# X-energy

> Source: https://aiwiki.ai/wiki/x_energy
> Updated: 2026-06-27
> Categories: AI Energy, AI Infrastructure
> From AI Wiki (https://aiwiki.ai), a free encyclopedia of artificial intelligence. Quote with attribution.

X-energy, Inc. is an American advanced nuclear reactor and fuel company, based in Rockville, Maryland, that develops the Xe-100, a high-temperature gas-cooled [small modular reactor](/wiki/small_modular_reactor) (SMR) rated at about 80 megawatts of electricity per unit and designed to be built in 320 MWe four-packs. Founded in 2009 by entrepreneur [Kam Ghaffarian](/wiki/kam_ghaffarian), it pairs that reactor with a proprietary pebble fuel, TRISO-X, making it one of the few SMR developers to own both the reactor design and the fuel supply chain. [3] X-energy became one of the most prominent players in United States advanced [nuclear power](/wiki/nuclear_power) largely because of a partnership with [Amazon](/wiki/amazon), which led a roughly $500 million financing round in October 2024 and committed to bringing more than 5 gigawatts of X-energy nuclear capacity online by 2039, the largest commercial SMR deployment target announced to date. [9] X-energy went public on the Nasdaq on April 24, 2026 under the ticker XE, raising about $1.02 billion in what was reported as the largest nuclear initial public offering on record. [21] The surge of investor interest reflects a wider bet that SMRs can supply the firm, carbon-free electricity that [AI data centers](/wiki/ai_data_center) increasingly require. [22]

## What is X-energy and who runs it?

X-energy was founded by Kam Ghaffarian, an Iranian-born American engineer and serial founder who also started or co-founded the space-services contractor Stinger Ghaffarian Technologies (SGT, sold to KBR for $355 million in 2018), [Intuitive Machines](/wiki/intuitive_machines), [Axiom Space](/wiki/axiom_space), the investment firm IBX, and Quantum Space. [2] Ghaffarian serves as X-energy's founder and executive chairman. Day-to-day leadership is held by chief executive J. Clay Sell, a former United States Deputy Secretary of Energy, who joined the company in 2019. [1] By the time of its IPO, X-energy had grown to nearly 1,000 employees and was operating design, testing, and training facilities in Maryland alongside its fuel operations in Tennessee. [1]

The company sells two linked products: the Xe-100 reactor and the TRISO-X fuel that powers it. That vertical integration, owning both the reactor design and the fuel supply chain, is one of the features X-energy uses to distinguish itself from other SMR developers such as [TerraPower](/wiki/terrapower), [Oklo](/wiki/oklo), and [Kairos Power](/wiki/kairos_power). [3]

## What is the Xe-100 reactor?

The Xe-100 is a [high-temperature gas-cooled reactor](/wiki/high_temperature_gas_cooled_reactor) (HTGR) of the pebble-bed type. It is moderated by graphite and cooled by inert helium gas, which leaves the core at over 750 degrees Celsius. That heat is passed through a helical-coil steam generator to produce superheated steam at about 565 degrees Celsius and 16.5 megapascals, conditions high enough to drive a conventional steam turbine or to serve industrial processes directly. [3]

Each Xe-100 module produces about 200 megawatts of thermal power (MWth), which converts at roughly 40 percent thermal efficiency to about 80 megawatts of electricity (MWe), or it can instead deliver up to 200 megawatts of process heat in the form of steam. [3] X-energy designs the reactor to be deployed in groups: a standard "four-pack" plant of four independently operating units generates about 320 MWe, and a single site can be scaled to as many as 12 units, or about 960 MWe. [3] The company targets a 60-year operating life and a 95 percent capacity factor, and says the design can ramp between 40 percent and full power in roughly 12 minutes, allowing it to follow load on a grid with variable renewable output. [3]

A central safety claim is that the Xe-100 cannot melt down. The reactor relies on passive physics rather than active intervention: as temperature rises, the nuclear reaction naturally slows, and the fuel itself is engineered to retain its radioactive material at temperatures well above normal operating conditions. The United States Department of Energy has described X-energy's design as a "pebble bed reactor that they say can't melt down." [4]

| Parameter | Specification |
|---|---|
| Reactor type | High-temperature gas-cooled, pebble-bed (HTGR) |
| Coolant | Helium |
| Moderator | Graphite |
| Thermal output, per unit | 200 MWth |
| Electrical output, per unit | about 80 MWe |
| Thermal efficiency | about 40% |
| Process heat option, per unit | up to 200 MW of steam |
| Helium outlet temperature | over 750 degrees Celsius |
| Steam conditions | about 565 degrees Celsius, 16.5 MPa |
| Standard plant | four units, about 320 MWe |
| Maximum site | up to 12 units, about 960 MWe |
| Fuel | TRISO-X pebbles, HALEU (under 20% U-235) |
| Pebbles per core | about 220,000 |
| Design life | 60 years |
| Load following | 40% to full power in about 12 minutes |
| Refueling | online, continuous, multi-pass |

