A look inside a lab making the advanced fuel to power growing US nuclear energy ambitions

OAK RIDGE, Tenn. (AP) — Near signs that warn of radioactive risk at Oak Ridge National Laboratory, a half-dozen workers from the nuclear power company X-energy are making what appear to be gray billiard balls. Inside, they’re packed with thousands of tiny black spheres that each contain a speck of uranium enriched beyond what today’s power plants use.

The United States is chasing a new age of nuclear power that banks on domestic production of reactor fuel like X-energy is making, and though the work at Oak Ridge is unfolding across just 3,000 square feet, X-energy and others are already revving up for big production.

President Donald Trump set a goal of quadrupling domestic production of nuclear power within the next 25 years, signing executive orders in May to speed up development. A new wave of advanced nuclear reactors could be operational around 2030.

But just like cars won’t run without gas, those plants won’t run without fuel. To expand nuclear energy long-term, the nation must maximize its nuclear fuel production, according to Trump.

In Oak Ridge, X-energy has broken ground on a massive, nearly $2 billion campus for a new fuel fabrication facility, the first in the United States in over half a century. The nuclear fuel company Standard Nuclear, also in Oak Ridge, aims to produce metric tons of fuel for advanced reactors. A supplier named Orano is likewise looking to build a multibillion-dollar uranium enrichment facility nearby.

“This is a unique time,” said Tyler Gerczak, Oak Ridge National Laboratory’s principal investigator for the cooperative with X-energy’s subsidiary TRISO-X. “The momentum is incredible.”

Making the ‘most robust nuclear fuel’

The Associated Press toured the lab where X-energy is making small amounts of fuel for testing. Anyone beyond a magenta-and-yellow chain that warns of radioactivity must wear gowns, two layers of gloves and radiation monitors. When they leave, they’re tested for radioactivity.

X-energy, a Maryland-based company, uses uranium to make so-called TRISO fuel — inside what’s known as “pebbles.” Those are the billiard balls. The Energy Department says it’s the most robust nuclear fuel on Earth because the particles cannot melt in a reactor.

At the lab, the first step is making a uranium cocktail that resembles dark yellow lemonade.

Uranium powder, in the form of triuranium octoxide, gets added to nitric acid, said Dan Brown, vice president of fuel development for TRISO-X. Then carbon and an organic solution are added. They have two glass containers set up — one wears a heated jacket, looking almost like a little sweater, that helps the uranium dissolve into the acid solution. The second cools the acid solution while the carbon source is added, which turns the mix near-black, he said.

At another station, in a long clear tube, the cocktail solidifies into small black spheres with a jellybean-like consistency. Those black balls, about the size of poppyseeds, then travel through machines under temperatures as high as 1,800 degrees Celsius to get protective carbon coatings — like candy dipping — that make them look like very tiny BBs.

X-energy uses graphite and other cohesive materials to bind 18,000 kernels together into a larger sphere. That gets coated in a final layer of graphite to seal the final pebble. In the end, it’s strong enough to withstand the weight of an SUV.

The pebbles will eventually give up their energy in the high-temperature gas-cooled nuclear reactor X-energy is developing, with about 220,000 pebbles per reactor, like gumballs in a gumball machine. When they exit the bottom, if energy remains, the pebbles will return to the top for another pass. Each one could be used about six times. X-energy also plans to make fuel products for other advanced reactor designs.

The national laboratory lends X-energy its expertise, research and high-tech equipment for analysis and will evaluate samples, as will some universities. Other samples are archived. Idaho National Laboratory received a batch for its advanced test reactor, Brown said.

Critics of building more nuclear reactors say they’re too expensive and riskier than other low-carbon energy sources.

“Without a substantial decrease in construction costs, it’s not worth the avoided greenhouse gas emissions,” said David Kemp, a Cato Institute policy analyst.

Kemp said Trump’s 25-year quadrupling goal is unrealistic because it would mean building nuclear reactors faster than ever. The United States lacks any next-generation reactors operating commercially and only two new large reactors have been built from scratch in nearly 50 years. Those two, at a Georgia nuclear plant, were completed years late and at least $17 billion over budget.

Working to ‘amp up’ domestic nuclear fuel production

Many next-generation reactors will use high-assay low-enriched uranium. It’s fuel that’s enriched to a higher level than traditional large nuclear reactors use, allowing the newer reactors to run longer and more efficiently, sit on smaller footprints and produce less waste, according to the Department of Energy.

There’s little of it made in the United States right now.

Only Russia and China currently have the infrastructure to make large amounts of high-assay low-enriched uranium. In the United States, Centrus Energy produced the nation’s first 20 kilograms of high-assay low-enriched uranium in more than 70 years in late 2023, to show it can produce limited quantities for commercial reactors.

A big takeaway from Trump’s executive orders is the need to “amp up” domestic production of nuclear fuel to reduce dependence on foreign sources and enable in the long term expansion of American nuclear energy, according to the Energy Department.

At the Nuclear Energy Institute trade association, Benjamin Holtzman, director of new nuclear, said he thinks the fuel will be ready for a new generation of U.S. nuclear reactors needed to meet the growing demand for electricity — if the right actions are taken now.

X-energy CEO J. Clay Sell said he hopes to help solve the fuel problem so it doesn’t hold back new reactor development. The Energy Department has awarded funding to X-energy. Amazon invested in X-energy too, and they’re collaborating to bring more than 5 gigawatts of new U.S. power projects online by 2039.

X-energy is the only one with an application before the U.S. Nuclear Regulatory Commission to license a new fabrication facility to transform enriched uranium into fuel products for nuclear reactors. Another applicant has asked to amend an existing license to make fuel for advanced reactors, according to the NRC. About five additional companies have told the NRC they are interested in making fuel for advanced reactors.

X-energy’s pilot lab at the National Laboratory started in 2016. The company now has 100 acres in Oak Ridge and growing for its nuclear fuel production complex.

The first factory could be operational by late 2027 or early 2028, capable at full operation of assembling enough fuel orbs to power 11 of its new-age reactors; a second by late 2029, with a capacity four times greater, said TRISO-X President Joel Duling.

“I’ve been through two or three ‘nuclear renaissances,’” Duling said. “This isn’t a renaissance. This is a game-changer.”

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McDermott reported from Providence, Rhode Island.

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