Guidance

New nuclear power plants: Generic Design Assessment guidance for Requesting Parties

Updated 19 October 2023

The Environment Agency is working with the Office for Nuclear Regulation (ONR) and Natural Resources Wales (NRW) to make sure that any new nuclear power station built in Great Britain meets high standards for:

• safety
• security
• environmental protection
• waste management

The ONR and the Environment Agency have developed an assessment process called Generic Design Assessment (GDA). The regulators use GDA to scrutinise new nuclear power plant designs and assess their acceptability for use in Great Britain.

ONR’s regulatory licensing responsibilities for nuclear plants extends to Great Britain while the Environment Agency’s and NRW’s regulatory responsibilities extend to England and Wales respectively.

The Environment Agency’s regulatory approach is set out in its radioactive substances regulation (RSR): objective and principles.

NRW participates in GDA where a new nuclear power plant design is likely to be proposed for construction in Wales. NRW also carry out any assessments that may be required in accordance with legislation specific to Wales. Find more information on how NRW regulates the nuclear industry.

The Environment Agency’s main aims when carrying out its regulatory duties are to protect or enhance the environment, taken as a whole, and to contribute towards achieving sustainable development. The Environment Agency and NRW expect to see relevant sustainability considerations taken into account in the design of new nuclear power plants. These considerations may include:

• carbon accounting
• climate change adaptation and resilience
• sustainable management of natural resources
• long term lifecycle impacts
• contribution to a circular economy

The regulators keep their GDA process under review. They updated it:

• in 2019 in light of lessons learned in past GDAs and to enable the process to be applied to advanced reactor designs
• in 2023 in light of recent learning and to strengthen sustainability and disposability of waste considerations

The regulators carry out GDA before the power plant has begun construction in England and Wales. It means they can identify any potential regulatory design or technical issues early, at the design stage, and ask the reactor designer to address them.

The ONR, the Environment Agency and NRW have set out a joint objective for GDA. This is to provide confidence that the proposed design is capable of being constructed, operated and decommissioned in Great Britain in accordance with the standards of safety, security and environment protection required.

For the Requesting Party (RP), the organisation submitting its reactor design for GDA, this offers a reduction in uncertainty and project risk regarding the design, safety, security and environment protection cases so as to be an enabler to future licensing, permitting, construction and regulatory activities.

GDA is not a legal requirement and the regulators will only consider carrying out GDA for the nuclear power plant designs that the UK government has asked them to consider. This is because decisions about which designs should be assessed are national strategic matters that are outside the regulators’ responsibility. A government-led GDA entry process also helps to make sure that regulatory resources are used effectively.

The Environment Agency recovers the costs of its GDA work, and any preliminary discussions with a RP, using a Section 37 agreement under the Environment Act 1995.

Following a successful GDA, the RP, another company or partnership (referred to as a ‘prospective operator’) may decide to construct the nuclear power plant design at a specific site in Great Britain. The prospective operator must make site-specific applications to the appropriate regulators and other bodies for all the relevant consents, licences and permits it needs.

Only if the regulators and the other bodies grant these permissions can the prospective operator construct and operate the nuclear power plant at a site. The regulators will take into account the work they have done during GDA, and the conclusions they have made, when they assess and make decisions about a prospective operator’s applications for site specific permissions.

Purpose of this guidance

This guidance is for anyone submitting a nuclear power plant design for GDA – a RP. A RP can be a reactor designer or vendor company on its own, or one partnered with a prospective operator of its nuclear power plant design.

This guidance explains:

• how the GDA process works
• what information the RP needs to provide when requesting a GDA
• the possible outcomes from a GDA

This guidance refers to the development of an environment case by the RP. We use the term ‘environment case’ to refer to the collection of documents submitted by the RP during GDA to demonstrate that their nuclear power plant design:

• meets our regulatory requirements and expectations
• uses Best Available Techniques (BAT) to prevent or minimise harm to people and the environment

The GDA process

The GDA process has up to 3 steps:

• Step 1: Initiation
• Step 2: Fundamental Assessment
• Step 3: Detailed Assessment

Before Step 1 can start, the Department for Energy Security and Net Zero (DESNZ) must request that the ONR and the Environment Agency (and NRW for designs likely to be developed in Wales) begin a GDA on the proposed design. If accepted, the regulators will then publish a statement on their joint website saying that GDA for the proposed design has started.

ONR and the Environment Agency have set up a Joint Programme Office (JPO) with staff from both regulators to help administer the GDA process. The JPO acts as a single point of contact between the regulators and the RP, helping to co-ordinate the administration of GDA. More information about the JPO is available on the joint website.

We can have early discussions with a RP (before GDA starts) if cost recovery arrangements are in place. We can provide advice on:

• the GDA process
• what we expect from the RP during GDA, including project management
• information the RP must provide for their environment case submission

Timeline and outcomes for GDA

Indicatively, the duration of a full GDA, carrying out all 3 steps without a pause, is around 48 months. Though we will be flexible where changes to the timescales are requested by the RP.

The overall duration of the GDA will likely be determined by the availability of information from the RP to inform the regulators’ assessments. The duration of each step includes time for regulatory consideration and implementation of our governance arrangements.

The 48 months is indicatively broken down as follows.

Step 1: Initiation

Step 1 can take around 12 months. The RP must agree with the regulators whether this will be a full GDA or one with a reduced but meaningful scope. At the end of the step we will publish a GDA Step 1 Statement setting out our regulatory position at this point. This will describe the scope of the GDA and progress made with the GDA.

Step 2: Fundamental Assessment

Step 2 can take around 12 months, after which the RP may stop or pause. At the end of the step we will publish a GDA Step 2 Statement setting out our regulatory position at this point and our findings from the Fundamental Assessment.

Step 3: Detailed Assessment

Step 3 can take around 24 months. The outcome from Step 3 will depend on the scope of the GDA and the conclusions we have come to. At the end of this step we will publish one or both a GDA Step 3 Statement and Decision Document as follows.

