Corporate report

Regulatory scrutiny and engagement for geological disposal: annual report 2025 to 2026

Updated 19 October 2026

Foreword

The Environment Agency is the independent environmental regulator for the nuclear industry in England. Our activities are guided by our plan ‘EA2030 change for a better environment’. This plan acts as our compass, enabling us and others to chart a course towards a healthier, greener and more prosperous country.

Our EA2030 plan sets out 3 strategic goals:

• healthy air, land and water supporting nature’s recovery
• sustainable growth
• a nation resilient to climate change

Our regulation of disposals of radioactive waste, including radioactive discharges to air and water, and disposal of solid waste to land, aligns with these goals. It helps ensure that these facilities are designed and operated in ways which minimise waste and protect the environment.

The Office for Nuclear Regulation (ONR) is the UK’s independent nuclear regulator for safety, security and safeguards at licensed nuclear sites in the UK. Our mission is ensuring safe nuclear operations for a secure and sustainable future.

ONR has the legal authority to regulate nuclear safety, nuclear security, safeguards and nuclear site health and safety at the 36 licensed nuclear sites in Great Britain. We also regulate the safety of transporting radioactive materials.

This is a joint Environment Agency and ONR publication that summarises our work relating to geological disposal of the most hazardous radioactive wastes during 2025 to 2026. As regulators for these wastes, we are working together to make sure that any future geological disposal facility (GDF) will meet the high standards for environmental protection, safety, safeguards and security that the law requires, and the public expects.

We have established agreements with Nuclear Waste Services (NWS), the organisation responsible for developing a GDF, to provide regulatory advice and to scrutinise its work. We are engaging with NWS early, before regulation starts, so that when a site is identified, NWS already clearly understands what it needs to do as part of the regulatory process. We also liaise with NWS to make sure that it gives the right advice to waste producers about packaging radioactive waste for future disposal at a GDF. This helps NWS understand what it needs to do to meet applicable legal requirements for environmental protection, safety, radioactive materials transport, safeguards and security. Early engagement also helps us better understand NWS’s work and lets us prepare in advance for any permit or licence applications we might receive from NWS, so that we can respond promptly and knowledgeably.

We have no regulatory role in the siting process or selecting potential sites for a GDF. However, we support communities that are considering hosting a GDF on matters relating to our respective areas of regulation. For example, we are available for communities to ask how a GDF will be regulated and to explain the role of regulators.

We have set out our regulatory expectations for geological disposal, covering our respective remits. The Environment Agency has issued guidance on requirements for authorisation (GRA) of disposal facilities for solid radioactive waste ^{[footnote 1]}. We plan to issue an updated version of this guidance, together with new guidance on staged regulation of a GDF, later in 2026, following consultation in 2024 to 2025 ^{[footnote 2]}. References to the GRA in this report refer to the 2009 published version. ONR has issued a technical assessment guide on geological disposal ^{[footnote 3]}, which it updated in March 2023. It will also draw on relevant aspects of the Safety Assessment Principles (SAPs) for Nuclear Facilities ^{[footnote 4]}, the Security Assessment Principles for the Civil Nuclear Industry (SyAPs) ^{[footnote 5]}, ONR Guidance for Nuclear Material Accountancy, Control and Safeguards (ONMACS) ^{[footnote 6]} and the Construction (Design and Management) Regulations 2015.

As independent regulators, we are committed to making our work open and transparent. This report will help us to continue to do this.

You can find further information on the Environment Agency’s role in Regulating the geological disposal of radioactive waste: environmental protection and ONR’s engagement on the GDF.

Executive summary

This report summarises the work that the Environment Agency and the ONR carried out to scrutinise NWS’s work related to geological disposal, and our associated interactions with the public, from April 2025 to March 2026 (the reporting period).

In 2026, after the end of the reporting period, NWS submitted to the Secretary of State for the Department for Energy Security and Net Zero (DESNZ) its decision on progressing to site characterisation in one or more communities (this would include deep borehole investigations). In advance of a response to NWS’s decision by the Secretary of State, our work during the reporting period focused on the generic parts of NWS’s programme that were independent of decisions on the siting of the GDF.

We observe that progress on the GDF programme slowed during the reporting period, where NWS needed to revise the programme to take account of the UK government’s 2025 Spending Review.

NWS is making good progress in developing its arrangements for preparing its first permit application and developing its GDF design and safety cases. NWS also continues to make good progress in making sure that its disposability assessments and GDF development remain current and consistent. This includes making sure that the UK’s stocks of civil plutonium will be immobilised in a waste form that is disposable to a GDF.

Based on NWS’s current planning assumptions, the Environment Agency does not expect to receive a permit application until at least 2 years after any decision to proceed to surface-based intrusive investigations has been made. Both the Environment Agency and ONR continue to enhance their regulatory capabilities and capacity in preparation for regulating a GDF, which will be a first-of-a-kind activity in the UK.

The Environment Agency and ONR consider that the timely delivery of disposal solutions is essential for the sustainable management of waste from the nuclear industry. This will only be achieved with adequate funding and focus. We seek to ensure that radioactive waste stored on nuclear licensed sites until a GDF is available is managed in a way that:

• protects the public, workforce and environment
• safeguards the interests of existing and future generations and the wider environment
• is in accordance with the nuclear site licence and environmental permit

Introduction

Radioactive waste has been, and continues to be, produced from the UK’s historic and current nuclear power, research and defence programmes, as well as from industries, hospitals and universities that use radioactive material.

There is no available route in the UK to dispose of the most hazardous radioactive waste, so it is stored on existing nuclear sites until a solution is implemented. The Environment Agency and ONR seek to ensure that radioactive waste stored on nuclear licensed sites until a GDF is available is managed in a way that:

• protects the public, workforce and environment
• safeguards the interests of existing and future generations and the wider environment
• is in accordance with the nuclear site licence and environmental permit

UK government policy for the implementation of geological disposal of the UK’s most hazardous radioactive waste is described in the 2024 UK policy framework for managing radioactive substances and nuclear decommissioning ^{[footnote 7]}. This sets out the framework for implementing geological disposal in England and Wales. Scottish Government policy does not include geological disposal. Rather, its policy is for the long-term management of higher activity waste (HAW) in near-surface facilities that are located as near to the site where the waste is produced as possible.

