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# Frequently Asked Questions about Land Disposal of Depleted Uranium and other Unique Waste Streams

On this page:
        - What is low-level radioactive waste?
        - Which regulations apply to land disposal of low-level radioactive waste?
        - Why is it necessary to update the regulations?
        - What is depleted uranium?
        - Why is depleted uranium considered a Class A low-level radioactive waste?
        - What are unique waste streams?
        - What are some of the key issues with disposal of unique waste streams?
        - What are other countries doing?
        - How should previously disposed of depleted uranium be addressed by the disposal facility sites?
        - Exposure to depleted uranium poses both radioactive and chemical risks. How is the chemical risk integrated into the risk assessment to demonstrate compliance with 10 CFR Part 61?
        - How does the NRC ensure Agreement States provide proper oversight?
        - How can depleted uranium be stored safely in a near-surface disposal facility?
        - How can the performance assessment account for long time periods, such as 10,000 years?

Index to All Frequently Asked Questions Pages

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**What is low-level radioactive waste?**

Low-level radioactive waste streams contain source, special nuclear, or byproduct material that are acceptable for disposal in a near-surface (i.e., within the upper 30 meters of the earth's surface) land disposal facility. For the purposes of this definition, low-level waste has the same meaning as in the Low-Level Radioactive Waste Policy Act, that is, radioactive waste not classified as high-level radioactive waste, transuranic waste, spent nuclear fuel, or byproduct material as defined in section 11e.(2) of the Atomic Energy Act (i.e., uranium or thorium tailings and waste).

Industries; hospitals and medical, educational, or research institutions; private or government laboratories; and nuclear fuel cycle facilities (e.g., nuclear power reactors and fuel fabrication plants) that use radioactive materials generate low-level wastes as part of their normal operations. These waste streams are generated in many physical and chemical forms and levels of contamination.

**Which regulations apply to land disposal of low-level radioactive waste?**

Regulations issued by the U.S. Nuclear Regulatory Commission (NRC) are found in Chapter I of Title 10, "Energy," of the Code of Federal Regulations (10 CFR). Chapter I is divided into Parts 1 through 199, which contain requirements that are binding for all individuals and entities that possess, use, or store nuclear materials or operate nuclear facilities under the NRC's jurisdiction. Of these, the regulations that are most relevant to land disposal of radioactive waste are contained in 10 CFR Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste."

**Why is it necessary to update the regulations?**

The licensing of new uranium enrichment facilities in the United States has raised depleted uranium to the forefront of low-level radioactive waste disposal issues. The depleted uranium waste stream is unique amongst LLRW streams; the relatively high concentrations and large quantities of depleted uranium that are generated by enrichment facilities were not considered in the Final Environmental Impact Statement (NUREG-0945) supporting the development of 10 CFR Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste." When NUREG-0945 was issued in 1982, there were no commercial facilities generating significant amounts of depleted uranium waste streams, therefore, NUREG-0945 considered only types of uranium-bearing waste streams being typically disposed of by U.S. Nuclear Regulatory Commission (NRC) licensees at that time.

With the existing U.S. Department of Energy enrichment facilities, and the recent NRC licensing of commercial enrichment facilities, more than one million metric tons of depleted uranium will require a disposition path. Existing disposal facilities such as the EnergySolutions' facility in Clive, Utah and the Waste Control Specialists' facility in Andrews County, Texas, have expressed interest to their Agreement State regulators in disposing of depleted uranium at their sites.

The NRC recognizes that the analysis supporting regulations in 10 CFR Part 61 did not address the disposal of significant quantities of depleted uranium, and that there may be a need to place additional restrictions at a specific site or deny such disposal based on unique site characteristics. Therefore, the NRC will update the regulations to specify a requirement for a site-specific analysis that demonstrates unique waste streams, including significant quantities of depleted uranium, can be disposed of safely.

**What is depleted uranium?**

The uranium fuel cycle begins by extracting and milling natural uranium ore to produce "yellow cake," a varying mixture of uranium oxides. Low-grade natural ores contain about 0.05 to 0.3% by weight of uranium oxide while high-grade natural ores can contain up to 70% by weight of uranium oxide. Uranium found in natural ores contains two principle isotopes – uranium-238 (99.3%) and uranium-235 (0.7%). The uranium is enriched in uranium-235 before being made into nuclear fuel. Uranium enrichment processes generate a product consisting of 3 to 5 percent uranium-235 for use as nuclear fuel and a product of depleted uranium (about 0.3 percent U-235). The depleted uranium has some commercial applications including counterweights and antitank armaments. However, the commercial demand for depleted uranium is currently much less than the amounts generated. For instance, the U.S. Department of Energy (DOE) has about 750,000 metric tons of depleted uranium in storage. Under the U.S. Enrichment Corporation Privatization Act, DOE is required to accept depleted uranium from a U.S. Nuclear Regulatory Commission (NRC) licensed uranium enrichment facility if the depleted uranium is determined to be low-level radioactive waste. If the depleted uranium has no commercial use, the licensee can transfer the material to DOE or dispose of it at a commercial disposal site if it meets the disposal site's requirements.

