Guidance

RSR guidance for nuclear sites undergoing decommissioning

Updated 8 February 2024

Applies to England and Wales

• Publication for Scotland

1. Introduction

This guidance is for the operators of nuclear sites in England and Wales undertaking decommissioning work under their radioactive substances activity environmental permit. It is set within the framework of Radioactive Substances Regulation (RSR) presented in the Environment Agency’s RSR objective and principles and aligns with International Atomic Energy Agency (IAEA) General Safety Requirements (GSR) Part 6.

1.2 Scope of guidance

Decommissioning is the administrative and technical actions taken to allow the removal of some or all the regulatory controls from a nuclear facility or site. Decommissioning is a transition phase where operations have finished but radioactive substances activities are still required to clean out radioactive waste and to dismantle nuclear facilities.

Decommissioning is a stage late in the lifecycle of a nuclear facility but it needs to be planned for and taken into account in all lifecycle stages, starting at the planning and design stage.

This guidance covers the period from the end of operations to the point when all planned work involving radioactive substance activities has stopped. During this time radioactive substances activities are still taking place and the radioactive substances activity environmental permit is still in force.

When all radioactive substances activities have stopped and the site reference state has been reached, operators apply to surrender their environmental permit by following guidance on requirements for release (GRR).

The GRR focusses on the management of radioactive wastes arising from the final stages of decommissioning and preparations for permit surrender. This guidance is about all decommissioning activities. It sets out what operators must do under the radioactive substances activity environmental permit before and during decommissioning. Figure 1 shows the time period when this guidance and the GRR are applicable. Operators should use this guidance and the GRR to fully understand all the Environment Agency’s requirements.

Figure 1: Timeline of when this guidance and GRR are applicable

This shows the lifecycle of a nuclear facility. The RSR guidance for nuclear sites undergoing decommissioning applies throughout:

• design and construction (10 years)
• commissioning and operation (50 to 60 years)
• defueling and transition from operations to decommissioning (10 years)
• decommissioning, including possible period of care and maintenance (10 to 100 years)
• final decommissioning – when all planned work involving radioactive substances is complete (10s of years)

The RSR GRR applies until the site reference state has been reached throughout:

• commissioning and operation (50 to 60 years)
• defueling and transition from operations to decommissioning (10 years)
• decommissioning, including possible period of care and maintenance (10 to 100 years)
• final decommissioning – when all planned work involving radioactive substances is complete (10s of years)
• validation monitoring (10 to 30 years)
• controls for radiological protection (10s to 100s of years)

This guidance does not apply to the closure of radioactive waste disposal sites or to on-site disposals of solid radioactive waste that might occur on decommissioning nuclear sites. This guidance does apply to the decommissioning of facilities, structures, systems and components that serviced those disposals, such as grouting plant or concrete crushing plant.

The operator’s arrangements for decommissioning nuclear facilities are regulated by the Office for Nuclear Regulation (ONR) under the Nuclear Installations Act 1965 and, for nuclear reactors, the Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations 1999. Some actions required to enable decommissioning, such as the disposal of radioactive wastes, are regulated by the relevant environmental regulator: the Environment Agency in England or Natural Resources Wales. This guidance focusses on the regulatory controls exercised through radioactive substances activity environmental permits on nuclear licensed sites in England and Wales.

Both the Environment Agency and Natural Resources Wales have a memorandum of understanding with ONR that describes the working arrangements between the nuclear safety regulator and the environmental regulator. The regulators will work together to enable decommissioning activities at nuclear sites.

2. Optimisation

You must use best available techniques (BAT) to make sure that radiation exposures to the public from the disposal of radioactive waste arising from decommissioning are as low as reasonably achievable (ALARA), taking into account environmental, economic and social factors.

Optimisation is one of the principles the Environment Agency use in the regulation of radioactive substances.

You should optimise the radiological risks to the public from all activities creating, discharging and disposing of radioactive wastes during decommissioning. Optimisation of exposures from radioactive wastes should also meet other obligations, such as worker protection, cost, transport and other relevant considerations.

Decommissioning activities can take place over very long periods of time, particularly if some activities are deferred (see section 3.1 on ‘deferred decommissioning’). Optimisation for the disposal of radioactive wastes should consider exposures of future generations as well as effects to present generations. You should also consider how the receiving environment might evolve over time, such as changes in land use, or population habits, or how climate change may affect the environment. The options you consider in your optimisation assessment may include trade-offs over long timescales. For example, deferring the decommissioning provides the benefit of radioactive decay but could prevent the early reuse of land.

