High-Assay Low-Enriched Uranium (HALEU)

Uses for HALEU

Operating Reactors – HALEU fuel enriched to between 5 and 10 weight percent U-235 could, subject to NRC regulations, be used in operating light water reactors. New technologies have the potential to enhance safety at U.S. nuclear power plants by offering better performance during normal operation, transient conditions, and accident scenarios.

Advanced Non-Light Water Reactors – HALEU fuel enriched to between 5 and 20 weight percent U-235 is the proposed fuel in many advanced non-light water reactor designs. These designs have may have increased fuel efficiency, smaller reactor cores, longer core lives, and decreased fuel waste relative to the currently operating reactors.

Medical Uses – HALEU can be used in the medical field to help produce medical isotopes. These radioactive isotopes are manufactured by irradiating targets via a uranium-235-produced neutron field.

Frequently Asked Questions

The following FAQs consider the front and back end of the nuclear fuel cycle. In-reactor safety is addressed in Fuel Qualification.

General HALEU Questions

HALEU Licensing Questions

HALEU Safety Questions

HALEU Research, Implementation and Application Questions

HALEU and International Partnerships

General HALEU Questions

What is HALEU?

HALEU, short for High-Assay Low-Enriched Uranium, is uranium enriched so that the concentration of the fissile isotope uranium-235 (U-235) is between 5% and 20% of the mass of uranium. For reference, natural uranium is made of about 0.7 % U-235 and traditional reactor fuel is enriched to between 3% and 5% U-235. Uranium enriched to 20% or greater in U-235 is termed high enriched uranium (HEU). Fuels that use HALEU are referred to as HALEU-containing fuel.

What is HALEU used for?

HALEU has several uses in fuel for different nuclear reactors and in producing isotopes for medical use. For example, some operating research and test reactors use HALEU-containing fuel. Several commercial developers have designs for advanced reactors that would use HALEU-containing fuel. Developers have proposed using HALEU in fuel for molten salt reactors or in TRISO fuel. Use of such fuel may allow for smaller designs that produce more power per unit of volume. Developers also expect that HALEU will allow their systems to be optimized for smaller reactor cores, longer core lives, increased efficiencies and better fuel utilization. Further, currently operating reactors could use HALEU-containing fuels to achieve higher burnups, and thus extract more power from fuel.

Who makes HALEU?

Two companies currently have NRC licenses to produce HALEU. Under its license, Centrus Energy may produce up to 600 kg of HALEU with uranium (U-235) enriched up to 19.75% and, under its license, Louisiana Energy Services may produce HALEU with U-235 enriched up to 5.5%.

How is HALEU produced?

There are two ways to produce HALEU: enrichment of uranium in U-235, or downblending uranium of greater U-235 concentration with lower-enriched material. For example, Centrus and Louisiana Energy Services are licensed by NRC to produce HALEU using gas centrifuges \ The U.S. Department of Energy plans to downblend high enriched uranium (uranium that is greater than 20% U-235) with current low-enriched uranium to produce HALEU.

As of publication, is HALEU used in existing commercial reactors?

HALEU is not currently used in commercial power reactors in the U.S. Some research and test reactors use HALEU-containing fuel.

HALEU Licensing Questions

Who licenses HALEU?

The NRC will license the commercial production, utilization, storage, and transportation of HALEU and HALEU-containing fuel. The Department of Energy can perform downblending of government-owned uranium at its facilities under its own authority.

Is the NRC prepared to license HALEU?

Yes. The NRC is leveraging the agency’s current experience (e.g., in licensing the fabrication of Naval and Research and Test Reactor fuel and certifying transportation packages for tri-structural isotropic particle fuel (TRISO fuel)) to ensure the safe fabrication and transportation and storage of advanced reactor fuels. In fact, the NRC is actively reviewing license applications for fuel enrichment facilities and fuel fabrication facilities to produce and utilize HALEU.

Has the NRC reviewed any HALEU-related licensing applications?

