Aalo Atomics
Table of Contents

⚠ Disclaimer: This entry may be incomplete, out of date, or inaccurate. It is AI-maintained on a best-effort basis. Do not rely on it as a sole source — verify claims independently using the sources listed below.

Summary

Aalo Atomics is an Austin, Texas microreactor developer founded in 2023 by Matt Loszak (CEO) and Yasir Arafat (President & CTO), the latter the former lead of Idaho National Laboratory’s MARVEL microreactor project and a founder of Westinghouse’s eVinci programme. Its reactor is a pool-type sodium-cooled, graphite-moderated design running on standard-assay LEU oxide fuel — deliberately avoiding both HALEU and TRISO, the two fuel forms that constrain most of this section’s other advanced reactor developers. The commercial product is the Aalo Pod: five 10 MWe Aalo-1 reactors sharing turbines for 50 MWe, marketed specifically at AI datacenter load and requiring no external water source.

On July 4, 2026 Aalo’s Critical Test Reactor achieved first criticality at INL — the fourth reactor to go critical under DOE’s Reactor Pilot Program, and the one that hit the Executive Order’s headline date exactly. The CTR is a full-scale zero-power critical assembly, not a power reactor; Aalo’s own press materials blur this, and much downstream coverage reported it as a 10 MWe reactor going critical, which it was not. See Claim Verification.

Aalo is distinguished from its criticality-cohort peers by an unusually credentialed team (INL, Westinghouse, TerraPower, SpaceX, Texas PUC alumni), a conventional and comparatively de-risked fuel supply chain (Urenco USA enrichment, Global Nuclear Fuel fabrication, Baker Hughes turbine), and — notably — an almost complete absence of the critical coverage directed at Valar Atomics. It is also the company with the largest gap between announced funding ($136M) and claimed funding ($300M+), and has no executed PPA despite three announced customer relationships.

Key Facts

  • Founded: 2023, as a two-person company
  • HQ: 5900 E Ben White Blvd, Austin, TX 78741
  • Type: Private
  • Co-Founder & CEO: Matt Loszak — nuclear engineering and physics background; previously founded Humi (nine-figure exit); Y Combinator alum
  • Co-Founder, President & CTO: Yasir Arafat — former lead of INL’s MARVEL microreactor project; founded Westinghouse eVinci; 10 years AP1000 R&D
  • Headcount: 200+ (from 2 at founding)
  • Reactor naming — three distinct things: Critical Test Reactor (CTR), a full-scale zero-power critical assembly (project codename “First Light”) — this is what went critical; Aalo-X, the 10 MWe / ~30 MWth experimental power plant, not yet operating; Aalo Pod, the commercial 50 MWe plant comprising five 10 MWe Aalo-1 reactors sharing turbines (marketed as an “XMR,” extra-modular reactor)
  • Reactor type: Pool-type sodium-cooled, graphite-moderated thermal reactor (“Sodium Thermal Reactor”); air-cooled balance of plant, no external water source required
  • Fuel: UO₂ ceramic pellets in Aalo-designed rods — not TRISO, not HALEU. Enrichment reported as 4.95% (CTR) and 5–8% (commercial); the company’s own site says “8% LEU+”
  • Power: Aalo-X ~30 MWth / 10 MWe; Aalo Pod 50 MWe. CTR is zero-power (watts to kilowatts)
  • Operating temperature: Company states 160–425 °C at near-atmospheric pressure; NucNet’s SMR database lists a 550 °C outlet — sources disagree
  • Other design claims: 36-month refueling interval; 80-year design life; 72+ hours fully passive decay-heat removal; automatic passive shutdown; target 3¢/kWh
  • Criticality: July 4, 2026, 12:20 a.m. MT, at the Aalo-X Campus at Idaho National Laboratory — fourth under the DOE Reactor Pilot Program. DOE’s release says “early Saturday, July 5”; July 4, 2026 was itself a Saturday, so treat DOE’s date as an error
  • Regulatory: DOE authorization (Reactor Pilot Program, EO 14301, framework DOE-STD-1271-2025); DSA approved ~April 30, 2026, announced early May. NRC: pre-application only — Regulatory Engagement Plan filed July 1, 2024 for the Idaho Nuclear Project; a COLA was targeted for 2026 but no confirmation of submission was found as of August 27, 2026
  • Funding: $6.26M seed (2023), $27M Series A (2024), **$100M Series B (Aug 19–20, 2025, led by Valor Equity Partners)** with Hitachi Ventures, NRG Energy, Fine Structure, Tishman Speyer and others. Stated total after Series B: "over $136 million." The company website now claims “$300M+” — no announcement supports this
  • Manufacturing: 40,000 sq ft Austin facility; planned 1,000,000 sq ft “GigaWatt Factory” targeted 2028
  • Business model: Aalo does not sell reactors — it intends to sell electricity under long-term PPAs. No executed PPA is disclosed

