MIT Spinoff Apollo Atomics Raises $31M to Build Nuclear Reactors in a Factory, Not a Megaproject

Apollo Atomics, an MIT spinoff developing a new generation of compact nuclear reactors, has raised 31 million dollars in oversubscribed seed financing to turn proven reactor technology into what the company describes as a factory‑built product rather than a one‑off construction megaproject.

The round was led by San Francisco venture firm FCVC and structured as 26 million dollars in equity alongside 5 million dollars in debt. Participants included Y Combinator, Telesoft Partners, Alumni Ventures, Robinhood Ventures, Nucleation Capital, Pelion VC, and Duke Capital Partners, alongside individual investors Paul Graham, Evan Meagher, Philip Johnston, Matteo Franceschetti, and Ray Rothrock. According to Dealroom, the round ranks in the 99th percentile of all US energy seed deals on record, an unusually large seed check for a company still working through demonstration testing and regulatory approval.

Apollo was founded in Cambridge, Massachusetts, by chief executive Assil Halimi, who holds a PhD in nuclear engineering from MIT and has roughly a decade of experience in reactor design and operations across manufacturers and utilities, alongside chief operating officer Drew Walker, a hard‑tech founder with prior experience scaling manufacturing at an electric truck company. That combination of deep nuclear engineering expertise and industrial manufacturing background shapes the company's central bet: rather than developing an entirely new form of nuclear energy, Apollo is taking reactor technology the industry already knows well, the pressurized water reactor design that powers the majority of the world's operating nuclear fleet, and re‑engineering it to be dramatically smaller and manufacturable at scale.

The company's core technical innovation centers on the steam generator, historically one of the largest and most complex components inside a conventional nuclear power plant. Apollo redesigned this system into a proprietary compact unit that the company says delivers roughly an order of magnitude greater power density than conventional designs, a change that shrinks the overall reactor footprint by approximately 40 times. That reduction in physical size is what makes factory‑based manufacturing genuinely feasible, allowing completed reactor units to be built on an assembly line, shipped by truck, and deployed at a customer site in under 24 months, a dramatically shorter timeline than the years typically required to construct a conventional nuclear plant from scratch.

Apollo is developing three reactor systems built around this compact steam architecture: the 10‑megawatt electric A‑10, the 50‑megawatt A‑50, and the 300‑megawatt A‑300, a portfolio designed to serve data centers, industrial facilities, utilities, and other large energy users with varying power needs. The company retains the core physics, light water coolant, and commercial‑grade low‑enriched uranium fuel of conventional pressurized water reactors, along with their established supply chains, technology that collectively represents more than 15,000 reactor‑years of operating experience, a deliberate choice aimed at minimizing the technology, supply chain, and licensing risk that has stalled many more exotic advanced reactor designs.

That approach appears to be resonating commercially well ahead of Apollo's first deployed unit. The company reports more than 20 gigawatts of signed letters of intent already in its commercial pipeline, a striking figure for a company still in the demonstration and regulatory phase of development. Apollo has already built and tested a low‑power, roughly 40‑kilowatt reactor system demonstrator at MIT's Department of Nuclear Science and Engineering, achieving full power criticality with its selected fuel configuration as part of a research collaboration announced earlier in 2026.

With the new capital, Apollo plans to construct its next demonstration facility, the A‑1, a 1‑megawatt commercial demonstrator targeted for 2027, alongside long‑duration reliability testing, vertical integration of key manufacturing processes, expansion of its engineering and operations teams, and continued engagement with the US Nuclear Regulatory Commission. The company's advisory board includes former NRC chairman Christopher Hanson, investor Ray Rothrock, MIT professor Koroush Shirvan, and utility executive Mike Rencheck, a roster that gives Apollo direct regulatory and utility‑sector relationships as it works through the licensing process, an area TechFundingNews has suggested may prove just as important to Apollo's success as its technical redesign.

Apollo enters an increasingly crowded field of venture‑backed advanced nuclear companies racing to solve the same underlying problem: AI data centers and other large energy users need substantial new baseload power, and traditional nuclear construction timelines and costs have made it difficult for the industry to respond quickly enough. Valar Atomics recently closed a 1 billion dollar Series B at a 6 billion dollar valuation, Antares has raised 470 million dollars against a Pentagon deadline, Radiant Nuclear secured 300 million dollars, and Blue Energy raised 380 million dollars pursuing a similar factory‑built approach, though centered on financing entire plants rather than redesigning the reactor core itself. Oklo, chaired by Sam Altman, has secured a 12‑gigawatt supply agreement with data center operator Switch but remains without full design approval from the NRC, while Kairos Power has become the first company in more than fifty years to receive an NRC construction permit for a non‑water‑cooled reactor and holds a 500‑megawatt agreement with Google.

Within that competitive landscape, Apollo's pitch is that sticking closely to conventional, already‑licensed reactor physics, while innovating primarily on manufacturing and footprint, offers a faster and lower‑risk path to full commercial licensing than reactor designs built around entirely new coolant types or fuel forms. Whether that bet pays off will likely come down to execution on the regulatory front over the next several years, precisely the work this seed round is intended to fund as Apollo moves from a lab‑tested demonstrator toward its first commercial‑scale reactor.