Introducing our SMR power rankings

16 startups, 1 champion: who wins?

Welcome to our first nuclear “Power Rankings.”

In October ROS co-founder Dan Steinhart and I scouted all the leading nuclear startups. You can find that in-depth review here.

Today we’ll check in on how the SMR race is unfolding, plus who’s winning (and losing) as of January 2026.

I’m borrowing this Power Rankings concept from sports. So for fun, I’ll compare each startup to an NBA team or player.

We even have a real shot clock, ticking down to July 4, 2026. The White House and Department of Energy (DOE) set a goal to turn on three new reactors by America’s 250th birthday.

Let’s have some fun!

Title favorites

#1: Valar Atomics

Valar takes the #1 spot the first and only SMR startup to split the atom so far. It completed a controlled chain reaction of its reactor at very low power.

Valar also broke ground on its Ward 250 reactor in Utah and just closed a massive $130 million Series A to fund its “Gigasite” vision.

This is the most aggressive team in the league.

NBA Comp: The “7 seconds or less” Phoenix Suns. They dominated the mid-2000s through speed, making quick decisions and attacking before their opponents could react. A new, high-speed strategy that blows away competitors.

#2: Radiant

Radiant holds two of the most valuable assets in the SMR race.

It secured the first slot at the DOME test bed, the DOE’s “testing arena” in Idaho. Radiant’s Kaleidos microreactor is sitting there ready to be fueled and tested.

Radiant recently secured the site for its R-50 Factory in Oak Ridge, Tennessee, where it plans to pump out 50 portable nuclear reactors a year.

And Radiant inked a deal with the US Army to deliver microreactors to Air Force bases within 36 months.

NBA Comp: The 2015 Golden State Warriors. Before the Warriors, everyone thought you needed big, lumbering centers to win. Golden State played small ball and ran everyone off the court.

#3: Aalo Atomics

At its SMR factory in Austin Aalo recently proved the reactor’s circulatory system (the liquid sodium plumbing) works perfectly without needing a single atom of uranium.

Aalo also broke ground in Idaho for its Aalo-X test reactor and doubled down on the most aggressive deadline: turning the reactor on by July 4, 2026.

It also signed a deal with Urenco to secure its own supply of enriched uranium, bypassing the bottlenecks choking many other startups.

NBA Comp: The Miami Heat. They win by outworking you in the gym (factory) and having a better system than everyone else.

#4: Kairos Power

Kairos’s late-2024 deal with Google to build a fleet of microreactors entered execution mode. Kairos recently completed the non-nuclear part of its Hermes reactor in Oak Ridge. It’s now targeting mid-2026 to turn the reactor on.

I’ll repeat what I said in our deep dive: Kairos is in pole position to be the first startup to flip the switch on a “civilian” SMR.

NBA Comp: The San Antonio Spurs. No hype. They execute fundamentals perfectly and win championships.

Playoff contenders

#5: Antares

The Defense Innovation Unit selected Antares for its fast-track program to build nuclear reactors on military bases.

Last month Antares raised $96 million to fund its “Mark-0” test reactor. The goal is to “go critical” with a low-powered demo at Idaho National Labs this year, then crank up to full power by 2027.

While other startups are begging for nuclear fuel, Antares is making its own TRISO (tiny kernels of uranium wrapped in ceramic armor).

NBA Comp: The 2004 Pistons. Defense-first, no flash, built to solve hard problems.

#6: X-Energy

Amazon just anchored a massive $500 million funding round to deploy X-Energy’s SMRs for its AI data centers.

X-Energy also inked a deal with the Pentagon and Air Force to deploy its rugged, container-sized reactors (XENITH), designed to keep military bases running when the grid goes down.

It also signed a major agreement with Centrica in the UK to deploy a fleet of 12 SMRs at the Hartlepool site.

NBA Comp: Giannis Antetokounmpo (The Milwaukee Bucks). A “two-way player” that can dominate both ends of the floor.

#7: Holtec

Holtec’s playbook is resurrecting shuttered nuclear plants.

The Palisades plant in Michigan received fuel late last year and is now on track to be the first restart in history. It’s now also considering restarting the Indian Point plant in New York.

Holtec also has a genius SMR strategy to bypass the hardest part of the game: permission. It’s planning to build two microreactors right next to the restarted Palisades plant.

NBA Comp: The late 90s Bulls. Everyone thought they were history, but they returned to dominate.

#8: TerraPower

TerraPower just landed the biggest sponsorship in the league. Meta inked a deal to fund two Natrium reactors. The SMR league finally got a national TV deal, and AI bought the broadcasting rights!

At TerraPower’s site in Kemmerer, Wyoming, the non-nuclear construction for its first reactor is almost complete.

The NRC issued its final safety evaluation report last month. That’s usually the “green light” before the nuclear construction permit.

NBA Comp: The LA Clippers. Steve Ballmer sunk $2 billion into the LA Clippers to brute-force a championship contender. His former boss, Bill Gates, spent some of his billions building TerraPower.

Dark horses

#9: Last Energy

While other SMR contenders were stuck in regulatory limbo Last Energy said, “screw it, we’re going to Europe.”

It signed an £80 million deal in the UK to build a dozen microreactors. A few weeks ago Last Energy got the official permission slip to plug its reactor into the national grid. Huge milestone!

