US-based Oklo and the Southern Ohio Diversification Initiative (SODI) have signed an agreement over the land necessary to host two of Oklo’s ‘Aurora’ design fast neutron microreactor. Oklo was granted a site permit in December 2019 from the US Department of Energy to build its first Aurora facility at Idaho National Laboratory (INL).

Then in March 2020, Oklo submitted to the US Nuclear Regulatory Commission a combined licence application to build and operate the Aurora microreactor at INL, and the application was accepted for review. DOE provisionally approved a specific site within the INL Site for the location of the powerhouse in late 2021.

However, in January 2022, NRC denied the application, saying  that it contained “significant information gaps” in its description of Aurora’s potential accidents as well as its classification of safety systems and components. Although the gaps prevented further review, NRC said it was prepared to re-engage with Oklo if the company submitted a revised application, which it did in September 2022.

SODI, a community-reuse organisation, plans to deploy two 15 MWe plants at its Portsmouth site near Piketon, Ohio. DOE began transferring parcels of the Portsmouth site to SODI in June 2018 for economic development.

Oklo says that the two Ohio units are expected to provide up to 30 MWe and more than 50 MW of heating, with opportunities to expand.

SODI is one of the partners for the Site Reuse Deployment Guidance for Advanced Reactors project, along with team members from Orano Federal Services, Southern Nuclear Company, Electric Power Research Institute, and INL. The project was funded through a grant from the DOE’s Office of Nuclear Energy to support the deployment of advanced reactor technology and the use of former nuclear sites.

The Aurora design uses heat pipes to transport heat from the reactor core to a supercritical carbon dioxide power conversion system. It uses metallic high-assay low-enriched uranium, (HALEU) fuel. The reactor is said to build 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’s initial design was a 1.5 MWe microreactor version of the Aurora, but it has expanded its capacity offerings and hopes to expand in time from 15 MWe to 100 MWe. The design is simplified with more affordable and simpler components, and is modular, which is said to allow the company to achieve cost competitiveness.