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Mixed Waste
Waste Management: 

About Mixed-Waste


Mixed-waste contains both radioactive and chemically hazardous waste.

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Regulating Mixed-Waste

A dual regulatory framework exists for mixed-waste, with the EPA or authorized states regulating the chemically hazardous portion of the waste and the U.S. Nuclear Regulatory Commission (NRC), the NRC agreement states, or the U.S. Department of Energy (DOE) regulating the radioactive portion of the waste.

NRC and DOE use their authority under the Atomic Energy Act (AEA) to regulate the radioactive components of mixed-waste. EPA uses its authority under the Resource Conservation and Recovery Act (RCRA) authority to regulate the hazardous waste portion. NRC is authorized by the AEA to issue licenses to commercial users of radioactive materials. RCRA gives EPA the authority to control hazardous waste from "cradle-to-grave."

Once a waste is determined to be a mixed-waste, the waste handlers must comply with both AEA and RCRA regulations. The requirements of RCRA and AEA are generally consistent and compatible. However, the provisions in Section 1006(a) of RCRA allow the AEA to take precedence in the event provisions of the two acts are found to be inconsistent.

Sources of Mixed-Waste

Mixed-waste can be generated anywhere radioactive materials are used in processes that also involve the use of chemically hazardous materials. There are two primary sources of mixed-waste:

Commercially Generated Low-Level Mixed-Waste

The radioactive component of almost all commercially-generated mixed-waste is low-level radioactive waste (LLRW). It is referred to as "Low-Level Mixed-Waste (LLMW);" it is produced in all 50 states.

Industrial, hospital, and nuclear power plant facilities use both radioactive and hazardous materials in a number of processes:

The Nuclear Regulatory Commission and EPA conducted a survey of commercial mixed-wastes, (National Profile of Commercially Generated Mixed-Waste). The results provided a cross-section of the approximately 4,000 cubic meters (m3) of LLMW generated in the United States in 1990:

The amount of mixed-waste generated by commercial facilities is very small (about two percent of the total) compared to the amount generated or stored by Department of Energy facilities.

Under the 1984 Amendments to RCRA, Land Disposal Restriction (LDR) regulations prohibit disposal of most mixed-waste including LLMW until it meets specific treatment standards. While most of the commercial mixed-waste that is generated and stored can be treated to meet the LDRs by commercially available treatment technology, there still exists a small percentage of commercial mixed-waste for which no treatment or disposal capacity is available.

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Department of Energy Mixed-Waste

DOE facilities primarily produce and/or stores three types of mixed-waste:

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Low-Level Mixed-Waste

DOE's low-level mixed-waste (LLMW) is generated, projected to be generated, or stored, at 37 DOE sites in 22 states. It comes from research, development, and production of nuclear weapons. Waste management activities will require management of an estimated 226,000 cubic meters (m3) of LLMW over the next 20 years.

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High-Level Mixed-Waste

DOE's high-level waste (HLW) is radioactive waste which is liquid prior to treatment and comes from reprocessing spent nuclear fuel and irradiated targets from reactors. Some of its elements will remain radioactive for thousands of years. Because it contains highly corrosive, organic, or heavy metal components that are regulated under RCRA, this HLW is considered a mixed-waste.

DOE's HLW is stored in large tanks at three locations:

DOE has treated some of the HLW by processing it into a solid form (e.g. borosilicate glass) that is not readily dispersible into the air or leachable into the ground or surface water. This treatment process is called vitrification. Between 1996 and 2001, the approximately 660,000 gallons of highly radioactive liquid waste stored at West Valley was vitrified. The vitrification process will ultimately generate approximately 29,000 canisters for disposal in a geologic repository. Currently, Yucca Mountain, Nevada, has been identified as the site for a potential geological repository. EPA's Yucca Mountain Standards pages contain information about the Agency's standards-setting role in the project.

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Mixed Transuranic Waste

DOE mixed transuranic waste (MTRU) is waste that has a hazardous component and radioactive elements heavier than uranium. The radioactivity in the MTRU must be greater than 100 nano Curies per gram (nCi/g) and contaminated with RCRA hazardous constituents. The principle hazard from MTRU is alpha-particle radiation through inhalation or ingestion.

MTRU is primarily generated from nuclear weapons fabrication, plutonium-bearing reactor fuel fabrication, and spent fuel reprocessing. The amount of MTRU generated by entities other than DOE is negligible. Approximately 55% of DOE's TRU waste is mixed-waste. Approximately 1,500 m3 of MTRU from Rocky Flats, Colorado has been retrieved for disposal and the site is closed. MTRU is currently being retrieved for disposal at five DOE sites:

DOE disposes defense-related MTRU at Waste Isolation Pilot Plant(WIPP) near Carlsbad, New Mexico. Before DOE can dispose of waste at the WIPP, it must demonstrate that the waste has been characterized in compliance with the EPA regulations at 40 CFR 194 and meets EPA's radioactive waste disposal standards (40 CFR 191). EPA approved DOE's initial compliance certification application (CCA) in May 1998. DOE must submit a Compliance Recertification Application (CRA) every five years to demonstrate that the WIPP continues to comply with EPA's TRU waste disposal standards. EPA approved DOE's recertifications in 2006 and 2010.

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Treatment of DOE's Mixed-Waste

DOE's 1995 Baseline Environmental Management Report estimated that the life-cycle costs for HLW, TRU (including MTRU), and LLMW were $34 billion, $13 billion, and $13 billion respectively over a 75 year period.

As mandated by the Federal Facilities Compliance Act (FFCA), which was signed into law on October 6, 1992, DOE has developed Site Treatment Plans for its mixed-wastes. DOE is implementing these plans through orders issued by EPA or the states. It also developed a Waste Management Programmatic Environmental Impact Statement (WM PEIS) for treatment, storage, and disposal of radioactive and hazardous waste. This plan will assist DOE in selecting waste management facilities. DOE, EPA, NRC, and the states will continue to work together to ensure the proper management and disposal of legacy wastes from the Cold War.

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