## What is TRISO-X fuel?

The Xe-100 runs on TRISO-X, X-energy's version of TRISO (tri-structural isotropic) fuel, manufactured through its wholly owned subsidiary TRISO-X, LLC to control supply and quality. [3] Each spherical fuel "pebble" is about 6 centimeters across and contains roughly 19,000 poppy-seed-sized kernels of enriched uranium oxycarbide, each individually coated in layers of carbon and ceramic silicon carbide that act as a miniature pressure vessel. A single Xe-100 core holds about 220,000 of these pebbles, which circulate through the reactor and pass the core several times before they are spent, so the reactor refuels continuously while running rather than shutting down for batch reloads. [3]

TRISO-X uses high-assay low-enriched uranium ([HALEU](/wiki/haleu)), meaning uranium enriched to less than 20 percent uranium-235, a higher level than the roughly 5 percent used in conventional light-water reactors. To make the fuel, X-energy's TRISO-X subsidiary is building a commercial fuel-fabrication plant, designated TX-1, on the 110-acre Horizon Center site in Oak Ridge, Tennessee. The company says the roughly 215,000-square-foot facility will employ around 500 people and produce about 700,000 pebbles per year, enough to fuel about 11 Xe-100 reactors. [14]

In February 2026 the [Nuclear Regulatory Commission](/wiki/nuclear_regulatory_commission) (NRC) issued TRISO-X a special nuclear material license (SNM-7007) authorizing it to possess and process HALEU at the Oak Ridge plant. [14] The 40-year license, which the NRC said runs to 2066, was the first Category II fuel-fabrication license the agency had ever issued and the first new commercial fuel-fabrication license it had granted in roughly 50 years. [15][16] X-energy and the Department of Energy both described it as a milestone for establishing a domestic HALEU fuel supply chain. [14]

## How did the DOE Advanced Reactor Demonstration Program fund X-energy?

In October 2020 the [U.S. Department of Energy](/wiki/department_of_energy) (DOE) selected X-energy, alongside TerraPower, as one of two winners of its Advanced Reactor Demonstration Program (ARDP), a flagship federal effort to get a commercial-scale advanced reactor operating before the end of the decade. Each company received $80 million in initial funding. [6] X-energy signed its ARDP cooperative agreement on March 1, 2021; under it, the company is eligible for up to roughly $1.23 billion in federal cost-shared funding over seven years to design, license, build, and demonstrate an Xe-100 plant together with a commercial TRISO fuel facility. [5] The total demonstration project has been valued at around $2.5 billion, with X-energy and its partners covering the balance beyond the federal share. [5]

X-energy originally planned to site the ARDP demonstration plant with the public utility [Energy Northwest](/wiki/energy_northwest) in central Washington. In 2023 it instead reached agreement with the chemical maker [Dow](/wiki/dow) to build the first Xe-100 plant at a Dow site on the Gulf Coast, and that project, the Long Mott Generating Station in Texas, became the program's lead demonstration. [12]

## What is the Dow Seadrift (Long Mott) project?

Dow is developing the Long Mott Generating Station through a wholly owned subsidiary, Long Mott Energy LLC, at its UCC Seadrift Operations chemical complex in Seadrift, Texas. The plant is planned as four Xe-100 units, a combined 320 MWe / 800 MWth, that would supply both electricity and industrial steam to the site, replacing aging gas-fired energy and steam assets. [12] X-energy and Dow describe it as the first grid-scale advanced nuclear facility built to serve an industrial site in North America. [12] On March 31, 2025 the two companies submitted a construction permit application to the NRC, which docketed it in May 2025 for an 18-month review. [12][13] In May 2026 the NRC completed its environmental assessment, ahead of schedule, and issued a Finding of No Significant Impact, an early regulatory step ahead of any decision to grant a construction permit. [13]

## What is the Amazon partnership?

X-energy and Energy Northwest signed a joint development agreement in 2023 for the deployment of up to 12 Xe-100 modules in central Washington, capable of generating up to about 960 megawatts. [11] In October 2024 Amazon anchored that effort: through its Climate Pledge Fund, Amazon led X-energy's roughly $500 million Series C-1 round and agreed to support an initial four-unit, 320 MWe project with Energy Northwest, with an option to expand to 12 units. [9][10] Amazon and X-energy said they aimed to bring more than 5 gigawatts of capacity online in the United States by 2039, which they characterized as the largest commercial SMR deployment target announced to date. [9]