GDA Step 3 Statement

This will set out our regulatory position and findings following the Detailed Assessment. We will do this where we have agreed with the RP in Step 1 that the GDA can be carried out based on a reduced but still meaningful scope. We will not issue a Statement of Design Acceptability (SoDA) for a reduced scope GDA.

Decision Document

This will set out our decision on whether we will issue a SoDA or interim Statement of Design Acceptability (iSoDA) for the nuclear power plant design. The decision document will set out the reasons for our decision, including where we have concluded that a SoDA or iSoDA will not be issued.

We would issue an iSoDA where we have completed our assessments but identify that there are still regulatory GDA issues to be addressed. We will only consider issuing an iSoDA if the RP provides us with resolution plans that in our view are credible to address those issues.

Before making our decision on whether or not we will issue a SoDA or iSoDA for a nuclear power plant design, we will consult on our preliminary findings during Step 3. We will consider all the consultation responses we receive before we make our decision.

The timeline is only an indication of how long the process might take. It is based on the RP:

• providing us with good quality information on time throughout the process – but particularly at the start of steps 2 and 3
• responding quickly and effectively to any questions we raise
• not needing a significant amount of time to resolve any concerns or issues we may identify – for example to make design changes or carry out further technical assessments

How long the process will take also depends on several factors including the availability of our regulatory resources and our familiarity with the reactor type. Additionally, it will depend on the nature of any issues we raise. Our experience so far is that we can complete an assessment within 48 months. However, overall timescales can be longer if the design and environment case submission evolve during the assessment process.

The RP can ask us to stop or pause a GDA at the end of Step 2 or Step 3. This may be for a number of reasons. For example, because the technology being assessed is not sufficiently mature, or because the RP needs to make some commercial decisions. A RP that initially requests a two step GDA can seek to extend the GDA by requesting to do so before the end of Step 2, subject to the written agreement of the regulators. Any such requests should be made as early as possible in the GDA.

The RP can ask to restart the GDA process from the point it paused. At that point the regulators would discuss with the RP and DESNZ the arrangements and timescales for restarting the GDA process. This will depend on the availability of regulatory resources and may also require a specific request from DESNZ to restart the process.

Step 1: Initiation

Initiation is the preparatory part of the design assessment process when we make agreements with the RP and provide advice on the scope and development of a submission. It includes confirming that the RP has established:

• project management and technical teams
• arrangements for undertaking a GDA
• arrangements for preparing and issuing submissions to regulators during Step 1
• arrangements that implement an adequate design development process
• arrangements for preparing for Step 2

We will work with the RP to make sure that they have a full understanding of the requirements and processes that will be applied during GDA. In particular, we will discuss the RP’s arrangements for resolving concerns and issues raised by the regulators.

An important objective for GDA is to reduce the risk to future build project. For the RP to maximise the value of the GDA, it should take a risk informed approach to identify and address any novel features in the design for the regulators’ consideration.

Objectives for Step 1

The objectives for Step 1 are for the RP and the Environment Agency to agree:

• the scope of the GDA
• how the RP will document its environment case and submit it for assessment during the GDA process
• how the RP will address any gaps in meeting regulatory requirements, the expectations that they have identified and their plan for this work
• the arrangements the RP has put in place to carry out the GDA
• the schedule and associated programme for subsequent steps, including plans for submissions and the development of the RP website and comments process ready for entry to Step 2

Charging arrangements

We will set up an agreement under Section 37 of the Environment Act 1995. The agreement enables the Environment Agency to recover the costs of our work to carry out the GDA from the RP. The agreement must be in place in advance of Step 1.

Preparatory discussions

Once the charging agreement is in place, we will discuss the GDA process with the RP to make sure that they understand:

• the process we will follow
• what we will expect from them
• the environment case information they need to provide for assessment

Project management and related arrangements

We will work with the RP and ONR to develop a project plan and other project management arrangements for the submission of their environment case. The RP must:

• put in place their project management and technical teams
• implement their arrangements for preparing the environment case submission
• include a plan for engaging with Nuclear Waste Services (NWS) to obtain an expert view on the disposability of radioactive wastes, including any more challenging wastes (such as problematic or novel waste streams) arising across the reactor lifecycle – check their disposability assessment guidance
• agree with us and implement the interface arrangements to be used throughout GDA, including meeting arrangements and the Master Document Submission List format
• make sure we have full access to any commercially confidential information relevant to our assessments, including information which is the property of third parties
• obtain all the necessary export licences to enable the transfer of information to and from the UK to all relevant organisations and countries for the GDA

The Master Document Submission List is a list of all the documents submitted by the RP during the GDA. It is maintained as a living document throughout the GDA so that it precisely references the latest revision of each submission made by the RP. In addition, the ONR’s guidance to RPs contains requirements relating to project management and control that is equally applicable for the Environment Agency’s assessment. We have chosen not to replicate these requirements here.

Expert view on disposability

The RP should include in its planning to begin engagement with NWS during Step 1 to obtain advice on the disposability of higher activity and more challenging wastes generated during the lifecycle of the reactor. This is to enable NWS to carry out its expert view process during Step 2. Where there is potential to generate more challenging low level waste (LLW), the RP should obtain a view from NWS on the disposability of LLW arisings so that any challenges the waste streams may pose to the waste acceptance criteria for disposal facilities are identified. 

We expect all RPs to engage with NWS during Step 1 and to carry out the expert review process during Step 2 in order for us to come to a judgement on the likely disposability of radioactive waste which is a fundamental aspect of our assessment. It is necessary to carry out the expert view process if the GDA is likely to stop at the end of Step 2.

The environment case

During Step 1 the RP must agree with us the scope of their environment case submission. They must also agree:

• the information they will include
• how they will structure it
• the format they will use

They must explain whether they intend to use information in the GDA that is already available to them – for example, if their design has already been licensed in another country. This could include the design documents and approvals from regulators in other countries. We will require summary information on regulatory assessments carried out in other countries to be provided during this stage.

