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Frequently asked questions

Why do we need new nuclear power stations?

The government states that the UK needs new and replacement energy supplies that can provide secure, reliable, low carbon electricity, and that nuclear power should play a part in this.

What is the ONR and Environment Agency involvement?

ONR and the Environment Agency are working together to assess new nuclear power station designs to ensure that they are safe, secure and environmentally acceptable. They are doing this using a process called Generic Design Assessment (GDA). The regulators will only conduct GDA on a new power station design following a request from the government.

What is generic design assessment?

Generic design assessment (GDA) is the process being used by the nuclear regulators ( ONR and the Environment Agency ) to assess the new nuclear power station designs. It allows the regulators to assess the safety, security and environmental implications of new reactor designs, separately from applications to build them at specific  sites.

How are Natural Resources Wales (NRW) involved in GDA?

GDA is a joint process between ONR and the Environment Agency. Natural Resources Wales (NRW), the environmental regulator in Wales since April 2013, also participates in GDA with the two other regulators and will be leading on engagement with people in Wales. While the GDA process is generic for England and Wales, it will also underpin the assessments NRW will need to make for any proposed development in Wales. All of the regulators will be working closely together over the next few years.

What are the benefits of Generic Design Assessment? (GDA)

GDA allows the regulators to get involved with designers at the earliest stage, where they have the most influence. By assessing at the design stage, any potential safety, security or environmental concerns can be identified and highlighted so they can be addressed by the Requesting Party (RP), the companies who have submitted a design for assessment, before commitments are made to construct any reactors based on that design. GDA is also designed to be generic, allowing the results of the regulators’ assessment to potentially be applied to multiple sites where that design is subsequently constructed.

How does the GDA work?

First, the government submits a formal request to ONR and the environmental regulators to begin GDA of a new reactor design. The regulators will only commence GDA when this request is received. Whilst there are detailed differences between the regulatory processes employed by ONR and the Environment Agency as part of GDA, the regulators assessment processes are closely aligned. Both regulators use a step-wise approach with the assessment becoming more detailed at each Step. ONR publish their findings at the end of each assessment Step. The Environment Agency carries out an initial assessment and a more detailed assessment prior to consulting on its findings. Throughout we conduct our work in an open and transparent way.

At the end of the GDA the regulators will provide their judgement on whether the design is adequately safe, secure and environmentally acceptable. Dependent upon the outcome of the GDA a number of potential outputs can be provided to the RP.

What reactors have been assessed or are currently going through GDA?

We completed GDAs for the EDF and AREVA UK EPR™, the Westinghouse AP1000®, the Hitachi-GE UK ABWR and the CGN/EDF/GNI UK HPR1000 designs in 2012, 2017, 2017 and 2022 respectively. Further details are available in the assessment of reactors section.

Rolls-Royce SMR Limited's Small Modular Reactor design entered Step 1 of the GDA process in April 2022 and the assessment is ongoing.

Holtec International’s SMR-300 Small Modular Reactor design entered Step 1 of the GDA process in December 2023 and the assessment is ongoing.

GE Hitachi’s BWRX300 Small Modular Reactor design entered Step 1 of the GDA process in January 2024 and the assessment is ongoing. 

Who pays for GDA?

The assessment and all related costs will be paid for by the Requesting Party (RP), the companies who have submitted a design for assessment.

How and to what extent, is security taken into account under GDA?

Security forms a major part of the GDA process and requires the RP to submit sufficient information to enable ONR to make a judgement of the adequacy of the security aspects of the generic design. Security is fully integrated with the safety assessment to ensure that the design incorporates security by design across the full spectrum of protective security measures, including physical protection, cyber and information and personnel security.

You say that you are working in an open and transparent way. What does that mean?

As nuclear regulators, we recognise that we are acting in the interests of the public. It is important therefore that we are open about what we do, and how and why we do it. In order to achieve this, we publish extensive information relating to the assessment including technical reports, guidance and regular progress updates through our website. People also have the opportunity to get involved in GDA via the RP’s public comments process and the Environment Agency’s consultation.

What does the public comments process involve?

It is a requirement of GDA for the RP’s to publish design information on their websites and encourage members of the public to comment. The RP’s will respond to all comments, and the regulators will consider the comments and the RP’s responses as part of our assessments.

What's the timescale for GDA?

Due to the complexity and the level of scrutiny required in the GDA process it is expected to take a number of years to complete. Further details of typical timescales for each Step can be found in the regulators guidance documents. Information on the timescales for previously completed GDAs can be found on our website.

The actual timescale for assessing a design will be largely dependent on the work programmes of the RP, the quality and timeliness of their submissions to the regulators, the significance of any issues that arise from our assessment and the RP’s ability to respond in a timely way.

Under what circumstances would you not be satisfied at the end of a GDA?

If the RP does not provide sufficient information, or if our assessment identifies safety, security or environmental issues that are so significant that we are not confident that they can be resolved.

Where can I find more information on GDA?

In addition to the reports that we publish throughout the process, we also publish update reports on our website. The regulators website also contains full details for all completed and on-going GDAs.

What else is required before a nuclear power station can be built and operated?

Before a new nuclear power station can be built and operated the operator must obtain a number of key site specific permissions from regulators and Government. These include a nuclear site licence and relevant consents from ONR, environmental permits from the Environment Agency or Natural Resources Wales and planning permission from the Department for Energy Security and Net Zero's Secretary of State. In both the licensing process and environmental permitting we also assess the capability of the operator and the potential impacts at the site.

What is a nuclear site licence?

A nuclear site licence is a licence that must be granted by ONR before a new nuclear power station can be built and operated on a specific site. Before we grant a licence, we will ensure that the site is safe and secure, the site is suitable for the particular design, and that the potential operator can adequately control construction, operation and maintenance of the plant to ensure safety and security.

When will site licensing begin?

Site licensing (the process of granting a nuclear site licence) will begin when we receive an application from a potential operator. If a nuclear site licence is applied for before the end of GDA, then we will progress this at the same time.

What is an environmental permit?

A number of specific environmental permits are required by operators so that they can build and operate a new nuclear power station.

If applications for permits are made by a potential operator the Environment Agency or NRW would decide if permits should be issued and, if so, the conditions they include. Operational permits include disposals and discharges of radioactive wastes, operation of standby generators and discharges of cooling water and liquid effluent.

Relevant environmental permits will also be required for the construction and operation of 'associated developments' for example infrastructure relating to construction such as workers accommodation or freight transfer facilities.

Who decides where the reactors will be built?

In the government nuclear national policy, eight sites were identified as potential suitable sites for nuclear development, all of which are close to existing nuclear licensed sites. Developers put forward their proposals to develop a particular power station design at a specific site, but a power station can only be developed if relevant licences, consents and permits are granted by the regulators.

Office for Nuclear Regulation Environment Agency Natural Resources Wales