Mar 16, 2026
Regulatory rationale for Rolls-Royce SMR
UK Secretary of State for Environment, Food and Rural Affairs, Emma Reynolds, has opted to provide regulatory justification for the Rolls-Royce SMR design, marking it as the first small modular reactor to obtain this approval.
Justification is a preliminary regulatory requirement necessary for new nuclear technologies in the country, assessing whether a new reactor design meets the criteria under The Justification of Practices Involving Ionising Radiation Regulations 2004.
The Nuclear Industry Association (NIA) submitted a request in July 2024 to the Department for Environment, Food and Rural Affairs (DEFRA) for justification of the Rolls-Royce SMR, establishing it as the first such request for a UK reactor design. Following this, DEFRA initiated a public consultation on the NIA's application in October last year, which concluded on 1 December. The consultation aimed to gather opinions on whether the proposed practice fits into a new or existing classification, whether it is suitably defined for justification, and if the application and supplementary information are adequate for DEFRA’s assessment of the associated benefits and drawbacks.
The Secretary of State for Environment, Food and Rural Affairs has now confirmed that the Rolls-Royce SMR is justified.
"Consideration of consultation responses regarding the application for the Rolls-Royce SMR, which was open from 6 October to 1 December 2025, and the insights of statutory consultees influenced this decision," stated DEFRA. "To implement the justification decision, secondary legislation must be approved by both Houses of Parliament."
Helena Perry, Director of Safety and Regulatory Affairs for Rolls-Royce SMR, expressed, "We appreciate the Secretary of State's decision, which provides regulatory justification for our power station—a crucial step in our journey to deploy the UK's first small modular reactors and our goal of providing clean, affordable energy for everyone."
As the representative body of the UK civil nuclear sector, the NIA frequently submits justification applications since these decisions can be utilized by any party and are not exclusive to specific reactor vendors or developers. The NIA has previously sought justifications for reactors such as Hitachi's Advanced Boiling Water Reactor, Westinghouse's AP1000, and Framatome's EPR.
The Rolls-Royce SMR is a 470 MWe design utilizing a small pressurized water reactor, expected to deliver reliable baseload generation for a minimum of 60 years. Approximately 90% of the SMR—approximately 16 meters by 4 meters—will be constructed in factory settings, minimizing on-site activities primarily to the assembly of pre-fabricated, pre-tested modules, which significantly mitigate project risks and could considerably reduce construction timelines.
Last June, Rolls-Royce SMR was chosen as the UK government's preferred technology for the nation's inaugural SMR project, with a final investment decision anticipated in 2029.
In November, the government revealed that Wylfa on the island of Anglesey, North Wales, will accommodate three Rolls-Royce small modular reactors. The site, currently decommissioning a Magnox plant, has the potential to support up to eight SMRs.
Justification is a preliminary regulatory requirement necessary for new nuclear technologies in the country, assessing whether a new reactor design meets the criteria under The Justification of Practices Involving Ionising Radiation Regulations 2004.
The Nuclear Industry Association (NIA) submitted a request in July 2024 to the Department for Environment, Food and Rural Affairs (DEFRA) for justification of the Rolls-Royce SMR, establishing it as the first such request for a UK reactor design. Following this, DEFRA initiated a public consultation on the NIA's application in October last year, which concluded on 1 December. The consultation aimed to gather opinions on whether the proposed practice fits into a new or existing classification, whether it is suitably defined for justification, and if the application and supplementary information are adequate for DEFRA’s assessment of the associated benefits and drawbacks.
The Secretary of State for Environment, Food and Rural Affairs has now confirmed that the Rolls-Royce SMR is justified.
"Consideration of consultation responses regarding the application for the Rolls-Royce SMR, which was open from 6 October to 1 December 2025, and the insights of statutory consultees influenced this decision," stated DEFRA. "To implement the justification decision, secondary legislation must be approved by both Houses of Parliament."
Helena Perry, Director of Safety and Regulatory Affairs for Rolls-Royce SMR, expressed, "We appreciate the Secretary of State's decision, which provides regulatory justification for our power station—a crucial step in our journey to deploy the UK's first small modular reactors and our goal of providing clean, affordable energy for everyone."
As the representative body of the UK civil nuclear sector, the NIA frequently submits justification applications since these decisions can be utilized by any party and are not exclusive to specific reactor vendors or developers. The NIA has previously sought justifications for reactors such as Hitachi's Advanced Boiling Water Reactor, Westinghouse's AP1000, and Framatome's EPR.
The Rolls-Royce SMR is a 470 MWe design utilizing a small pressurized water reactor, expected to deliver reliable baseload generation for a minimum of 60 years. Approximately 90% of the SMR—approximately 16 meters by 4 meters—will be constructed in factory settings, minimizing on-site activities primarily to the assembly of pre-fabricated, pre-tested modules, which significantly mitigate project risks and could considerably reduce construction timelines.
Last June, Rolls-Royce SMR was chosen as the UK government's preferred technology for the nation's inaugural SMR project, with a final investment decision anticipated in 2029.
In November, the government revealed that Wylfa on the island of Anglesey, North Wales, will accommodate three Rolls-Royce small modular reactors. The site, currently decommissioning a Magnox plant, has the potential to support up to eight SMRs.