Austin-based Aalo Atomics fired up its Critical Test Reactor at Idaho National Laboratory this week, becoming the third startup to hit criticality under the Department of Energy's Reactor Pilot Program ahead of President Trump's July 4 deadline for a new atomic age.
Project First Light Goes Critical
Aalo's CEO Matt Loszak said the reactor — built in about ten months on what was a bare dirt field in Idaho — reached a stable, self-sustaining fission chain reaction as Aalo staff loaded uranium fuel bundles and pulled control rods on a live video stream. He called the moment "the first light of the second atomic age" and marked it under a company milestone Aalo calls Project First Light. The CTR is the first new reactor stood up at INL in roughly 50 years.
Sodium-Cooled Roadmap For AI Data Centers
The Critical Test Reactor is one of three prototypes Aalo is running toward its Aalo-1 commercial product, a factory-built sodium-cooled reactor sized around AI data-center load. Next up: Project Crucible, which validates non-nuclear systems in the Aalo-0 test rig, then Project Ascension, in which the 10 MWe Aalo-X demonstration reactor is integrated with data-center power infrastructure. The company argues nuclear is the only carbon-free baseload dense enough to co-locate with hyperscale campuses, echoing the pitch behind Valar Atomics' NVIDIA-powered microreactor and X-energy's 6 GW UK build.
Third Reactor In The July 4 Sprint
The Trump executive order that created the DOE Reactor Pilot Program challenged US developers to reach criticality on three advanced reactors by July 4. Aalo now joins Valar Atomics' Ward 250 and Antares' Mark-0, which achieved criticality earlier this year at INL. Energy Secretary Chris Wright had confirmed weeks ago that Aalo was on track to make the deadline; hitting it puts the DOE 3-for-3 on the challenge.
From Zero To Reactor In Three Years
Aalo was founded in 2023, and the company says it went from incorporation to a physical reactor at a national lab in under three years — a timeline the nuclear establishment had dismissed as fantasy. Supply-chain partners including Paragon Energy Solutions and Amsted Graphite are already tooling up for production, and CTO Yasir Arafat has told employees Aalo intends to scale to "several gigawatts per year" of factory-built reactor capacity within five years. The next milestone is the Aalo-0 non-nuclear sodium test loop, followed by the full-power Aalo-X.
Reporting based on coverage from Aalo Atomics, Forbes, World Nuclear News, ANS Nuclear Newswire and Interesting Engineering.