X-energy chief executive J. Clay Sell framed the deal as a watershed for the sector: "Amazon and X-energy are poised to define the future of advanced nuclear energy in the commercial marketplace." [9] Speaking on CNBC about the partnership, Sell added: "It's not just about buying energy, it's about building it." [22] Kevin Miller, an Amazon vice president, called the collaboration "a significant step toward accelerating advanced nuclear technologies." [9]

In August 2025 the partnership expanded internationally. X-energy, Amazon, Korea Hydro & Nuclear Power (KHNP), and Doosan Enerbility announced a strategic partnership to accelerate Xe-100 and TRISO-X deployment in the United States, with the parties aiming to mobilize up to $50 billion in public and private investment for Xe-100 projects and supply-chain expansion. The Korean industrial partners agreed to support the existing target of more than 5 gigawatts of new nuclear energy across the United States by 2039. [24]

## What other projects and partnerships does X-energy have?

In 2025 X-energy partnered with the British energy company [Centrica](/wiki/centrica) to develop a fleet of up to 6 gigawatts of Xe-100 reactors in the United Kingdom. By late 2025 the company reported an orderbook and commercial pipeline of more than 11 gigawatts, equivalent to roughly 144 Xe-100 reactors. [19]

| Partner | Project and location | Scope | Status |
|---|---|---|---|
| [Dow](/wiki/dow) (Long Mott Energy) | Long Mott Generating Station, Seadrift, Texas | four Xe-100 units (320 MWe / 800 MWth) for power and industrial steam | construction permit application submitted March 31, 2025; docketed May 2025; NRC Finding of No Significant Impact May 2026 |
| Energy Northwest | central Washington | joint development agreement for up to 12 Xe-100 units (about 960 MWe) | signed 2023 |
| Amazon | United States deployment | up to 5 GW by 2039; initial four-unit, 320 MWe project via Energy Northwest | announced October 2024 |
| KHNP / Doosan Enerbility | United States, plus global | up to $50B investment to scale Xe-100 for AI infrastructure | announced August 2025 |
| Centrica | United Kingdom | fleet of up to 6 GW of Xe-100 reactors | announced 2025 |

## How has X-energy been funded, and what was its IPO?

X-energy raised capital through a series of private rounds before listing publicly. It finalized a $235 million Series C in December 2023, anchored by funds affiliated with Ares Management and by Ghaffarian himself, with earlier participation from Ontario Power Generation, Curtiss-Wright, DL E&C, and Doosan Enerbility. [7] The Amazon-led Series C-1 of about $500 million followed on October 16, 2024, joined by Citadel founder Ken Griffin, Ares, NGP, and the University of Michigan. [9][10] On November 24, 2025 the company closed an oversubscribed Series D of roughly $700 million led by the trading firm Jane Street, with new investors including ARK Invest, Point72, XTX Ventures, Galvanize, Hood River Capital Management, and Reaves Asset Management, plus existing backers such as Ares, Emerson Collective, NGP, and Segra Capital Management. [17][18] In total the company raised more than $1.4 billion privately before going public. [17]

Earlier, X-energy had attempted to reach the public markets through a special purpose acquisition company. In December 2022 it agreed to a business combination with Ares Acquisition Corporation that valued the combined company at about $2 billion and was expected to close in 2023. The two sides mutually terminated the merger on October 31, 2023, citing difficult market conditions and weak trading by comparable companies; an Ares-affiliated vehicle then made a private investment to support X-energy's operations instead. [8]

The company finally completed a conventional IPO in April 2026. It priced an upsized offering of 44,254,659 shares of Class A common stock at $23 each, above the initial marketed range of $16 to $19, and the shares began trading on the Nasdaq Global Select Market on April 24, 2026 under the ticker XE. [20] The sale raised about $1.02 billion. [21] The stock closed roughly 27 percent above the offering price on its first day, valuing X-energy at around $11.5 billion. [22] In its first results as a public company, reported on June 4, 2026, X-energy posted first-quarter 2026 revenue of about $43 million, up roughly 109 percent year over year, while continuing to operate at a loss as it scaled up. [23]

| Round | Date | Amount | Lead and notable investors |
|---|---|---|---|
| Series C | December 2023 | $235 million | Ares Management, Kam Ghaffarian; earlier OPG, Curtiss-Wright, DL E&C, Doosan |
| Series C-1 | October 16, 2024 | about $500 million | Amazon Climate Pledge Fund (lead); Ken Griffin, Ares, NGP, University of Michigan |
| Series D | November 24, 2025 | about $700 million | Jane Street (lead); ARK Invest, Point72, XTX Ventures, Galvanize, Hood River, Reaves |
| IPO (Nasdaq: XE) | April 24, 2026 | about $1.02 billion | 44,254,659 Class A shares at $23 |

