The biggest barrier for next-gen nuclear, however, is likely to be the fuel supply. Some small reactor companies have been proactive here. Aalo, for example, has opted for the most commonly used reactor fuel on the planet, low-enriched uranium, so it can tap into the existing global supply chain.
But most advanced nuclear startups are banking on what’s known as fourth-generation reactors. These designs rely on coolants other than water and mostly aim to use one of two types of fuel: high-assay low-enriched uranium, commonly known as HALEU (pronounced HAY–loo), or tristructural isotropic fuel, for which HALEU is typically an input. Tristructural isotropic fuel is also known as TRISO.
HALEU, which firms like TerraPower and microreactor developer Oklo plan to use, is only really produced at a commercial scale by Russian and Chinese state-owned companies. Efforts to bring new centrifuges online in America are slow-going. Meanwhile, the TRISO fuel that startups such as Valar Atomics or Radiant need requires not only securing HALEU but also separating that enriched uranium into ceramic-coated pellets the size of poppy seeds. Manufacturers admit that TRISO may never cost less than low-enriched uranium.
The complications don’t stop there. Because HALEU is up to four times more enriched than traditional reactor fuel, it comes with stricter regulations. On the Nuclear Regulatory Commission’s security-clearance scale of category one, which allows for handling normal reactor fuel, to three, which includes military-grade enrichment levels, facilities with HALEU need to be rated at a category two. No such facilities exist in the U.S. today, though the commission just issued its debut permit for one last month.
As for traditional fuel, the existing supply of low-enriched uranium falls short of what would be required to meet the U.S. goal of quadrupling the nation’s nuclear capacity to 400 gigawatts by 2050.
“The supply chain is pretty well suited to support a fleet of 100 operating reactors,” Allen said, referring to the 94 commercial reactors in service in the U.S. “But then you can have 150, then 180, and pretty soon 200 after that. If you double that demand on the LEU supply, it’s not just the enrichment” that’s a limiting factor.
It’s also, he said, the production of raw uranium and the facilities to carry out conversion, where purified uranium ore is turned into a gas, and deconversion, where it’s solidified once again.
Expanding these upstream operations may be challenging, but it isn’t impossible. In fact, Allen said he came away from writing the report with the impression that supply chains are more capable of scaling up than he previously thought. But his team’s work demonstrates the steep obstacles faced by the entire industry — not only advanced reactor firms — as it attempts to bolt into action following decades of anemic construction in America.
The biggest impression the research left on Allen, he said, is that the AP1000 has a good shot at becoming the next reactor built in the U.S. Its costs are more predictable — and thus easier to finance — thanks to the lessons learned during construction of the two units that came online at Southern Co.’s Alvin W. Vogtle Electric Generating Plant in central Georgia in 2023 and 2024.
“I’m more bullish on the AP1000 than I was when I started this effort,” he said. “I’m broadly bullish on the supply chain.”
The DOE is considering alternatives to the AP1000 to satisfy President Donald Trump’s order to facilitate construction on at least 10 large-scale reactors by the end of the decade. In response to the news that the administration held talks with its rivals, Westinghouse said the AP1000 is“the only construction-ready, gigawatt-scale, advanced modular reactor that is fully licensed and operating in the U.S.”
The U.S. ultimately should focus on designs it can scale up rather than spreading its efforts in many different directions, said Stephen Comello, the executive director of the Nuclear Scaling Initiative. At that point, nuclear power will become cheap enough to be “boring.”
“Once you start accumulating that knowledge from repetition, nuclear construction becomes boring — just like natural gas combined-cycle plants, just like all other complex megaprojects and energy infrastructure that’s out there,” he said.
There’s little doubt that the AP1000 has a well-established supply chain and data showing it runs well, he said.
The question is, “Can you do it in a repeatable, cost-effective way? That’s where the risk lies with the AP1000,” Comello said. “It runs, the technology is great. But we have to prove to investors that we can overcome the execution risk. But here’s the thing: All reactors share execution risk to some extent. Others have a technology risk because they are still not proven at scale.”
{
if ($event.target.classList.contains(‘hs-richtext’)) {
if ($event.target.textContent === ‘+ more options’) {
$event.target.remove();
open = true;
}
}
}”
>