When carrying out optimisation, it is important to have input from interested parties who are likely to be directly or indirectly affected by the options being considered. You should consult with relevant stakeholders when developing your decommissioning strategies and plans.

You should take a graded approach to optimisation. The resources you devote to the protection of people and the environment should be proportionate to the magnitude of the risks and their responsiveness to control.

The optimisation requirement is reflected in your permit through the conditions requiring the use of BAT to minimise the volume and activity of radioactive wastes. Your permit also requires you to select optimised disposal routes.

Guidance on how to demonstrate BAT is described in principles of optimisation, which recognises the need to balance the wider environmental, social and economic considerations. It also recognises that optimisation is not just about minimisation of radiation doses to people. Considering environmental factors means also taking into account the radiological risks to the environment and how the non-radiological properties of radioactive wastes could impact both people and the environment.

You may already have information available that can support optimisation, for example your waste management plan (WMP), site wide environmental safety case (SWESC) or, where available, radioactive waste management cases (RWMCs).

3. Decommissioning strategy

You need to prepare and maintain a decommissioning strategy for your site. Your decommissioning strategy should be integrated with other relevant strategies and plans.

The UK government’s 2004 policy statement on ‘The Decommissioning of the UK Nuclear Industry’s Facilities’, expects nuclear operators to produce and maintain a decommissioning strategy for their sites. Your decommissioning strategy should be informed by your WMP, SWESC and optimisation process. You should systematically evaluate and compare alternatives in terms of their impacts on people and the environment, taking account of economic and social costs and benefits, as well as other factors.

The strategy should describe the significant assumptions, uncertainties and risks associated with its achievement, and how these will be managed. The initial strategy should be produced during the planning stage of a new site or facility.

Your decommissioning strategy should:

• be consistent with government policies and strategies for managing radioactive waste
• use a graded approach, containing information of a type and level of detail proportionate with the scale and complexity of the site, its associated environmental hazards and risks, waste arisings and anticipated decommissioning timescales
• address the full lifecycle of the permitted site
• consider existing facilities as well as planned ones, in the context of reusing facilities for decommissioning activities and as eventual wastes
• involve interested parties at an early stage and describe, or refer to, how stakeholder views will be taken into account during optimisation of decommissioning activities
• identify when all radioactive substances activities on the site will end, when the site reference state is expected to be reached and when you plan to apply for permit surrender and release from regulatory control
• describe how BAT will be used to minimise the generation of radioactive and non-radioactive wastes
• include a commitment to appropriate financial arrangements for decommissioning and restoration of the site
• describe, or refer to, the decommissioning options and the timescales considered, the reasons for selecting the chosen options and the graded approach taken for determining the relative priorities of decommissioning projects and their associated radioactive waste arisings
• take account of relevant factors, such as those affecting the timing of decommissioning, the magnitude of the remaining hazard, the duration of the work, resources, and the fact that the overall objective of the work is to remove the hazard and protect the public and the environment

Interdependencies between facilities or between plants within facilities should be identified and considered as part of the strategy. This should include interactions between facilities undergoing decommissioning and those facilities continuing to operate.

Your decommissioning strategy should be integrated with other relevant strategies. Depending on the site, these might include strategies for:

• managing radioactive wastes, effluents and discharges, including any on-site disposals of solid waste
• dealing with specific structures, such as pipelines
• wider radioactive waste management and decommissioning, such as those set by the Nuclear Decommissioning Authority or the Ministry of Defence
• control and remediation of radioactively contaminated land and groundwater, including wastes generated through remediation
• asset management and maintenance

You should update and refine your decommissioning strategy during the lifecycle of the site. Updates should take into account changes in policy, regulation and developments in BAT. You should adopt a graded approach to the development of your decommissioning strategy with more detail added as the time for decommissioning approaches.

3.1 Deferring decommissioning

Operators should follow a strategy of early or immediate decommissioning, including the associated decision-making about radioactive waste disposals. However, it is possible that deferred decommissioning is the optimal strategy for a particular facility or site. Deferred decommissioning means that after removal of the radioactive materials, such as nuclear fuel, all or part of the facility is prepared so that it can be safely left in storage and maintained until it is subsequently decontaminated and dismantled. Preparations can involve the early dismantling of some parts of a facility, and the early processing and removal of some radioactive waste before the remaining parts of the facility are placed into storage.