## Why is X-energy relevant to AI data centers?

X-energy's rise has been propelled by the electricity demands of artificial intelligence. Training and serving large models has pushed [AI energy consumption](/wiki/ai_energy_consumption) sharply higher, and operators want power that is both round-the-clock and carbon-free, a profile that fits nuclear better than intermittent renewables. Hyperscale cloud providers have responded with a wave of nuclear deals: Amazon's investment in X-energy is one example, [Microsoft](/wiki/microsoft) contracted with [Constellation Energy](/wiki/constellation_energy) to restart a reactor at Three Mile Island, and [Google](/wiki/google) agreed to buy capacity from Kairos Power. [22] The Xe-100's modular four-pack format, relatively small land footprint, and ability to supply high-temperature steam as well as electricity are pitched as advantages for siting near data centers and industrial loads. [3]

Coverage of X-energy's Series D and its IPO repeatedly tied the company's valuation to this trend. Technology and financial press described the listing as a "data center-driven IPO," and analysts pointed to the surge in AI-related power demand, together with Amazon's offtake commitment, as the reason a pre-revenue-scale reactor developer could raise more than a billion dollars in a single sitting. [21][22] The 2025 KHNP and Doosan agreement made the rationale explicit, framing up to $50 billion of investment as serving "data centers and artificial intelligence." [24] The company itself markets advanced nuclear as a way to power the AI buildout, while cautioning, as does most of the sector, that its first reactors will not begin operating until around the end of the decade. [22]

## Timeline

| Date | Event |
|---|---|
| 2009 | X-energy founded by Kam Ghaffarian |
| October 2020 | Selected by DOE for the Advanced Reactor Demonstration Program, alongside TerraPower |
| March 1, 2021 | ARDP cooperative agreement signed (up to about $1.23 billion federal cost share) |
| December 2022 | Agrees to a SPAC merger with Ares Acquisition Corporation |
| 2023 | Dow and X-energy agree to build the first Xe-100 plant at Dow's Gulf Coast site |
| October 31, 2023 | SPAC merger with Ares Acquisition Corporation terminated |
| December 2023 | $235 million Series C finalized |
| October 16, 2024 | Amazon-led Series C-1 of about $500 million |
| March 31, 2025 | Dow and X-energy submit Long Mott construction permit application to the NRC |
| August 2025 | Amazon, KHNP, and Doosan partnership to mobilize up to $50 billion for AI-driven SMR deployment |
| November 24, 2025 | Series D of about $700 million closed |
| February 2026 | NRC issues TRISO-X fuel-fabrication license (SNM-7007) |
| April 24, 2026 | X-energy completes its Nasdaq IPO (ticker XE) |
| May 2026 | NRC issues Finding of No Significant Impact for the Dow Long Mott project |