The Nuclear Decommissioning Authority (NDA) is responsible for implementing UK government policy on the long-term management of radioactive waste. NWS, which is part of the NDA Group, is responsible for delivering a GDF.

The Environment Agency and ONR will regulate any future GDF in England or in Wales (ONR only) to the high standards necessary to protect people and the environment when it is being developed, while it is operating, and after it has closed. Natural Resources Wales (NRW) has similar environmental protection responsibilities for Wales as the Environment Agency has in England, and we keep them aware of matters arising and important outcomes from our work.

We will be responsible for granting the necessary environmental permits and nuclear site licence, and for our respective regulatory roles of environmental protection, safety, security, radioactive materials transport and safeguards. Regulatory oversight of the GDF development would begin with environmental permitting of surface-based intrusive investigations at a ‘candidate premises’. This is the location the developer is seeking to determine whether it is a potentially suitable site for a GDF. Regulatory oversight is likely to be required for at least 150 years.

We are engaging with NWS now to make sure that any future applications to develop a GDF take account of all permitting and licensing requirements. We also want to make sure that NWS gives the right advice to waste producers, so that radioactive waste packaged at their sites:

• is suitable for future disposal
• can be safely stored pending disposal
• can be safely transported to a future disposal site

Our discussions with NWS will also help us prepare in advance for any permit or licence application we might receive, so that we can respond promptly and knowledgeably.

At this stage, before considering issuing permits or a licence, we are providing regulatory advice rather than making regulatory decisions. We have no role in identifying candidate sites for a GDF.

In line with policy ^{[footnote 7]}, NWS has been tasked by the UK government to implement geological disposal. The GDF siting process is ongoing. Following the closure of the Theddlethorpe Community Partnership in June 2025, as of March 2026, 2 communities remain in the siting process. These are the Mid Copeland and South Copeland GDF Community Partnerships.

Regulatory preparations

Engaging with NWS on geological disposal helps us prepare for any environmental permit or nuclear site licence application that we might receive, so that we can respond promptly to what will be a first-of-a-kind activity for the UK.

We anticipate that regulated activities relating to a GDF will continue for around 150 years from the start of intrusive site investigations, during its construction, operation and closure and through to its release from regulation. Regulation of the development of a GDF will take place in stages. Approval is required from regulators for surface-based intrusive investigations, and, in due course, for underground investigations, construction, operation, closure and release from regulation. The developer cannot progress from one stage to the next without first securing the relevant permissions. The purpose of this staged approach to regulation is to ensure that the development is always carried out safely and securely, and in ways that ensure that people and the environment are properly protected without inadvertently undermining the long-term performance of the disposal system.

The regulatory process will start when the developer wants to carry out surface-based intrusive investigations, such as drilling deep boreholes. At this stage, the developer will need to apply to the Environment Agency for an environmental permit before starting any such works. Joint regulation by the Environment Agency and ONR will begin before starting any excavations to gather detailed information about the underground geology and conditions at the site (‘underground investigations’). At the underground investigations stage, the developer would need to obtain both a nuclear site licence and an appropriate environmental permit.

We recognise that regulatory responsibilities and requirements may change and evolve during the delivery of a GDF. We give advice and scrutinise information provided by NWS based on the latest knowledge, directions and legal requirements. We maintain and enhance our capabilities to meet our responsibilities in regulating geological disposal. This includes working collaboratively with other regulators and international programmes relevant to radioactive waste disposal.

Permitting and guidance

The Environment Agency plans to issue an updated version of its GRA of disposal facilities for solid radioactive waste and new guidance on staged regulation of a GDF later in 2026. During the reporting period, we worked with the Scottish Environment Protection Agency (SEPA), NRW and the Northern Ireland Environment Agency (NIEA) to address feedback received during a public consultation exercise held in 2024 to 2025 ^{[footnote 2]}. We also considered further comment and clarification from NWS after the public consultation exercise concluded. The consultation exercise has helped us address and better communicate recurring themes and certain complex technical issues. Our objective is to ensure that the staged regulation guidance and GRA are clear, proportionate and usable when published.

We produced a draft template for the intrusive investigations permit and shared it with NWS in 2024. NWS will provide us with feedback on the draft template when the updated guidance has been issued. This will enable us to finalise the permit template ahead of NWS’s application for a permit to carry out intrusive investigations work. We will also ensure the permit template is aligned with the new staged regulation guidance and GRA.

Environment Agency’s capability building

The permitting of geological disposal is a first-of-a-kind activity in the UK. Therefore, while regulating geological disposal is similar to ongoing regulatory activities, it also has some significant differences. The Environment Agency will need to enhance its regulatory capabilities in line with the stages in permitting a GDF, and to maintain these capabilities over extended periods during the design, construction and operation of the facility.

We are continuing to review and develop our capabilities to ensure that we can regulate a GDF over the coming decades, starting with getting ready to permit intrusive investigations. We recruited 4 new assessors during the reporting period, all of whom have the necessary skills and experience to support our future GDF work.

We continue to attend training on topics relevant to geological disposal. In the reporting period, this included:

• NWS providing a GDF programme update to our full GDF team
• an international training course on GDF site selection by Nagra, the Swiss radioactive waste management organisation, which focused on its borehole drilling campaign processes and lessons learned
• international training on research and development (R&D) requirements and the planning of in situ experiments in underground research laboratories (URLs), which included a visit to the Grimsel Test Laboratory in the Swiss Alps, one of Nagra’s URLs
• European Joint Programme on Radioactive Waste Management (EURAD) and International Atomic Energy Agency (IAEA) virtual international seminars providing training and learning from experience, including on:
  • Cigéo, the French GDF project
  • disposal of spent fuel in Canada
  • Swiss GDF siting programme
  • Beishan URL in China
  • EU pilot project on a ‘Joint European Approach towards Radioactive Waste’
  • artificial intelligence (AI) applications to support nuclear decommissioning and waste management
  • the IAEA integrated expert peer review service for radioactive waste and spent fuel management, decommissioning and remediation programmes (ARTEMIS)
• NWS’s Research Support Office (RSO) conference in January 2026, including presenting on the role of R&D in regulating a GDF

The Environment Agency issued an invitation to tender titled ‘Technical Support to Regulatory Assessments of Solid Radioactive Waste Disposal Framework’ early in 2026. Suppliers appointed will provide technical support to help us in our overall regulation of solid radioactive waste disposals. The framework includes support for the GDF programme in site characterisation, site descriptive model (SDM) development, and the design and safety case. We evaluated the tender responses in early summer 2026.