If you want to defer the decommissioning of a facility or site, your decommissioning strategy should show that:

• this is the optimised solution for radioactive waste disposals, recognising different radiological risks in a range of situations
• it does not place an undue burden on future generations
• facilities will be adequately maintained to prevent the unnecessary generation of radioactive wastes
• options for implementing earlier decommissioning will not be foreclosed

Entry into and exit from deferred decommissioning is likely to be a change with significant repercussions for the management of radioactive waste. You need to evaluate entry into or exit from deferred decommissioning from the perspective of protecting people and the environment. You should assess the impacts of this change on your radioactive waste generating activities and be able to show that:

• deferred decommissioning is consistent with regulatory principles and requirements
• deferment will not foreclose options for the future management and disposal of radioactive waste

Where necessary, you must revise your management arrangements before entering or exiting deferred decommissioning to continue to comply with your permit.

Expectations for deferred decommissioning

To prepare for entry into deferred decommissioning you should:

• take a graded approach to address the requirements in this guidance, which are still applicable when entering, during and exiting deferred decommissioning
• dispose of any low-level waste (LLW) from the facility or site – including any liquids such as pond water and non-radioactive waste
• make sure any higher activity wastes (HAW), including any LLW that cannot be disposed of at present, that remains on site is covered by an RWMC – following joint regulatory guidance on the management of higher activity radioactive waste on nuclear licensed sites
• store radioactive waste remaining on site in a passively safe state to avoid the generation of secondary radioactive wastes and enabling future disposal
• remove or seal discharge pathways to the environment that have no current or planned future use, such as drains and ventilation routes
• minimise discharge pathways that are used during deferred decommissioning, or being retained for later use – you may need a permit for this activity
• minimise the need for active environmental protection, monitoring systems or human intervention in relation to permitted activities and maintain appropriate surveillance monitoring during the period of deferment
• implement an asset management system to manage ageing, degradation and obsolescence risks, both in relation to the environmental protection during deferred decommissioning and for the duration of the remaining decommissioning activities

Some LLW, for example contaminated structures or infrastructure, may remain on site and pending later disposal by an optimised route.

Inspection and monitoring arrangements during deferred decommissioning

During any deferral period, you should put in a place a programme of inspection and monitoring sufficient to detect deviations from expected performance. This should be based on the systematic assessment of environmental protection structures, systems and components. This may include physical or remote inspection, process monitoring, discharge monitoring and environmental monitoring as appropriate. Monitoring should allow you to promptly detect and report abnormal events or discharges proportionate to their scale and speed of development. This programme may form part of your asset management arrangements.

You should have arrangements in place to respond to alarms or other indications of abnormal events. You should prioritise alarms at remotely monitored sites by their significance. You should specify appropriate response times in your management arrangements. You should make sure a suitably qualified person attends within the alarm response time specified. This may require the use of contractors or locally based staff if there are no qualified personnel on site.

4. Planning for decommissioning

Before decommissioning starts, you will need to prepare a plan for each facility to identify and address the type and quantity of wastes to be managed, including solid, liquid and gaseous wastes, and the timescales over which the wastes will arise.

You will have a decommissioning programme and your permit requires you to have a WMP. You must use your WMP to document your anticipated decommissioning wastes, as well as operational wastes. The WMP should be consistent with your decommissioning programme. The WMP should provide information on how you will:

• manage and dispose of all wastes, including secondary wastes
• minimise wastes arising from your decommissioning activities
• characterise your decommissioning wastes
• identify the optimised disposal route for each type of waste produced by your decommissioning activities.

Further information on the purpose and content of a WMP can be found in the guidance on requirements for release.

The expectations presented in this guidance should be addressed in your planning for decommissioning and you should develop measures to track how you implement these as part of your management arrangements.

4.1 Planning and regulatory engagement for decommissioning

During decommissioning, regimes regulated by the Environment Agency and Natural Resources Wales other than radioactive substances, such as non-radioactive waste management and groundwater protection, will become more prominent. You may have less experience of these regimes and should take appropriate legal, technical and regulatory advice to make sure you comply with all relevant environmental protection regulations. The environmental regulators may also be consultees to other regulatory regimes, such as the Town and Country Planning regime and the Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations 1999, as well as to ONR’s permissioning process through the nuclear site licence. Where relevant, you should keep your environmental regulator informed of your plans to make relevant applications and submissions under these other regimes.

To minimise regulatory risks to your decommissioning programme, you should keep your environmental regulator informed about your decommissioning activities. You should contact them for advice about any permits you need and the time frame for applying so that you can allow enough time for determination in your programme.

