What is HALEU?

The Rt Hon Lord Hunt of Kings Heath OBE recently explained at the World Nuclear Symposium 2024 that the investment aims to diversify the nuclear energy market and increase the fuel options for countries with nuclear energy facilities. Geopolitical conflicts and natural disasters can lead to significant disruption to the global energy supply chain, and in circumstances where many countries are dependent on others to supply their energy, the diversification of the nuclear energy market can assist in stabilising supplies, as well as making the energy market more competitive.

But what is HALEU, and do the benefits reflect this investment?

How does HALEU work?

Nuclear reactors use uranium as fuel. Uranium contains an isotope (atom) called U-235. Fission taking place within the nuclear reactor splits U-235, generating energy. Most commercial nuclear reactors use LEU. This type of uranium contains less than 5% of the U-235 isotope. HALEU, by contrast, uses uranium which contains greater than 5% and less than 20% of the U-235 isotope, meaning that there is more of the isotope to split, which will generate more energy.² There is also Highly Enriched Uranium (“HEU”), which contains more than 20% U-235, but this is rarely used.

Key Advantages of HALEU

The key advantages of HALEU over LEU stem from its aforementioned ability to generate more energy than the traditional LEU, which is, of course, itself an intrinsic advantage.

• Efficiency & Performance: First, HALEU enables reactors to be more efficient; the higher concentration of fissile U-235 means that less of it is needed to produce the same amount of energy as LEU, i.e. it has greater energy density and so a higher ‘burn-up’ rate. This in turn means that reactors which utilise HALEU can be more flexibly sized (including smaller than traditional nuclear power plants), making them a good option for communities which might not have high availability of land for a reactor, for example a densely populated area. Indeed, many designs for small modular reactors (“SMRs”) are already optimised for HALEU fuel, meaning significant potential for greater amounts of energy to be produced in a much smaller, more compact footprint.
• Maintenance: Increased efficiency also means that the HALEU reactors need not be refuelled as frequently as their LEU counterparts to generate the same (or greater) amount of energy, further contributing to HALEU reactors’ ability to be flexibly deployed, for example, in remote communities.
• By-Products & Reduction in Waste: Nuclear fission naturally creates by-products, such as heat, which can be used to generate other forms of energy like hydrogen, and for use in desalination plants. The increased U-235 therefore means increased heat output to be recycled in these by-product processes. The spent HALEU can be also be recycled. Light water reactors (“LWR”) for example can operate using depleted uranium with U-235 far below 5%, so the HALEU uranium can be used multiple times over, in different energy-generating processes.³

The increased energy output of HALEU will likely make it critical in achieving the COP-28 goal of tripling global nuclear power capacity by 2050, as well the UK’s own target to quadruple its nuclear energy generation by 2050, particularly in circumstances where the UK’s electricity consumption is ever-increasing. It is expected that the UK’s electricity demands alone will increase by 50% by 2035, doubling or even trebling by 2050, making it essential that the UK find ways to meet this demand.⁴

In addition, a more stable supply of energy will be instrumental in the broader transition to renewable energy. Renewables such as wind and solar can be intermittent, affected by, for example, clouds or a lack of wind. Creating a more stable, consistent supply of nuclear energy can help complement these types of renewables, generating energy when they cannot and facilitating a smoother transition away from carbon sources.

What does this mean for the energy market?

HALEU is not naturally occurring and has to be artificially enriched by plants such as that at Capenhurst. The process is volatile, and as a result, the facilities designed to carry out the enrichment process have to be carefully designed to ensure their safety. Once the cost of such facilities is taken into account, the cost to produce and process HALEU can be much higher than its LEU counterparts. In addition, the enrichment of HALEU means that it is (comparatively) easier to convert to HEU, which is used in nuclear weapons, than LEU. Accordingly, HALEU necessitates elevated security and safeguards (including transportation and disposal) to ensure it is handled responsibly.

Moreover, HALEU is currently only commercially produced by one country, and as such the potential for wider global use and demand is, at this stage, unclear. As a result, funding for reactors that solely use HALEU, or for facilities like those at Capenhurst, may be difficult to initially find, although, as mentioned, HALEU is likely to be critical in achieving global nuclear energy goals in the near future.

Despite concerns regarding demand, the United States is also developing its own domestic supply of HALEU. Centrus Energy began construction of a facility in Ohio, USA, in 2019, and in November 2023, completed its first phase, delivering 20kg of HALEU. Moving to its second phase, it is hoped that the facility will produce 900kg of HALEU in 2024.⁵

¹ https://www.gov.uk/government/news/uk-first-in-europe-to-invest-in-next-generation-of-nuclear-fuel.

² https://world-nuclear.org/information-library/nuclear-fuel-cycle/conversion-enrichment-and-fabrication/high-assay-low-enriched-uranium-haleu.

³ https://world-nuclear.org/information-library/nuclear-fuel-cycle/conversion-enrichment-and-fabrication/fuel-fabrication#secondary-supply-from-recycle.

⁴ DESNZ Civil Nuclear: Roadmap to 2050

⁵ https://www.energy.gov/ne/articles/centrus-produces-nations-first-amounts-haleu.