International engagement

The Environment Agency and ONR regularly engage with other regulators and international programmes relevant to geological disposal, both virtually and in person. This engagement provides us with valuable information and learning from international organisations, GDF developers and regulators from countries that are in various stages of GDF siting and development.

The Environment Agency participated in the following international meetings during the reporting period:

• discussions with the Canadian regulator, the Canadian Nuclear Safety Commission (CNSC), to share learning from experience on regulator readiness for geological disposal
• the 2025 annual meeting of the Nuclear Energy Agency (NEA) Integration Group for the Safety Case (IGSC) which is attended by both regulators and developers – this included a day focused on ‘Safety Assessments, Safety Cases and Requirements Management – Learning from Facilities in Operation or Under Construction’
• the BIOPROTA 2025 annual meeting and international workshop on biosphere site characterisation, which included a site visit to Andra’s URL, specimen bank and biosphere atmospheric monitoring station – the meeting provided informative presentations, discussion and international perspectives on best practice and important learning points from operators with direct experience of site characterisation, including Svensk Kärnbränslehantering Aktiebolag (SKB, Sweden), Posiva (Finland), Andra (France) and Nuclear Waste Management Organization (NWMO, Canada)
• the NEA Digital Safety Case Symposium, which included learning about developments in the use of AI and machine learning safety case development, and discussion on what a future ‘digital safety case’ would look like, and the opportunities and challenges it would bring
• the Federal Office for the Safety of Nuclear Waste Management (BASE, German regulator) safeND research symposium on the safety of nuclear waste disposal practices – this offered useful insights into the differences between site selection programmes in European countries, research programmes underpinning site selection and safety case development and the importance of international collaborative R&D.

During the reporting period, ONR participated in the IAEA Technical Meeting of the Underground Research Facilities Network for Geological Disposal on Global Progress in Geological Disposal Programmes. This provided learning from experience from the international community on geological disposal, including the commissioning of the Onkalo spent fuel repository in Finland and the construction of the Beishan URL in China.

As an associated member of European Safeguards Research and Development Association (ESARDA), ONR Safeguards actively contributes to the Safeguards for Final Disposal Working Group. This focuses on implementing safeguards for conditioning facilities and geological repositories for radioactive waste and spent fuel. During the reporting period, ONR Safeguards attended the group’s meeting in Sweden. The event featured visits to the Swedish nuclear fuel and waste management company SKB’s Canister Demonstration Facility and the Central Interim Storage Facility for Spent Nuclear Fuel (Clab).

Both the Environment Agency and ONR attended an IAEA technical meeting to launch the new International Forum on the Safety Case for All Radioactive Waste Management Activities and Facilities. At the meeting we, along with SEPA, gave a joint presentation on UK regulation. This forum is relevant to geological disposal as well as near-surface disposal. We will use learning from it to update Environment Agency guidance and improve our assessment work.

Geological disposal programme

We expect NWS to have a clear and comprehensive programme of work to implement geological disposal that meets our regulatory requirements and to demonstrate progress against it (GRA Requirement 4). We recognise that such a programme also needs to meet other requirements as well as regulatory matters. However, these wider needs are not part of our regulatory responsibilities and so do not form part of the scope of our work.

This programme should give us confidence that NWS understands what it needs to do to achieve its goals at each phase of its work. It should also enable us to plan and focus our pre-application engagement and scrutiny work, assess NWS’s progress towards meeting our requirements, and ensure we can put regulatory resources in place when required.

We engage with NWS at quarterly GDF programme meetings and at supporting technical and keep in touch meetings. Progress on the GDF programme slowed during the reporting period when NWS needed to revise the programme to take account of the government’s 2025 Spending Review. We are also aware that the NDA Group, including NWS, is reducing staff numbers. As part of our ongoing engagement with NWS, we will need assurance that there will be enough capability and capacity to implement the next phase of the GDF programme. In addition, in 2026 after the end of the reporting period, NWS submitted its decision on progressing to site characterisation in one or more communities (this would include deep borehole investigations) and was awaiting a response from the Secretary of State for DESNZ. In advance of a decision, our engagement with NWS during the reporting period focused on work that was independent of the decision.

The Environment Agency and ONR consider that the timely delivery of disposal solutions is essential for the sustainable management of waste from the nuclear industry. This will only be achieved with adequate funding and focus. We seek to ensure that radioactive waste stored on nuclear licensed sites until a GDF is available is managed in a way that:

• protects the public, workforce and environment
• safeguards the interests of existing and future generations and the wider environment
• is in accordance with the nuclear site licence and environmental permit

Organisational capability and development

The developer and operator of a GDF should foster and nurture a positive organisational culture (promoting safety, security, safeguards and environmental compliance) at all times. It should also have a suitable management system, organisational structure and enough resources to provide essential functions (GRA Requirement 4, ONR Licence Condition (LC) 17 and 36).

We expect NWS to continue to develop its organisational capability and management systems, so that it can meet the requirements of environmental permits and a nuclear site licence to construct and operate a GDF.

The Environment Agency needs to be confident that NWS is ready to comply with environmental permit requirements before we issue environmental permits for surface-based intrusive investigations at potential sites.

ONR recognises that NWS is not currently close to submitting a licence application for a GDF, and that its organisation is being developed for the next tranche of work. Our current focus is on providing advice on the management arrangements and processes needed to support a capable organisation in line with the requirements of our LCs.

