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 - 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.

Resources

Environment Agency / Natural Resources Wales

GDAs started after 2019

New nuclear power plants: Generic Design Assessment guidance for Requesting Parties (Environment Agency)
This updated guidance from the Environment Agency explains the Generic Design Assessment (GDA) process for organisations who want to submit a nuclear power plant design for assessment. (First published 2019, revised 2023.)

GDAs started before 2019

Process and Information Document for Generic Assessment of Candidate Nuclear Power Plants
Guidance from the Environment Agency setting out how it will assess environmental issues. (Version 1 published 2013). The Generic Design Assessment process also includes the requirement for a comments process at the start of Step 2.
- Information on this guidance

ONR

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: