What the Hell is HALEU?

May 11, 2022

HALEU (High Assay Low-Enriched Uranium) is something that almost all the proposed new nuclear designs need, but which at the current time, is produced almost entirely in Russia.
Bill Gate’s favored startup TerraPower originally had planned to use Russian HALEU for it’s design, but now says it will find another source.
Here’s the write up from DOE. I highly recommend the Energy Gang podcast from last week which covers this and several other sobering topics.


More than 20 U.S. companies are developing advanced reactors that will completely change the way we think about the nuclear industry.

Most of these new reactor designs will be smaller, more flexible and less expensive to build and operate. Some of them may consume used nuclear fuel or help bring clean water and reliable power to communities never thought possible.

The majority of these designs will require a fuel that isn’t yet available at a commercial scale.

It’s what the industry calls high-assay low-enriched uranium, or HALEU for short, and these companies can’t bring their reactors to life without it.

What is High-Assay Low-Enriched Uranium?

Our existing fleet of reactors runs on uranium fuel that is enriched up to 5% with uranium-235—the main fissile isotope that produces energy during a chain reaction.

By definition, HALEU is enriched between 5% and 20% and is required for most U.S. advanced reactors to achieve smaller designs that get more power per unit of volume. HALEU will also allow developers to optimize their systems for longer life cores, increased efficiencies and better fuel utilization.

There’s a pressing need for HALEU now that could force some companies to reevaluate their plans if they can’t access this fuel.

The industry anticipates it may need nearly 600 metric tonnes of HALEU by 2030 in order to deploy new reactors to the market.

To help mitigate that risk, the U.S. Department of Energy (DOE) is exploring three options to support the testing and demonstration of these advanced reactors with HALEU fuel.

Near-Term Solutions

DOE and its national labs are working on two chemical processes to provide small amounts of HALEU to vendors in the near-future. Both methods involve the recycling of used nuclear fuel from government-owned research reactors to recover highly enriched uranium (greater than 20%) that can then be downblended to make HALEU fuel.

Electrochemical Processing

Irradiated fuel from DOE-research reactors is prepared and placed into a high-temperature molten salt chemical bath. An electric current is then used to separate the highly enriched uranium metal from the fission products. The recovered uranium is cleaned and mixed with lower enriched uranium to create HALEU. The uranium is then fabricated into new fuel in a high-temperature furnace.

Idaho National Laboratory is working to make up to 10 metric tons of HALEU using this process in the near-term to support current testing and demonstration projects.

Hybrid Zirconium Extraction Process (ZIRCEX)

Irradiated fuels are dissolved in hydrochloric acid gas to remove the aluminum or zirconium cladding. The fuel is then passed through a modular solvent extraction system to separate the uranium from its fission products. The uranium is then downblended with lower enriched uranium and returned to its solid form to produce HALEU.

Idaho National Laboratory is currently testing a small-scale pilot facility on unirradiated materials to research and scale-up a new ZIRCEX process. Argonne, Oak Ridge and Pacific Northwest national laboratories are collaborating on this project.

The Long-Term Solution

A three-year demonstration project is underway to send a strong signal to potential vendors that there will be a proven domestic capability to produce HALEU when the market demands it.

DOE is partnering with Centrus to manufacture 16 advanced centrifuges for deployment at an enrichment facility in Piketon, Ohio.

The company’s AC-100M machine was developed through the years with support from DOE and will demonstrate enrichment of uranium hexafluoride gas to produce HALEU.

The HALEU will be used for advanced reactor fuel qualification testing and reactor demonstration projects. The AC-100M technology will be available for commercial deployment at the conclusion of the demonstration.

2 Responses to “What the Hell is HALEU?”

  1. rhymeswithgoalie Says:

    Most of these new reactor designs will be smaller, more flexible and less expensive to build and operate.

    After all of these decades, I’m no longer accepting projections about nuclear power technology.

    I’ll believe it when I see it, and not before.

  2. John Oneill Says:

    Electrochemical processing – similar to the way fluoride salts are used as an electrolyte to produce aluminium – could also be used to extract plutonium from the spent fuel left from ordinary power reactors. These have about as much fissile material still left in them as unenriched uranium, straight out of the mine. Some is unburnt U235, the rest various isotopes of plutonium, produced from ordinary U238 over the five years or so that the fuel rods sat in the reactor. Fission products also accumulate in the fuel, and, besides being highly radioactive and hard to work with, some of them are ‘neutron poisons’, which absorb too many neutrons and interfere with the reactor’s chain reaction.
    Canadian Candu reactors, which use heavy water as moderator, normally run on unenriched uranium, with only 0.7% U235 instead of the usual 3 – 5 %. They can run perfectly well on spent fuel from light water reactors, cut up, heated to remove fission gases, and retubed into Candu fuel bundles. This has been trialled in South Korea and China. Moltex, a British/Canadian startup, is working on using spent fuel in an electrochemical process to make plutonium-uranium chlorides, for use in fast molten salt reactors. Fast reactors are less affected by fission products, as the fast neutrons are much less likely to be absorbed. Bill Gates’ company, Terrapower, is working on a fast reactor that will initially run on HA-LEU, but produce its own plutonium during operation. That uses solid fuel rods, but the company is also working on a liquid fueled, molten chloride fast reactor.
    That said, this database lists about fifty small modular reactor designs, most of which are to have the same enrichment levels as the reactors used now. Some are already in use, or construction has started.

    Click to access SMR-Book_2018.pdf

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