Originally published November 26, 2015. Updated September 24, 2026.
Nuclear power provides 19% of the electricity generated in the US today, and American plants are doing something the industry has never done before. Reactors that fully shut down are switching back on instead of staying closed for good. The country’s fleet holds at 94 reactors across 54 plants, producing about 97 gigawatts. Worldwide, reactor counts are flat too, but roughly half of the new construction is happening in China, and nuclear’s share of the world’s electricity has slid to 9%, down from a peak of 17.5% in 1996, according to the World Nuclear Industry Status Report.
How many reactors are running right now
Add up every plant in the country and you get 94 reactors at 54 sites, producing roughly 97 gigawatts of capacity. Nuclear doesn’t clean up the US grid by itself. Across the first ten months of 2023, nuclear and renewables together supplied about 40% of US generation, with nuclear responsible for 18 of those percentage points and renewables the other 22. Worldwide, the fleet is bigger and holding roughly steady too. The World Nuclear Association counts about 440 reactors running in 31 countries, with combined capacity of 400 to 404 gigawatts. That total hides some churn. In 2025, the IEA counted 3 gigawatts of nuclear capacity retired worldwide, mostly in Belgium, offset by 3 gigawatts added in China, India and Russia, so closures are still happening even where the fleet overall holds steady. What’s shrinking is nuclear’s slice of a power market that keeps getting bigger.
American plants are coming back online
Palisades, an 805-megawatt plant in Michigan, shut down in May 2022 and began reloading fuel in late August 2026, aiming to become one of the first US commercial reactors to fully restart after closing for good. Then it hit a real snag. The NRC confirmed on September 23, 2026, that a fuel assembly had tipped during loading, with no radiological release, and the plant’s final restart date is on hold while regulators sort out next steps. Pennsylvania’s Three Mile Island Unit 1, rebranded the Crane Clean Energy Center, is targeting a 2027 commercial restart at 835 megawatts. Iowa’s Duane Arnold, at 601 megawatts, is aiming for an early 2029 return. And California’s Diablo Canyon, once scheduled to close around 2025, got a 20-year license renewal from the NRC in April 2026 and remains the state’s only operating nuclear plant. If you want the numbers on how nuclear’s safety record compares with other sources of power, Energy Collective has a separate explainer.
AI’s power demand is paying for the restarts
The restarts aren’t happening out of nostalgia. Microsoft signed a 20-year, roughly $16 billion power purchase agreement in September 2024 to buy electricity from the Crane Clean Energy Center once it’s running, and the US Department of Energy backed the project with a $1 billion loan in November 2025. Microsoft isn’t the only one writing checks like that. By July 2026, tech companies had committed to roughly 9.8 gigawatts of nuclear power across 13 separate deals. Meta’s agreements add up to as much as 5.2 gigawatts, including 4 gigawatts of TerraPower’s Natrium reactor for delivery between 2032 and 2035, plus 1.2 gigawatts from Oklo’s Aurora reactor. Amazon has committed to up to 960 megawatts through a dozen X-energy Xe-100 small reactors, backed by a $700 million investment. Google struck its own deal with Kairos Power for a 500-megawatt fleet of small reactors aimed at 2030.
China is building about half of the world’s new reactors
China’s fleet stands at 64 reactors totaling 63,985 megawatts, and the country isn’t slowing down. Another 38 reactors are under construction there, adding up to 39,694 megawatts, which is close to half of the roughly 80 reactors the World Nuclear Association counts under construction worldwide. In March 2026, China’s 15th Five-Year Plan set a target of 110 gigawatts of nuclear capacity by 2030. Outside China, growth is thin. Of the 10 new reactor construction starts worldwide in 2025, nine were in China and one was in Russia, according to the International Energy Agency.
Small reactors are closer to real, years behind schedule
NuScale was supposed to prove small modular reactors could work in the US, and it didn’t. Its VOYGR design became the first SMR certified by the NRC, in January 2023, but its flagship Utah project collapsed in November 2023 after costs rose from $5.3 billion to $9.2 billion, pushing the price past its $58-per-megawatt-hour target to $89. For a fuller look at how nuclear’s costs stack up against other power sources, Energy Collective has a separate breakdown. NuScale’s lead project shifted to Romania, a 462-megawatt plant with six modules that reached a final investment decision, though construction hadn’t started there as of this year. Back in the US, the Tennessee Valley Authority’s BWRX-300 reactor at Clinch River got an NRC staff recommendation for a construction permit in June 2026, with a mandatory hearing held August 13, 2026, and commissioners’ final decision still pending. Kairos Power broke ground on its Hermes 2 demonstration reactor in Oak Ridge, Tennessee, in April 2026, its first design meant to generate power, separate from the non-power Hermes 1 test unit it’s been building since 2024. And TerraPower’s Natrium reactor in Kemmerer, Wyoming, became the first full-scale advanced reactor design to win an NRC construction permit, in March 2026, a 345-megawatt design that stores heat in molten salt, backed by up to $2 billion in Department of Energy cost-sharing.
Nuclear’s slice of the world’s power keeps shrinking
Nuclear’s share of global electricity has fallen to 9% in 2025, down from a peak of 17.5% in 1996, according to the World Nuclear Industry Status Report, a group that’s generally critical of the nuclear industry but whose numbers get cited widely anyway. That 2025 figure is a lot lower than it was in 2015, the year energy-industry consultant Jarret Adams wrote an analysis arguing that climate goals couldn’t be met without nuclear, pointing to France’s mostly carbon-free grid as evidence that reliable, always-on power beat intermittent renewables on that score, and pushing back on plans for 100% renewable grids as underestimating the cost of the infrastructure involved. A decade later, the answer looks mixed. Nuclear hasn’t grown enough worldwide to prove Adams’s point on its own. But the restart wave in the US and the buildout in China both point toward more capacity coming online through the rest of the decade.
What could change this before 2030
A handful of near-term dates will show whether this pace holds. The NRC’s commissioners still have to rule on the Tennessee Valley Authority’s Clinch River permit after the August 13, 2026 hearing, and that decision will show whether another next-generation reactor design gets built in the US, alongside TerraPower’s Natrium. Palisades’ final restart timeline is on hold while regulators finish reviewing the September 23, 2026 fuel-assembly incident, which the NRC says caused no radiological release. Duane Arnold is aiming for an early 2029 return, and China still has to close most of the distance to its 110-gigawatt target for 2030 from a current base of roughly 64 gigawatts operating and 40 gigawatts under construction. Watch those four dates. They’ll say whether 2026 turns out to be the start of a longer reversal or a one-year blip.