If the RP does plan to use existing information, they should explain its:

• scope
• background
• regulatory basis

The RP must identify any gaps or shortfalls in their design and environment case with respect to the information that we are expecting them to provide. We will provide advice to the RP to help identify such gaps or shortfalls. The RP must agree with us how they propose to resolve these gaps and meet our regulatory requirements and expectations.

Where insufficient or no information is available on a particular topic, we may agree to exclude that topic from the GDA scope. We will only agree to exclude the topic if the GDA remains meaningful and the topic can be addressed effectively at a later stage. A later stage includes during the application for site-specific environmental permits and during detailed design and procurement.

We may decide that we do not have enough information to proceed with a meaningful GDA if:

• too many topics have been excluded from the scope of the GDA
• a critical topic has been excluded
• there is likely to be insufficient substantiation of the nuclear power plant design in the agreed scope of the environment case

If this is the case, we will not continue with the GDA.

We recognise that full engineering details may not be available at the GDA stage. It is normal to finalise some of these once the site-specific and operator requirements are known and during the procurement and construction programme. However, we expect the RP to provide sufficient functional specifications for their design so we can carry out a meaningful GDA. We will provide advice to the RP to help them produce a sufficiently detailed environment case.

During Step 1, we will begin to assess whether the RP’s management arrangements for its design development process, producing and managing the environment case submission, and supporting the GDA process, are acceptable. This is to give us confidence in the quality of their submission.

We expect the RP to share their plans to develop the following information in preparation for the Step 2 assessment:

• relevant plant and process descriptions – including engineering drawings, process flow diagrams and other information that will help us understand the nuclear power plant design, its underpinning design philosophy and its environment protection features
• a description of the type of sites where the power plant could be built (the generic site) – where potential sites are known, this description should include their environmental characteristics and constraints, such as protected habitats
• strategies, methods, models and standards that the RP will use to demonstrate design acceptability
• information on the source of radioactive waste arisings (‘source term’) in line with our joint regulatory interests with ONR in the minimisation of radioactive waste and the management of higher activity wastes, as detailed in ONR GDA Technical Guidance 007
• the quantities and types of radioactive waste (gaseous, liquid and solid), including more challenging wastes, and spent fuel that are likely to arise during normal operations and in decommissioning
• a description of gaseous, liquid and solid waste management systems and their proposed operations
• information on applicable operational experience (OPEX) and relevant good practice (RGP) for radioactive waste management, decommissioning and the spent fuel interim store (SFIS)
• the likely impact on people and the environment of any proposed discharges of gaseous and liquid radioactive wastes
• a credible plan to obtain a view from NWS on the disposability of any solid radioactive waste arisings, including more challenging wastes and non-radiological hazardous substances arising across the reactor lifecycle
• the assessment of radioactive waste should address the waste form and any non-radioactive components that could have a bearing on its management and disposability
• during its engagement with NWS, the RP should identify any challenges the waste streams may present to the waste acceptance criteria for disposal facilities
• a credible plan to obtain a view from NWS on disposability of more challenging LLW arisings
• information about conventional aspects of the design, including potential impacts on people and the environment of discharges from back-up generators, cooling and process water discharges, other waste disposals, and information about their approach to applying BAT (where applicable)
• the RP’s approach and methodology for determining BAT to prevent or minimise radioactive wastes and their impact during the lifecycle of the plant – design, construction, commissioning, operation and decommissioning
• worked examples demonstrating the BAT approach and methodology sufficient to provide confidence that any fundamental concerns should be identified in Step 2
• information about how the RP has taken account of Environment Agency guidance, including our radioactive substances regulation (RSR): objective and principles and RSR generic developed principles: regulatory assessment – we expect the RP to be familiar with the developed principles and address their requirements in the submission
• the RP’s considerations at the design stage for meeting the joint regulators’ guidance on the decommissioning of nuclear sites and release from regulation
• information on how sustainability is taken into account in decisions relating to the design. Our RSR principles support this objective and aim to ensure our regulation of radioactive substances activities contributes towards the achievement of sustainable development – these include principles relating to optimisation, BAT and lifetime planning for radioactive substances
• information on how climate change adaptation is taken into account in decisions relating to the design

Climate change adaptation is covered in our guidance on how to develop a management system for environmental permits. Joint regulatory guidance on climate change has been published by the ONR and the environment agencies including use of the latest climate projections for the UK.

We would expect the RP to provide the environment case information about these aspects during Step 1 for the beginning of Step 2. By exception, information not available for Step 2 commencing should be identified and agreed and a submission date agreed with the regulators. The section on information required for environment case submission explains in more detail what the RP must provide for the whole GDA process.

We will not start detailed assessments of the technical information in the environment case submission until Steps 2 and 3.

We will agree with the RP a schedule for submitting the environment case information by the end of Step 1.

Regulatory questions

Regulatory questions, concerns and issues will arise throughout the GDA process. In Step 1 we will agree with the RP the arrangements for handling such questions. We will use a tiered approach to the questions we raise:

1. Regulatory Query (RQ) – this is a request by the regulators for clarification and additional information – it does not necessarily indicate a perceived regulatory shortfall in the design or its substantiation.
2. Regulatory Observation (RO) – this is raised when the regulators identify a potential regulatory shortfall in the design or its substantiation – the RP must take action to resolve it.
3. Regulatory Issue (RI) – this is raised when the regulators identify a serious regulatory shortfall in the design or its substantiation which could prevent them from issuing a SoDA (or a Design Acceptance Confirmation (DAC) from ONR) – the RP must take action to resolve it.

A question raised as a RQ could escalate to a RO or RI if the RP does not respond to it or resolve it in a way that satisfies the regulators.

The RP must develop resolution plans for ROs and RIs and provide these to the regulators. These resolution plans should set out:

• the actions and work the RP will do to address the potential concerns or issues identified in the RO or RI
• the RP’s plan for this work, including making updates to GDA documents

Resolution plan contents will vary. They need to be detailed enough to satisfy the regulators that the RP is addressing the concerns or issues raised within the time frame specified in the plan.