Over the first half of the reporting period, we continued to engage with NWS on its review of GDF programme management arrangements, with topics covered including: 

• NWS’s development of its integrated management system (IMS)
• quality assurance (QA) arrangements
• organisational baseline
• competency framework
• intelligent customer (IC) arrangements
• site characterisation and R&D
• safety case development

NWS’s focus on site characterisation and research, development and demonstration (RD&D) is on the near-term (next 2 years) development of its management arrangements. This includes supply chain management and procurement, and the production of formalised and assured delivery plans. Beyond this, there will be further developments as the programme matures and as the challenges of the surface-based intrusive investigations stage emerge. We noted that the approach includes identifying and mitigating risks, particularly in relation to the availability of supply chain capability. 

On safety case development, NWS is transitioning its former Radioactive Waste Management (RWM) generic Disposal System Safety Case (gDSSC) into an Environmental, Safety, Security and Safeguards (E3S) Case. The environmental aspects of the transition are directed by an Environmental Safety Case Strategy. The updated documents and arrangements will be captured in the consolidated NWS IMS. We have highlighted to NWS that the new arrangements will need to address the alignment of the E3S case with design. This is to ensure that the developing design uses best available techniques (BAT) and that doses are as low as reasonably practicable (ALARP). 

Over the second half of the reporting period, we had very limited engagement with NWS on organisational development as it was making its decision on progressing to site investigations. We expect regular engagement to resume following the response by the Secretary of State.

Over the year, we also monitored NWS’s plans for, and progress on, its first internal readiness inspection of management arrangements for the GDF programme, which was completed in June 2025. Formal response from NWS on this inspection was delayed by its GDF programme review. We now expect to receive this in 2026 to 2027, along with a first issue of a Management Arrangements Header Report. The Environment Agency will use these submissions in planning for our first permit readiness inspection. This was originally scheduled for 2025, but we now plan to carry this out in the second half of 2026 to 2027.

During the reporting period, NWS transitioned from using supply chain support to in-house resources to bring its management arrangements to sufficient maturity to allow us to permit surface-based intrusive investigations. Going forward, we will be looking for assurance that NWS is providing adequate resources to progress this work.

Preparing for intrusive investigations

As specified in our staged regulation process for geological disposal, NWS will need to apply to the Environment Agency for an environmental permit to carry out the drilling of deep site investigation boreholes. The applications must take full account of our environmental permitting requirements (GRA section 5). Based on current planning assumptions, we do not expect to receive a permit application until at least 2 years after any decision to proceed to surface-based intrusive investigations has been made. We are currently developing our guidance on staged regulation and the permitting templates (see Regulatory preparations).

NWS will also require a Development Consent Order (DCO) to begin the intrusive investigations. The Environment Agency is a statutory consultee in this process.

Advice on major permissions

The Environment Agency is providing advice to NWS on our requirements for the surface-based intrusive investigations permit application and the supporting initial site evaluation (ISE).

We attended monthly meetings with NWS throughout the reporting period about its proposals to implement major permissions. We also provided regular updates to NWS on progress concerning the development of our guidance and permit template documents.

Following a query from NWS on whether the Ministry of Defence (MoD) is a formal consultee on our permitting process, we explained that consultation for new permits will be guided by the current memorandum of understanding between the Environment Agency and the MoD. We will cooperate, hold joint meetings and work in partnership on areas of mutual interest, which could include engaging on permit applications of interest to the MoD.

We clarified with NWS that the definition of groundwater in our staged regulation guidance and GRA aligns with the definition in the relevant legislation and wider UK regulatory guidance.

We advised NWS that our guidance on the management of radioactive waste from decommissioning nuclear sites will not apply until there is radioactive waste or material on the site. Therefore, this would not apply to a site that is investigated but is not taken forward as a site for waste disposal. This includes permit surrender applications at the underground investigations stage of GDF permitting even though a nuclear site licence is also likely to be in place. This is because there will be no radioactive waste or material that may benefit from in situ or onsite disposal. We will specify surrender requirements in our staged regulation guidance that are proportionate and consistent with environmental permitting legislation.

Site evaluation

Regulators are independent of the site selection and evaluation process, but we will provide advice on matters relevant to our respective regulatory remits. We did not engage with NWS on its site evaluation during the reporting period. We expect to engage with them to understand the information supporting the decision on whether to proceed to surface-based intrusive investigations after the decision is announced.

Site understanding

The potential GDF host rock of interest in Copeland is in the inshore area. The underground part of the facility would be located deep below the seabed, but within the outer limit of UK territorial waters at around 22km offshore.

NWS needs to demonstrate that it adequately understands the geological and hydrogeological environment to justify its proposals for intrusive investigations. It is developing a SDM for Copeland to summarise the existing knowledge of the areas of focus. This is intended to collate relevant available data that underpin the evaluation topics, for example, geological, hydrogeological and geotechnical data, and to identify information gaps and uncertainties that it will need to address in its developing safety cases. The SDM will be based initially on:

• desk-based information
• the results of a marine seismic survey of the geology in the inshore region off the Copeland coast during summer 2022
• the results from legacy seismic surveys in the Copeland region that NWS has purchased and reprocessed

NWS gave the Environment Agency regular updates on the development of its SDM for Copeland during the reporting period. Towards the end of 2025, we received copies of the latest version of the SDM for review. We will provide feedback on these documents to NWS later in 2026.

Site investigation programme development

The Environment Agency expects NWS to have appropriate plans and procedures in place to carry out the site investigation and characterisation work needed to implement geological disposal, and to inform the safety cases and GDF design and construction (GRA Requirement 11). At this stage, we want to make sure that NWS’s plans and actions for future site investigations are consistent with our permit requirements and would not compromise the integrity of potential GDF sites.

NWS gave the Environment Agency regular updates on the development of its site characterisation plan (SCP) for Copeland during the reporting period. Towards the end of 2025, we received copies of the latest version of the SCP for review. We will provide feedback on these documents to NWS later in 2026.

The Environment Agency met with NWS in September 2025 to understand its arrangements for managing geoscientific data, including data from its site investigations. We agreed the importance of making sure that data are available in an enduring format that will be accessible throughout the lifetime of the GDF programme.

GDF development

NWS’s applications to carry out activities leading to the development of a GDF must be consistent with government policy (the UK policy framework for managing radioactive substances and nuclear decommissioning ^{[footnote 7]}). They must also comply with relevant legislation (for example, the Environmental Permitting Regulations 2016) and the duties placed on operators of a licensed nuclear site (nuclear safety, security, safeguards, radioactive materials transport, and nuclear site health and safety).