You should prepare and maintain a regulatory engagement plan with your environmental regulator. The regulatory engagement plan should:

• identify all regulatory regimes administered by your environmental regulator or which they are consultees to that are relevant to your decommissioning activities
• identify permits or consultation responses needed from your environmental regulator during decommissioning
• propose the frequency and format of regulator interactions
• include objectives and deliverables, including the requirements in this guidance
• agree hold points for key activities, for example presentation of radioactive waste characterisation results, higher activity waste disposability assessments, pre-application advice meetings, and prospective application dates for new permits, variations or surrenders
• indicate timescales to allow for pre-application discussions, consultation and permit determination

5. Design for decommissioning

You must design your facilities using BAT so that they can be decommissioned in a way that protects the public and the environment from the radiation exposures from radioactive waste disposals.

Your permitted activities must use BAT to minimise the generation of radioactive waste and its impact on people and the environment, this includes how your facilities are designed, built, maintained, operated and dismantled. The design of nuclear facilities, including waste stores and modifications to existing facilitates, should:

• enable decommissioning in a way that minimises impacts on people and the environment from radioactive waste disposals, taking into account our guidance on Engineering: generic developed principles
• containment, prevent radioactive contamination and enable decontamination, which contribute to minimising the creation of radioactive waste during decommissioning
• support minimisation of resource use and application of the waste hierarchy to prevent and minimise wastes from decommissioning or allow materials from structures, systems and components to be re-used or recycled
• use materials that minimise activation so they don’t become radioactive waste at the time of decommissioning
• avoid the creation of problematic wastes without a disposal route during decommissioning
• facilitate the characterisation, segregation, packaging and disposal of radioactive and non-radioactive wastes during decommissioning
• be maintained appropriately during decommissioning to minimise the creation of radioactive waste and prevent the spread of contamination
• allow for building reuse during decommissioning where possible, avoiding the need to construct new buildings which will also require decommissioning

The implications for decommissioning and the generation of radioactive waste should be considered throughout the lifecycle of a facility, especially when modifications to facilities or methods of operation are proposed.

6. Asset management

When operations end, you must manage structures, systems and components so that they do not deteriorate and become a risk to the public and the environment or generate additional radioactive wastes.

You should maintain nuclear facilities that have finished operations to prevent them from deteriorating and becoming an environmental hazard or generating additional radioactive wastes, this is particularly important when decommissioning is deferred.

You should develop an asset management system to make sure facilities on your site are appropriately managed during decommissioning. Your system should identify which assets:

• are end of life and require disposal
• can be reused
• are still required during the decommissioning phase.

Your system should take a graded approach and maintenance of facilities should be optimised throughout their lifecycle.

Redundant buildings that are contaminated with radioactivity are unlikely to be radioactive waste while they are intact and being adequately maintained. However, any radioactive waste that will be produced when a building is decontaminated or dismantled should be included in your WMP.

7. Disposals during decommissioning

You must review your permit before entering and throughout decommissioning to ensure that it covers your planned activities and that your disposal limits reflect the change from operations to decommissioning.

Decommissioning activities will change the volumes and characteristics of your radioactive wastes in comparison to your operational wastes. You should use your WMP to identify these changes and predict when you should make an application to vary your radioactive substances activity permit. The times when you need to change your permit should be identified in your decommissioning strategy and plans.

During decommissioning you must still meet the permit conditions requiring you to minimise the volume and activity of radioactive waste using BAT. If you need to increase your radioactive waste disposals, introduce new disposal routes or commission new waste management facilities to enable decommissioning you must follow the normal permitting process. You should justify increases in disposals within a framework of progressive reductions as decommissioning proceeds over time and following your decommissioning strategy.

When reviewing your permit, you should engage with your environmental regulator and apply for a variation to your permit if required. The Environment Agency will also review your permit regularly and initiate variations if necessary.

8. Waste characterisation

You must characterise all wastes from decommissioning for their radiological and non-radiological properties using BAT to enable effective waste management and facilitate optimised disposal.

You must characterise radioactive wastes using BAT so that wastes can be effectively managed and sent for disposal by an optimised disposal route, as required by your permit.

Characterisation data should be used to inform your WMP and any RWMCs and should include the non-radiological properties of the radioactive waste. During decommissioning, characterisation of structures, systems and components will be essential to the planning of decommissioning activities and the subsequent disposal of decommissioning wastes.