The work and timeframe set out in a resolution plan could be treated as indicative. The RP may later choose to adopt an alternative approach to achieving an acceptable environment protection outcome or substantiation of their environment case.

Public comments and communication

The RP must put processes in place that allow the public to interact with them throughout Steps 2 and 3 of the GDA process.

They should provide information on a public website about the proposed design and how it will meet standards for environmental protection, safety and security. The website should enable the public to:

• see the information the RP has provided to the regulators as part of the GDA
• make comments and ask questions

The RP must agree with the regulators the information that they will publish on their website. The RP will be expected to update this public information whenever they make any significant changes to the information they submit to the regulators. For example, if the regulators ask them to provide additional information between Steps 2 and 3.

Security sensitive information must be removed, and commercially confidential information should be removed, from what the RP makes publicly available.

The RP must also agree with regulators the process and timescales they will use for responding to comments from the public. The RP must provide the comments and questions raised by the public to the regulators, as well as their responses.

End of Step 1

At the end of Step 1, we will issue a Step 1 Statement that includes:

• the scope of the GDA – including whether it will be a 2 or 3 step assessment, or a full 3 step assessment targeting issue of a SoDA and DAC
• an overall timetable for GDA
• an agreed schedule for submitting the environment case information – to make sure we have enough information to progress our assessment
• confirmation that an interface agreement is in place

The interface agreement sets out:

• how the RP will submit information and how we will track it
• arrangements for correspondence and meetings
• how we will raise and track RQs, ROs and RIs

The Step 1 Statement will be published on GOV.UK and the NRW website (if NRW are participating in the GDA). It will also be accessible through the joint regulator’s website.

We will also conduct a readiness review with the RP to make sure that they can meet the requirements for GDA Step 2. This includes assessment of the adequacy of the management arrangements to deliver Step 2. We will only move to Step 2 when we are satisfied that we and the RP are ready to progress.

Step 2: Fundamental Assessment

Step 2 is the first substantive technical assessment step. It focuses on the environment protection fundamentals of the RP’s design. It includes assessing the methodologies, approaches, codes, standards and philosophies the RP is using to substantiate their environment case. We will require information on any more challenging wastes that may be generated together with information on how these waste arisings will be minimised and managed safely across the lifecycle.

Objectives for Step 2

The main objectives for Step 2 are for the:

• Environment Agency to carry out an assessment to identify any fundamental environment protection shortfalls in the design
• RP to complete the submissions needed for Step 2 (and in preparation for Step 3, if necessary) and to publish the submissions on its website
• RP to launch and publicise its public comments process

We will assess the design against regulatory requirements and expectations. This includes identifying any fundamental environment protection shortfalls that could prevent the design from being potentially acceptable for sites in England – and for Wales where NRW is taking part in the GDA.

The RP must finish producing the submissions needed for assessment during Step 2, as well as future submissions needed for Step 3 if necessary. This includes (but is not limited to) providing additional documentation needed to fill gaps in complying with UK regulations and Environment Agency guidance, as identified in Step 1.

We will have told the RP about any concerns that we have identified during Step 1. During Step 2, they must demonstrate that they:

• have understood our concerns and the regulatory approach used in the UK
• are dealing with any improvements needed

The purpose of Step 2 is to identify whether the design can comply with UK regulations and Environment Agency guidance. We may find that the RP needs to provide more information or do more work. For example, they may need to carry out more assessments or calculations to show how the design will comply with our requirements.

We will also identify if:

• there are any matters which are unacceptable
• we are likely to require significant design modifications to meet our regulatory expectations

The RP must address any improvement actions identified during Step 1 before our Step 2 assessment can start.

During Step 2 we will:

• continue to provide advice and guidance
• check that all the information we need for GDA will be available by the end of Step 2
• agree with the RP any changes needed to the GDA scope to make sure that the assessment remains meaningful
• agree any changes to the overall GDA timescales and associated schedules for submitting information

The scope of our technical assessment will be informed by learning from Step 1 and regulatory OPEX.

We will examine the information in the RP’s environment case that provides the framework for environment protection. This includes the:

• strategies
• standards
• codes
• models
• underpinning methods
• identification of environment protection functions

We will continue to look in detail at the RP’s arrangements for producing and managing the environment case submission. We may carry out on-site assessments of those management arrangements. The RP will need to agree to and facilitate any assessments we want to carry out, which may include work at third parties where relevant.

We also expect the RP to send us its initial Design Reference Point for the GDA and to update this periodically in the light of changes made to the design. We will look at design change control arrangements and how the RP will transfer environment protection functions to an operator (see the guidance on engineering: generic developed principles). This is to make sure that environment protection functions:

• are designed to be effective
• are capable of being implemented
• can be used by a future permit holder

We will also carry out more detailed assessments of the:

• generic site description to make sure it appropriately reflects the constraints of any known potential deployment sites
• proposed discharges so we can give early assurances that the proposed design can comply with dose limits and constraints
• radiological assessment methodology, method and assessment outcome
• BAT assessment methodology and methods used

In Step 2 we assess the claims and arguments, whilst looking to ensure that there are plans in place to gather and present the necessary evidence for future assessment, either in Step 3 or pre-application and post application permitting work dependent on which regulatory route is selected.

We will continue to raise regulatory questions, assess the responses received from the RP and review their resolution plans for any ROs and RIs we have raised.

We expect that by the end of Step 2, the RP will fully understand what they need to do to meet UK regulations and Environment Agency guidance.

End of Step 2

Once we have finished our Fundamental Assessment we will publish a GDA Step 2 Statement setting out our findings. This will identify:

• the work we have done and the conclusions we have reached so far
• any additional information required
• where changes to the design might be needed
• whether the scope of the assessment remains meaningful and, if not, what changes are needed
• areas we will examine closely at Step 3, Detailed Assessment
• any issues or concerns to be resolved at Step 3, or where the RP has requested a Step 2 assessment only, in a future GDA Step 3 or when developing site specific proposals

When producing this statement we will consider any relevant comments received from the public or interested organisations and the responses the RP has made to those comments. The statement will include comments and advice from NRW where appropriate.

