Why Can't We Deal With It? There is currently no satisfactory disposal or recycling route for tritiated mixed waste of high tritium content. With mounting concerns regarding land burial and potential environmental releases (atmospheric, vegetation, surface water, and ground water), it is essential to develop processes for ensuring that contaminated materials may be disposed in the most environmentally benign manner. This problem exists on a large scale in the DOE weapons complex, and to a lesser extent in the pharmaceutical industry where isotopes such as tritium and carbon-14 are regularly used in research and drug development projects, and process solvents are contaminated. On a smaller scale, academic institutions conducting life science and biomedical research invariably produce mixed waste. In general, the mixed waste streams of concern to the National Tritium Labelling Facility (NTLF) have organic or biological hazardous components, and are radioactively contaminated with tritium. It is so widely recognized that there is insufficient capacity for mixed waste treatment and disposal that the U.S. Environmental Protection Agency (EPA) has a policy of low priority enforcement against the storage limitations in the Resource Conservation and Recovery Act regulations. As a direct result, mixed waste is accumulating in all research institutions across the country, with little hope for resolution. As a step towards providing leadership, the Federal Facilities Compliance Act requires federal facilities to develop Site Treatment Plans (STP), which commit to schedules for identifying unique waste streams and solutions. Although the DOE has built various advanced incineration devices to address mixed waste (Mixed Waste Disposal Facility, INEEL), the fact that the radioactive isotope in tritiated mixed waste would be released with the incineration products (i.e. as tritiated water) rather than retained in the ash makes these approaches environmentally unsound for tritium. Since a disposal route exists for radioactive aqueous waste, free of hazardous materials, one solution to the problem could be efficient conversion of the hazardous organic components to water and CO2. A number of traditional methods exist for converting organic solvents to water and CO2, and the processes should be adaptable to use with chemicals containing tritium or carbon-14. We have embarked on a study of the treatability of tritiated mixed waste by catalytic chemical oxidation (CCO), which will yield the products HTO and CO2. CCO technology has been successfully applied to destroy hazardous organic chemicals for many remediation projects. With a mature waste treatment technology, the major roadblock to the widespread use of such processes is regulatory; specifically, materials derived from a listed waste are listed in perpetuity. These types of legal problems need to be squarely addressed by groups such as the DOE Tritium Focus Group, the International Isotope Society, and other professional societies whose members feel the negative impact of such unproductive and restrictive legislation. At the very least, catalytic oxidation technology can reduce or eliminate the hazardous nature of mixed wastes (i.e. their """"""""characteristic""""""""), thereby allowing more flexible management of these materials. With some thought, planning and co-operation between institutions, some tritiated mixed waste streams might cease to exist, and the tritium they contained could be made available for recycling. The equipment for this project was funded by two separate grants from the Department of Energy. The first grant allowed the construction of an oxidizer unit and purchase of a state of the art GC/MS instrument. Ending in September 1997, the DOE Mixed Waste Focus Area (MWFA) funded the construction of a second oxidizer, dedicated to the destruction of radioactive waste. In addition the MWFA funded construction of ancillary equipment for preparation of liquid waste for oxidation, and upgrades of existing oxidation hardware. A brief description of the project can be found on the MWFA WWW server, at: http//wastenot.inel.gov/mwfa/treatment/unique/thermox.html In the past year, DOE provided funding to LBNL to support the application of this technology to oxidation of the NTLF inventory waste. In particular, a technician was supported from May through December 1998 to extract, characterize and oxidize the contents of 60 quart cans of inventory mixed waste at LBNL. This fulfilled an STP milestone, requiring completion of this work by 12/31/98. Since the first sample of mixed waste was oxidized in March 1987, 16 liters of mixed waste containing more than 1400 Ci of tritium has been oxidized. If available, oxidation of this waste through a commercial vendor would have cost more than $160,000,000. All high activity inventory waste at LBNL compatible with this process has been oxidized. This project has been both essential and restrictive for the NTLF, especially with the need to process inventory waste during the latter part of 1998. The time requirements of this project have been much less from January 1, 1999, with only two days of staff time devoted this year to oxidation of newly generated mixed waste. At this rate, this process should require only 6-10 work days per year to completely manage this difficult aspect of operations.
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