The UK Generic Design Assessment process for nuclear new-build
Trevor Jones is an independent consultant with over 35 years ' experience in the civil and defence nuclear sectors, including new build and decommissioning projects.
In 2007, the UK Government introduced Generic Design Assessment( GDA) to streamline the development of new nuclear power stations. Earlier nuclear projects were licensed on a site-by-site basis, meaning major design issues were only addressed after significant investment. The GDA process allows regulators to examine reactor designs before site-specific applications, identifying potential issues sooner, reducing uncertainty for developers, and providing greater transparency for the public. It is not mandatory for reactor designs to be submitted to GDA, and regulators will only commence an assessment if requested by government.
GDA is an integrated process by which the Office for Nuclear Regulation( ONR) and Environment Agency( EA) or Natural
Resources Wales( NRW) conduct parallel regulatory scrutiny of reactor designs proposed for construction in England and Wales. Scottish Government policy does not support nuclear new build, so the process does not apply in Scotland. GDA normally takes around four years, and initially consisted of three stages of increasing technical detail: initiation, fundamental assessment and detailed assessment. More recently, the process was made more flexible to facilitate the assessment of Small Modular Reactors( SMRs) and less mature designs, with the option to stop after two stages.
Reactor designs and GDA The first GDA applications were for large gigawatt-scale reactors. The UK EPR, developed by EDF and Areva, is a ~ 1,630 MWe( Megawatt electrical) Pressurised Water Reactor( PWR) incorporating double containment and multiple redundant safety
systems. GDA assessment of the design began in 2007, and the process was completed in 2012. Two UK EPR reactors are now under construction at Hinkley Point C, with two more planned at Sizewell C.
The second Hinkley Point C reactor pressure vessel arriving in January 2026
GDA of the Westinghouse AP1000 began in 2007. This 1,100 MWe PWR design incorporates extensive passive safety systems that rely on gravity, natural circulation and stored energy rather than active pumps. After a decade of assessment and design revisions, the AP1000 received regulatory approval in 2017.
The 1,350 MWe Hitachi-GE UK Advanced Boiling Water Reactor( UK ABWR) features internal recirculation pumps and enhanced safety systems derived from earlier designs deployed in Japan. It began GDA in 2013 and was granted regulatory approval in 2017, although its planned construction at Wylfa in North Wales was later cancelled.
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