**Why is depleted uranium considered a Class A low-level radioactive waste?**

The regulations at 10 CFR 61.55, "Waste Classification,” specify classes of low-level radioactive waste for near-surface disposal considering the longevity of the radionuclides contained in the waste. Disposal of Class A waste streams must meet minimum requirements while Classes B and C waste must meet more rigorous requirements to ensure stability of the waste and protect against inadvertent intrusion. Radioactive waste requiring disposal methods more stringent than those for Class C is not generally suited for near-surface disposal.

Depleted uranium is a source material as defined by Section 11(z) of the Atomic Energy Act, and if treated as a waste would fall under the definition of Class A low-level radioactive waste under 10 CFR 61.55(a). However, the Commission recognizes that the assessment supporting 10 CFR 61.55 did not address the disposal of significant quantities of depleted uranium. The Commission tasked the staff to evaluate the issue and provide recommendations to the Commission resulting in the staff's analysis (SECY-08-0147) dated October 7, 2008. In a Staff Requirements Memorandum (SRM-SECY-08-0147), dated March 18, 2009, the Commission approved staff's recommendation to proceed with rulemaking in 10 CFR Part 61 to specify a requirement for a site-specific analysis for the disposal of unique waste streams, including but not limited to significant quantities of depleted uranium.

**What are unique waste streams?**

Depleted uranium is unique because the relatively high concentration and large quantity generated by uranium enrichment facilities were not considered by the U.S. Nuclear Regulatory Commission (NRC) in the Final Environmental Impact Statement (NUREG-0945) supporting regulations in 10 CFR Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste." The NRC recognizes that the analysis supporting the criteria did not address the disposal of significant quantities of depleted uranium, and that there may be a need to place additional restrictions at a specific site or deny such disposal based on unique site characteristics.

Therefore, the NRC will update the regulations in 10 CFR Part 61 to specify a requirement for a site-specific analysis that demonstrates unique waste streams, including significant quantities of depleted uranium, can be disposed of safely. As currently envisioned, unique waste streams could include those that emerge in the future from new facilities that generate significantly different concentrations or quantities of waste not previously considered in NUREG-0945.

**What are some of the key issues with disposal of unique waste streams?**

The U.S. Nuclear Regulatory Commission (NRC) staff has identified several key issues for initial discussion with stakeholders. These include defining key regulatory terms such as unique waste streams and significant quantities of depleted uranium as well as technical parameters of a site-specific analysis including a time period of performance, appropriate exposure scenarios for protection of the public and individuals from inadvertent intrusion. The NRC staff is also soliciting stakeholder views on technical issues for a site-specific analysis of near-surface disposal of significant quantities of depleted uranium. These technical issues include appropriate considerations for depleted uranium waste form(s), uranium geochemistry, and radon migration and exposure. These issues arose from the results of the NRC staff's technical analysis (SECY-08-0147) that was submitted to the Commission on October 7, 2008, in response to Commission Order CLI-05-20 regarding depleted uranium. Given those issues, the Commission's related Staff Requirements Memorandum (SRM-SECY-08-0147), dated March 18, 2009, instructed the staff to begin engagement with stakeholders and interested parties to initiate development of the technical basis for possible revision of the 10 CFR Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste." 

**What are other countries doing?**

Depleted uranium exists in several countries around the world, particularly those which are currently or have operated uranium enrichment facilities. Currently, most countries, including the United States, consider depleted uranium a potentially valuable resource and are safely storing it. Depleted uranium has potential economic value as an energy source through re-enrichment processes, industrial applications including counterweights and radiation shielding, and military uses such as antitank armaments. However, the demand for depleted uranium is currently much less than the amounts generated. Therefore, a number of countries are conducting their own research and development programs into potential applications. Long-term disposition of depleted uranium will be needed if depleted uranium stockpiles are determined to have no economic potential. The International Atomic Energy Agency recommends that countries pursuing disposal establish limits for long-lived radionuclides, such as depleted uranium, based on the assessment of a specific near-surface disposal facility.

