Oklo Fabricates Fuel Prototypes at Idaho National Laboratory

The developer of a miniature nuclear reactor said it has successfully demonstrated prototypes of its metallic fuel — a key development for the company and for the U.S. advanced nuclear reactor community, whose years-long timelines to deployment often beget sporadic messaging wins.

Oklo Inc. fabricated fuel prototypes with the Idaho National Laboratory, with multiple prototype fuel elements reaching production specification, for anticipated use in its 1-2 megawatt-electric compact fast reactor, which is intended to generate both process heat and electricity.

The demonstration is “one of the bigger steps on the pathway for us moving towards ultimately submitting a license application and trying our first reactor on,” said Jacob DeWitte, chief executive of the Sunnyvale, Calif.-based company, in an interview ahead of the announcement. The fuel prototype demonstration “ramps well into our plans” to build a commercial unit in the early 2020s, he said.

A very small reactor, DeWitte said, aligns with Oklo’s business model and technology development side. Reactors of Oklo’s size are geared especially toward use in remote areas, such as on islands or in Alaska, that often rely on expensive and emitting diesel fuel for energy.

"I think this can scale up into those markets and even more broadly,” said Zachary Bogue, a co-founder and managing partner with DCVC who sits on Oklo's board and whose firm invests in the company. “I would like to see this become a major contributor to not only providing industrial heat, but also providing baseload electricity."

“The simplest, cheapest, easiest process is what worked in production spec” right away, said DeWitte, who had patent application drafts at the ready in case more elaborate alternate methods of fuel fabrication had been required. Those methods are still under consideration but would take longer to develop, he said.

Oklo, which in 2016 became the first advanced fission company to begin paid pre-application talks with the Nuclear Regulatory Commission, demonstrated and intends to use U-10wt.%Zr fuel for its first reactor. To fabricate the fuel, zirconium and uranium was melted, casted, taken apart and then examined, DeWitte explained. The company favors a supercritical carbon dioxide power conversion system. 

While metallic fuels have been developed before, the specification performed was new and “to an extent challenged what had been done before,” DeWitte said. The demonstrations showed reusability and repeatability across parts of the fabrication, which lends itself toward “longer-term opportunities for closing the fuel cycle and actually recycling nuclear materials.”

Oklo fuel would be enriched to between 5 and 20 percent, or high-assay low-enriched uranium. But similarly for 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,” DeWitte said.

The licensing process runs parallel to the fuel issue, DeWitte said. Oklo is aiming to submit its license application to the NRC in the next six months, working toward filing a combined construction and operation license application in late 2019.

Some other U.S. advanced nuclear companies are also working on fuel fabrication, such as TerraPower LLC and X-Energy LLC. But ultimately, multiple companies making progress in this area “is going to help also support the development of the actual front-end infrastructure that we have,” DeWitte said.

Oklo’s fuel work was facilitated through vouchers provided via the Energy Department’s Gateway for Accelerated Innovation in Nuclear (GAIN) program.

GAIN creates “enduring technical relationships” and trust between the lab complex and companies, “so that you're not constantly starting from ground zero” throughout development, said John H. Jackson, a distinguished staff scientist and engineer at the Idaho lab who is also the technical interface for GAIN.

The program, DeWitte said, has created an impetus for national labs to work more nimbly and partner with industry in a targeted manner. The ability to work with Idaho National Laboratory on this demonstration was helpful to Oklo because the lab is set up both to handle the materials and examine them afterward with cutting-edge equipment.

“Moving quickly is really important for us, and government money ultimately just slows you down,” with complex contracts often taking months to negotiate, DeWitte said. Under the voucher system, the lab gets the Energy Department funding instead of the company to provide assistance to the developers, with an 80-20 cost-share that companies can meet with in-kind contributions.

By total value, Oklo has submitted the most proposals for GAIN support that have received awards, according to the company, which has gotten three such vouchers to date. 

This article was updated with corrected information from DCVC on its name, provided after publication.