Centrica plc and X-Energy, Inc. (NASDAQ: XE) announced that X-energy's Xe-100 small modular reactor has been accepted into the United Kingdom's Generic Design Assessment (GDA) process, a step required before site-specific licensing and permitting can proceed.

The GDA, which is expected to take approximately three years, will be administered by the UK Office for Nuclear Regulation, the Environment Agency, and Natural Resources Wales. The assessment formally begins the process of evaluating the reactor design's acceptability for deployment and operation in the UK.

Under their partnership, which was signed in September 2025, Centrica and X-energy intend to deploy up to 6 gigawatts of new nuclear capacity across the UK, equivalent to 10 to 20 Xe-100 power stations depending on the size of each installation. The first proposed site is Hartlepool.

X-energy's Xe-100 is a high-temperature gas-cooled reactor. Each unit is engineered to provide 80 megawatts of electricity or 200 megawatts of thermal heat for industrial use, and is designed to operate in multi-unit plants ranging from 320 megawatts to 960 megawatts.

The companies said the UK submission is expected to benefit from collaboration between UK regulators and the U.S. Nuclear Regulatory Commission, allowing transfer of reviewed design documentation and safety analyses between jurisdictions.

Since signing their agreement, the companies said they have begun site studies, planning activities, and workforce development efforts in Hartlepool, including the launch of a Nuclear and Electrical Trades Academy.

X-energy is also advancing an initial Xe-100 plant with Dow Inc. on the Texas Gulf Coast and is developing a further plant with Energy Northwest in collaboration with Amazon.

Michael Shanks, UK Minister of State for Energy, said the announcement represents "another important step towards bringing advanced nuclear technologies to the UK" and that such projects would deliver "clean, secure and homegrown energy" while bringing investment and jobs to Hartlepool.