Last week, the Department of Energy gave a commercial company the green light to test fuel made from spent uranium.
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 thrilledby 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.
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.
INL is using spent fuel from the Experimental Breeder Reactor-II, a nuclear power station that provided electricity for much of the lab for nearly 30 years and also used recycled fuel. To turn the reactor’s spent fuel into Haleu, INL scientists first separate the uranium-235 from unwanted elements, such as plutonium, produced during the reactor’s operation. This involves soaking the spent fuel in a bath of molten salt and then zapping the concoction with a big dose of electricity to heat it to nearly 1,000 degrees Fahrenheit.
Since the uranium-235 used in the Experimental Breeder Reactor was enriched to 67 percent, it must also be blended to bring it to enrichment levels below 20 percent by mixing the uranium-235 with other isotopes that can’t be used as fuel. Finally, the downblended uranium-235 is converted into small pucks just a few centimeters across that can be used as feedstock for the fuel fabrication process.
Last year, Department of Energy officials announced they had awarded the nuclear energy company Centrus a $115 million contract to kickstart the commercial production of Haleu fuel at the Centrus uranium enrichment plant in Ohio. Earlier this month, the department gave another nuclear energy company, BWX Technologies, a $3.6 million contract to produce the fuel, which BWX plans to deliver by 2024.
Read more at Recycled Nuclear Waste Will Power a New Reactor