NWS’s applications should also address regulatory expectations, including those expressed in this report and previous reports in this series, as well as showing awareness of new and emerging regulations and guidance.

Any application for an environmental permit relating to a proposed disposal of solid radioactive waste must be supported by a suitable environmental safety case (ESC) as described in the Environment Agency’s GRA for the disposal of solid radioactive waste ^{[footnote 1]}. Similarly, any application for a nuclear site licence to construct and operate a GDF will need to be supported by adequate demonstrations of nuclear safety, security and safeguards ^{[footnote 3] [footnote 4] [footnote 5] [footnote 6]}.

We want to establish a clear and common understanding with NWS of the requirements of permit and licence applications to make sure that any future applications take full account of our regulatory requirements.

The Environment Agency plans to issue an updated version of its GRA later in 2026, accompanied by separate guidance on the staged regulation of the development of a GDF in England.

During the year, we held routine meetings with NWS to discuss its design and safety case work area and schedule. We also provided regulatory feedback on a number of NWS’s documents that it will use to guide its design and safety case development.

The Environment Agency commented on NWS’s draft site characterisation BAT case template. We considered this a useful opportunity to make sure that our requirements for the demonstration of BAT will be taken into account in the development of the site characterisation. We made 2 recommendations for NWS to consider in its forward work:

• make sure that BAT will be identified and used in intrusive investigation work to acquire information and data to determine the suitability of a site for underground disposal
• review and rationalise its documentation on optimisation and BAT for the GDF programme

This feeds into ongoing Environment Agency and ONR engagement with NWS on ensuring demonstration of optimisation of radiological protection during GDF development. In addition, the Environment Agency and ONR reviewed and provided feedback on developing work in this area.  

The Environment Agency also reviewed NWS’s modelling strategy. This describes a logical approach to model strategy development, and we support NWS’s intention to extend the modelling strategy to cover Low Level Waste Repository (LLWR) modelling in a future phase. We identified good practices in NWS’s development of a cross-disciplinary modelling community of practice, and its intent to develop a model hierarchy diagram. However, we made a number of comments and 5 recommendations on topics for NWS to consider in a future update to the document. We also encouraged NWS to continue to engage in regulatory dialogue on modelling and related issues.

ONR has closed out Regulatory Issue (RI) on GDF fire safety assessment (GDF_RI_015) on the basis that:

• NWS has provided further information on the development of its hazard management strategies with the objective of producing a preliminary safety report
• as the location and site geology are still to be identified, NWS has complied with the requirements of the RI as far as is possible at this stage of the project in relation to developing credible design provisions for adequate life fire safety arrangements for the programme

The Environment Agency and ONR provided feedback to NWS on the GDF Sponsor’s Requirements (an NDA document), and NWS’s Stakeholder Needs and Requirements report and the associated governance procedure. We provided our comments on the NDA’s GDF Sponsor’s Requirements for NWS to consider when discussing the document with NDA.

We will continue to engage with NWS as it develops its design and safety case. Work planned during 2026 to 2027 includes reviewing updates to topics on which we provided feedback during 2024 to 2025, including GDF design principles, technical management and safety case development. We also anticipate engaging with NWS in 2026 to 2027 on:

• its concept of operations
• its technical management plan, operational and operational environmental safety assessment and hazard management strategy
• the pre-concept ESC
• the conceptual biosphere model

Following any decision on a site (or sites) to take forward to surface-based intrusive investigations, we have asked NWS to arrange a workshop with us. This is to outline its plans for site characterisation, design and safety case inputs to the site evaluation and the envisaged structure and content of the ISE, which will accompany the intrusive investigations permit application.

Waste management

Waste producers are responsible for appropriately characterising, segregating, treating and packaging the UK’s most hazardous radioactive waste. This is waste in the inventory for geological disposal, which should meet the expected waste acceptance criteria (WAC) of a GDF. The operator of a GDF will establish WAC that are consistent with the assumptions made in the GDF safety cases. Along with the consignee, they will also be responsible for making sure that the consigned waste is consistent with the WAC, including transport and handling (GRA Requirement 13 and LC 4). Once the waste is consigned, the operator of a GDF will be responsible for ensuring the facility, including the packaged waste within, is compliant with its nuclear site licence and environmental permit.

NWS provides an assurance of disposability process to reduce risk from the waste treatment and packaging stages by assessing whether packaging proposals are compatible with the current geological disposal concept and designs. Through this process, NWS provides disposability advice on the treatment and packaging of the UK’s most hazardous radioactive waste to waste producers and potential waste producers, such as those involved in nuclear new build. This also allows the GDF design to accommodate the packaged wastes it must receive. At this stage of the GDF design process and in the absence of WAC, the assurance of disposability process guides operators on how to treat and package their waste in the inventory for geological disposal to reduce the risk of producing a product that is not eventually disposable.

We expect NWS to assess packaging proposals for the UK’s most hazardous radioactive waste against clear and consistent published specifications and guidance. This is to assure us that NWS’s disposability advice is underpinned and clearly traceable to its developing GDF requirements and safety case. In turn, we expect waste producing sites to use this advice to make appropriate decisions, consistent with BAT and ALARP principles for the whole waste lifecycle. This is to ensure that the UK’s most hazardous radioactive waste is suitably packaged for handling, transport to, and disposal in, a GDF.

We expect NWS to work effectively with waste producers, particularly where there is a need to understand and help resolve tension between near-term waste management priorities on existing nuclear sites, such as site hazard reduction and longer-term disposability priorities. We also expect NWS to share good practice in waste packaging, including through published guidance to waste producers. We engage with NWS to build confidence that:

• the UK’s most hazardous radioactive waste will be packaged in a way that is suitable for transporting to, handling and disposing of at a GDF in line with the safety case and with no, or minimal, reworking
• the UK’s most hazardous radioactive waste will be conditioned to a safe, passive, transportable and disposable form as soon as is reasonably practicable
• NWS’s procedures, guidance, specifications and limits encompass the full range of wastes destined for geological disposal and are likely to ensure compliance with permit requirements so that they are acceptable for disposal

Integration of assurance of disposability with GDF systems engineering

In April 2025, NWS provided us with its response to our RI on keeping assurance of disposability and GDF development current and consistent (GDF_RI_016). We followed this up with a meeting in June 2025 to discuss the status of each of the 7 actions in the RI and the expected completion date. Overall, we consider that NWS has made significant progress towards addressing the actions, with 1 of the 7 actions being completed, 3 awaiting minor revisions and the remaining ones showing significant development. The initial request and status of each RI action are as follows.