Characterisation data should also be used to provide assurance that:

• radioactive wastes consigned to other operators meet the written specification, or waste acceptance criteria, of the waste receiver
• on-site disposals meet permitted limits and conditions

9. Pre-disposal management of wastes without a disposal route

You must be able to demonstrate that any radioactive wastes from decommissioning activities without a disposal route can be disposed of safely in the future when a route does become available.

Radioactive wastes that do not currently have a disposal route, for example most HAW, may be stored on nuclear sites for many years. The need to establish and maintain long term stores for radioactive wastes should be fully reflected in your decommissioning strategy and plans. ONR regulates these wastes while they are accumulated and stored on-site. These wastes will eventually be disposed of and must be capable of being disposed of in accordance with an environmental permit. You should use BAT to manage these wastes to allow disposal when an ideal route becomes available. You should use your WMP to show that these wastes, including secondary wastes from their management, are controlled.

HAW should be managed following the guidance provided in the regulators’ joint guidance on the management of higher activity waste. You should use RWMCs to support your demonstration that HAW are being conditioned, treated, stored and contained safely. Each waste stream currently without a disposal route should be covered by a disposability assessment as soon as is reasonably practicable. This will provide assurance that waste packages can be disposed of in the future.

10. Integrated management systems for decommissioning

You must review and, if necessary, modify your integrated management system before and during decommissioning to make sure that protection of the public and the environment is explicitly addressed, given appropriate prominence and sufficiently resourced.

The requirements for nuclear operators to have an integrated management system is well established. Your environmental permit requires a written management system sufficient to achieve compliance with the permit conditions. The transition from operations to decommissioning will bring significant change to your business. Your management system should control the environmental risks of this change as well as address all the ongoing goals of operating your organisation, including decommissioning goals and the associated radioactive waste arisings. You are required by your permit to notify your environmental regulator of significant, relevant changes to your management system, resources, WMP or SWESC.

There is further guidance to nuclear operators about their management arrangements in several sources:

• Regulatory guidance series RSR 2: The regulation of radioactive substances activities on nuclear licensed sites, discusses radioactive waste management arrangements
• the generic developed principles on management and leadership for the environment contain high-level advice about management systems
• Radioactive substances regulation: Management arrangements at nuclear sites, provides a wide range of guidance around expectations for management arrangements for nuclear operators
• guidance to nuclear operators on how to comply with their environmental permit contains information about compliance with the management conditions in the permit
• joint guidance with ONR on the use of an integrated management prospectus by nuclear operators

10.1 Records management

You must keep records in line with your permit conditions and your management system should include appropriate arrangements for keeping relevant records in the long term. To facilitate decommissioning and management of associated wastes, the process of making and preserving documents and records should start at the planning and design stage and continue throughout the whole lifecycle of the facility. During decommissioning, particular attention should be given to records relating to:

• the as-built facility design and subsequent modifications, this will help identify environmental protection systems that may need to be maintained as well as identify materials that require specialist disposal, for example, asbestos, electrical and electronic equipment or hazardous wastes
• operational history, including information from current and past workers, incidents, accidents and unusual occurrences that may lead to the generation of radioactive waste, such as contamination events
• radiological surveys, which will be useful in the radiological characterisation of the building
• waste characterisation data
• RWMCs, letters of compliance and disposability assessments
• historic storage locations of radioactive material and radioactive waste within a facility
• BAT assessments and waste disposals
• regulatory interactions
• the physical condition of structures, systems and components relevant to environmental protection and radioactive waste management
• the decommissioning history, including decommissioning reports and records, with a view to meeting the GRR requirements and preparing to make an application for permit surrender

Knowledge management

Given the timescales involved in the decommissioning of nuclear facilities you should make sure your management system has arrangements for capturing and recording information about facilities and the wider site. This could include corporate knowledge as well as knowledge held by key staff from the facility. Read the guidance, Radioactive substances regulation: Management arrangements at nuclear sites.

10.2 Sufficient competent resources

The transition from operations to decommissioning may require significant changes to the size and capability of your workforce. You should take an integrated approach to managing skills and resources during decommissioning. Significant changes to your workforce should be notified to your environmental regulator in accordance with your permit. The guidance, Radioactive substances regulation: Management arrangements at nuclear sites, provides expectations for resourcing.

Intelligent customer

Decommissioning is a time when you may choose to employ contractors for specific tasks and activities. Your management arrangements should make sure that the work of contractors is appropriately specified and controlled to ensure permit compliance. Contractors need to be competent to enable you to comply with your permit. The guidance, Radioactive substances regulation: Management arrangements at nuclear sites, provides expectations for intelligent customer capability.