We will consult with ONR on environment, safety and security matters where we have a common interest. We will seek expert advice from other regulators and government bodies where needed, for example, the Food Standards Agency and UK Health Security Agency.

The RP should provide an updated and consolidated environment case to reflect any changes or modifications made during the GDA to allow effective future assessment in Step 3.

We will carry out a readiness review with the RP to make sure they can meet our requirements for Step 3 before progressing any further. We will only start Step 3 if we consider that we and the RP are ready.

The RP may have planned to stop or choose to pause the GDA at the end of Step 2.

Step 3: Detailed Assessment

During this step we will carry out a detailed assessment of the RP’s environment case submission.

Objectives for Step 3

The objectives for Step 3 are to carry out a:

• detailed assessment of the design and supporting environment case against UK regulations and Environment Agency guidance – so that we can come to a conclusion on the acceptability of the design
• public consultation on our preliminary findings so far during Step 3 – where the RP and the Environment Agency have agreed the scope of the GDA is sufficient to target the issue of a SoDA

Where relevant, we will provide either:

• views in a GDA Step 3 Statement
• conclusions in a Decision Document – we will issue a SoDA or iSoDA if appropriate, after considering all the responses received during our public consultation and completing our assessments

We will examine the detailed information the RP has provided to support the environment protection claims they are making for their design. We will not examine all of the information at the same level of detail. We will take a risk-based approach to deciding where to focus our efforts so we can be confident the submission meets regulatory requirements and expectations.

We will assess both radioactive and conventional environment protection aspects. We will use our regulatory principles to guide our assessment of information about radioactive waste management and disposal.

Consultation during Step 3

We will only carry out a consultation if we have agreed with the RP that the GDA scope is sufficient to consider issuing a SoDA. Where this is not the case we will not consult and the outcome from the GDA will be a GDA Step 3 Statement. Where appropriate NRW will carry out a consultation for designs proposed for Wales.

For GDAs that involve consultation we will prepare a consultation document that sets out:

• what we have considered during GDA
• the preliminary findings from our detailed assessment so far
• other relevant information relating to the consultation

The consultation document may include a draft SoDA or iSoDA where there are still regulatory issues (referred to as GDA issues) that the RP needs to address.

We will ask for views on our findings so far and consult with:

• other regulators
• government departments and bodies
• non-governmental organisations
• other interested parties
• the public

We will tell stakeholders about the consultation, the matters on which we are consulting and arrange engagement events if needed.

We will make sure we publicise our consultation documents in those areas where power stations may be sited. For example:

• those listed as potentially suitable in the National Policy Statement for Nuclear Power Generation
• specific localities where a prospective operator or vendor has announced that it wants to build the design being assessed

We will target starting the consultation within 12 to 15 months of the start of the Step 3 assessment, subject to having received all the information we need for that assessment.

We will consider the Cabinet Office’s consultation principles when we develop our consultation arrangements and decide how long we will consult for – this may be up to 12 weeks.

Post consultation review

After the consultation has ended we will consider the responses we have received. If we receive comments about areas that we are not responsible for, we will pass these on to the appropriate regulator, government department or other public body.

When considering comments, we may obtain advice from other organisations with specialist expertise on other topics, for example:

• government departments
• Food Standards Agency
• UK Health Security Agency

If needed, we will also obtain information or clarification from the RP. We will also consider any issues from ONR’s assessment that are relevant to us.

We will complete our assessment and Decision Document and decide whether to issue a SoDA or iSoDA, once we have carefully considered all the information we have received, including comments from the consultation.

We would only consider issuing an iSoDA if, after assessing the resolution plans put forward by an RP to address each GDA issue, we conclude that they are credible and likely to address our concerns. If we issue the iSoDA we would include the GDA issues and RP’s resolution plans in our decision document and iSoDA as appropriate.

If we issue an iSoDA, then the GDA process can continue whilst the RP addresses the GDA issues. When we are satisfied that the GDA issues have been resolved we will consider issuing a full SoDA.

If the ONR’s interim Design Acceptance Confirmation (iDAC) contains GDA issues that are not part of our iSoDA, but could affect the environment case, we will work with the RP and ONR to assess the implications. We will ensure these are taken into account if we decide to issue a SoDA.

We would expect any GDA issues to be resolved before a prospective operator makes a site specific permit application. In exceptional cases, the GDA issues may be addressed as part of a permit application. We would not issue a SoDA without further consideration.

GDA is not intended to provide a complete assessment of a fully detailed proposed nuclear power plant design. The fully detailed nuclear power plant design and its substantiation must take account of:

• site-specific information
• the prospective operator’s choices about design, specific features or organisational matters
• post procurement manufacturers’ or suppliers’ information and detailed design
• the technology choices that will be made later in the design or construction phases so as to avoid design obsolescence
• the information that will only become available when a plant is under construction or during commissioning tests and trials and during initial operation

If there are environment protection matters identified during GDA that can only be properly addressed at a later stage, the Environment Agency will specify these as Assessment Findings. These must be resolved at the appropriate stage of a site-specific project. The Environment Agency will also identify Assessment Findings for environment protection matters where the level of design detail needed to address them is beyond what is required for GDA.

A prospective operator must address relevant Assessment Findings as part of normal regulatory business during the following phases of new build nuclear power plant projects:

• detailed design
• procurement
• construction
• commissioning

We may include Assessment Findings as pre-operational requirements, information requirements and other conditions in site-specific permits.

End of Step 3

The RP must provide final, updated and consolidated GDA submissions to reflect the changes or modifications made during the GDA. This must include the Design Reference Point and the Master Document Submission List which we will refer to in our final documents, including a SoDA or iSoDA where appropriate.

