Apollo Atomics closed a $31M seed round to advance its factory built, truck transportable compact PWRs that shrink reactor footprints roughly 40x via a high density steam generator redesign, targeting 2028 commercial deployment for data centers and industry.
Apollo Atomics raised an oversubscribed $31 million seed round, consisting of $26 million in equity led by FCVC and $5 million in equipment financing from Oak Ridge Financial. The Cambridge, Massachusetts-based MIT spinoff and Y Combinator (Spring 2026) company is commercializing compact pressurized water reactors (PWRs) designed for factory manufacture, truck transport, and deployment in under 24 months.
FCVC led the equity portion. Participants included Y Combinator, Telesoft Partners (also referred to as TeleSoft Partners), Alumni Ventures, Robinhood Ventures, Nucleation Capital, Pelion VC (or Pelion Venture Partners), and Duke Capital Partners. Additional backers listed across reports include New Era Ventures, Orange Collective, Stanford University, E14 Fund, and Neutron Power Ventures.
Notable individual investors include Paul Graham, Ray Rothrock, Philip Johnston (or Johnson), Matteo Franceschetti, and Evan Meagher. Early supporters referenced by the company include Genesis Fund, Arjun Gupta, New Era Ventures, MIT Sandbox, and MIT’s Department of Nuclear Science and Engineering.
PitchBook data indicates total capital raised of approximately $31.5 million, with the company founded around 2024–2025 and employing roughly 9–10 people at the time of the round. The round ranks in the 99th percentile of U.S. energy seed deals on record.
How will Apollo Atomics use the funds?
Proceeds will fund construction of the A-1, a 1-megawatt commercial demonstrator (targeted for 2027); long duration reliability testing; vertical integration of key manufacturing processes; expansion of engineering and operations teams; and continued regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC).
Apollo retains the core physics, light water coolant, commercial grade low enriched uranium fuel, and established supply chains of conventional PWRs (which power the majority of the world’s nuclear fleet and represent more than 15,000 reactor-years of experience). Its primary innovation is a proprietary compact steam generator (or compact steam system) that delivers roughly an order of magnitude higher power density.
This shrinks the overall reactor footprint by approximately 40 times relative to conventional designs, enabling factory assembly, truck transport of high power units (including those above 80 MW), and deployment timelines under 24 months. The company projects reactor production costs 4–5 times lower than existing designs and levelized electricity costs of about 3 cents per kWh, with the explicit goal of undercutting natural gas.
The steam generator uses a compact metal block with fine channels for more efficient heat transfer between the primary coolant and secondary steam loops, replacing large, hand built conventional units. Safety features include fully passive systems. The company is also developing software for autonomous control, licensing support, and modeling to lower operating expenses and shorten deployment.
Product lineup:
- A-10 (10 MWe)
- A-50 (50 MWe)
- A-300 (300 MWe)
These target data centers (especially AI related), industrial facilities, utilities, and other large energy users. The company reports more than 20 GW of signed letters of intent.
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A low power (approximately 40 kW) reactor system demonstrator has already been built and tested at MIT’s Department of Nuclear Science and Engineering. The selected fuel configuration has achieved full power criticality. A research collaboration with MIT NSE was announced earlier in 2026.
Assil Halimi (Co-Founder & CEO) holds a PhD in Nuclear Engineering from MIT and has roughly a decade of experience in reactor design and operations with manufacturers and utilities. Drew Walker (Co-Founder & COO) is a hard tech founder with prior experience scaling manufacturing at an electric truck company, founding an electric boat company, and serving as a White House director for operations and events.
The advisory board includes former NRC Chairman Christopher Hanson, investor Ray Rothrock, MIT professor Koroush Shirvan, utility executive Mike Rencheck, and other senior utility leaders.
Apollo submitted a regulatory engagement plan to the NRC earlier in 2026 and is seeking authorization by the end of 2026 for commercial use of its selected fuel configuration. The company emphasizes reliance on already licensed materials, fuel, and PWR operating principles to reduce technology, supply chain, and licensing risk compared with many advanced reactor programs that pursue novel fuels or coolants. Commercial deployment is targeted for 2028.
The raise occurs amid rising electricity demand from data centers, industry, and electrification that existing grids and long lead conventional nuclear projects struggle to meet. Apollo’s thesis prioritizes de-risking through proven PWR technology while attacking the size, cost, and construction timeline bottlenecks via a single high leverage component redesign and factory production. This contrasts with many advanced nuclear startups focused on new reactor architectures. The combination of technical progress at MIT, early LOI traction, high caliber investors, and a relatively capital efficient path to a commercial demonstrator underpins the unusually large seed round for the sector.
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