Decision

GDA Step 1 of the Holtec SMR: statement of findings public summary

Published 1 August 2024

Applies to England and Wales

Executive summary

New nuclear power stations are an important part of the government’s plans for generating secure low carbon energy.

As regulators of the nuclear industry, the Environment Agency, Natural Resources Wales and the Office for Nuclear Regulation (ONR) are working together to make sure that any new nuclear power stations built in the UK meet high standards of safety, security, environmental protection and waste management.

The generic design assessment (GDA) process allows the UK’s nuclear regulators to assess new nuclear power station designs at an early stage of the regulatory process and to provide confidence that these new designs can be operated in the UK. Early assessment of the design allows us to identify any potential design issues and ask the reactor design company to address them. This will help to avoid potentially costly and time-consuming changes when the reactor is being built.

Holtec International submitted the SMR-160 small modular reactor design to the UK government for entry into GDA in January 2023. Following a design change, the reactor was renamed the SMR-300 in January 2024. The government decided that Holtec International was ready to enter GDA. It asked the regulators (the Environment Agency, ONR and Natural Resources Wales) to begin the assessment process which started on 18 October 2023.

Holtec International, also known as the Requesting Party (RP) for this GDA, is the company that is designing the reactor. Holtec Britain Limited, a wholly owned UK subsidiary of Holtec International, will manage the GDA process in the UK.

Holtec International specialises in nuclear power station design, engineering and manufacturing. Its SMR-300 small modular reactor was designed in the United States of America. The company is proposing to build its first SMR-300s at a site in the USA. Holtec Britain Limited’s work includes the Sizewell B Dry Storage Project. Holtec Britain Limited has shortlisted 4 locations for a UK small modular reactor factory which will produce 2 to 4 reactors a year.

The SMR-300 is a pressurised water reactor (PWR) which is capable of generating 300 megawatts of electricity. Holtec Britain Limited says it could power around 300,000 homes.

We have now completed Step 1 of GDA (called ‘initiation’) on the Holtec International SMR-300 design. We have concluded that we can progress to Step 2 of GDA which is called ‘fundamental assessment’.

Holtec International has applied for a 2-step GDA.

This document summarises our main report and provides background on the GDA process, consents, our public engagement and next steps.

1. New nuclear power stations – the government’s view

Energy policy, including the use of nuclear power, is a matter for government. Government published an Energy white paper: Powering our Net Zero Future in 2020 that set out the need for nuclear power, among other measures, to help the UK achieve net zero by 2050.

In 2022, the government also published the British Energy Security Strategy. This states an aim that by 2050, up to 24 gigawatts or a quarter of the electricity used in Great Britain will be from nuclear. This ambition was reinforced through the Civil Nuclear Roadmap, published in January 2024, which sets out the government’s vision for the sector and important enabling policies to achieve this.

The Environment Agency has published its own plan EA2025 creating a better place to guide its activities.

The Environment Agency’s 5-year action plan (EA2025) sets out 3 goals:

• a nation resilient to climate change
• healthy air, land and water
• green growth and a sustainable future

Natural Resources Wales has published a corporate plan to 2030 with a vision of nature and people thriving together. This will be achieved through collective action towards:

• nature’s recovery
• resilience to climate change
• minimising pollution

We will continue to work with the government, regulatory partners, industry and others to enable nuclear energy production. And we will make sure that people and the environment are properly protected. Nuclear is a low carbon energy source that could contribute significantly towards net zero goals and implementing the British Energy Security Strategy.

Our processes align with the goals in EA2025 because they help make sure that nuclear power stations are designed and operated in ways which minimise waste, consider sustainability and protect the environment.

2. Regulating nuclear power stations

The Environment Agency and Natural Resources Wales regulate the effects of nuclear sites in England and Wales on people and the environment. They do this by issuing environmental permits which cover:

• preparing the site and constructing the power station
• operating and decommissioning the power station

We also work closely with ONR, which regulates the nuclear safety, conventional health and safety, security and safeguards aspects of nuclear sites.

Our process for assessing and permitting new nuclear power stations can include 2 stages; generic design assessment and environmental permitting.

2.1 Generic design assessment (GDA)

GDA is where we assess the environmental aspects of a power station design that would be relevant to any site. We call this a ‘generic site’. Later, when we assess applications for environmental permits, we use the actual characteristics of the specific site where the developer proposes building the power station. The site-specific characteristics may be different from those of the GDA generic site.

