Office for Nuclear Regulation, Environment Agency & Natural Resources Wales

Assessment of reactors

Current assessments

GE Hitachi BWRX-300

The Department for Energy Security and Net Zero (DESNZ) asked ONR, the Environment Agency and Natural Resources Wales to begin a two-step Generic Design Assessment (GDA) for GE Hitachi’s BWRX-300 reactor.

Step 1 of the GDA will focus on agreeing the scope and schedule for step 2. The GDA assessment will look to actively explore opportunities to maximise the value of international regulatory collaboration and identify efficiencies in processes.

Holtec International SMR-300

The Department for Energy Security and Net Zero (DESNZ) has asked ONR, the Environment Agency and Natural Resources Wales to begin a Generic Design Assessment (GDA) for Holtec International’s SMR-300.

The GDA assessment will look to actively explore opportunities to maximise the value of international regulatory collaboration and identify efficiencies in processes.

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.

Previous assessments

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.