X-energy Submits Xe-100 HTGR for UK Generic Design Assessment

X-energy, Inc. (NASDAQ: XE) (“X-energy” or “the Company”), a leading developer of advanced nuclear reactors and fuel technology, today submitted an application to enter the United Kingdom’s Generic Design Assessment (“GDA”) process for its Xe-100 High Temperature Gas-cooled Reactor (“HTGR”). Subject to acceptance, submission marks a significant milestone in X-energy and Centrica’s efforts to deploy up to 6 GW of new nuclear in the United Kingdom, initiating a critical step in the UK licensing process.

Generic Design Assessment is the UK’s established regulatory pathway for licensing new nuclear technologies, evaluating safety, security, safeguards, and environmental impact independent of site-specific considerations. The assessment will be administered by the UK Office for Nuclear Regulation (ONR), Environment Agency, Natural Resources Wales and the Department for Energy Security and Net Zero (DESNZ), and is expected to conclude by the end of 2029.

X-energy has been in active dialogue with UK regulatory authorities since 2024 through the Early Engagement process. The Company’s latest submission builds on its U.S. licensing progress and is expected to further benefit from expanded collaboration between ONR and the U.S. Nuclear Regulatory Commission that allows for direct transfer of design documentation and safety analyses. This streamlined approach allows applicants to leverage NRC-approved technical documents throughout the assessment, creating opportunities for enhanced efficiency in the UK’s licensing process.

“Advanced Modular Reactors like the Xe-100 are the cornerstone of Britain’s future energy security, and would bring clean, reliable power as well as renewed opportunities for British industry,” said Alistair Black, Vice President and UK Market Lead at X-energy. “We welcome the Regulators’ recent steps towards a more efficient GDA process, and look forward to working collaboratively to support an efficient, thorough review. GDA submission marks an important milestone in bringing our technology to the UK on a fleet-scale, with the potential to create thousands of high-quality jobs where needs are greatest.”

The Xe-100 is an 80 MWe HTGR deployed in four-or-twelve-unit plants, capable of providing both electricity, and high-temperature heat and steam for industrial applications. In September 2025, X-energy and Centrica signed a Joint Development Agreement for the UK’s first advanced nuclear fleet, targeting 6 GW nationwide with Hartlepool identified as the preferred first site for a 12-unit/960 MWe Xe-100 plant. The project is currently advancing through the UK Government’s Advanced Nuclear Pipeline assessment.

The United Kingdom has extensive operational experience with gas reactor technology, with eight currently-operating Advanced Gas-Cooled Reactors, a predecessor to X-energy’s HTGR technology. In 2024, X-energy was selected for DESNZ’s Future Nuclear Enabling Fund to develop UK-specific deployment plans including assessment of domestic manufacturing opportunities, supply chain development, constructability, modularization studies, and fuel management. This culminated in multiple technical and commercial studies estimating a minimum of £40 billion in lifetime economic value, with £12 billion arising from the first project alone. X-energy and Centrica’s agreement helps to strengthen U.K. energy security and supports the Government’s commitment to expand access to clean, safe, reliable energy.

About X-energy

X-energy, Inc. is a leading developer of advanced small modular nuclear reactors and fuel technology designed to establish a new standard in clean, safe, reliable energy. X-energy’s intrinsically safe Xe-100 high-temperature gas reactor and TRISO-X particle fuel expand applications for nuclear technology, with commercial projects underway with Dow, Amazon, and Centrica across grid, industrial, and AI applications. Together, X-energy’s technology drives enhanced safety, lower cost, faster construction timelines, and scalable deployment when compared with other SMRs and conventional nuclear.

Forward-Looking Statements

This press release contains forward-looking statements regarding our business, including statements with respect to when we believe the GDA assessment will be completed. These forward-looking statements are only predictions and may differ materially from actual results due to a variety of factors. You should not rely on our forward-looking statements as predictions of future events. More information about potential risks and uncertainties that could affect our business and financial results is more fully detailed under the caption “Risk Factors” in our Form S-1 filed with the Securities and Exchange Commission, which is available on our Investor Relations website at https://investors.x-energy.com/ and on the SEC website at www.sec.gov. In addition, please note that any forward-looking statements contained herein are based on assumptions that we believe to be reasonable as of this date. We undertake no obligation to update these statements as a result of new information or future events.

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Contact

Leon Flexman, UK Corporate Affairs

lflexman@x-energy.com

+(44) 07920 143732



Robert McEntyre, Corporate Communications

media@x-energy.com

+1 240.673.6565



Patricia Gil, Investor Relations

+1 301.558.3040

investors@x-energy.com