At the end of Step 3 we will either issue a GDA Step 3 Statement that will include any Assessment Findings that we have identified during the course of the GDA – or, we will issue a Decision Document setting out our decision to either:

• issue a SoDA – because we are satisfied that the design is capable of being constructed, operated and decommissioned in a way that complies with our regulatory requirements and expectations so ensuring that people and the environment are properly protected
• issue an iSoDA – if we have completed our assessments and are satisfied with the environment protection aspects, but there are GDA issues to resolve and the RP has provided credible resolution plans for addressing them
• not issue a SoDA or iSoDA – because the design is unsuitable and will not provide the right levels of environment protection, or because there are GDA issues and no credible resolution plan

Where we are issuing a Step 3 Statement (because we have not carried out a full GDA including consultation) it will identify:

• the work we have done and the conclusions we have reached
• Assessment Findings that can only be resolved at the site-specific stage
• any issues or concerns remaining to be resolved at a later stage including when developing site specific proposals
• any other relevant matters

When producing this statement we will consider any relevant comments received from the public or interested organisations and the responses the RP has made to those comments. The statement will include comments and advice from NRW where appropriate.

We will consult with ONR on environment, safety and security matters where we have a common interest. We will seek expert advice from other regulators and government bodies where needed, for example, the Food Standards Agency and UK Health Security Agency.

We will target publishing a GDA Step 3 Statement or Decision Document within 24 months of starting Step 3 or as agreed with the RP.

Submitting the environment case

The RP must provide all information in English, and if possible, in electronic format.

They must send their information submissions to the JPO which is the single point of contact for the regulators. The JPO will make the information available to the regulators and their technical support contractors (if appropriate).

The RP must allow the regulators to access all the relevant information they need to assess the design. This includes:

• sensitive nuclear information
• commercially confidential information
• information that belongs to third parties

The RP can provide the information as a single submission covering the information requirements of the Environment Agency, NRW for sites in Wales, and ONR. If they do this, they must provide a guide or ‘route map’ showing where each regulator can find the information specific to their regulatory requirements.

Sensitive and commercially confidential information

Any information submitted to the JPO must have the appropriate security markings following the UK government’s security policy framework.

We would expect all the information in a submission to be made available to the public – preferably via the RP’s website. However, this does not include:

• sensitive nuclear information as defined in the Anti-terrorism, Crime and Security Act 2001 – which must not be made available
• commercially confidential information – a trade secret or where confidentiality is provided by law to protect a legitimate economic interest – which should not be made available

Sensitive nuclear information or commercially confidential information must be clearly marked and placed preferably in separate annexes. The RP must give their reasons for giving the information this status. This also applies to relevant materials covered by export controls.

The RP must put in place any arrangements needed to allow commercial information or intellectual property to be shared with the regulators and their technical support contractors. This includes securing export control agreements.

As a public body, we may have to release environmental information if we receive a request under either the:

• Freedom of Information Act 2000
• Environmental Information Regulations 2004 (EIR04)

We must consider all such requests and our legal requirements under this legislation.

We may be able to withhold information that is sensitive nuclear information or commercially sensitive information if both of the following apply:

• the information meets the rules for an exception under EIR04
• it is in the public interest to withhold rather than release the information

Commercial confidentiality does not apply to environmental information about emissions. So we would not be able to use this as a reason for withholding this information.

When considering the public interest factors of sensitive nuclear information we will follow ONR’s advice as they are the regulator for civil nuclear security. The role of their Civil Nuclear Security Programme is to:

• make sure civil nuclear installations are secure
• protect the public interest from threats to that security

ONR has produced guidance about the sensitivity of nuclear information and its disclosure.

If we must release information under EIR04, we will remove it from the confidential annexes and add it to our publicly available information.

Overprotecting information can complicate the process for handling documentation and this may cause delays.

Information required for environment case submission

The starting point for the Environment Agency’s assessments is the information provided by the RP in its environment case.

General information about the RP and the design

Information to be provided includes:

• details about the RP, including its company structure and its experience of reactor design and plants in service
• a simple, outline description of the design including schematic diagrams
• a brief history of the design, identifying predecessor plant and the main design changes from this plant
• information from other regulatory assessments including findings and recommendations
• the identification of discharge points to the environment for gaseous and aqueous radioactive wastes
• a summary of the proposed discharges of radioactive waste and their potential impact on members of the public and non-human species at the generic site
• a summary of the conventional environmental impacts of the facility
• a description, and the characteristics, of the generic site (or sites) that the RP will use for its assessment of radiological impacts (see our initial radiological assessment methodology) and conventional impacts on people and the environment
• a summary document that provides a high-level description of the nuclear power plant design that will help the public understand the RP’s environment case.

Any GDA statement, SoDA or iSoDA that we may issue will be based on the characteristics of the generic site specified by the RP. The RP may choose a range of generic sites with coastal, estuarine and inland characteristics.

Description of the RP’s management arrangements and responsibilities

The RP must provide a description of their management system and how management responsibilities for GDA are allocated in its organisational structure. The description should cover the management arrangements and responsibilities relating to:

• developing the design, including the RP’s design process
• managing the GDA project, including the assumptions and commitments made
• managing and controlling contractors and others involved in the GDA
• establishing the methodology used for identifying BAT and making sure they are used in the design – see radioactive waste management arrangements
• producing and maintaining the submission
• ongoing communications with the regulators and matters raised by them during GDA
• maintaining records of design and construction
• controlling and documenting design modifications, both during and after completion of GDA
• transferring information to prospective operators and providing ongoing support to them throughout the nuclear power plant reactor’s lifecycle

Detailed information about the design

Information to be provided includes:

• a technical description of the facility’s main plants, systems and processes, supported by process diagrams
• a technical description of the plants, systems and processes which have a bearing on radioactive waste (solid, liquid and gaseous) generation, treatment, measurement, assessment and disposal
• consideration of the potential for the creation of hazardous waste and the presence of hazardous substances and other pollutants in waste streams
• a technical description of the plants, systems and processes which have a bearing on the conventional environmental impacts of the facility
• a description of the philosophies, principles, policies, strategies, plans, methodologies, codes and standards used by the RP in developing, substantiating and specifying the design, especially those that are relevant to, or underpin, the environment case
• assurance that the generic design is compatible with relevant UK approaches for management of radioactive wastes, decommissioning and long-term interim storage of spent fuel and final disposal of waste and spent fuel