The Environment Agency and ONR developed the assessment process. Natural Resources Wales participates in GDA where a new nuclear power station design is likely to be proposed for construction in Wales.

The GDA of a new design is not a legal requirement. Developers of nuclear power stations may choose to apply to the government to enter GDA to get an early view from regulators on their design. This helps to reduce risks to the developer over the entire project and allows the regulators to ask for changes to the design before construction begins. The government asks the regulators to start a GDA if it decides the nuclear power station design company is ready to enter GDA.

GDA allows us to begin scrutinising the environmental aspects of new nuclear power station designs well in advance of construction starting. It means that we can identify any potential design issues early and ask the reactor design company to address them.

GDA is a flexible process with up to 3 steps. The assessment becomes increasingly more detailed with each step. At the end of each step, we will issue statements and reports about our findings. If the reactor design company still has significant issues to resolve after we have completed our planned assessments, we can (with agreement) add further steps to the process to resolve any remaining issues.

Step 1: Initiation

This is the preparatory part of the design assessment process when we make agreements with the reactor design company and provide advice on the scope and the information it needs to provide for the GDA. As part of this step, we carry out a readiness review and confirm that the reactor design company has put in place the arrangements needed for the GDA process.

This is the step we have just completed for the Holtec International SMR-300 design.

Step 2: Fundamental assessment

This is when the first technical assessment takes place. It focuses on the environmental protection features of the design. The regulators will issue a Step 2 statement at the end of the step. A requesting party may wish to stop the GDA at the end of Step 2 or proceed into Step 3. Getting to the end of Step 2 normally takes around 2 years.

Holtec International has applied for a 2-step GDA and our assessment of the SMR-300 would stop at this point.

Step 3: Detailed assessment

This is a detailed assessment of the environment case. This step is optional and includes a public consultation where we ask for views. We consider all relevant responses before completing our assessments and making our decision. Getting to the end of Step 3 normally takes 4 years. At the end of Step 3, we will issue a Step 3 statement.

At the end of Step 3, we will publish a decision document that sets out our decision about which of the following steps we will take.

Issue a Statement of Design Acceptability (SoDA)

We will issue a SoDA if the design is acceptable. This means we:

• have not found any GDA issues
• consider that the design is capable of being constructed, operated and decommissioned in a way that complies with our regulatory requirements and expectations
• believe that people and the environment will be properly protected

Issue an interim Statement of Design Acceptability (iSoDA)

We will issue an iSoDA if we are broadly content with the environmental protection aspects, but there are still issues to be resolved and the RP has provided credible plans for addressing them. Normally, once it addresses these issues, we will issue a full SoDA.

Not issue a SoDA or iSoDA

We will not issue a SoDA or iSoDA if the design is unsuitable and will not provide the right levels of environmental protection. This could also be because there are GDA Issues but no credible plan to resolve them. We may also not issue either a SoDA or iSoDA if the requesting party did not want to carry out a full GDA.

Our GDA guidance for the reactor design company sets out in detail the process that we follow.

Completed GDAs

We have previously carried out generic design assessment on 4 different reactor designs:

• EDF-Areva’s UK EPR, completed in December 2012 and currently under construction at Hinkley Point C in Somerset and proposed for use at Sizewell C in Suffolk
• Westinghouse’s AP1000, completed in March 2017
• Hitachi-GE’s Advanced Boiling Water Reactor (ABWR), completed in December 2017
• General Nuclear System Limited’s UK HPR1000, completed in February 2022

Current GDAs

We are currently assessing the following reactor designs:

• Rolls-Royce SMR Limited’s Small Modular Reactor
• Holtec International’s SMR-300 small modular reactor
• GE Hitachi Nuclear Energy’s BWRX-300 small modular reactor

2.2 Environmental permits

In order to build and operate a new power station at a specific site, a company must apply for environmental permits from the Environment Agency or Natural Resources Wales if the site is in Wales.

These permits cover site investigation and preparation, construction works and associated developments such as workers’ accommodation, operation and decommissioning.