Now it’s taking advantage of the US nuclear U-turn, inking a deal to power data centers in Haskell County, Texas.

NBA Comp: Luka Doncic (Lakers). Proves skills in Europe before moving to the US.

#10: Oklo

Many SMR founders told me privately they have real concerns about Oklo. One critique: It’s a fully remote company. That works for coding an app—not when you’re trying to split atoms.

Despite these concerns Oklo is putting points on the board.

It signed a huge deal with Meta to develop a 1.2-gigawatt nuclear campus in Pike County, Ohio. It inked a power purchase agreement with data center giant Equinix too.

Oklo also broke ground on site prep for its microreactor at Eielson Air Force Base in Alaska.

I still have major reservations about Oklo. It shouldn’t be a public company. But it’s scoring points and is moving up the league.

NBA Comp: The Lakers. Flashy, huge media attention, celebrity backers (OpenAI CEO Sam Altman is Magic Johnson). But do they have what it takes to win?

#11: GE Hitachi

While some startups are throwing release parties for renderings of reactors, GE Hitachi is pouring nuclear-grade concrete at its Darlington site in Ontario right now.

It also inked a massive agreement with the Tennessee Valley Authority to deploy its BWRX-300 design across the state.

It’s not the most exciting story in the league, but GE Hitachi is getting the job done.

NBA Comp: The Boston Celtics. A team with great history and present.

#12: Terrestrial Energy (Rookie)

I left Terrestrial out of our initial deep dive. But the DOE selected it for its Reactor Pilot Program, and it has one of the most unique “styles” in the league.

Terrestrial is building a molten salt reactor with a killer feature: the “Core-Can.” Instead of building a reactor you carefully maintain for 60 years, Terrestrial designed the core as a sealed, replaceable unit. Every seven years you swap out the old “cartridge” for a fresh one.

Terrestrial is developing its first commercial unit at the RELLIS campus in Texas (the closest thing nuclear has to a startup accelerator). A dark horse to watch.

NBA Comp: The 2011 Dallas Mavericks. A team of savvy veterans who found a way to win.

The relegation zone

#13: Natura Resources

Natura is building a molten-salt reactor on the campus of Abilene Christian University (ACU). The DOE just granted Natura a critical allocation of nuclear fuel for its reactor at ACU. Natura is using the “university testing loophole” to build faster and prove its tech works before scaling up.

Natura wants to put microreactors in the Permian Basin, the heart of American oil and gas. It’s planning to use the reactor’s massive waste heat to desalinate the briny wastewater from oil drilling and turn it into fresh water.

It was recently selected by Texas A&M to deploy its first commercial unit at the RELLIS campus and is aiming for operation by 2030.

NBA Comp: The Kentucky Wildcats. Not in the pro league yet, but an elite university.

#14: Westinghouse

In a historic move last month the White House announced an $80 billion deal to buy reactors from Westinghouse. Westinghouse will build eight “full-scale” nuclear reactors alongside a fleet of its eVinci microreactors.

I’m the most pro-nuclear guy on the planet, but this worries me. The whole promise of the SMR revolution is to make nuclear cheaper. If we’re still paying $10 billion per reactor, the renaissance will be dead on arrival.

NBA Comp: The Houston Rockets. Are they just living off history?

#15: Deep Fission (Rookie)

Deep Fission is our second rookie and the wildest play in the entire league.

It’s drilling a 30-inch borehole one mile deep and dropping a microreactor straight into the earth. By shrinking and then burying a traditional reactor a mile underground, Deep Fission eliminates the need for expensive containment domes.

Sounds like a gimmick, but it just raised $30 million and signed Letters of Intent to build in Texas, Utah, and Kansas.

It was also one of the ten startups selected by the DOE under its Reactor Pilot Program.

NBA Comp: The Harlem Globetrotters. Doing trick plays that defy physics.

#16: NuScale

NuScale holds the historic distinction of having the first NRC-certified SMR design. But “First to License” doesn’t mean “First to Build.”

Its flagship Idaho project was canceled last year. Meanwhile its Romania deployment is now delayed until 2027. NuScale spent years fighting the referees (regulators) and ran out of energy before the game started.

But don’t count NuScale out just yet. It just caught a massive “Hail Mary” with the Tennessee Valley Authority signing a deal to potentially deploy “gigawatts” worth of reactors.

NBA Comp: The Washington Wizards. They perpetually promise fans, “next year is our year.”

2026 is the year…

At least three new nuclear microreactors go critical on US soil. It’s the dawn of the second atomic age.

Here are the four keys I’m watching:

1. The DOE Reactor Pilot Program remains the clearest path to victory. Valar, Radiant and Aalo are currently in the lead.

2. The DOME at Idaho National Labs is where teams can plug-and-play their reactors. Radiant is scheduled to start fueled experiments in the coming months.

3. The Pentagon is quietly building its own league. The military often adopts tech faster, so watch the leading SMR defense players.

4. Wildcard: nuclear plant restarts. Palisades (Michigan), Three Mile Island (Pennsylvania) and Duane Arnold (Iowa) are all being resurrected. Any plant that can be restarted will be restarted.

Which SMR contender do you think will become champion? Let me know in the comments below. And remember to click “like” and “restack” to help us spread rational optimism.

—Stephen McBride