What It Is / How It Works

A deliberately boring fuel cycle. The most consequential design decision Aalo made is not the sodium coolant but the fuel: conventional UO₂ ceramic pellets at standard-to-slightly-elevated LEU enrichment, fabricated by Global Nuclear Fuel — GE Vernova’s existing commercial fuel alliance — from Urenco USA feedstock. This sidesteps both chokepoints this section tracks: the HALEU queue that constrains Oklo and X-energy, and the concentration of US TRISO fabrication on BWXT that Kairos Power, X-energy, Radiant Industries, NuCube Energy and Antares Nuclear all depend on. Aalo’s fuel went from contract signature (March 2026) to delivery (early April 2026) in weeks — a schedule impossible on either constrained pathway. Note that the earlier published Aalo-1 concept used uranium zirconium hydride fuel; the UO₂ design supersedes it.

Sodium at low temperature, graphite for moderation. Unlike the sodium fast reactors at TerraPower (Natrium) and Oklo (Aurora), Aalo’s design is a thermal-spectrum reactor: graphite moderates neutrons while liquid sodium at near-atmospheric pressure carries heat. Sodium’s high boiling point removes the need for a pressurized primary system, and the pool configuration provides substantial passive heat capacity. The stated 160–425 °C operating band is low for a sodium system, which reduces materials and chemistry difficulty relative to a fast reactor but caps thermal efficiency and rules out high-temperature process heat. The air-cooled balance of plant — no cooling water — is a specific and increasingly relevant answer to datacenter siting constraints in water-stressed regions.

The “XMR” packaging argument. Aalo’s commercial unit is not a reactor but a plant: five 10 MWe reactors feeding shared turbines to make 50 MWe. The argument is that microreactor economics fail on per-unit fixed costs — licensing, security, staffing, grid interconnection — and that amortizing those across five cores inside one boundary is what makes small reactors pencil. This is structurally similar in intent to Valar Atomics’ “gigasite” thesis, arrived at from the opposite direction (Valar aggregates hundreds of units and sells fuel, Aalo aggregates five and sells electricity).

What the CTR actually demonstrated. ANS states it precisely: a “full-scale zero-power version” of the planned 10 MWe Aalo-X. The core geometry, fuel loading, control systems and fueling procedures were validated at commercial scale; no power was produced and no electricity generated. Aalo’s own claim that criticality “validated our supply chain, reactor physics, control systems, and fueling procedures at commercial scale” is defensible on geometry and procedures, and says nothing about thermal-hydraulic performance, materials behaviour under sustained flux, or power operation — none of which a zero-power assembly can test.

Notable Developments

  • 2026-07-30: Crusoe partnership announced — a Crusoe Spark modular datacenter at INL in 2027 powered by Aalo-X (10 MWe proof of concept), then Aalo Pods at commercial Crusoe facilities by end-2029. Framed as a “strategic partnership” with intent language; no PPA and no binding commitment disclosed. (GlobeNewswire; POWER)
  • 2026-07-04: Critical Test Reactor achieves first criticality at 12:20 a.m. MT at the Aalo-X Campus, INL — fourth under the DOE Reactor Pilot Program, meeting the Executive Order deadline on the date itself. Energy Secretary Chris Wright personally signed the critical notice. (Aalo; ANS; WNN)
  • 2026-04: Global Nuclear Fuel delivers fuel (contracts signed March 2026); Urenco USA LEU hexafluoride feedstock completed March 2026. (ANS)
  • 2026-04-30: DOE-Idaho approves the Documented Safety Analysis for the Aalo-X Critical Test Reactor (announced early May; NucNet dates the announcement May 6). (WNN; NucNet)
  • 2025-08-19: **Series B — $100M**, led by Valor Equity Partners, with Fine Structure Ventures, Hitachi Ventures, NRG Energy, Tishman Speyer, Kindred, 50Y, Harpoon, Crescent Enterprises, Crosscut and others. ([BusinessWire](https://www.businesswire.com/news/home/20250820559252/en/Aalo-Atomics-Secures-$100-Million-in-Series-B-Funding-to-Build-Modular-Nuclear-Plants-Purpose-Built-for-Powering-AI-Data-Centers); TechCrunch)
  • 2025-08: Selected for the DOE Reactor Pilot Program.
  • 2025-08 to 2026-01: Construction of the CTR facility at INL — sources disagree on the start date (WNN: August 2025; NEI: September 2025; POWER: January 2026), with the company claiming “less than eight months.”
  • 2025-02-04: Selected as one of four developers for the Texas A&M RELLIS 1 GW initiative — “up to 1 GW” via multiple 50 MW Pods; exploratory, not a binding contract. (Aalo)
  • 2024-07-01: Regulatory Engagement Plan filed with the NRC for the Idaho Nuclear Project — initially seven Aalo-1 reactors, expandable to fourteen, at INL’s Central Facilities Area; operations targeted 2029. (WNN)
  • 2024: Series A — $27M. **2023:** Seed — $6.26M; company founded.