Site preparation and construction works permits include activities such as:

• drilling boreholes
• abstracting groundwater
• discharging treated effluents
• using mobile diesel electricity generators

Operational permits are needed to:

• dispose of and discharge radioactive waste
• operate standby power supply systems using diesel generators
• discharge returned abstracted water (from the cooling water system and fish recovery and returns system) and other liquid trade effluents (including treated sewage effluent) to the sea or inland water body

If we receive permit applications, we will decide whether or not to grant the permits and, if so, what conditions we should apply. When making decisions about site-specific permit applications, we will take account of matters relevant to the specific site as well as the GDA for the design proposed for the site.

We will also carry out a public consultation before deciding whether to grant permits for a specific site. We will make our decision once we have considered the comments we receive in the consultation. We may also receive applications for changes (variations) to the environmental permits and, where appropriate, we will consult on these.

3. The SMR-300

There are currently around 440 nuclear reactors operating around the world. One of the most common types is the pressurised water reactor (PWR), with around 300 PWRs operating.

There are a range of sizes and uses for PWRs, including power generation and marine propulsion.

The SMR-300 is a PWR which is capable of generating 300 megawatts of electricity (MWe), enough to power around 300,000 homes according to Holtec International.

The SMR-300 is still being designed and is, therefore, not yet in operation. The Canadian Nuclear Safety Commission completed a Phase 1 vendor design review of the SMR-160 design in August 2020. The United States Nuclear Regulatory Commission began pre-licensing interactions with Holtec International initially on the SMR-160 design and currently on the SMR-300 design. Holtec International plans to construct the first of a kind SMR-300 at its Palisades site in Michigan, USA.

Figure 1. An illustration of the reactor

© Holtec Britain

How does a PWR reactor work?

In the reactor core, some of the uranium atoms that make up the fuel split in a process called nuclear fission. These fission reactions produce energy in a continuous process known as a chain reaction.

The energy created by the fission reactions heats water inside the reactor, which is circulated by pumps in the primary circuit to a steam generator. In the steam generator, the very hot primary circuit water is used to heat water in the separate secondary circuit, producing steam which is fed to a turbine. This makes the turbine spin and drives a generator that produces electricity.

The primary circuit of a PWR is at a very high pressure, giving this type of reactor its name.

There is a third water circuit which is used to cool the condenser of the turbine, converting the steam of the secondary circuit back to water. This is then pumped back around the secondary circuit to flow through the steam generator again.

In UK nuclear power stations, which tend to be in coastal locations, sea water is usually used in the third water circuit, but this can be replaced by water from rivers or estuaries, or water can be cooled using cooling towers.

Other features include:

• a spent (used) fuel storage pond
• spent fuel dry store
• water treatment systems for maintaining the chemistry of the water circuit
• radioactive waste treatment and storage facilities
• back-up systems for providing power in the event of loss of electrical supply from the grid

The Holtec International SMR-300 would be mostly constructed and assembled in factory-built modules. Holtec Britain Limited has shortlisted 4 locations for a UK small modular reactor factory which will produce 2 to 4 reactors a year.

Find out more on the Holtec Britain website.

4. About Step 1 (initiation) and our decision

We began GDA on Holtec International’s SMR-300 design in October 2023. We have now completed Step 1, the initiation stage, and will publish our report during Step 2 (fundamental assessment) stage.

The objectives of Step 1 were to:

• agree the scope of the GDA
• agree the processes that will be followed in the GDA, including the environment case information Holtec Britain Limited needs to provide for assessment
• work out if the company is ready to proceed to Step 2

During Step 1, we carried out a joint assessment with ONR of the GDA project management arrangements to give us confidence in the quality of the GDA submissions.

We also provided feedback and advice to Holtec Britain Limited on:

• the GDA scope
• a proposed schedule for submitting information
• the structure of the information submissions
• the information we expected the RP to include in the parts of the submissions relevant to the environment case

We also agreed detailed working arrangements with Holtec Britain Limited covering matters such as:

• tracking documents
• how the company will document its environment case and submit it for assessment
• how the company will address any gaps in meeting our regulatory requirements
• the schedule for subsequent steps
• the arrangements for the public comments process

Our Step 1 review concluded that:

• the proposed scope of the GDA should be sufficient for Holtec Britain Limited to aim for a Step 2 Statement to be issued after Step 2
• the documents provided adequately address all of the information requirements set out in our GDA guidance for Requesting Parties for Step 1

Our review also concluded that Holtec Britain Limited has carried out a gap analysis and readiness review so it can progress to Step 2).

