The Nuclear Regulatory Commission (NRC) has allowed Centrus Energy—a firm contracted by the  U.S. Department of Energy (DOE) to demonstrate high-assay low-enriched uranium (HALEU) production with domestic technology—to introduce uranium hexafluoride (UF6) into its uranium enrichment centrifuge cascade in Piketon, Ohio.

The development marks yet another critical milestone for Bethesda, Maryland–headquartered company in its efforts to begin first-of-a-kind HALEU production at its American Centrifuge cascade in Ohio by December 31, 2023. When completed, the facility could be the first new U.S.-owned, U.S.-technology enrichment plant to begin production in 70 years, it has noted. 

The Big Step to Address a Crucial Nuclear Fuel Supply Gap

While delayed by supply chain constraints and the COVID pandemic, the pioneering demonstration has been eagerly awaited, given its implications for alleviating—even if moderately—supplies of HALEU, a form of uranium-235 fuel enriched to 20%. Experts note that because HALEU is enriched higher than the 4% to 5% level typically used in existing reactors, it may provide more power per volume than conventional reactors, and its efficiency allows for smaller plant sizes. The fuel type also promises longer core life and a higher burn-up rate of nuclear waste.

Several advanced nuclear reactor designs, including nine of the 10 designs awarded under the DOE’s Advanced Reactor Demonstration Program (ARDP), require HALEU. However,  HALEU is currently available from only two sources: limited amounts from the DOE via down-blending of existing stockpiles of material and from commercial supplies via TENEX, a nuclear fuel company owned by Russian state-owned company Rosatom.

Centrus’s American Centrifuge cascade uses gas centrifuge machines, which feed uranium hexafluoride (UF6)—heated to a gaseous state—into a rotor inside the centrifuge machine. A rotor spinning at high speed inside a steel casing uses centrifugal force to concentrate the heavier U-238 isotopes at the outer wall of the rotor and the lighter U-235 isotopes toward the rotor center. The streams are then fed to the next machines in a “cascade” to achieve the desired level of enrichment. Centrus will use a 4.95% LEU feed material for its planned HALEU 16 AC100M-centrifuge cascade. It suggests roughly 85% of the separative work units (SWU)—a measure of enrichment needed to produce HALEU—is already contained in the LEU feed material

Centrus Energy’s original AC100 machine was developed with support from the Department of Energy and later refined by Centrus to the current AC100M machine under contract with Oak Ridge National Laboratory. Centrus Energy will demonstrate 16 of its centrifuges at its enrichment facility in Piketon, Ohio. The machines will be used to enrich uranium hexafluoride gas to produce an initial 20 kilograms of HALEU by December 2023 to support advanced reactor fuel qualification testing and reactor demonstration projects. Courtesy: Centrus

NRC Green Light Follows Operational Readiness Reviews

The company began building its cascade of 16 AC100M centrifuges in 2019, after entering into a $115 million cost-shared contract with the DOE, under which the DOE agreed to reimburse the company for 80% of its costs incurred in performing the contract. While the contract was modified several times, the government’s total contract funding currently amounts to $173 million.

In 2022, the DOE elected to move the operational portion of the demonstration to a competitively-award contract to prolong the operational period. After a solicitation process, it awarded a $150 million “definitized contract” to Centrus under two phases through 2024. Phase 1 calls for the completion of the cascade and the start of operations to produce an initial 20 kg of HALEU UF6 (19.75% enriched) by December 31, 2023. Centrus in February 2023 completed construction and initial testing of its advanced uranium enrichment centrifuge cascade as well as most of its associated support systems.

Under Phase 2, Centrus plans to continue production for a full year at an annual production rate of 900 kg of HALEU. The DOE will own the HALEU produced from the demonstration cascade. The operation contract also gives the DOE options to pay for up to nine additional years beyond the base contract, though those options will be subject to the availability of Congressional appropriations.

According to Centrus, the NRC’s approval issued on Thursday to allow Centrus to possess uranium and introduce it into the demonstration cascade follows the federal regulator’s operational readiness review. “The operational readiness reviews were required under Centrus’ NRC license, which was successfully amended in 2021 to make the Piketon site the only NRC-licensed HALEU production facility,” the company noted.

Next Steps: Scaling Up?

Now that construction and initial testing have been wrapped up, and the NRC has authorized Centrus to introduce UF6 into the HALEU cascade, Centrus will focus on completing construction on an on-site HALEU storage area. It plans to also conduct final testing activities prior to operation as slated by year-end.

Centrus is separately also exploring the possibility to scale up the Piketon facility for expanded HALEU production. Provided that it can secure sufficient funding or off-take contracts, the company estimates that a full-scale HALEU cascade—consisting of 120 individual centrifuge machines with a combined capacity of approximately 6,000 kg of HALEU per year (6 MTU/year)—could be brought online within about 42 months. “Centrus has the capability to add an additional cascade every six months after that,” it said.

DOE Takes Notable Steps to Boost Domestic HALEU Availability

The DOE estimates that more than 40 metric tons (40,000 kg) of HALEU could be needed by 2030 to deploy a new fleet of advanced reactors in a timeframe that supports the Biden administration’s goal of 100% carbon-free electricity by 2035.

Under the HALEU Availability Program, which Congress established in the Energy Act of 2020, the DOE has so far established a “HALEU Consortium,” a public-private coordination effort. The DOE has meanwhile also begun working to establish a temporary domestic demand for HALEU to stimulate a diverse supply of commercial HALEU. It hopes that these efforts could ultimately lead “to a competitive HALEU market and more certain domestic HALEU demand.”

On June 12, notably, the DOE’s Office of Nuclear Energy issued a notice to prepare an environmental impact statement in accordance with the National Environmental Policy Act (NEPA) for the DOE’s proposed efforts to facilitate and commercialize domestic HALEU production. 

On Monday, the agency also issued two draft requests for proposals (RFPs) focused on HALEU acquisition. The first RFP is related to services and HALEU material production. The second RFP focuses on deconversion activities to convert enriched UF6 gas into metal or oxide forms, which can be used to fabricate fuels needed by several advanced reactor developers.

Sonal Patel is a POWER senior associate editor (@sonalcpatel@POWERmagazine).