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Mixed Waste
Waste Management: 

National Profile of Commercially Generated Mixed-Waste - Summary

Mixed-Waste

The following summary of the results comes from a 1990 NRC-EPA survey of commercially generated low-level mixed-waste. This is the most recent available data. A complete description of the results and survey is given in the NRC publication, National Profile on Commercially Generated Low-Level Radioactive Mixed-Waste, (NUREG/CR-5938).

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Results of the National Profile of Commercially Generated Low-Level Radioactive Mixed-Waste NUREG/CR-5938

Uncertainties in the volume and characteristics of low-level radioactive mixed-waste have been one of the principal barriers to commercial development of treatment and disposal facilities for mixed-waste. To address this uncertainty, the Nuclear Regulatory Commission and the Environmental Protection Agency (EPA) have jointly developed the National Profile on Commercially Generated Low-Level Radioactive Mixed-Waste (the National Profile). The National Profile was developed for NRC and EPA by the Oak Ridge National Laboratory and is based on a 1991-1992 survey of nuclear facilities licensed by NRC and the Agreement States.

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Mixed-Waste Generated in 1990

The survey indicated that approximately 140,000 ft3 of mixed-waste were generated in the United States in 1990. Four categories accounted for approximately l00,000 ft3:

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Approximate Generation by Sector

The predominant radionuclides:

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Mixed-Waste in Storage at the End of 1990

The profile indicated that about 75,000 ft3 of mixed-waste were in storage as of December 31, 1990. Mixed-waste contaminated with cadmium made up the largest portion of the mixed-waste in storage (35 %) and LSF (17%).

It is important to note that the total amount of mixed-waste at the end of 1990 cannot be derived from the sum of the amount of waste in storage and the amount of waste generated in 1990. Some of the waste generated in that year may have been treated or destroyed prior to the end of 1990.

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Comparisons with Previous Estimates

The National Profile confirmed earlier estimates that mixed-waste generation is a small fraction of the overall generation of low-level radioactive waste (LLW).

The National Profile also confirmed previous estimates that the amount of mixed-waste generated in the commercial sector is a small fraction of the amount generated by DOE. A recent Federal register notice indicated that DOE annually generates approximately 800,000 ft3 of LDR mixed-waste (57 FR 22024).The volume of DOE mixed-waste is expected to increase significantly in the future as a result of DOE's environmental restoration and decommissioning program.

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Uncertainties in Estimates

The National Profile represents a "snapshot" of mixed-waste generated or in storage in 1990. As such, some waste streams may not have been included in the survey population if facilities included in the survey were not generating these wastes during 1990. Also, approximately 8,000 ft3 of sewer cleaning sludges containing cadmium and uranium resulting from clean-up operations was included in the National Profile and would have distorted the figures.

The types and volumes of mixed-wastes that could result from facility decommissioning or remedial actions are extremely variable. Accurate projections of these mixed-wastes will be difficult. Factors that affect projections include past facility operations and practices, as well as the methods used to decontaminate the facility.

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Treatment Demand vs. Capacity

The treatability assessment in the National Profile concludes that adequate treatment capacity exists for most mixed-waste. ORNL contacted commercial vendors to determine the extent of currently available treatment capacity for mixed-waste and compared the capacity with the mixed-waste types and volumes identified in the National Profile.

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Uncertainties in Treatability Assessment

ORNL relied on information obtained from the facilities offering the treatment services. The treatment capacity reported by these facilities may, in some cases, be overly optimistic. The treatment facilities have not been tested at the design capacities reported. Other factors could affect the ability of these facilities to treat mixed-waste at capacity. These factors may include limited pretreatment or preparation capacities; the timing of treatment campaigns and downtime between campaigns; and the limitations on their ability to process simultaneously multiple mixed-waste streams of diverse or similar characteristics.

The report also does not consider the impact that treatment of the Department of Energy's (DOE's) mixed-wastes may have on the ability of the treatment facilities to treat commercial mixed-waste. As described in the Draft Implementation Plan for DOE's Programmatic Environmental Impact Statement for Environmental Restoration and Waste Management, DOE is considering use of commercial vendors to treat mixed-waste and hazardous waste generated by the cleanup and management of the nuclear weapons complex. Given the large volumes and generation rates of DOE mixed-waste, commercial treatment of DOE mixed-waste could result in competition and a shortfall in capacity for commercial mixed-wastes.

ORNL also informally queried several mixed-waste generators about why so much mixed-waste was presently being stored when a large treatment capacity exists for most mixed-waste. The reason given by the generators and other factors developed by ORNL based on their observations and discussions with generators are outlined below. A discussion of these factors will appear in the NUREG on the National Profile.

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Thermal Treatment as a Treatment Option

In order to determine the most appropriate treatment technology for each waste category identified in the National Profile, an evaluation of treatment options available for each mixed-waste category was performed and a recommended treatment or sequence of treatments was identified. Treatment options were those technologies that were considered to be feasible, based on the capability of the treatment technology to achieve the EPA mandated treatment standard. The range of treatment options was compiled from several references including 40 CFR Part 268, drawing on those technologies that have been demonstrated to meet the EPA requirements for waste streams that were similar to the waste streams identified in the National Profile.

For each waste stream a recommended treatment technology was selected based on the ability of the treatment to satisfy the regulatory requirements, its economic feasibility, the likelihood that the treatment technology would become available in about one year. For those waste streams where the treatment standard is a specified technology, such as incineration, the specified technology was selected as the recommended treatment option.

Required annual thermal treatment capacity or "demand" was defined as the 1990 generation plus material in storage as of the end of 1990. By being defined in this fashion demand may "double count" some mixed-waste that was generated in 1990 and was being stored as of the end of 1990. However, in order to evaluate the need for thermal treatment capacity, an estimate of waste that could be in storage at a facility was needed as this waste would have an impact on the demand for treatment capacity. It was felt that using 1990 storage information, provided a conservative estimate of the mixed-waste volumes and types that could be stored at a facility.

Based on this evaluation, approximately 143,000 ft3 or 67 percent of the mixed-waste generated and in storage as of the end of 1990 can be treated by thermal destruction techniques. The mixed-waste that can be treated by thermal treatment is comprised of 113,000 ft3 of LSF, 13,860 ft3 of "other organic" compounds, 11,500 ft3 of waste oil, 3,500 ft3 of chlorinated organic compounds, 650 ft3 of CFCs and 120 ft3 of fluorinated organic compounds.

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Conclusion

Overall, the National Profile is most broad and comprehensive characterization available of the types and volumes of mixed-waste generated by licensed nuclear facilities. This article summarizes and analyzes the results of the National Profile. As with any survey, and as discussed above, uncertainties may exist concerning the results and conclusions drawn from the data collected. However, NRC, EPA and ORNL believe that the National Profile presents a complete and accurate picture of mixed-waste generation for 1990. Readers are encouraged to review NUREG/CR - 5938 "National Profile on Commercially Generated Low-Level Radioactive Mixed-Waste" for greater detail in the construction, implementation, and analysis of the mixed-waste survey that provides the foundation for the Profile.

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