Action 1 – Change request (CR) implementation

We asked NWS to prioritise its CR implementation plan due to a backlog of requests. This will ensure that NWS has a clear baseline for its GDF programme and assurance of disposability. We asked NWS to demonstrate how its CR database is used to allow us to close this action. This will take place during 2026 to 2027.

Actions 2 and 3 – Maintenance of early-stage disposability assessments and periodic reviews

We asked NWS to expand its periodic review to include significant and impactful waste streams. This was to ensure that where operators had spent significant resources and effort, any subsequent changes in disposability requirements with respect to NWS’s design, or treatment and packaging by the operator, would be captured at an earlier stage.

Significant and impactful waste streams are where operators are making or reviewing management decisions that could have a large effect on GDF design and safety cases, or may be challenging to make disposable. This includes waste streams that are in the early stages of disposability assessment as well as those in the final stage.

Our request is important because the early advice may be acted on in waste management BAT/ALARP assessments and decisions on nuclear sites. NWS provided an updated periodic review which included some positive changes towards this task. However, we require further engagement to ensure that all significant and impactful waste streams are included before this task is closed.

Action 4 – Effects of complexity in waste for disposal

We asked NWS to provide evidence that it understands the effects of complexity arising from multiple waste types on the modelling that supports the ESC, and particularly the limitations in the 2016 gDSSC baseline in this regard. NWS provided us with a storyboard which outlined the various models it is developing that sit within its model hierarchy. While this was good progress, it did not sufficiently explain how different waste packages would be considered within the model. Therefore, we have requested additional information on this, particularly how previously developed models are being considered.

Action 5 – Maintaining validity of disposability assessments with GDF siting and design developments

We asked NWS to set out in its arrangements as to how it will continue to provide and maintain its disposability advice as more detailed underpinning knowledge emerges and as GDF requirements develop; this could include site-specific knowledge. NWS provided us with its GDF Design and Configurations Report. We did not feel that the report provided all the information we needed and, therefore, an additional meeting took place in December 2025. NWS explained how changing from a generic design to a site-specific design would not jeopardise the validity of currently endorsed disposability assessments due to its assurance of disposability concept. This engagement provided the information we needed and we will close this action after NWS has updated its report to reflect this discussion.

Action 6 – Waste disposal bounding geological conditions

We asked NWS to demonstrate how waste package considerations are bounded by site evaluation criteria. NWS will respond to this action following the decision on whether to go forward to surface-based intrusive investigations.

Action 7 – Lifecycle disposability risk management

We asked NWS to facilitate a focused workshop on the topic of waste lifecycle BAT and ALARP with the Environment Agency, ONR and other relevant stakeholders. This workshop took place in October 2025, with a further follow-up engagement in February 2026. It resulted in a productive discussion around the requirements for lifecycle thinking for the management of radioactive waste from generation to processing, storage and disposal. A plan for future engagement was agreed.

Lifecycle BAT and ALARP

As a response to Action 7 of GDF_RI_016, NWS facilitated regular engagements with the Environment Agency and ONR on how lifecycle thinking can be applied to BAT and ALARP in the context of radioactive waste disposal. This concept takes account of the fact that a solution that is BAT and ALARP at one stage of the radioactive waste’s lifecycle may not be the best approach when considering the lifecycle as a whole.

We made good progress in achieving consensus with NWS on the requirements of lifecycle thinking and how this will ultimately affect the lifecycle thinking of waste producers and NWS. We will continue to engage with NWS on this topic. Once suitable progress and consensus have been made, we have requested that waste producers are brought into the process to ensure there is sufficient buy-in from all organisations responsible for managing the UK’s most hazardous radioactive waste across its lifecycle.

Disposability of high heat generating waste (nuclear material)

In February 2026, the Environment Agency and ONR reviewed NWS’s ‘Plutonium Integrated Project Team (Pu-IPT) Hold Point 2’ report. This report summarises the various areas of research that NWS is currently undertaking to design a suitable disposal package and GDF disposal vault for the UK’s plutonium stockpile. This highlighted the good progress NWS is making to ensure that the eventual plutonium waste form is disposable and also, with respect to lifecycle thinking, that it is in a form that suits Sellafield Ltd (SL) and NDA requirements. The Pu-IPT has shown a collaborative approach to the research and design and has clearly considered BAT and ALARP within its processes.

Disposability of high heat generating waste (spent fuel)

The Environment Agency and ONR have started to engage with NWS to understand how it is working with SL to ensure that SL’s Enterprise Integrated Fuel Study does not result in an unacceptable amount of spent fuel being disposed of through the GDF’s low heat generating waste route. NWS is working closely and together with SL and NDA to ensure that an acceptable solution is reached for all parties. While we are suitably confident in the current arrangements, we will be engaging and scrutinising this further in 2026 to 2027.

NWS’s research, development and demonstration

The developer and operator of a GDF needs to carry out timely RD&D to inform its activities and ensure it fulfils its obligations, such as demonstrating optimisation to keep doses from radiation as low as reasonably achievable or practicable (ALARA or ALARP).

We expect NWS to have a targeted and prioritised RD&D programme in place, informed by wider national and international research or implementation programmes. NWS will need to identify and address issues that require RD&D to meet our requirements in a timely way. NWS should be clear, through its management process, why the RD&D it carries out is needed and what knowledge gaps it will fill.

In the reporting period, the Environment Agency had several engagements with NWS on its RD&D programme. In April 2025, we met with NWS to get an update on its Backfill, Gas, and Non-radiological contaminant IPTs. We also attended the NWS RSO geoscience webinar in May. 

