Key Takeaways:
X-energy's bid to enter the UK's Generic Design Assessment marks the first formal step toward deploying the country's first advanced nuclear fleet, with a 960 MWe plant planned for Hartlepool.
X-energy on Tuesday submitted its Xe-100 high-temperature gas reactor for UK regulatory review, advancing a partnership with Centrica to deploy as much as 6 GW of advanced nuclear capacity nationwide.
"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," Alistair Black, vice president and UK market lead at X-energy, said.
The Generic Design Assessment, administered by the Office for Nuclear Regulation and the Environment Agency, evaluates safety, security and environmental impact independent of site-specific factors. The review is expected to conclude by the end of 2029. X-energy has been in active dialogue with UK regulators since 2024 through an Early Engagement process, and the submission builds on US licensing progress with the Nuclear Regulatory Commission. A new collaboration between ONR and the NRC allows direct transfer of design documentation and safety analyses, potentially accelerating the UK process.
The Xe-100 is an 80 MWe high-temperature gas-cooled reactor that can be deployed in four- or 12-unit configurations, providing both electricity and high-temperature heat for industrial applications. X-energy and Centrica signed a joint development agreement in September 2025 targeting 6 GW nationwide, with Hartlepool identified as the preferred first site for a 12-unit, 960 MWe plant. The project is advancing through the UK government's Advanced Nuclear Pipeline assessment.
UK's Gas Reactor Heritage Gives X-energy an Edge
The United Kingdom operates eight Advanced Gas-Cooled Reactors, a technology lineage that shares design principles with X-energy's HTGR. That operational experience could ease regulatory familiarity with the Xe-100's gas-cooled architecture, which uses helium as a coolant rather than water. The reactor runs on TRISO-X particle fuel — uranium kernels coated in layers of carbon and ceramic that contain fission products even at extreme temperatures, a safety feature X-energy describes as intrinsically safe.
In 2024, the Department for Energy Security and Net Zero selected X-energy for its Future Nuclear Enabling Fund to develop UK-specific deployment plans covering domestic manufacturing, supply chain development, modularization and fuel management. Those studies estimated a minimum of £40 billion in lifetime economic value from the partnership, with £12 billion attributable to the first project alone.
What the GDA Process Means for Investors
The Generic Design Assessment is the UK's established regulatory pathway for licensing new nuclear technologies. While the review runs through 2029, acceptance into the process unlocks a clearer path to revenue for X-energy, which listed on Nasdaq in April 2026 through a $1.02 billion IPO. The company trades at $26.44, with Cantor Fitzgerald initiating coverage at Overweight with a $38 price target, implying about 44 percent upside.
Beyond the UK, X-energy has commercial projects underway with Dow in Texas — where the company recently received environmental assessment approval from the NRC — as well as with Amazon and Centrica across grid, industrial and AI data center applications. The UK fleet alone represents a potential multi-billion-dollar construction program, though X-energy and Centrica have not disclosed the project's total capital expenditure estimate.
This article is for informational purposes only and does not constitute investment advice.