Detailed description of radioactive waste management arrangements

Information to be provided includes:

• identifying the strategic considerations for radioactive waste management which underpin the design
• a description of radioactive wastes, more challenging wastes and spent fuel arisings throughout the nuclear power plant’s lifecycle, including sources of radioactivity and other matters affecting radioactive waste arisings – lifecycle includes commissioning, operation and decommissioning
• a description of the proposals for the management and disposal of all radioactive wastes, including solid, liquid and gaseous wastes and spent fuel, throughout the nuclear power plant’s lifecycle – including commissioning, operation and decommissioning
• a description of how the production, discharge and disposal of radioactive waste and spent fuel will be managed to protect the environment and people
• a description of the optimisation process used to identify and justify that the proposed techniques are BAT
• for Step 2, a worked example demonstrating the application of the RP’s optimisation process
• the justifications for each of the techniques that have been identified as BAT
• the justifications for how each of the techniques have been implemented or will be implemented in the design so that they are BAT

The optimisation process for BAT should take account of:

• the technology to be used and the way the facility is designed and will be built, maintained, operated and dismantled
• the wastes arising throughout the lifetime of the facility, including more challenging wastes
• the potential radiological impact of wastes on people and the environment and how this is used to prioritise optimisation of the design
• preventing and minimising (in terms of radioactivity) the creation of radioactive waste
• minimising (in terms of radioactivity) discharges of gaseous and aqueous radioactive wastes
• minimising the impact of those discharges on people, and protecting other species
• minimising (in terms of mass and volume) solid and non-aqueous liquid radioactive wastes and spent fuel
• selecting optimal disposal routes (taking account of the waste hierarchy and the proximity principle) for those wastes
• the suitability for disposal of any wastes and spent fuel for which there is no currently available disposal route and how they will be managed in the interim so as not to prejudice their ultimate disposal (this should take account of the view of NWS on the disposability of such wastes and spent fuel)
• the full range of anticipated feeds into the radioactive waste management systems, consistent with the Source Term

It is important for the generic case to be clear on its use of ‘best estimate’ and ‘design basis’ data, when and how these data will practically apply and for how long related challenges will be imposed on the radioactive waste systems.

Quantification of radioactive waste disposals

Quantitative estimates of waste arisings for normal operation are required including:

• discharges of gaseous and aqueous radioactive wastes
• arisings of combustible waste and disposals by on-site or off-site incineration
• arisings of other radioactive wastes – by category and disposal route (if any) – and spent fuel

Normal operation includes the operational fluctuations, trends and events that are expected to occur over the lifetime of the facility. This includes start-up, shutdown and maintenance as well as expected faults. The RP should provide its approach to identifying fluctuations, trends and events expected over the lifetime of a facility and for assessing their impacts on discharges and wastes. Care needs to be taken where RPs refer to radioactive waste operational data from other countries, as the circumstances from which that data was collated may not be representative of the conditions that will apply in England and Wales.

Normal operation does not include increased discharges arising from other events inconsistent with the use of BAT, such as:

• inadequate maintenance
• inadequate operation
• accidents

For gaseous and aqueous radioactive waste, the RP must estimate the monthly discharges:

• on an individual radionuclide basis for significant radionuclides
• on a group basis (for example ‘total alpha’ or ‘total beta’) for other radionuclides
• via each discharge point and discharge route

Significant radionuclides are those which:

• have a radiological impact on people or non-human species
• are discharged in high quantities of radioactivity
• have long half-lives, may persist or accumulate (or both) in the environment, and may contribute significantly to collective dose
• are indicators of facility performance and process control

We recognise that the EU recommendation 2004/2/Euratom represents good practice for standardised radioactive discharges reporting and the radionuclide selection should be consistent with this recommendation.

For combustible and other radioactive wastes, the RP must estimate the annual arisings and disposals during operation and give an indication of the likely arisings during decommissioning.

The RP must identify wastes in terms of their:

• category – High Level Waste, Intermediate Level Waste, Low Level Waste, Very Low Level Waste
• physico-chemical characteristics
• proposed management and disposal route

They must quantify the activity of important individual radionuclides and overall groupings of radionuclides (for example, total beta), together with mass or volume.

Estimates of discharges and disposals should clearly show the contribution of each constituent aspect of normal operations, including:

• routine operation (typically, the design basis or ‘flowsheet design’ and the minimum level of disposals)
• start-up and shutdown
• maintenance and testing
• infrequent but necessary aspects of operation, for example, plant start-up, trips, maintenance, shutdown and refuelling
• foreseeable (based on a fault analysis), unplanned events during normal operation that remain consistent with using BAT, for example, occasional fuel pin or plant failures

The RP must support estimates with performance data from similar facilities, where such facilities exist. They must also explain, where relevant, how changes in design or operation from those facilities affect the expected discharges and disposals.

The RP must demonstrate that discharges and waste arisings will not exceed those of comparable power stations across the world (as required by UK government policy). Some information on discharges and wastes arisings from other power stations is published in chemical discharges issue 1.

The RP must provide proposed limits for:

• gaseous discharges
• aqueous discharges
• disposal of combustible waste by on-site incineration (if proposed)

The RP must provide proposals for:

• annual site limits (on a rolling 12-month basis) for gaseous and aqueous discharges
• monthly limits for disposals by on-site incineration (if proposed)

The RP must describe how they derived these limits. They can also propose limits to reflect an operating cycle (campaign limits).

Sampling arrangements, techniques and systems for measuring and assessing discharges and disposals of radioactive waste

The RP must provide details of their arrangements for:

• in-process monitoring, including measuring parameters relevant to waste generation and management and process control
• monitoring final discharges of gaseous and aqueous wastes
• monitoring disposals of non-aqueous liquid and solid wastes

The RP must demonstrate that their proposals represent BAT for monitoring and confirm that the sensitivity is sufficient to:

• readily demonstrate compliance with the proposed limits
• meet the levels of detection specified in 2004/2/Euratom, which we consider to be good practice

The RP must describe the facilities provided for independent periodic sampling (by the regulator) of final discharges of gaseous and aqueous wastes.

