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Assessment of reactors

Active assessments

Rolls Royce SMR Ltd's 470MW SMR

In March 2022, the Department for Business, Energy and Industrial Strategy asked ONR, the Environment Agency and Natural Resources Wales to begin a three-step Generic Design Assessment (GDA) for Rolls Royce SMR Ltd's 470MW Small Modular Reactor design. The 12-month Step 1 assessment to agree the scope and schedule for future technical engagements commenced April 2022 and successfully concluded March 2023. In April 2023, the regulators started a 16-month assessment of the fundamental acceptability of Rolls-Royce SMR design for deployment in Great Britain. In July 2024, the regulators issued a Step 2 GDA statement and Rolls-Royce SMR entered Step 3 of the GDA process.

Previous assessments

  • Holtec International SMR-300 reactor technology was issued with a GDA statement from ONR and the Environment Agency in March 2026.
  • GE Vernova Hitachi BWRX-300 reactor technology was issued with a GDA statement from ONR and the Environment Agency in December 2025.
  • General Nuclear System Limited's UK HPR1000 reactor technology was issued a Design Acceptance Confirmation (DAC) and a Statement of Design Acceptability (SoDA) from the Environment Agency on 7 February 2022.
  • Hitachi-GE's UK Advanced Boiling Water Reactor (UK ABWR) was granted Design Acceptance Confirmation and a Statement of Design Acceptability in December 2017.
  • The Westinghouse AP1000 reactor design completed GDA in March 2017. We confirmed that Westinghouse's AP1000 reactor design is suitable for construction in the UK, granting design acceptance through formal documents, DAC and SoDA.
  • The EDF/AREVA's European Pressurised Reactor (EPR) design completed GDA in December 2012. We confirmed that EDF and AREVA's UK EPR reactor design is suitable for construction in the UK, granting design acceptance through formal documents called Design Acceptance Confirmation (DAC) and Statement of Design Acceptability (SoDA).

Future assessments

Nuclear new build is a policy matter for the government, who will determine if any further reactor designs will be considered for construction in the UK and prioritise those designs for assessment. A formal request for any further assessments will be submitted by government to ONR, the Environment Agency and Natural Resources Wales.

Office for Nuclear Regulation Environment Agency Natural Resources Wales

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