In July 2025, NWS updated the Environment Agency on its underpinning research and RD&D planning. This meeting covered the background of NWS’s RD&D Plan, the core topics and topic owners. NWS presented how it is developing the plan, the information it will contain and its structure. NWS expects to send its plan to us for review in 2026 to 2027. We also met with NWS in October 2025 to discuss its social science and biosphere research.

The Environment Agency was invited to 2 of NWS’s internal training sessions on non-human biota assessment and non-radiological contaminants which several assessors and regulators were able to attend. We also received access to the recordings of past training which covered a broad range of topics and will be a valuable resource in upskilling our staff to meet the needs of the GDF programme. 

In January 2026, the Environment Agency attended NWS’s RSO conference. We presented on how we will regulate a GDF and the importance of R&D in underpinning the ESC. The conference was a useful opportunity for us to learn about current research NWS is carrying out or sponsoring. It also provided an opportunity for academics to better understand the context of GDF development and where their research will underpin future safety cases.

NWS withdrew its management support from the RSO at the end of the reporting year, so this was the last RSO conference. NWS informed us that it would continue to fund existing research commitments and provide subject matter expert support. NWS has also informed us that it will be implementing a new academic strategy to sustain investment in research activities within the constraints of the Spending Review. We will engage with NWS to understand how the knowledge and skills developed over the course of the RSO’s duration is being captured and managed so that it can continue to contribute to the GDF programme. We are also encouraging NWS and senior research leaders to investigate how this level of academic engagement can continue.

Support for the siting process

We have no regulatory role in selecting potential sites for a GDF. However, we are:

• providing support to communities that are considering hosting a GDF
• sharing regulatory information with community partnerships in Cumbria
• advising on matters relating to our respective areas of regulation

In June 2025, Lincolnshire County Council made the decision to withdraw from the Theddlethorpe Community Partnership. This followed East Lindsey District Council’s formal decision to withdraw in April 2025 and ended the siting process in the area. As of March 2026, there were 2 GDF community partnerships in England: Mid Copeland and South Copeland.

The potential GDF host rock of interest in Copeland is in the inshore area. The underground part of the facility would be located deep below the seabed, but within the outer limit of UK territorial waters around 22km offshore.

The Environment Agency’s engagement plan for geological disposal sets out our objectives, stakeholders and activities. These activities include publishing information and infographics, producing materials to use at public exhibitions and online, as well as engaging with groups and community partnership members to explain our role. The information includes:

• a short animation about the regulators’ role in geological disposal available on YouTube
• an overview of the regulatory processes that the Environment Agency and ONR will apply to the development, operation and closure of a GDF in England
• information pages on Regulating the geological disposal of radioactive waste: environmental protection on GOV.UK and ONR’s website
• our annual reports, including this one

Mid Copeland and South Copeland Community Partnerships

We were not invited to attend any community partnership events or NWS organised events in Cumbria during the reporting period.

We offered to host a meeting with members of both community partnerships to explain our role and share how we are scrutinising the work of NWS, but we did not receive a request to do this during the reporting period.

Wider stakeholder engagement and consultation on geological disposal

In May and November 2025, the Environment Agency held its bi-annual ‘meet the regulator’ engagement forum for stakeholders in Cumbria, which provides an opportunity for discussion and questions about geological disposal. Invitees include both local stakeholders and community partnership members. We also updated stakeholders at our national ‘meet the regulator’ meeting.

During these meetings, we provided updates on our geological disposal work, our annual report and the ongoing work on guidance following the GRA and staged regulation consultation. We also answered questions on geological disposal.

ONR’s Non-Governmental Organisation (NGO) Forum meets twice a year. The meetings provide an opportunity to discuss and engage with members of the NGO community on a range of issues, including geological disposal. During the reporting period, the forum met in April and November 2025. Minutes from the meeting are available in Engaging with Non-Government Organisations (NGOs) and campaign groups on ONR’s website.

Both the Environment Agency and ONR have responded to several enquiries from the public and NGOs about how we would regulate geological disposal.

Both regulators promoted our previous year’s joint annual report on regulatory scrutiny and engagement on geological disposal widely to stakeholders. The Environment Agency issued social media, a press release and an e-bulletin in Cumbria.

The Environment Agency provided information about regulating geological disposal to MPs in Cumberland and Westmorland through established local routes and Area Director updates.

Both regulators attended several meetings of the West Cumbria Sites Stakeholder Group during the year where we provided updates on geological disposal, including:

• 2 NWS themed meetings in August 2025 and February 2026
• NWS working groups in May 2025 and November 2025

Both regulators attended the DESNZ NGO forum to observe discussions. Geological disposal featured in discussions at these meetings.

Working with NWS

The Environment Agency and ONR meet regularly with NWS’s community engagement and communications team. These meetings enable NWS to share its plans for community engagement and help us support community discussions. During this year, we reviewed and updated our terms of reference.

We work with NWS to consider how best to share information about regulation with community partnerships and any future working groups that may emerge. We also receive updates from NWS on its corporate communications on geological disposal, national stakeholder engagement, and its work with the Committee on Radioactive Waste Management (CoRWM).

Engagement with the Committee on Radioactive Waste Management (CoRWM)

The Environment Agency and ONR met with CoRWM twice in the reporting period.

ONR hosted a workshop on the storage of HAW in January 2026, which will inform CoRWM’s work on interim storage.

We held a virtual meeting with members of CoRWM’s sub-group on Planning and Regulation in February 2026. Topics on the agenda included the Spending Review, recommendations from the 2025 Nuclear Regulatory Review relevant to geological disposal and international practice. CoRWM members were reassured that both the Environment Agency and ONR extensively engage internationally on topics related to radioactive waste disposal.

Summary

The Environment Agency and ONR engaged with NWS during 2025 to 2026 to provide pre-application advice and scrutiny of its developing GDF programme, as well as to prepare for future regulation and to support the siting process.

We observed that progress on the GDF programme slowed during the reporting period when NWS needed to revise the programme to take account of the UK government’s 2025 Spending Review. We are aware that the NDA Group, including NWS, is reducing staff numbers. As part of our ongoing engagement with NWS, we will need assurance that there will be enough capacity and capability to implement the next phase of the GDF programme.

