The Generic Design Assessment (GDA) is the UK Office for Nuclear Regulation's (ONR) multi-step process for evaluating new nuclear power plant designs against UK safety, security, and environmental requirements. Analogous to the NRC's Design Certification in the United States, the GDA allows reactor designers to obtain regulatory pre-approval of their technology independent of any specific deployment site, providing confidence to utilities and investors that the design meets UK standards before committing to site-specific licensing and construction. The GDA progresses through four steps: Step 1 (initiating the process), Step 2 (fundamental safety overview), Step 3 (overall design safety review), and Step 4 (detailed design assessment), with each step providing increasing levels of regulatory scrutiny and confidence.
Rolls-Royce SMR is the most advanced SMR in the UK GDA process, currently in Step 3 with expected completion in August 2026. Rolls-Royce's 470 MWe PWR design was selected as the UK's technology of choice in June 2025, and the Wylfa site in Anglesey, Wales was selected in November 2025 for the first deployment, with up to 3 initial units and potential for 8. If the GDA completes on schedule, first concrete could be poured as early as 2027 with first unit revenue service targeted for 2031. Holtec International's SMR-300 is expected to enter GDA Step 2 in early 2026, pursuing the UK as a parallel deployment market alongside its U.S. licensing efforts.
Newcleo's LFR-AS-200 was accepted into the GDA in June 2025 as the first advanced modular reactor (non-light-water) to enter the UK assessment process, though the company subsequently relocated its headquarters from the UK to Paris after the UK decided to immobilize its plutonium stockpile rather than make it available for MOX fuel fabrication. The status of Newcleo's UK GDA is uncertain following this strategic shift. The GDA process is a critical element of the UK's nuclear renaissance strategy, with Great British Energy and Great British Nuclear providing government backing for SMR deployment. The UK's approach of pre-assessing designs before site selection allows multiple vendors to compete for deployment, though Rolls-Royce SMR's head start in the GDA gives it a significant timeline advantage over other entrants.