The NRC has reviewed HALEU-related licensing applications. The NRC staff has issued a certificate of compliance for a transportation package that can transport tri-structural isotropic particle fuel (TRISO fuel) that includes uranium enriched to higher than 5% uranium-235 (U-235). Further, the NRC staff has issued a license to Centrus Energy, under which it will produce HALEU enriched up to 19.75% U-235.

HALEU Safety Questions

How will the NRC know if HALEU and HALEU containing fuel is safe?

The NRC regulations contained in Title 10 of the Code of Federal Regulations provide reasonable assurance of adequate protection of public health and safety. All licensees, including those producing and utilizing HALEU, must meet all applicable regulations. The NRC staff has reviewed the regulations in Title 10 of the Code of Federal Regulations and concluded that they are sufficient to provide reasonable assurance of adequate protection of public health and safety with regard to HALEU. When the NRC receives HALEU-related applications, the NRC will review them to determine whether they meet the regulatory requirements. Based on that review, the NRC will make a determination on whether to approve or deny a particular application.

Is the NRC actively engaging stakeholders regarding HALEU?

The NRC is actively engaging with a broad range of stakeholders to better prepare to review future applications related to commercial HALEU use. NRC is engaging with the Department of Energy (DOE) and international partners to learn about new fuel concepts. The NRC is collaborating with DOE and international partners on fuel qualification activities. The NRC also participated in meetings with stakeholders to understand the industry’s near- and long- term plans for the HALEU-use in non-light water reactors. More information is available on the new fuels public engagement fuel page.

HALEU Research, Implementation and Application Questions

Does the NRC have to make any changes to the regulations to allow licensees to use HALEU?

The NRC has assessed the current regulatory framework and has determined that it is sufficient to review applications to and, if appropriate, license the safe use of HALEU for concepts and designs that are currently anticipated. Further, as with any new technology being submitted for NRC review, the NRC is prepared to establish new and/or refine existing regulatory requirements in a timely manner if concept-specific HALEU features warrant it.

How does the NRC assess when to conduct potential research related to HALEU and HALEU-containing fuel?

The staff is proactively assessing anticipated needs and pursuing research activities to ensure the staff is ready to effectively review license applications for HALEU and HALEU-containing fuel. In doing so, the staff is leveraging information from the Department of Energy Advanced Reactor Demonstration Program and from pre-application engagements with vendors and other stakeholders to align our research activities with the anticipated licensing requests.

How is the NRC using information from DOE in its research in this area?

The NRC is coordinating with DOE on research through the Gateway for Accelerated Innovation in Nuclear (GAIN) initiative, to investigate criticality safety issues related to shipment of higher-enriched (>5.0 weight percent uranium-235) uranium hexafluoride (UF6), which is one form of HALEU. This research will evaluate the availability of critical experiments that use configurations similar to UF6 packaging configurations for validation of the codes and nuclear data used to determine Keff (Keff is a measure of the sustainability of a nuclear reaction). Results of this research will be used to inform NRC technical reviews of higher-enriched UF6 package designs.

Are there medical uses for HALEU?

Yes, medical isotope production facilities may use HALEU to produce isotopes used to diagnose and treat certain diseases.

HALEU and International Partnerships

Is the NRC working with international partners?

NRC is actively engaged with international partners. For example, the NRC staff has been engaged with Transport Safety Standards Committee (TRANSSC) at the IAEA. The NRC has been engaging with TRANSSC about any changes to international standards that may be necessary for transportation of advanced reactor fuels, including HALEU. So far, none have been identified. In addition, the NRC participates in various IAEA technical and consultancy meetings, as well as workshops and conferences, to exchange information on the technical challenges and advances in fuel fabrication and discuss experience in the application of the IAEA safety standards to nuclear fuel cycle facilities. The NRC also supports and participates in the Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installations (CSNI) working group on fuel cycle safety. NRC participation on the WGFCS involves sharing insights, lessons learned, and engagement on topics and issues related to the fuel cycle facilities, including advanced reactor fuels. In additional to leveraging our participation in IAEA and NEA forums and activities, the NRC also participates in bilateral technical information exchanges with our regulatory counterparts on advanced fuels and issues related to nuclear fuel facilities.