Apollo Atomics has raised $31 million in seed funding for nuclear reactors that can be built in a factory, shipped by truck and deployed in under two years. The Cambridge, Massachusetts startup, an MIT spinoff, says it already holds signed letters of intent for more than 20 gigawatts of capacity.
FCVC ran the table on an oversubscribed round that pulled in Y Combinator, Telesoft Partners, Alumni Ventures, Robinhood Ventures, Nucleation Capital, Pelion VC and Duke Capital Partners, with angels including Y Combinator co-founder Paul Graham and Ray Rothrock.
Apollo’s bet is deliberately conventional: pressurized water reactor technology with decades of operating history, redesigned around a compact steam system it claims delivers roughly ten times the energy density of conventional designs and shrinks the reactor footprint about 40 times. The startup plans three commercial systems, 10 MW, 50 MW and 300 MW units, aimed at data centers, industrial facilities and utilities.
Founders Assil Halimi, who earned a PhD in nuclear engineering from MIT, and Drew Walker, a former White House director, have built and tested a reactor-system demonstrator on MIT’s campus. Apollo submitted a regulatory engagement plan to the US Nuclear Regulatory Commission and is seeking authorization by the end of 2026 to use its fuel configuration commercially.
The new funding finances the A-1, a 1 MW commercial demonstrator, plus reliability testing and in-house manufacturing as the company tries to move nuclear plants from construction sites to assembly lines.
