# Did Aalo Atomics Achieve Criticality at Idaho National Laboratory?

At 12:20 a.m. MT on July 4, 2026, Aalo Atomics' sodium-cooled test reactor achieved [nuclear criticality](https://smrintel.com/glossary/criticality) at Idaho National Laboratory — making it the fourth DOE-authorized reactor to hit the milestone set by Executive Order 14301. The reactor is a full-scale zero-power version of Aalo's planned 10-MWe Aalo-X, fueled with [low-enriched uranium](https://smrintel.com/glossary/leu). Aalo went from breaking ground to a sustained chain reaction in eight months, according to Yasir Arafat, the company's president and chief technical officer. The company's commercial target is a 50-MWe "Aalo Pod" — multiple 10-MWe units packaged for AI data center power. A second, electricity-generating reactor under Project Ascension is already under construction at the INL site, with an on-site data center targeted for 2027.

Executive Order 14301 set a stretch goal of at least three test reactors achieving criticality by July 4. That bar was cleared before Aalo even started: Antares and Valar Atomics reached criticality earlier in June under the DOE's Reactor Pilot Program, and Deployable Energy — operating under the separate Nuclear Energy Launch Pad program — became the third last week. Aalo is the fourth.

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## What EO 14301 Required — and What Happened

Signed on May 23, 2025, Executive Order 14301, "Reforming Nuclear Reactor Testing at the Department of Energy," directed DOE to establish a Reactor Pilot Program and pegged a July 4, 2026 deadline for at least three test reactors to achieve criticality. The order created two distinct pathways: the Reactor Pilot Program, which Antares, Valar Atomics, and Aalo participated in, and the Nuclear Energy Launch Pad, which Deployable Energy used.

The EO's July 4 target was met — and then exceeded. Four reactors are now critical, not three, and the timeline held despite the compressed schedules involved. For Aalo specifically, "going from breaking ground to a sustained chain reaction in just eight months" represents one of the faster reactor builds in recent U.S. history, according to the company's own characterization.

INL Director John Wagner was direct in his assessment: "This is exactly what a nuclear renaissance looks like: American companies, moving at American speed, proving novel reactor designs real one after another."

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## Aalo's Reactor: Sodium-Cooled, LEU-Fueled, Purpose-Built for Data Centers

Aalo's test reactor is a full-scale core designed to validate the nuclear components of a 10-MWe unit. The reactor uses [low-enriched uranium](https://smrintel.com/glossary/leu) fuel and sodium cooling — a [fast neutron spectrum](https://smrintel.com/glossary/fast-spectrum) architecture. Zero-power criticality tests don't generate electricity; their purpose is to confirm reactor physics, control system response, and fuel assembly performance at commercial scale before heat and power generation begin.

The company's description of its scope within the Reactor Pilot Program is notable: "We built, licensed, and operated the reactor facility from scratch. We stood up our own safety programs, built 10 MW worth of fuel assemblies, and manufactured and quality-controlled commercial-scale systems in-house." That self-characterized scope is broader than what some other Reactor Pilot Program participants undertook at existing DOE test infrastructure.

The supply chain assembled in 2026 includes fuel fabrication contracts with Global Nuclear Fuel, uranium hexafluoride enrichment completed by [Urenco](https://smrintel.com/companies/urenco) USA, and a 10-MWe steam turbine generator set from Baker Hughes. That Urenco USA delivered enriched UF6 feedstock to GNF for fuel rod fabrication earlier in the year means the criticality test was backed by a functioning commercial fuel supply chain — not just a one-off research batch.

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## Project Ascension and the Aalo Pod Commercial Strategy

Criticality on a zero-power test reactor is a technical milestone, not a commercial one. What matters now is the execution timeline for Project Ascension — Aalo's plan to install a commercial-scale 10-MWe electricity-generating reactor at its INL site and power an on-site data center in 2027.

The commercial product, the "Aalo Pod," bundles multiple 10-MWe units into a 50-MWe modular plant explicitly marketed to AI data center operators. The company has announced plans to open a one-million square-foot factory to apply assembly-line manufacturing to reactor production — a necessary condition for any serious FOAK-to-NOAK cost reduction story.

The data center angle deserves scrutiny. Signing a PPA or co-location agreement with a hyperscaler requires more than a critical test reactor — it requires demonstrated electricity generation, regulatory authorization for commercial operation, and a credible delivery schedule. A 2027 on-site data center is an aggressive target for a company that achieved first criticality on July 4, 2026. It is not impossible, but it compresses the timeline for systems testing, heat-to-electricity commissioning, and any regulatory sign-offs on the commercial unit.

