Centrica and US nuclear developer X-energy have advanced their UK nuclear partnership after regulators accepted the Xe-100 small modular reactor design into the UK's Generic Design Assessment, a step that matters because GDA acceptance is the formal gateway UK regulators require before any new reactor design can be licensed for construction.

Centrica is a UK and Ireland-focused integrated energy company operating British Gas, Bord Gáis Energy and Centrica Business Solutions.

X-energy is a US-based small modular reactor developer listed on Nasdaq, designing the Xe-100 high-temperature gas-cooled reactor and TRISO-X fuel, with projects underway in Texas and Washington state.

X-energy chief executive J. Clay Sell said the company is "advancing fleet-scale deployment of our technology, and it begins with a strong regulatory foundation." Centrica chief executive Chris O'Shea said, "Without energy security, we don't have true national security," adding that deploying up to 6GW "will not only strengthen our energy security, but it will create tens of billions of economic value and thousands of highly skilled jobs."

X-energy enters GDA well behind the front-runner: Rolls-Royce SMR is already in Step 3, the final stage, and was named the UK's preferred domestic SMR technology by Great British Energy – Nuclear after a two-year competition, alongside GE Hitachi, Westinghouse, Holtec and Newcleo all pursuing the same pathway.

That crowded field means Centrica's bet is less about picking a winning design outright than securing early access to Hartlepool site development and supply chain positioning while the wider competition plays out. The three-year GDA timeline, plus subsequent site-specific licensing, means Xe-100 units at Hartlepool remain years from construction regardless of today's milestone.

For the sector, a UK utility partnering directly with a US reactor vendor rather than waiting for the government's own SMR competition to conclude signals growing appetite among incumbent energy suppliers to build proprietary nuclear positions ahead of, rather than through, state-led procurement processes.

Source: X-energy / Nuclear Consulting