We carried out a review of Holtec Britain Limited’s readiness to enter Step 2 and have decided that the arrangements and resources the company has put in place to carry out the GDA will be adequate.

We have concluded that we can progress to Step 2 of GDA. Our GDA Step 1 of the Holtec SMR: statement of findings full report provides more detail.

ONR has also concluded that it can progress to Step 2 of GDA and its Step 1 report is available on the ONR website.

5. Permissions and consents for a nuclear power station

Any company that wants to build and operate a new nuclear power station must obtain several site-specific permissions. These include:

• environmental permits from the Environment Agency or Natural Resources Wales
• a nuclear site licence and relevant consents from ONR
• planning permissions from the Planning Inspectorate

Holtec Britain Limited has been selected by Great British Nuclear to advance to the next phase of the Small Modular Reactor competition for innovative nuclear technologies. Great British Nuclear is expected to then carry out a selection process and announce successful technology providers along with allocated sites for development.

Currently, no developers have applied for an environmental permit to use the SMR-300 in the UK.

5.1 Nuclear site licence

ONR regulates the nuclear safety, conventional health and safety, security and safeguards at nuclear sites. Any organisation that wants to carry out nuclear activities must apply to ONR for, and be granted, a nuclear site licence. It must do this before it starts building a new nuclear power station. Granting a nuclear site licence is a significant step, but, on its own, it does not give an organisation permission to start nuclear-related construction. For that, it must get a regulatory permission from ONR.

5.2 Planning permission

A developer using the SMR-300 needs a Development Consent Order from the Secretary of State for the Department for Energy Security and Net Zero. The Secretary of State makes a decision having received a recommendation from the Planning Inspectorate.

The environment agencies are consultees in this process and provide advice throughout.

5.3 Electricity generation licence

An operator would need an electricity generation licence from Ofgem, the regulator for the gas and electricity markets.

5.4 Other permissions

The operator will also need agreement from government about a Funded Decommissioning Plan and Regulatory Justification for the use of a new reactor design.

Other requirements could include additional permits and licences from the Marine Management Organisation (England), Natural England, Natural Resources Wales, and local district and county councils.

6. Public and stakeholder engagement for this GDA

We have set up our GDA process to be open and transparent.

Public comments process

Holtec Britain Limited is encouraged to publish detailed design information on its website and to update it as new information becomes available. Anyone can view that information and comment on it.

Holtec Britain Limited is required to respond to questions and comments about its design. We see the questions and the responses, so that we can consider them in our assessments. Comments can also be made to the nuclear regulators’ Joint Programme Office.

Holtec Britain Limited’s comments process was launched at the start of Step 2 (fundamental assessment) on 1 August 2024, so that the public can view and comment on the information the company is submitting for GDA.

There is also information about GDA and the comments process on the:

• joint regulators’ webpage
• Environment Agency webpage on assessing reactor designs for new nuclear power stations
• ONR webpage on new reactors
• Natural Resources Wales webpage on how they regulate the nuclear industry

Holtec Britain Limited has published the information it is submitting for GDA (apart from any sensitive nuclear or commercially confidential information) on its website, allowing people to make comments through the website or by post.

Holtec Britain Limited is promoting the publication of this information, the comments process, and the new website.

The nuclear regulators are also publicising the second step of GDA and the comments process through the media and directly to stakeholders.

We, the regulators will consider comments we receive up to 30 June 2025, and Holtec Britain Limited’s responses to those comments, during our Step 2 assessments.

Get involved

You can get involved in our GDA by:

• reviewing the information and commenting through Holtec Britain Limited’s website
• talking to us at public, stakeholder and industry events

The regulators have published an approach to engagement for this GDA on their joint webpages.

If you have any comments on the plan, please email nuclear@environment-agency.gov.uk.

7. GDA timetable and next steps

The GDA of the SMR-300 is currently planned to last 24 months.

• Step 1 (initiation) started in October 2023 and finished on 1 August 2024
• Step 2 (fundamental assessment) started on 1 August 2024 and is expected to finish in October 2025

At the end of Step 2, we will publish a Step 2 Statement. This will be the end of the GDA process for the SMR-300.

There will be no public consultation in a 2-step GDA.

8. Contact us

You can feed back on this document or our work on assessing this design.

Email your questions and comments to nuclear@environment-agency.gov.uk