The NRC said Oklo’s application, submitted on 11 March, is for approval of what would be the first NRC licence for an advanced non-light-water reactor design.
The NRC and Oklo have engaged in “pre-application” discussions since 2016, a statement said.
In December 2019 the US Department of Energy granted a site use permit to Oklo to build a demonstration Aurora plant on the Idaho National Laboratory site.
The Aurora is an advanced fission power system that consists of a small reactor with integrated solar panels. It uses liquid metal to move fission heat out of the reactor core and into a secondary power generation system and generates approximately 1.5 MW of power.
Oklo has said it has budgeted “in the order of” $10m for construction and $3m a year for operations of the Aurora plant.
On fuel cycle costs Oklo said that because of the type of reactor and fuel cycle, only a single core load is required for the licence lifetime of 20 years.
The Aurora will generate both usable heat and electricity, run for at least 20 years on one load of fuel and operate without the need for water. The plant can also recycle fuel and ultimately convert nuclear waste to clean energy.
Oklo, which is solely venture-funded and backed primarily by US-based investors, announced last year that it had successfully demonstrated prototypes of a metallic fuel at INL for the Aurora reactor. It said it had fabricated prototypes with multiple fuel elements reaching production specification.
Oklo would use high-assay low-enriched uranium (Haleu) fuel. However, in common with many other advanced reactor developers, the lack of reliable access to Haleu remains a challenge – one that Congress has set its sights on addressing.
The sooner Oklo can “have access to be able to work with that, the faster we’re going to be able to actually get something built,” company co-founder Jacob DeWitte said.
Haleu fuel has many advantages that improve reactor performance. Because the fissionable isotope U235 is more concentrated in Haleu fuel, the fuel assemblies and reactors can be smaller, which is one reason why many small modular reactor designs will run on Haleu. The reactors do not need to be refuelled as often, and they can achieve higher burnup rates, which means less fuel will be required and less waste will be produced.