The nuclear power industry is having a bit of a moment, with startups raking in cash to build advanced reactors in a bid to cut costs. But recent projections suggest those reactors won't be competing with fossil fuels on price anytime soon. Enter Apollo Atomics, a startup that thinks the industry has been chasing the wrong problem. Instead of designing yet another fancy reactor, Apollo is reimagining how thermal energy becomes electricity - specifically, the steam generator.

“We focus on the largest component, the steam generator,” CEO Assil Halimi told TechCrunch. “We have been able to shrink that component and make the whole system way more compact than any other reactor in the market.”

Steam generators are the unglamorous workhorses of power plants, turning reactor coolant into steam to spin a turbine. Most are hand-built and several stories tall, but Apollo says its version is about the size of a person and can be mass-manufactured. That has allowed the startup to build a reactor that's 40-times smaller than one using a conventional steam generator. Because nothing says 'nuclear' like compactness.

The company recently closed a $26 million seed round (including $5 million in debt) to build a demonstration reactor, with commercial deployment planned for 2028. Apollo's design is based on research from MIT, because why not borrow from the best? Halimi projects an Apollo plant could generate electricity at 3 cents per kilowatt hour. “We don’t want to be incremental in nuclear and just improve a small thing,” he said. “Our target is to beat natural gas.”

Existing steam generators, Halimi argues, have room for improvement - a polite way of saying they're outdated. They borrow heavily from coal and natural gas plants, but those fossil fuels have much lower energy density than nuclear fuels like uranium. “You have this high-potential fuel, but you’re converting just a small piece of it,” he said, lamenting the wasted potential of nuclear fuel.

Apollo's generator threads two fluid loops through a compact block of metal laced with needle-thin channels, transferring heat more efficiently and shrinking the whole system. This lets Apollo assemble the reactor and steam generator in a factory rather than on site, saving labor and space. Halimi expects a 300-megawatt plant could be built in less than 24 months, with the reactor costing four to five times less to produce than existing designs.

Apollo has already built a small, 40-kilowatt reactor at MIT to demonstrate the technology, and plans to offer three sizes, from 10 megawatts-electric to 300 megawatts. The funding round was led by FCVC, with participation from Telesoft Partners, Y Combinator, Alumni Ventures, Robinhood Ventures, Nucleation Capital, Pelion VC, Duke Capital Partners, New Era Ventures, Orange Collective, Stanford University, E14 Fund, and Neutron Power Ventures. Apollo was part of Y Combinator’s Spring 2026 batch - because every startup needs a little acceleration.