Apollo Atomics
Startup building compact, truck-transportable nuclear reactors for power-hungry data centers.
On the record
Checkpoint: Targeted filing of NRC construction permit application
The call
Apollo Atomics has an open technical window and no shipped competitor yet, but zero named customers and a 2028 permit timeline leave it far behind better-funded peers like Oklo and Kairos.
Apollo Atomics designs compact nuclear reactors small enough to power artificial intelligence data centers, a market that barely exists yet because no company has delivered a working small reactor by mid-2026. Right now, rivals like Oklo and Kairos have signed deals with tech giants such as Meta and Google, while Apollo has none, making it hard to prove the idea works in the real world. The company's plan to use common reactor fuel instead of a scarce type is a real technical advantage against other startups, but it is not hard for giant nuclear companies like Westinghouse or GE to copy if the market proves real. The single thing that would change everything: Apollo landing a signed contract with a data center company to actually buy and use one of its reactors.
Why
01
AI pressure: None apparent. AI data centers are Apollo's target buyers for power, not a force displacing its reactor business. Could AI do the core job? Unlikely.
02
Bigger players: Westinghouse, GE Vernova, Rolls-Royce SMR, BWXT, Framatome. These OEMs already build SMR designs like AP300 and BWRX-300 and could shrink reactors further once demand proves out. Could a giant copy it? Yes, easily.
03
What protects it. No compact reactor has actually gone operational yet, and Apollo's conventional PWR plus LEU fuel skips the HALEU supply bottleneck slowing rivals.
What would change this call
Apollo announces a named hyperscaler or DoD anchor customer PPA. Would show buyers believe the compact-PWR thesis over Oklo, Kairos, X-energy, Radiant.
Apollo closes a priced Series A of $75M or more. Would show investor confidence matches better-funded peers like Oklo and Kairos.
Apollo meets NRC pre-application milestones on schedule for its 2028 construction-permit filing. Would show regulatory progress is real, not just a stated target.
Apollo closes a priced Series A of $75M or more. Would show investor confidence matches better-funded peers like Oklo and Kairos.
Apollo meets NRC pre-application milestones on schedule for its 2028 construction-permit filing. Would show regulatory progress is real, not just a stated target.
Key numbers
- A-0 demonstrator hit full-power criticality
- About $22M raised to date, per investor memo
- 2 employees listed on YC's directory
Named risks
- Zero named anchor customers versus peers with Meta, Google, Amazon, or USAF deals already signed.
- Conflicting and unverified funding figures ($500K vs ~$22M) leave capital adequacy for reactor buildout unclear.
- 2028 NRC construction permit target with no confirmed pre-application milestones achieved yet.
- Extremely small team (2 employees per YC directory, 2026-07-24) against capital-intensive hardware and regulatory workload.
- Better-capitalized nuclear OEMs (Westinghouse, GE Vernova, Rolls-Royce, BWXT, Framatome) face no structural barrier to copying the compact-PWR approach.
Rivals, as read in July 2026
| Rival | Direction | Evidence |
|---|---|---|
| Oklo Inc. | losing to | Oklo reports ~15 GW order book with Meta and Switch as of 2026-07-26; Apollo has zero named customers |
| Kairos Power | losing to | Kairos got NRC construction permit Dec 2023 and Google supply deal Oct 2024; Apollo targets permit filing in 2028 |
| X-energy | losing to | X-energy completed IPO valued ~$1.1B in April 2026 per investor memo; Apollo still in seed round as of June 2026 |
| Radiant Industries | losing to | Radiant raised $100M Series C Nov 2024 and won USAF microreactor site selection April 2026 |
| Westinghouse, GE Vernova, Rolls-Royce SMR, BWXT, Framatome | contesting | No structural block stops these OEMs from pursuing similar compact-PWR miniaturization; only licensing timeline separates them |
Questions people ask
- Is Apollo Atomics profitable?
- No. As of July 2026 Apollo Atomics is a pre-revenue, pre-licensing hardware startup with no commercial reactor shipped. Its only reported technical milestone is an A-0 demonstrator reaching full-power criticality before July 4, 2026, per the company's own YC launch post.
- Does Apollo Atomics have any named customers?
- No. As of 2026-07-26 no named customer contracts, PPAs, or utility/data-center logos have surfaced for Apollo Atomics, unlike peer Oklo, which reports a roughly 15 GW order book via agreements with Meta and Switch.
- Who is Apollo Atomics' biggest competitor?
- Oklo, Kairos Power, X-energy, and Radiant Industries are ahead on both funding and traction: Kairos got an NRC construction permit in December 2023 and a Google supply deal in October 2024, while Apollo targets its permit filing only in 2028.
- Could AI replace Apollo Atomics?
- No. Reactor design, physical manufacturing, and NRC licensing are not tasks large language models perform. Apollo is instead a downstream beneficiary of AI-driven data-center electricity demand, per its own May 27, 2026 YC launch materials, not a target of AI substitution.
- Who owns Apollo Atomics and who founded it?
- Apollo Atomics is private and founder-led. CEO Assil Halimi holds a PhD in Nuclear Engineering from MIT and several reactor/fuel patents; co-founder Drew Walker serves as COO. It is a Y Combinator company from the Spring 2026 (P26) batch.
- When does Apollo Atomics plan to file for an NRC construction permit?
- Apollo Atomics targets filing a construction permit application with the NRC in 2028, according to an April 16, 2026 press release announcing its regulatory engagement plan and a two-loop hardware testing collaboration with MIT's nuclear engineering department.
Timeline
- 2026-07-24YC energy directory lists Apollo Atomics with 2 employees
- 2026-06-29MIT Sandbox newsroom notes Inc. feature on Apollo among 5 YC companies to watch
- 2026-06-16Third-party writeup details roadmap: truck-transportable A-10, A-50, A-300 reactors
- 2026-06-11Orange Collective memo claims ~$22M raised, active seed round for A-1 MW-scale facility
- 2026-05-27YC Launch post: A-0 demonstrator reaches full-power criticality before July 4
- 2026-04-16MIT DNSE research collaboration announced; NRC engagement plan, 2028 permit target stated
- 2026-04-15CB Insights lists founding year as 2025, conflicting with Pitchbook's 2024
Revision history
27 July 2026
First assessed. Losing its protection. The text above is fixed as of this date and is not edited afterwards.
In the same band
Sources
- Energy Startups funded by Y Combinator (YC) 2026 (2026-07-24)
- Apollo Atomics, Inc.: We make the most compact nuclear reactors
- Launch YC: Apollo Atomics: The Modern Nuclear Company (2026-05-27)
- Apollo Atomics Announces Research Collaboration with MIT's Department of Nuclear Science and Engineering (2026-04-16)
- Apollo Atomics 2026 Company Profile: Valuation, Funding & Investors
- Apollo Atomics, Investment Memo · Orange Collective (2026-06-11)
- Apollo Atomics Can Build Nuclear Power Plants in 2 Years (2026-06-16)
- Oklo Inc. -> Aurora Powerhouse (2026-07-26)
- Three advanced US reactors are racing to flip the switch before year-end (2025-11-30)
- US Air Force announces selections for microreactor deployments (2026-04-24)
- SMR Stock Report, IPO CLUB (2026-07-12)
- Newsroom, MIT Sandbox (2026-06-29)