The GDA is a voluntary pre-licensing process that evaluates the safety, security, and environmental aspects of new reactor designs before site-specific permissions are sought. Launched for advanced nuclear technologies including SMRs in May 2021, it consists of three steps and concludes with a Design Acceptance Confirmation from ONR and a Statement of Design Acceptability from the Environment Agency.
GE Vernova Hitachi submitted its application for the 300 MWe boiling-water BWRX-300 in December 2022. The reactor uses natural circulation and passive safety systems, building on the licensed ESBWR design. Step 1, which defined the scope for deeper review, started in January 2024 and finished on 12 December 2024. Step 2, examining the fundamental acceptability of the design and supporting documentation, has now been completed with positive outcomes.
Currently, no operator has announced plans to build the BWRX-300 in Great Britain, and no sites have been selected. Any future deployment would require additional detailed assessment—either through a return to complete GDA Step 3 on a generic basis or as part of site-specific licensing—before construction or environmental permits could be granted.
Rob Exley, ONR’s Head of the BWRX-300 GDA, noted: "GE Vernova Hitachi opted for a shorter two-step GDA, making it the first requesting party to take advantage of the flexibility we introduced in our modernised GDA process. This means it is the quickest GDA engagement completed to date, facilitated by GE Vernova Hitachi's responsiveness, the quality and maturity of its submissions, learning from previous GDAs, and our active collaboration with regulatory colleagues in the US and Canada who have been evaluating the BWRX-300 in parallel to our assessment."
Saffron Price-Finnerty, the Environment Agency's New Reactors Programme Manager, said: "The accelerated pace of this first two-Step GDA was enabled by the delivery of a complete set of documentation by GE Vernova Hitachi at the start of Step 2. This helped our assessment team to plan their work effectively and efficiently. Their assessments were targeted and proportionate in ensuring that there were no fundamental shortfalls in environmental protection."
Paul Gibson, Natural Resources Wales Nuclear Team Leader, added: "Throughout Step 2 we have worked closely with the Environment Agency and Office for Nuclear Regulation towards the fundamental assessment of the GE Vernova Hitachi SMR, resulting in the successful delivery of this first two-step GDA."
The BWRX-300 is the latest design to progress through the UK's GDA framework, joining previously accepted large reactors such as the UK EPR, AP1000, UK ABWR, and UK HPR1000. Ongoing assessments include the Rolls-Royce SMR, Holtec SMR-300, Westinghouse AP300 (entered August 2024), and TerraPower's Natrium reactor (submitted last month). This milestone demonstrates the adaptability of the modernised GDA process to accelerate reviews of advanced reactor technologies while maintaining rigorous safety and environmental standards.
