The US Nuclear Regulatory Commission (NRC) on 6 January issued a determination denying US-based Oklo Power's application to build and operate its Aurora compact fast reactor in Idaho. NRC said gaps in the information supplied by the company presented its review of the combined licence application from moving forward. Oklo can submit a "complete application" in the future and can request a hearing on the NRC decision.
Oklo submitted its application in March 2020 for the advanced reactor, to be built at the Idaho National Laboratory site. The NRC accepted the application in June 2020, using a novel, two-step approach to docketing the application to allow Oklo to fill in identified information gaps before developing a review schedule. Oklo submitted reports and supplementary information on several topics in July and October 2021, bur the information was insufficient to close those gaps, NRC concluded.
"Since Oklo submitted its application almost 22 months ago, our engagement with the company has included multiple information requests, audits and public meetings," said NRC Director of the Office of Nuclear Reactor Regulation Andrea Veil. "We thoroughly considered Oklo's proposals for satisfying our safety requirements."
She added: "Oklo's application continues to contain significant information gaps in its description of Aurora's potential accidents as well as its classification of safety systems and components. These gaps prevent further review activities. We are prepared to re-engage with Oklo if they submit a revised application that provides the information we need for a thorough and timely review."
The Aurora design is a fast neutron reactor that uses heat pipes to transport heat from the reactor core to a supercritical carbon dioxide power conversion system to generate electricity. It will use metallic High-Assay Low-Enriched Uranium (HALEU) fuel to produce about 1.5MWe as well as usable heat. Oklo's was the first combined construction and operation licence for an advanced fission technology to be accepted for review by NRC.
NRC staff found that the topical reports did not adequately address previously identified gaps and were not sufficiently complete to support efficient, detailed technical reviews. “Allowing an additional opportunity to address the gaps in the topical reports will require substantial time and resources and would not support a timely, detailed technical review of either the topical reports or the custom combined licence application they are intended to support. Therefore, the NRC staff has decided to not accept the revised topical reports for docketing or provide further opportunity to supplement them. The NRC staff activities on the reviews have ceased, and the associated charge numbers have been closed,” NRC said
It added: “This decision is made without prejudice and does not convey any findings related to the general acceptability of the methodologies proposed in the revised topical reports. The NRC staff’s rejection of these topical reports does not prevent Oklo from submitting other topical reports on these or other topics for NRC staff review. All topical reports will be subject to a completeness determination at the time of submittal. Incomplete submittals will not be accepted for docketing or a detailed technical review.”
In a statement Oklo said: “We are eager to continue moving forward on not just this project with the NRC, but also other projects we are already engaged on with the NRC, including other budgeted application submittals. Our combined license application was the first ever accepted for an advanced plant, so there are many new things for all to learn from and work through to support a successful review, and it provides a foundation from which we can supply additional information and continue work with the NRC. The application was accepted as an important step for the nation's interest, and we are continuing our work on advanced fission unabated as key to a clean energy future.”
Photo: Oklo Aurora Powerhouse (Courtesy of Gensler)