Guidance on assessment of new nuclear power stations

The nuclear regulators have published guidance material on the Generic Design Assessment process for new nuclear power stations. These documents are aimed primarily at organisations intending to submit their reactor designs for assessment, but may also be helpful to other parties interested in the process.

Regulators assessment of civil nuclear reactors - new policies and approaches published

The Office for Nuclear Regulation, Environment Agency and Natural Resources Wales have published two new policies and approaches setting out how they will collectively simplify and speed up the process of assessing new nuclear reactor designs in Great Britain.

The UK government has given clear direction through the Prime Minister’s strategic steer and its acceptance of the principles of the Nuclear Regulatory Review to accelerate new nuclear deployment. The updated reactor design assessment framework and a new Leveraging International Regulators Judgements Policy reflect regulators' commitment to making regulatory activity more efficient, without compromising on safety standards.

The new reactor design assessment framework sets out updates to the Generic Design Assessment (GDA) being implemented now, as well as setting the direction for a single reactor assessment framework bringing together the existing GDA and Early Engagement processes, aligning with the ambition of delivering reactor design assessment in two years — a reduction that will help support the deployment of new nuclear technologies in the UK. This update is designed to provide clarity to reactor vendors and support the nuclear regulators' goal of launching updated guidance in Spring 2027.

The Leveraging International Regulators' Judgements Policy sets out the principles we will follow when drawing on the work of international regulators, reducing duplication and making better use of assessments already carried out by trusted counterparts around the world. This includes work under the Transatlantic Partnership as well as collaboration with a broader range of international regulators. The policy includes case studies that demonstrate how these principles are already being applied in practice.

Together, the documents signal a significant step forward in our ambition to create a more streamlined regulatory environment that supports the UK's nuclear energy ambitions while maintaining the rigorous safety standards the public expects.

Regulators assessment of civil nuclear reactors - update September 2025

The Atlantic Partnership for Advanced Nuclear Energy announced on 15 September 2025 includes commitments from nuclear regulators to significantly accelerate timeframes for decisions, by working much closer together on specific technologies where timeframes align.

We are currently reviewing our processes and guidance to enact this and ensure that we maintain standards, and retain our independent decision-making role. We anticipate this to be available in early 2026.

This will affect the Generic Design Assessment and Licensing Nuclear Installations processes and guidance. These processes remain valid for projects currently in progress, and we will work with those vendors and developers on an individual basis to explore acceleration opportunities. 

For new projects we will use the early engagement processes to facilitate discussions on regulatory pathways whilst we develop revised processes and associated guidance.

Licensing

An organisation wishing to carry out prescribed nuclear activities must apply for, and be granted, a nuclear site licence before it starts installation of a nuclear safety-related plant. A site licence puts the licence holder under strict legal obligations and, importantly, gives specific regulatory powers to ONR to ensure the safe construction, commissioning and operation of a nuclear site. For example a licence holder would typically have to request a consent from ONR to begin nuclear safety related construction.

• Further information on ONR's licensing process for nuclear power stations

Environmental permits

Organisations wishing to construct and operate a new nuclear power station will need a number of environmental permits from the Environment Agency in England and Natural Resources Wales in Wales.

Guidance and application forms relating to this process:

• Environment Agency
• Natural Resources Wales