That said, Aalo's criticality does validate the reactor physics and fuel assembly design at commercial scale. As the company stated: "Criticality has validated our supply chain, reactor physics, control systems, and fueling procedures at commercial scale." For investors and data center operators evaluating nuclear offtake, that validation removes one category of technical risk — not all of them.

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## Industry Implications: Four Criticals in Six Weeks

The concentrated run of criticality events — Antares and Valar Atomics in June, Deployable Energy days before July 4, and Aalo on the deadline itself — represents a structural shift in U.S. advanced reactor development pace that has no modern parallel. A year ago, the question was whether any private company could achieve criticality under the compressed EO 14301 timeline. Four have now done so.

The implications extend beyond the headline numbers. Each critical test reactor generates real operational data on fuel performance, neutronics, and control system behavior that feeds directly into commercial licensing dossiers. For companies like [Kairos Power](https://smrintel.com/companies/kairos-power), which is pursuing a different pathway with its Hermes demonstration reactor in Oak Ridge, the competitive pressure from Reactor Pilot Program participants achieving criticality on accelerated timelines is a factor worth tracking.

The DOE's dual-track structure — Reactor Pilot Program and Nuclear Energy Launch Pad — has also demonstrated that regulatory flexibility can coexist with safety rigor when program parameters are well-defined. That precedent matters for future advanced reactor applicants and for the ongoing NRC/DOE coordination around Part 53 rulemaking.

For uranium and fuel supply chain analysts: Aalo's use of Urenco USA for enrichment and Global Nuclear Fuel for fabrication establishes a working commercial-scale LEU supply chain for a sodium-cooled fast reactor — a data point relevant to fuel demand forecasting as more fast spectrum designs approach deployment.

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## Key Takeaways

- **Aalo Atomics achieved criticality at 12:20 a.m. MT on July 4, 2026**, at Idaho National Laboratory, becoming the fourth DOE-authorized reactor to hit the milestone.
- The reactor is a **full-scale zero-power core** designed to validate the nuclear components of a **10-MWe sodium-cooled, LEU-fueled Aalo-X** unit.
- Aalo went **from breaking ground to sustained chain reaction in eight months**, according to company president Yasir Arafat.
- **Executive Order 14301's goal of three criticals by July 4 was surpassed** — four reactors are now critical across the Reactor Pilot Program and Nuclear Energy Launch Pad.
- The company's commercial target is a **50-MWe "Aalo Pod"** of multiple 10-MWe units purpose-built for AI data centers.
- **Project Ascension** targets a commercial-scale electricity-generating reactor at INL powering an on-site data center in **2027** — an aggressive but stated schedule.
- Fuel supply chain includes **Urenco USA** for enrichment, **Global Nuclear Fuel** for fabrication, and **Baker Hughes** for the steam turbine generator set.
- A **one-million square-foot manufacturing factory** is planned to support assembly-line reactor production.

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## Frequently Asked Questions

**What did Aalo Atomics achieve on July 4, 2026?**
Aalo Atomics achieved nuclear criticality — a self-sustaining fission chain reaction — in its sodium-cooled, low-enriched uranium test reactor at Idaho National Laboratory at 12:20 a.m. MT. The reactor is a full-scale zero-power version of the company's planned 10-MWe Aalo-X design.

**What is Executive Order 14301 and why does it matter for SMRs?**
Signed in May 2025, EO 14301 directed the Department of Energy to create the Reactor Pilot Program and set a stretch goal of at least three test reactors achieving criticality by July 4, 2026. It provided an authorization pathway for private developers to build and operate first-of-a-kind reactors at DOE facilities on compressed timelines. Four reactors have now met or exceeded that target.

**What is the Aalo Pod and who is it designed for?**
The Aalo Pod is Aalo's planned commercial product: a fully modular 50-MWe nuclear plant composed of multiple 10-MWe units, purpose-built to power AI data centers. The company has announced plans for a one-million square-foot factory to support assembly-line manufacturing of the system.

**What is Project Ascension?**
Project Ascension is Aalo's next phase at INL — constructing a commercial-scale 10-MWe reactor at the same INL site that will generate electricity and power an on-site data center, with a stated target of 2027.

**How does Aalo's criticality compare to other Reactor Pilot Program participants?**
Four reactors have now achieved criticality under the combined DOE programs: Antares and Valar Atomics in June 2026, Deployable Energy (under the Nuclear Energy Launch Pad) days before July 4, and Aalo on July 4 itself. Each used different reactor technologies and fuel types; Aalo's sodium-cooled fast reactor is the only one in this cohort to use that cooling approach at the INL site under this program structure.

**What fuel supply chain did Aalo use?**
Urenco USA completed enrichment of the uranium hexafluoride feedstock and delivered it to Global Nuclear Fuel, which fabricated the fuel rods. Baker Hughes was selected for the 10-MWe steam turbine generator set. These contracts were announced in March 2026.