How Aalo Reached a Nuclear Milestone for Data Centres

US startup Aalo Atomics has achieved criticality with its Aalo-X Critical Test Reactor at Idaho National Laboratory (INL), bringing its commercial data centre ambitions a step closer.

The milestone, achieved on 4 July under US Department of Energy (DOE) authorisation, marked the reactor reaching criticality.

It also makes Aalo-X the fourth reactor to reach the milestone through the DOE's Reactor Pilot and Nuclear Energy Launch Pad programmes.

The achievement is notable for the data centre industry because Aalo's reactors are being designed specifically to provide on-site power for AI-driven facilities.

A reactor built with data centres in mind

Unlike many advanced nuclear projects aimed at national grids, Aalo has focused its commercial plans squarely on digital infrastructure.

Its Aalo-X reactor is based on a 10MWe design, with the company planning to deploy modular "Aalo Pods" to supply commercial data centres once regulatory approvals are secured.

Matt Loszak, CEO of Aalo Atomics, says: "Reaching criticality is our most significant milestone to date, as it paves the way for the deployment of the Aalo Pod to power commercial data centres once it receives authorisation from the Nuclear Regulatory Commission.

"More importantly, the Aalo-X Critical Test Reactor has the same full-scale core components as our commercial reactors.

"The Aalo-X’s 10 MWe reactor design positions it as the premier power provider for the modern data centre."

The Reactor Pilot Program itself was established in June 2025 following US President Donald Trump's Executive Order 14301, which challenged the DOE to enable at least three test reactors to achieve criticality through its authorisation process by 4 July 2026.

From testing to commercial deployment

While the criticality milestone marks the completion of one phase, Aalo has already moved on to the next.

The company is constructing a second reactor adjacent to the Aalo-X facility at Idaho National Laboratory as part of Project Ascension.

The commercial-scale system is intended to generate electricity for an on-site data centre in the coming months, providing a practical demonstration of how its modular reactors could support digital infrastructure.

Microsoft and NVIDIA partnership

Separately, Aalo recently announced a collaboration with Microsoft and NVIDIA to develop an automated co-piloting system intended to support the safe operation of fleets of nuclear reactors.

The test reactor's fuel rods were manufactured by GE Vernova's nuclear fuel business, Global Nuclear Fuel, before being delivered to Idaho in April.

Following completion of readiness assessments and final approval from US Energy Secretary Chris Wright to load fuel, the reactor successfully achieved criticality.

Reflecting on the achievement, Chris says: "President Trump asked for three advanced reactors to be authorized and achieve criticality before the 250th anniversary of our great country.

"I’m pleased to share that through the dedication and hard work of Aalo, INL and DOE, we have surpassed that ask and delivered four!"

The next phase

For Aalo, reaching criticality is only the beginning of its roadmap towards commercial deployment.

Yasir Arafat, President & CTO of Aalo Atomics, says: "Aalo has demonstrated unprecedented speed, as well as a commitment to quality and safety, in bringing its first nuclear reactor to life, but now is not the time for rest.

"Criticality is just the beginning. In the coming months we will continue building and testing multiple reactors, including the commercial Aalo Pod design which in the next 18 months will provide a scalable and affordable power option to data centers and enterprises."

Aalo will hold a commemorative event in Idaho Falls on 30 July 2026 to mark the reactor reaching criticality, a milestone the company intentionally celebrated in the spirit of Chicago Pile-1, the world's first controlled, self-sustaining nuclear chain reaction achieved in 1942.