Key People

Matt Loszak — Co-Founder & CEO

  • LinkedIn: linkedin.com/in/mattloszak
  • Background: Nuclear engineering and physics degree; previously founded Humi (Canadian HR/payroll company, nine-figure exit); Y Combinator alum
  • Notes: Unlike several founders in this cohort, Loszak has formal nuclear training alongside a completed startup exit — a combination that has largely insulated Aalo from the founder-credentials criticism directed at peers

Yasir Arafat — Co-Founder, President & CTO

  • LinkedIn: linkedin.com/in/yasiraalo
  • Background: Former technical lead of INL’s MARVEL microreactor project; founded Westinghouse’s eVinci microreactor programme; ten years of AP1000 R&D
  • Notes: ⚑ Overlap: Arafat’s eVinci lineage is directly relevant — Westinghouse eVinci is now a competing Army Janus awardee (Fort Drum), and Arafat’s INL background is the plausible explanation for how a 2023-founded company sited, licensed and built at INL faster than more established developers

Tim Frazier — SVP Government Programs

Other named leadership

  • Scott Reynolds — CFO (ex-Bloom Energy); Michael So — VP Programs (ex-Tesla); Jon Guidroz — SVP Commercial & Strategy (ex-Microsoft, Google, Amazon energy)
  • Named in the Series B release without stated titles: Jimmy Glotfelty (former Texas PUC commissioner), Bryson Gentile (ex-SpaceX Falcon 9 manufacturing lead), Pete Gaillard (ex-TerraPower regulatory affairs head), Nick Touran (ex-TerraPower; founder of What Is Nuclear?). Whether these are employees or advisors is not disclosed

People — Last Reviewed: 2026-08-27

Supply Chain Position

Layer Detail
Enrichment Urenco USA (Eunice, NM) — LEU hexafluoride feedstock completed March 2026. Standard commercial enrichment; no HALEU dependency
Fuel fabrication Global Nuclear Fuel (GE Vernova / GE Hitachi alliance) — contracts March 2026, fuel delivered early April 2026. No TRISO, therefore no BWXT dependency
Turbine Baker Hughes — 10 MWe steam turbine-generator set, delivery targeted end-2026
Components Paragon Energy Solutions (I&C); Amsted Graphite (moderator)
Manufacturing In-house — 40,000 sq ft Austin facility; planned 1,000,000 sq ft “GigaWatt Factory” (2028)
EPC None named for reactor construction
Coolant Liquid sodium; supplier not disclosed
Site Aalo-X Campus, Idaho National Laboratory (separate from INL’s main campuses)
Regulatory DOE authorization; NRC pre-application only

⚑ The least fuel-constrained microreactor in this section. Aalo is the only company among the 2026 criticality cohort using neither TRISO nor HALEU. Every other developer here queues behind either BWXT’s Lynchburg TRISO line or the very limited US HALEU enrichment base (Centrus and, prospectively, General Matter). Aalo buys from Urenco USA and GNF — established, licensed, operating commercial suppliers. If the design works, this is a material schedule advantage, and it is the single most defensible claim the company makes.

⚑ Paragon Energy Solutions appears twice in this section — supplying I&C to both Aalo and NuScale Power (HIPS platform, June 2026 contract). Worth watching as a shared I&C dependency across otherwise unrelated SMR programmes.

⚑ GE Vernova appears on both sides. GNF is a GE Vernova/Hitachi alliance, making GE Vernova simultaneously Aalo’s fuel fabricator and, through GE Vernova Hitachi, a competing SMR vendor.

Claim Verification

Claim: “Aalo-X Critical Test Reactor (10 MWe)” went critical

Status: Misleading as widely reported — the reactor that went critical is a zero-power assembly

Supporting: Aalo’s own BusinessWire headline reads “Aalo-X Critical Test Reactor” and juxtaposes the 10 MWe figure; Data Center Dynamics reproduced this as “the Aalo-X Critical Test Reactor (10MWe capacity).”

