US-based fission technology company Oklo has signed a Memorandum of Understanding (MOU) with Centrus Energy Corp to support deployment of Oklo’s advanced Aurora fission powerhouses and advanced nuclear fuel production in Southern Ohio. Oklo and Centrus became partners in 2021 after signing a Letter of Intent to cooperate in the development of a High-Assay, Low-Enriched Uranium (HALEU) fuel facility.

Oklo is developing the Aurora microreactor, which uses heat pipes to transport heat from the reactor core to a supercritical carbon dioxide power conversion system to generate electricity. It will use HALEU fuel. Oklo says the reactor builds on the Experimental Breeder Reactor-II (EBR-II) and space reactor legacy. EBR-II features a hexagonal fuel element with a sealed heat pipe and a passive air-cooling system. Oklo initially marketed a 1.5 MWe microreactor version of the Aurora, but has now expanded its capacity offerings from 15 MWe to 100 MWe.

Oklo received a site permit in 2019 from the US Department of Energy (DOE) to build its first Aurora facility at Idaho National Laboratory (INL). In 2020, Oklo submitted a combined licence application to the Nuclear Regulatory Commission (NRC) to build and operate the Aurora microreactor at INL. However, NRC denied the application, citing the company’s failure to provide sufficient design information. A revised application was submitted in September 2022.

HALEU fuel contains uranium enriched to 5-20% uranium-235 (higher than the 3-5% typically used in light water reactors). HALEU is required by most of the advanced reactor designs being developed under the DOE's Advanced Reactor Demonstration Program. Currently there is no commercial supply chain to support HALEU production and DOE to launch a programme to stimulate the development of a domestic supply. Centrus plays a key role in DOE’s plans. At the American Centrifuge Plant in Piketon, Ohio, Centrus has constructed the first US HALEU production facility licensed by NRC. In June Centrus completed its operational readiness reviews and received regulatory approval to possess uranium at Piketon and to introduce uranium into the cascade of centrifuges there. Centrus expects to begin production of HALEU by the end of 2023.

Under the new MOU, Oklo and Centrus are planning a range of collaboration programmes to support the development and operation of the Aurora powerhouses including the supply of HALEU produced by Centrus at its fuel production facility in Piketon, Ohio. Oklo also has a partnership with Southern Ohio Diversification Initiative at the Piketon Site for two more plants. Centrus intends to buy energy from Oklo’s planned Ohio plants to power its HALEU Production Facility.

Oklo and Centrus intend to enter into one or more definitive agreements related to the following collaborative activities:

  • Oklo would purchase HALEU from the production facility Centrus is planning to build in Piketon, which is the only such facility licensed by NRCto produce HALEU.
  • Centrus would purchase electricity from the two Aurora powerhouses Oklo is planning to build in Piketon. These are designed to power homes and businesses in addition to the HALEU production facility. In turn, the HALEU production plant is designed to be scaled up to support hundreds of reactors.
  • Centrus would manufacture components for Oklo’s Aurora powerhouse at Centrus’s advanced manufacturing facility in Oak Ridge, Tennessee, as well as manufacturing capacity at the American Centrifuge Plant in Piketon, where HALEU production will take place.
  • Centrus and Oklo would work together to establish and license the capabilities necessary to deconvert HALEU from uranium hexafluoride to uranium metal and fabricate fuel assemblies.

Oklo Co-founder & CEO Dr Jacob DeWitte said the partnership with Centrus “is expected to span fuel production, manufacturing, and power off-take, exemplifying the early market interest in our scalable power plants and differentiated business model, involving selling power, not power plants”.

Centrus President & CEO Daniel B. Poneman stressed that establishing a domestic HALEU supply chain requires a public-private partnership. “We are excited to see strong support from industry leaders like Oklo as well as growing bipartisan support in Congress and the Administration for robust investment in domestic uranium enrichment.”

Image: Computer-generated image of how an Aurora powerhouse could look (courtesy of Oklo)