In 2026, after the end of the reporting period, NWS submitted to the Secretary of State for DESNZ its decision on progressing to site characterisation in one or more communities, which includes deep borehole investigations. At the time of publishing this report, the Secretary of State had not provided a response to NWS’s decision. Based on NWS’s current planning assumptions, the Environment Agency does not expect to receive a permit application until at least 2 years after any decision has been made to proceed to surface-based intrusive investigations. In advance of a decision, the Environment Agency and ONR’s pre-application advice and scrutiny of the GDF programme during the reporting period focused on the generic parts of the programme that were independent of decisions on the siting of the GDF.

During the reporting period, we:

• provided feedback to NWS on the GDF Sponsor’s Requirements document, NWS’s Stakeholder Needs and Requirements report and the associated governance procedure
• reviewed GDF programme management arrangements for site characterisation and the E3S – due to NWS programme delays, the Environment Agency postponed a planned first permit readiness inspection until late 2026 to 2027
• began reviews of the latest versions of the SDM and SCPs for Copeland
• reviewed the template for the site characterisation BAT case, which we considered to be a useful opportunity to make sure that our requirements for the demonstration of BAT will be taken into account in the development of the site characterisation methodology
• reviewed NWS’s GDF modelling strategy, which we considered a logical approach to model strategy development
• closed out a RI on fire safety assessment, concluding that NWS has developed credible design provisions for adequate life fire safety arrangements as far as is possible at this stage of the GDF programme
• concluded that NWS has made significant progress against addressing actions from a RI on keeping assurance of disposability and GDF development current and consistent – this included discussion around the requirements for lifecycle thinking for the management of radioactive waste from generation to processing, storage and disposal (we cannot close out the RI until after the GDF siting decision has been made)
• continued to engage with NWS’s Pu-IPT – we consider that NWS is making good progress in satisfying itself that the eventual plutonium waste form is disposable in a form that suits SL and NDA requirements
• advised NWS to investigate how academic engagement will continue following closure of its RSO

We continued to enhance our regulatory capabilities and capacity in preparation for regulating a GDF, which will be a first-of-a-kind activity in the UK. This includes recruitment of new staff, attending internal and external seminars on topics relevant to geological disposal and continuing our international engagement activities. The Environment Agency is also procuring external technical support through a new ‘Regulatory Assessments of Solid Radioactive Waste Disposal Framework’.

The Environment Agency, working with SEPA, NRW and NIEA, updated GRA of disposal facilities for solid radioactive waste and produced new guidance on staged regulation of a GDF in response to feedback received during public consultation [2]. We plan to issue these documents later in 2026. The template for the intrusive investigations permit will be aligned with this guidance.

The Environment Agency and ONR provided updates on their geological disposal work at relevant stakeholder meetings throughout the year. We were not invited to attend any community partnership events or NWS organised events in Cumbria during the reporting period.

The Environment Agency and ONR consider that the timely delivery of disposal solutions is essential for the sustainable management of waste from the nuclear industry. This will only be achieved with adequate funding and focus. We seek to ensure that radioactive waste stored on nuclear licensed sites until a GDF is available is managed in a way that:

• protects the public, workforce and environment
• safeguards the interests of existing and future generations and the wider environment
• is in accordance with the nuclear site licence and environmental permit

Annex A: List of Regulatory Issues and Observations

Regulatory Issue	Title	Status
GDF_RI_001	Leadership and governance	Closed
GDF_RI_002	Organisational capability	Closed
GDF_RI_003	Control and assurance	Closed
GDF_RI_004	Organisational learning	Closed
GDF_RI_005	Assessment of innovative packaging proposals	Closed
GDF_RI_006	Resolution of periodic review findings	Closed
GDF_RI_007	Assurance of packaging assessments and advice	Closed
GDF_RI_008	Board governance of important areas of risk/performance	Closed
GDF_RI_009	Corporate Health, Safety, Security, Environment and Quality (HSSEQ) structure	Closed
GDF_RI_010	Disposability assessments and endorsements sensitive to changes	Closed
GDF_RI_011	Waste package records	Closed
GDF_RI_012	Workforce capability plan	Closed
GDF_RI_013	Characterisation and assessment of the non-radioactive component of waste in the inventory for disposal	Open
GDF_RI_014	Operational environmental safety assessment	Open
GDF_RI_015	Approach to fire safety assessment	Closed
GDF_RI_016	Keeping disposability assessments and GDF development current and consistent	Open

Regulatory Observation	Title	Status
GDF_RO_001	Protection against non-radiological hazards	Closed
GDF_RO_002	Optimisation	Closed
GDF_RO_003	Lessons from the Fukushima disaster	Closed
GDF_RO_004	Defining waste package fissile limits for disposal	Closed
GDF_RO_005	Lessons from the Waste Isolation Pilot Plant (WIPP) incident	Closed
GDF_RO_006	Building confidence in data and modelling	Closed
GDF_RO_007	Auditable evidence in support of an environmental safety case (ESC)	Closed
GDF_RO_008	Defining waste package fissile levels	Closed

References

1. Environment Agency and Northern Ireland Environment Agency, February 2009. Geological disposal facilities on land for solid radioactive wastes: Guidance on requirements for authorisation. [Accessed 18 August 2026] ↩ ↩²

2. Environment Agency, Natural Resources Wales, Scottish Environment Protection Agency and Northern Ireland Environment Agency, October 2025. Consultation summary: guidance on the requirements for authorisation and staged regulation for the disposal of solid radioactive waste. [Accessed 18 August 2026] ↩ ↩²

3. ONR, March 2023. ONR Technical Assessment Guide. Geological disposal. [Accessed 18 August 2026] ↩ ↩²

4. ONR, January 2020. Safety Assessment Principles for Nuclear Facilities ONR CM9 Ref 2019/367414. 2014 Edition, Revision 1. [Accessed 18 August 2026] ↩ ↩²

5. ONR, March 2022. Security Assessment Principles for the Civil Nuclear Industry. 2022 issue, version 1. [Accessed 18 August 2026] ↩ ↩²

6. ONR, ONR Nuclear Material Accountancy, Control and Safeguards Assessment Principles (ONMACS). [Accessed 18 August 2026] ↩ ↩²

7. Department for Energy Security and Net Zero, