Recycled Nuclear Waste Will Power a New Reactor

Idaho National Laboratory sprawls across nearly 900 square miles in the southeastern corner of its namesake state. Home to America’s first nuclear power plant, INL has served as the proving grounds for the future of nuclear energy technology for decades. Along the way, the lab has generated hundreds of tons of uranium waste that is no longer efficient at producing electricity. The spent fuel resides in temporary storage facilities while politicians duke it out over where to bury it .

Most of this spent fuel will probably end up underground, although where and when are open questions. As it turns out, a lot of people aren’t thrilled by the idea of having nuclear waste buried in their backyards. But at least some of the spent fuel may have a second chance at life feeding advanced nuclear reactors that will be smaller and safer than their predecessors. For the past year, scientists at INL have started recycling spent uranium to meet the fuel needs of a new generation of small commercial reactors.

Last week, INL tapped the nuclear energy startup Oklo as the first company to gain access to its stock of recycled uranium fuel. Oklo’s reactor, known as Aurora, will be a lot different from the reactors on the grid today. Each of America’s 96 nuclear reactors are housed on sprawling campuses and are capable of providing anywhere from 600 to 4,000 megawatts of power. Aurora, meanwhile, will look like a small A-frame cabin and generate just 1.5 megawatts. Oklo’s reactor also departs from legacy nuclear systems in its fuel of choice. Known as “high-assay, low-enriched uranium” or Haleu, this fuel packs more energy into a smaller package.
In nature, uranium ore mostly consists of the isotope uranium-238 and a sprinkling of uranium-235. Only uranium-235 can sustain the fission reaction that makes nuclear reactors tick, so turning the ore into usable fuel requires separating the uranium-238 out in a process called enrichment. Today, all the nuclear reactors in the US only use fuel enriched to less than 5 percent, but Haleu fuel is enriched to anywhere from 5 to 20 percent. According to Jacob DeWitte, the co-founder and CEO of Oklo, the fuel used in Aurora will be at the higher end of that range.
“The cool thing about advanced reactors is you can go to those higher levels of enrichment and make things smaller, which helps drive the economics of the system,” says DeWitte. “It’s exciting that they’re making this material available for us to use that isn’t otherwise being produced by US suppliers right now.”INL’s decision is a big step forward for Oklo and advanced nuclear energy systems in general. The lab is currently the only facility in the US capable of producing Haleu fuel, which means any advanced nuclear system that uses the fuel must secure the lab’s blessing before it can begin demonstrating its reactor.
Oklo is currently preparing an application to build its first Aurora reactor and plans to submit it to the Nuclear Regulatory Commission for review next month. DeWitte says he expects the approval process to take two years and construction of the reactor to take another. Assuming everything goes according to plan, Oklo’s Aurora would be the first American reactor to run on Haleu derived from spent nuclear fuel.

A Materials and Fuels Complex researcher works on fuel in a glovebox at INL's Experimental Fuels Facility. Photograph: Chris Morgan/INL