Office for Nuclear Regulation

We are the United Kingdom’s independent statutory regulator for nuclear safety, civil nuclear security, safeguards and conventional health and safety on licensed sites. Through our independent decision making and oversight, we provide confidence that nuclear activities across Great Britain meet the standards expected by Parliament and the public, ensuring people and the environment are protected.

Our responsibilities span the full lifecycle of nuclear operations from the existing reactor fleet and fuel cycle facilities, through waste management and decommissioning, to defence and other licensed and authorised sites.

We also regulate the safe transport of civil nuclear and radioactive materials, oversee the protection of sensitive nuclear information and account for civil nuclear materials in line with the UK’s international safeguards obligations. As new reactor designs, small modular reactors (SMRs), and advanced nuclear technologies (ANTs) emerge, we play an essential role in enabling innovation to progress safely and securely.

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Find out how to get in touch with the Office for Nuclear Regulation including whistleblowing and health and safety concerns.

These web pages have been produced by the Office for Nuclear Regulation (ONR), Environment Agency and Natural Resources Wales (NRW). Regulators are working together to ensure any new nuclear power stations built in Great Britain meet high standards of safety, security, environmental protection and waste management, through a voluntary process called Generic Design Assessment (GDA).

We have designed these pages so they are accessible to anyone with an interest in the GDA process, including the general public and other regulators. They also contain technical information for organisations submitting designs for GDA, which can be found in the assessment of reactors section .

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.

Our assessment has identified no fundamental safety, security or safeguards shortfalls with the design that could prevent its deployment in Great Britain.

Nuclear regulators have announced a new initiative to streamline regulation and accelerate the deployment of advanced nuclear reactors across UK and US markets.