Apollo Atomics Targets Cheaper Nuclear Power by Shrinking the Steam Generator

Apollo Atomics is not starting with a new reactor design alone; it is focused on shrinking the steam generator, a major component that converts reactor heat into steam for turbines. The company says this overlooked part can be made far more compact, helping reduce the size and cost of the overall system. Its approach targets one of nuclear power’s persistent challenges: making plants more competitive with lower-cost power sources.

Traditional steam generators can be hand-built and several stories tall, while Apollo says its version is about the size of a person and can be mass-manufactured. The startup says that compact component enables a reactor that is 40 times smaller than one using a conventional steam generator. Its design routes two fluid loops through a compact metal block with needle-thin channels, aiming to transfer heat more efficiently.

Apollo recently closed a $26 million seed round, including $5 million in debt, to build a demonstration reactor ahead of a planned commercial deployment in 2028. FCVC led the round, 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. The company was part of Y Combinator’s Spring 2026 batch, and its design is based on research from MIT.

Apollo CEO Assil Halimi projects an Apollo power plant can generate electricity at 3 cents per kilowatt hour, with a goal of beating natural gas. The company expects factory assembly, smaller size, and labor savings to help it build a 300-megawatt power plant in less than 24 months. Apollo says it has already built a small 40-kilowatt reactor at MIT and plans to offer systems ranging from 10 megawatts-electric to 300 megawatts.