## References

1. "X-energy." Wikipedia, accessed 2026-06-08. https://en.wikipedia.org/wiki/X-energy
2. "Kam Ghaffarian." Wikipedia, accessed 2026-06-08. https://en.wikipedia.org/wiki/Kam_Ghaffarian
3. "Xe-100: High-Temperature Gas-Cooled Nuclear Reactors (HTGR)." X-energy, accessed 2026-06-08. https://x-energy.com/reactors/xe-100
4. "X-energy is Developing a Pebble Bed Reactor That They Say Can't Melt Down." U.S. Department of Energy, Office of Nuclear Energy. https://www.energy.gov/ne/articles/x-energy-developing-pebble-bed-reactor-they-say-cant-melt-down
5. "X-energy signs Department of Energy's Advanced Reactor Demonstration Program (ARDP) Cooperative Agreement." X-energy, March 1, 2021. https://x-energy.com/news/x-energy-signs-department-of-energys-advanced-reactor-demonstration-program-ardp-cooperative-agreement/
6. "X-energy formally begins SMR partnership with DOE." World Nuclear News, 2021. https://www.world-nuclear-news.org/Articles/X-energy-formally-begins-SMR-partnership-with-DOE
7. "X-energy Finalizes $235 Million Series C Financing." X-energy, December 2023. https://x-energy.com/media/news-releases/x-energy-finalizes-235-million-series-c-financing
8. "Mutual Termination of Business Combination Agreement (Ares Acquisition Corporation / X-Energy), Form 8-K Exhibit 99.1." U.S. Securities and Exchange Commission, October 31, 2023. https://www.sec.gov/Archives/edgar/data/0001829432/000119312523266738/d397916dex991.htm
9. "Amazon Invests in X-energy to Support Advanced Small Modular Nuclear Reactors and Expand Carbon-Free Power." X-energy, October 16, 2024. https://x-energy.com/media/news-releases/amazon-invests-in-x-energy-to-support-advanced-small-modular-nuclear-reactors-and-expand-carbon-free-power
10. "Amazon Leads $500 Million Capital Raise for Small Modular Nuclear Technology Company X-Energy." ESG Today, October 2024. https://www.esgtoday.com/amazon-leads-500-million-capital-raise-for-small-modular-nuclear-technology-company-x-energy/
11. "Energy Northwest and X-energy Sign Joint Development Agreement for Xe-100 Advanced Small Modular Reactor Project." X-energy, 2023. https://x-energy.com/news/energy-northwest-x-energy-joint-development-agreement-xe-100/
12. "Dow and X-energy Submit Construction Permit Application to the U.S. Nuclear Regulatory Commission for Proposed Advanced Nuclear Project in Texas." X-energy, March 2025. https://x-energy.com/media/news-releases/dow-and-x-energy-submit-construction-permit-application-to-the-us-nuclear-regulatory-commission-for-proposed-advanced-nuclear-project-in-texas
13. "NRC Issues Environmental Assessment with Finding of No Significant Impact for Dow and X-energy's Proposed Advanced Nuclear Project in Texas." X-energy, 2026. https://x-energy.com/news/nrc-issues-environmental-assessment-with-finding-of-no-significant-impact-for-dow-and-x-energys-propsed-advanced-nuclear-project-in-texas/
14. "TRISO-X Receives First-Ever Part 70 HALEU Fuel Fabrication License." X-energy, February 2026. https://x-energy.com/news/triso-x-receives-first-ever-part-70-haleu-fuel-fabrication-license/
15. "NRC grants license for TRISO-X fuel manufacturing using HALEU." American Nuclear Society, Nuclear Newswire, February 2026. https://www.ans.org/news/article-7762/nrc-grants-license-for-trisox-fuel-manufacturing-using-haleu/
16. "US Regulator Grants Licence To Triso-X For Haleu Fuel Production In Tennessee." NucNet, February 2, 2026. https://www.nucnet.org/news/us-regulator-grants-licence-to-triso-x-for-haleu-fuel-production-in-tennessee-2-2-2026
17. "X-energy Closes Oversubscribed $700 Million Series D Financing Round to Continue Expansion to Meet Global Energy Demand." Business Wire, November 24, 2025. https://www.businesswire.com/news/home/20251124774353/en/X-energy-Closes-Oversubscribed-$700-Million-Series-D-Financing-Round-to-Continue-Expansion-to-Meet-Global-Energy-Demand
18. "X-energy raises $700M in latest funding round." American Nuclear Society, Nuclear Newswire, November 25, 2025. https://www.ans.org/news/article-7581/xenergy-raises-700m-in-latest-funding-round/
19. "X-energy rides nuclear wave, raises $700M Series D." TechCrunch, November 24, 2025. https://techcrunch.com/2025/11/24/x-energy-rides-nuclear-wave-raises-700m-series-d/
20. "X-energy Announces Pricing of Upsized Initial Public Offering." X-energy, April 23, 2026. https://x-energy.com/news/x-energy-announces-pricing-of-upsized-initial-public-offering/
21. "Nuclear startup X-energy raises $1B in data center-driven IPO." TechCrunch, April 24, 2026. https://techcrunch.com/2026/04/24/nuclear-startup-x-energy-raises-1b-in-data-center-driven-ipo/
22. "Nuclear reactor company X-energy shares surge 27% as AI drives interest in its IPO." CNBC, April 24, 2026. https://www.cnbc.com/2026/04/24/nuclear-reactor-company-x-energy-begins-trading-as-ai-drives-interest-in-the-industry.html
23. "X-energy Reports First Quarter 2026 Results." GlobeNewswire, June 4, 2026. https://www.globenewswire.com/news-release/2026/06/04/3306595/0/en/X-energy-Reports-First-Quarter-2026-Results.html
24. "X-energy, Amazon, Korea Hydro & Nuclear Power, and Doosan Enerbility Announce Partnership to Scale Advanced Nuclear Energy for AI Infrastructure." X-energy, August 25, 2025. https://x-energy.com/media/news-releases/x-energy-amazon-korea-hydro-amp-nuclear-power-and-doosan-enerbility-announce-partnership-to-scale-advanced-nuclear-energy-for-ai-infrastructure