Prospective radiological assessment at the proposed limits for discharges and for any on-site incineration

The RP must provide a radiological assessment of proposed limits for:

• annual dose to most exposed members of the public for liquid discharges*
• annual dose to most exposed members of the public for gaseous discharges (separately identify the dose associated with on-site incineration where applicable)*
• annual dose to the most exposed members of the public for all discharges from the facility*
• annual dose from direct radiation to the most exposed members of the public

The RP must also provide:

• annual dose to the representative person for the facility
• potential short-term doses, including via the food chain, based on the maximum anticipated short-term discharges from the facility in normal operation
• a comparison of the calculated doses with the relevant dose constraints
• an assessment of whether the build-up of radionuclides in the local environment of the facility, based on the anticipated lifetime discharges, might have the potential to prejudice the activities of other legitimate users or uses of the land or sea
• collective dose truncated at 500 years to the UK, European and world populations
• dose-rate to non-human species*

The RP must state which models they have used to calculate these doses and why the models are appropriate. They must set out all the data and assumptions they have used as input to the models, together with reasoning as to why these assumptions are appropriate.

For items marked with an asterisk (*), we recommend that the RP uses the Environment Agency’s Initial Radiological Assessment Tool. They must refine the default data to reflect the characteristics of the facility and generic site.

Information relating to other environmental regulations

The RP must provide information explaining how they will meet other relevant environmental regulations.

Water use and abstraction

For water use and abstraction, the RP must provide details and estimates of:

• freshwater requirements for the design
• cooling water requirements for the design relevant to the generic site

The RP should include its consideration of:

• seawater or river water abstraction
• use of conventional cooling towers or hybrid cooling towers
• abstraction inlet fish deterrent schemes
• fish return systems

Discharges to surface water

For discharges to surface water the RP must provide a description of how aqueous waste streams will arise, be managed and disposed of throughout the facility’s lifecycle, including:

• sources and quantities of contaminants (including disinfectant and biocides), highlighting any priority substances as specified in the Priority Substances Directive
• identifying effluent and surface water runoff streams contributing to the overall discharge and how they are controlled
• potential options and the associated environmental impact for the disposal of each individual effluent stream
• the means of control if unplanned radioactive (or other) contamination of the discharge is detected
• the options for beneficial use of the waste heat produced
• the environmental impact of thermal discharges

Guidance is provided in surface water pollution risk assessment for your environmental permit.

Discharges to groundwater

If there are planned discharges to groundwater, the RP must describe the nature and quantity of those discharges and provide an assessment of the impact on groundwater. We do not normally allow discharges to groundwater.

The RP must describe how accidental discharges of radioactivity to land and groundwater will be prevented in the detailed information they provide about their radioactive waste management arrangements. Please see also our contaminated land and groundwater: RSR generic developed principles.

Operation of installations (combustion plant and incinerators)

The RP must identify the combustion plant that is provided in their nuclear power plant design, for example standby generators or auxiliary boilers. If the aggregate rated thermal input of all combustion plant is greater than 50MW, they must provide a comparison of the proposed technology against the relevant guidance.

If the aggregate rated thermal input of all combustion plant is greater than 20MW, they must describe how they will monitor greenhouse gas emissions.

If the design includes an on-site incinerator with a capacity of 1 tonne or more per hour, they must provide a comparison of the proposed technology against our sector guidance.

Operation of medium combustion plant and specified generators

The RP must identify the medium combustion plant that is provided in their nuclear power plant design, for example standby generators. If the aggregate rated thermal input of all medium combustion plant is more than or equal to 1MW and less than 50MW, they must provide a comparison of the proposed technology against the relevant guidance and our sector guidance.

Control of Major Accident Hazards Regulations (COMAH)

The RP must identify whether they will store quantities of substances on site that are above the qualifying thresholds in COMAH 15.

They must describe the measures taken in the design to prevent a major accident to the environment if they exceed a COMAH threshold.

Fluorinated greenhouse gases and ozone-depleting substances

The RP must identify whether any equipment included in the design will contain fluorinated greenhouse gases or ozone-depleting substances – as defined in the Fluorinated Greenhouse Gases Regulations 2015 and Ozone Depleting Substances Regulations 2015. See our guidance on fluorinated gases (F gases)

If so, they must describe the measures taken in the design to prevent and minimise the leakage of such substances.

GDA process and prospective operators

When a prospective operator applies for an environmental permit to build and operate a nuclear power plant design, we will take account of the work we have already done during GDA. We will focus our efforts on assessing the detailed design of the plant as it develops after GDA, together with operator-specific or site-specific issues. This will include how the prospective operator has addressed, is addressing or will address matters arising from GDA, including Assessment Findings.

The RP should make sure that the information they provide in their environment case can also be used for site-specific permit applications – preferably without needing a substantial rewrite. This will enable prospective operators to make efficient use of the GDA process.

We recognise that GDA may take place well before a prospective operator has chosen the technology that they propose to use in their nuclear power plant. However, we encourage prospective operators to work with the RP during the GDA process. This will benefit the prospective operator and the RP. It will help them demonstrate that they understand the:

• plant’s environmental performance
• plant’s environmental hazards and how to control them
• plant’s environmental protection functions and measures
• environmental protection legal framework in England and Wales
• commitments and assumptions made during GDA that potentially impact on or limit operations, for example on maintenance, inspection or testing

It will also help the operator become an ‘intelligent customer’ for the design and any further work that it needs to commission.

Involving a prospective operator in GDA will also help make sure that the plant can be operated using BAT and meet regulatory requirements and expectations. This is because it should enable the prospective operator to influence the design and how it would be operated. In this way, input from prospective operators can help reduce future project risks.

When issuing a SoDA or iSoDA, as well as providing Assessment Findings, we will include other relevant requirements and expectations for site-specific permitting as appropriate. This information will help prospective operators apply for an environmental permit and will cover issues we could not include as part of GDA.