So, I was keeping an eye on something pretty interesting over the July 4th holiday, and it had nothing to do with fireworks or barbecues. There was a big, symbolic deadline looming for the future of US nuclear power, and frankly, I wasn't sure they were going to make it.
A little backstory: the Trump administration set a pretty ambitious goal last year. They challenged the industry to get three new microreactors to "achieve criticality" by America's 250th birthday. It was a lofty target, meant to light a fire under the emerging nuclear tech scene.
And you know what? They did it. In a last-minute scramble, not just three, but four companies hit the mark. It’s a genuinely positive sign for a world that’s desperate for more clean, reliable electricity. But here’s the thing—and it’s a big "but"—achieving criticality isn't what most people think it is. It doesn't mean these reactors are about to start powering our homes.
Let's untangle what really happened, what it means for nuclear power in the US, and where these companies go from here.
So, What Was This Big Race All About?
Basically, the government created a fast-track program for prototype reactors. The Department of Energy picked 11 projects and gave them land and support from our national labs to speed up development.
All of these are what we call microreactors. When you picture a nuclear plant, you're probably thinking of the massive light-water reactors that power the grid today. These new designs are tiny in comparison—we're talking tens or even hundreds of times smaller.
The race to the deadline was pretty exciting to watch.
- Antares Nuclear was the first to cross the finish line in June.
- Then came Valar Atomics and Deployable Energy.
- Aalo Atomics slid in right under the wire, hitting their target in the early hours of July 4th. Talk about a photo finish!
What’s really impressive here is the speed. The nuclear industry is famous for massive projects that drag on for years and blow through their budgets. The fact that Valar, Antares, and Aalo were all founded in 2023 (and Deployable in 2025) and hit this milestone so quickly is, on its own, a big deal.
But now for the reality check.
"Criticality" Isn't What You Think It Is
This is the most important part of the story. Reaching criticality and actually producing usable electricity are two completely different things. It’s not even close.
All four of these reactors reached what’s called zero-power criticality.
Think of it like this: imagine you’ve just built a brand-new car engine from scratch. Zero-power criticality is the moment you turn the key for the very first time. You hear it roar to life, and you know the fundamental combustion process works. It's a huge moment! You’ve proven your core concept.
But… the engine isn't connected to a transmission, wheels, or a cooling system. You can’t actually go anywhere. You’re just making noise and a little bit of heat. That’s essentially what these companies have done. They’ve proven they can start and sustain a nuclear chain reaction, but with no meaningful power coming out of the reactor.
Kathryn Huff, a former top official for nuclear energy, put it perfectly on a podcast earlier this year. She said a zero-power-criticality test "can be achieved without making real engineering progress on fuel or design." It’s a crucial first step, but it's just that—step one.
The Long, Hard Road from 'Critical' to 'Connected'
Now that the deadline is met and the champagne has been popped, the real work begins. To turn these testbeds into actual power plants, these companies have to solve some massive technical challenges.
For starters, they need to add major equipment, like the cooling systems that will transfer the immense heat out of the reactor core and use it to generate electricity. That’s not a small task.
And true to startup form, their timelines are… let's call them optimistic. Aalo says it’s already working on a second reactor and plans to generate 10 megawatts to power a data center by 2027. Deployable Energy is aiming for commercial reactors by 2028.
Look, I’m a tech optimist at heart, but I’ve learned to take timelines from startups—especially nuclear startups—with a huge grain of salt. These are incredibly complex machines. On top of the technical hurdles, they’re about to run into a wall that’s often even bigger: government regulation.
The Nuclear Regulatory Commission (NRC) is the gatekeeper for all things nuclear in the US. Historically, their approval process has been, to put it mildly, slow. We're talking years, sometimes decades.
To be fair, the agency did propose a new, faster framework for microreactors earlier this year. But we have no idea how that will play out in practice. And some nuclear experts are already raising red flags, worrying that the Trump administration might be loosening safety rules a little too much in the name of speed. It’s a tricky balance to get right.
Is This Even the Right Goal?
While many are celebrating this milestone, not everyone in the pro-nuclear camp is thrilled. Some see this whole microreactor race as a distraction.
A recent analysis from Third Way, a public policy think tank, called the federal focus on this program an "unhelpful diversion." Their argument is that we need to be focused on meaningfully increasing our total nuclear capacity, not just celebrating small-scale science projects.
As their memo bluntly states, "Artificially accelerating project timelines is a short-term solution, not a long-term fix." It’s a fair point. Are we getting caught up in the excitement of shiny new tech while losing sight of the bigger picture?
So, where does that leave us?
This was absolutely a big first step. Seeing four companies move this fast is a testament to the innovation happening in the nuclear space. But it’s crucial we keep it in perspective. Criticality is a starting pistol, not a finish-line tape.
A lot more has to go right for any of these microreactors to ever send a single watt of power to the grid. It's an exciting story, for sure, and one I'll be watching closely. But for now, the journey has just begun.