**How should previously disposed of depleted uranium be addressed by the disposal facility sites?**

Previously disposed of volumes of DU should be addressed through each site's performance assessment. The performance assessment is meant to be a living tool for both the licensee and regulator to be able to assess future compliance of the disposal facility with the performance objectives in 10 CFR regulations protecting workers and the public and ensuring long-term stability of the disposal site after it is closed (Part 61.41-61.44). During the licensing of a disposal site, assumptions must be made about the possible final inventory of a site or a specific disposal unit within a site based on expected waste volumes and streams. As operations occur, the uncertainty in the inventory decreases as actual waste volumes, constituents, and concentrations are known. The performance assessment should be regularly updated with these actual values and any revised information of future waste to be received. The results of the performance assessment can then be used to evaluate whether there is reasonable assurance that the disposal unit or site will remain in compliance with the performance objectives.

If the result of the performance assessment is that compliance with performance objectives is uncertain or unlikely, then several options may be used depending on the specifics of the situation. Additional data collection and modeling may be performed to reduce the uncertainties in those factors driving the results. Another option is modification of the facility, such as the final cover design. A third option is to reduce future waste volumes, or specific radionuclide quantities or concentrations. The decisions on what actions to take should involve both the site operator and the appropriate regulator(s).

**Exposure to depleted uranium poses both radioactive and chemical risks. How is the chemical risk integrated into the risk assessment to demonstrate compliance with 10 CFR Part 61?**

The chemical risks are not integrated directly into the compliance assessment for a Part 61 license. The regulatory criteria, including concentration values and limits, in 10 CFR Part 61 have been established based on radiation risk alone. As part of requesting a license for a radioactive waste disposal facility, the applicant would also have to obtain all other required permits or licenses. These will include licenses or permits from other Federal or State agencies that have authority over the elements or compounds, in this case depleted uranium, which may pose a chemical risk. Examples of other regulatory authorities might include a general authority to protect underground sources of drinking water in the general environment or through a site's National Pollutant Elimination Discharge System permit(s).

**How does the NRC ensure Agreement States provide proper oversight?**

NRC is required by the Atomic Energy Act to periodically review Agreement States' regulatory programs to ensure that they are adequate to protect public health and safety and are compatible with NRC regulations. These periodic reviews of the Agreement States' radiation protection programs are performed as part of NRC's Integrated Materials Performance Evaluation Program (IMPEP). Agreement States' regulatory programs are reviewed every four years. If performance issues are identified with an Agreement State program, more frequent reviews or formal interactions are performed. In some circumstances, the State will prepare and implement a Program Improvement Program, which is reviewed by the NRC. In addition to IMPEP reviews, NRC conducts management meetings with the Agreement States between the reviews. NRC also performs detailed technical and legal reviews of all Agreement State regulations to ensure compatibility with NRC regulations. For most NRC amendments to the regulations, the Agreement States are required to adopt compatible regulations within three years. In addition to overall programmatic guidance provided by NMSS, NRC Regional-based State-Agreement Officers also provide direction and guidance to the Agreement States within their Region.

**How can depleted uranium be stored safely in a near-surface disposal facility?**

The safe disposal of depleted uranium is the responsibility of licensed waste disposal facilities. Demonstration of compliance with 10 CFR Part 61 criteria will ensure safe disposal of DU in a near-surface environment. NRC staff performed a screening analysis to evaluate whether **significant** quantities of DU can be disposed of in the near-surface. The results of the screening analysis suggest that disposal facility performance is strongly dependent upon site-specific conditions. For instance, suitable covers and robust radon barriers may effectively limit exposures to radon gas at arid sites, while humid sites with viable water pathways are probably not appropriate for significant quantities of DU. Therefore, near-surface disposal of significant quantities of DU may be appropriate, but not under all site conditions. The analysis to assess performance of disposal of significant quantities of DU at a particular site should be supported by as much site-specific data as appropriate to demonstrate compliance with the performance objectives in 10 CFR Part 61.

**How can the performance assessment account for long time periods, such as 10,000 years?**

The performance assessment is a systematic analysis that identifies the features, events, and processes (i.e., specific conditions or attributes of the geology, biosphere (including climate), degradation, deterioration, or alteration processes of engineered barriers, and interactions between the natural and engineered barriers) that may affect the performance of the disposal facility. The applicable features, events, and processes that need to be considered for evaluation depend on the time period of analysis. Different features, events and processes may need to be included for a performance assessment for 1,000 and 10,000 years. As the period of analysis is extended through time, the uncertainty in the analysis grows. At longer time periods, analyses may need to rely on stylized scenarios, based on current scientific knowledge and assumptions about features, events and processes, such as major global climatic cycles including warming cycles and ice ages, rather than discrete modeling of the evolution of the disposal site, due to the large degree of uncertainty. Arguments can be presented both for and against extended performance analysis of near-surface facilities (both for DU and any other long-lived waste constituent such as technicium-99 or chlorine-36) due to these uncertainties.

Page Last Reviewed/Updated Tuesday, February 13, 2024

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Page Last Reviewed/Updated Tuesday, February 13, 2024