The archive · Climate & Energy · Strategic decision · 2009–2026
X-energy bets Amazon's AI power hunger makes TRISO-fueled SMRs real
Amazon's Climate Pledge Fund put $500M into X-energy, betting Xe-100 SMRs plus TRISO fuel can power AI data centers; the startup IPOs at $1B+ in April 2026.
X-energy
What the business is
X-energy designs the 80 MWe Xe-100 high-temperature gas-cooled small modular reactor and manufactures its own TRISO pebble fuel, selling carbon-free power to industrial and data-center customers.
Starting capital：$500M Series C-1 anchored by Amazon Climate Pledge Fund (Oct 2024, with Ken Griffin, NGP, University of Michigan), upsized to a $700M close (Feb 2025); $700M Series D (Nov 2025); over $1B IPO proceeds (Apr 2026).
How it started
Founded in 2009 in Rockville, Maryland, X-energy spent more than a decade developing the Xe-100, an 80 MWe high-temperature gas-cooled reactor that runs on TRISO pebbles: 18,000 coated uranium particles sealed in a billiard-ball-sized graphite pebble, 200,000 pebbles per reactor, with helium carrying heat at 750°C. The founding bet was that melt-proof fuel could revive gas-cooled reactors commercially in the US.
What happened
In October 2024 Amazon's Climate Pledge Fund led a $500M Series C-1 and agreed to bring over 5 GW online by 2039, starting with Energy Northwest's four-reactor Cascade project in Washington (~320 MW, expandable to 960 MW); the round closed upsized at $700M in February 2025. In May 2025 the NRC accepted the construction permit application for Dow's four-unit Seadrift, Texas plant for an 18-month review. In August 2025 X-energy signed a manufacturing partnership with KHNP and Doosan Enerbility targeting up to $50B in mobilization, and in November 2025 it began vertical construction of TX-1, the first US commercial advanced nuclear fuel facility (5 metric tons of uranium, or 700,000 pebbles a year, enough for 11 Xe-100s), while qualification testing of TRISO-X fuel started at Idaho National Laboratory.
How it ended up
X-energy went public in April 2026, raising over $1B by selling 44.3 million shares at $23, well above the $16–19 range, after Amazon had led the 2024 round and Dow, Energy Northwest and Centrica (6 GW commitment) anchored demand. TX-1 construction was due to complete mid-2026 with NRC fuel license approval expected by May 2026; no Xe-100 reactor has generated power yet, with first electricity expected in the early 2030s.
Background
X-energy's bet was that AI-era electricity demand would make small modular reactors bankable, and that the winning SMR company would own the fuel. Its Xe-100 is an 80 MWe high-temperature gas-cooled reactor running on TRISO pebbles — 18,000 coated uranium particles per billiard-ball-sized graphite pebble, 200,000 pebbles per core — whose melt-proof design removes the containment dome that dominates conventional nuclear cost.
Amazon became the proof point. In October 2024 the Climate Pledge Fund led a $500M Series C-1 into X-energy and signed up for more than 5 GW of new nuclear by 2039, starting with Energy Northwest's four-reactor Cascade project in Washington. The round closed upsized at $700M in February 2025; in May 2025 the NRC accepted the construction permit application for Dow's four-unit Seadrift, Texas plant.
In 2025 X-energy built out the industrial chain: a partnership with KHNP and Doosan Enerbility aimed at mobilizing up to $50B, and in November 2025 the start of vertical construction of TX-1 in Oak Ridge — the first US commercial advanced nuclear fuel fabrication facility, producing 700,000 TRISO pebbles a year, while fuel qualification testing began at Idaho National Laboratory.
The payoff came in April 2026, when X-energy raised over $1B in an IPO at $23 a share, above the $16–19 range, with Amazon, Dow, Energy Northwest and Centrica anchoring demand. As of September 2026 the fuel plant is still under construction and no Xe-100 has generated power; first electricity is expected in the early 2030s, so the original bet remains unproven at grid scale.
What has to be true
- TRISO fuel's melt-proof safety case attacks nuclear's biggest cost driver — the containment dome — rather than competing on reactor physics.
- Vertical integration made X-energy the sole supplier of fuel for its own reactors, turning a technical claim into a supply-chain moat.
- Amazon's 5 GW commitment converted a capital-intensive vendor into a customer-anchored platform before any reactor was built.
- The fuel plant milestone (first US commercial advanced fuel facility in over 50 years) gave investors a hard, checkable event ahead of reactor revenue.
What can be applied
Own the fuel. X-energy turned TRISO fabrication into a moat that made Amazon an investor and carried it to a $1B IPO before any reactor ran — the supply chain was the story.
Aftermath
As of 2026-09-02, X-energy is public after raising over $1B in its April 2026 IPO at $23/share (44.3M shares). It reports over 11 GW of new nuclear capacity in development: Dow's four-unit Seadrift plant under NRC review, Energy Northwest's Cascade project with Amazon, and a 6 GW Centrica commitment. TX-1 fuel fabrication in Oak Ridge is due to complete mid-2026 pending NRC license approval, with fuel qualification testing ongoing at Idaho National Laboratory. No Xe-100 has yet produced electricity; first power is projected for the early 2030s.
Sources
- Amazon jumps on nuclear power bandwagon by investing in X-energy and promising small reactors
- X-energy, Amazon, Korea Hydro & Nuclear Power, and Doosan Enerbility Announce Partnership to Scale Advanced Nuclear Energy for AI Infrastructure
- X-energy Begins Vertical Construction for First-in-the-Nation Advanced Nuclear Fuel Fabrication Facility
- Amazon-Backed Nuclear Tech Company X-Energy Raises Over $1 Billion in IPO
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