Refuting / questioning: ANS states the milestone precisely as Aalo’s “critical test reactor — a full-scale zero-power version of its planned 10-MWe Aalo-X.” POWER is equally explicit: “CTR is zero-power physics reactor… experimental, non-power-producing.” No electricity was generated. Aalo-X, the actual 10 MWe power plant, is not yet built.

Summary: Full-scale in geometry, zero in power. This is the single most important distinction in the entry and the one most often lost in secondary coverage. The same caveat applies across the entire 2026 criticality cohort.

Claim: “$300M+ in venture capital raised”

Status: Company-sourced only; unsupported by any announcement

Supporting: aalo.com/company currently states “$300M+ in venture capital.”

Refuting / questioning: The last announced round is the $100M Series B of August 2025, after which the company itself stated "over $136 million" total (BusinessWire) and Sacra reported $133M. No press release or trade-press report of any round between August 2025 and August 2026 was found. A third-party marks platform lists a $450M valuation, also unverified.

Summary: Likely an unannounced Series C, but this cannot be confirmed. Cite $136M as the last confirmed total and note the $300M+ claim as company-sourced.

Claim: “Microsoft-backed”

Status: Unsubstantiated characterization

Supporting: Data Center Dynamics labels Aalo “Microsoft-backed,” and Microsoft does appear in Aalo materials.

Refuting / questioning: DCD’s own text concedes “specific investment details aren’t disclosed.” Microsoft is not in any disclosed cap table. The only confirmed Microsoft relationship is a technical collaboration with Microsoft and Nvidia on an automated co-piloting system for reactor safety — not an investment and not an offtake.

Summary: Do not describe Microsoft as an Aalo investor.

Claim: Construction start date and “under eight months” build

Status: Unresolved — three incompatible dates

Supporting: WNN reports construction began August 2025 (groundbreaking to criticality under eight months); NEI reports September 2025 with a 36-day building and 40-day reactor assembly; POWER reports January 2026 with 36-day building, 28-day Austin fabrication, and 540 fuel rods assembled in 2.5 days.

Refuting / questioning: The company’s “less than eight months” claim is consistent with an Aug–Nov 2025 start and inconsistent with POWER’s January 2026 date — yet POWER’s account is the most granularly sourced.

Summary: Unresolved. The build was fast by any of these accounts; the specific figure should not be cited without qualification.

Claim: Operating temperature

Status: Sources disagree

Supporting: aalo.com states 160–425 °C at near-atmospheric pressure; NucNet’s SMR database lists a 550 °C outlet.

Summary: Unresolved. The distinction matters for whether Aalo can serve industrial process heat or is electricity-only.

Risk & Skepticism Notes

  • Every customer relationship is non-binding. Crusoe is a “strategic partnership” with intent language and no disclosed PPA; Texas A&M RELLIS is a selection to explore “up to 1 GW”; NRG Energy is a Series B investor, not an offtaker. Aalo’s stated business model is selling electricity under long-term PPAs, and not one has been executed.
  • No NRC application confirmed. A COLA was targeted for 2026 and leadership said in March 2026 they planned to “submit our first commercial license this year,” but no submission could be confirmed. As ANS puts it for the whole programme: “without NRC approval, none of the companies involved will be able to deploy their designs commercially.”
  • Timeline internally inconsistent. ANS reports Aalo-X facility completion end-2026 while aalo.com says Q1 2027; the Crusoe release targets Aalo-X powering a datacenter in 2027 while POWER frames Aalo-X as “construction/licensing 2027, operations 2028.”
  • Unusually little critical coverage. ANS’s own assessment of its criticality reporting: “None detected. The article presents Aalo’s achievement without critical analysis.” Aalo has attracted none of the founder-credential, radiation-claim or investor-tie scrutiny directed at Valar Atomics. That absence is a gap in the record, not evidence of soundness — and Katy Huff’s critique of zero-power criticality (“simply checks if you can multiply neutrons”) applies to Aalo exactly as it does to Valar.
  • A sodium thermal reactor is still first-of-a-kind. Conventional fuel does not make the reactor conventional: graphite-moderated pool-type sodium systems have no operating commercial precedent, and graphite behaviour under long-term flux in a sodium environment is the kind of materials question a zero-power assembly cannot answer.

Sources

See Also

Nuclear section overview: Nuclear Energy Research — deployment status tracker and DOE Reactor Pilot Program context.

The 2026 criticality cohort: Antares Nuclear, Valar Atomics, Deployable Energy, Oklo.

Crusoe elsewhere in this research: Blue Energy — Crusoe’s other nuclear supplier, developing 1.5 GW at Port of Victoria, TX.

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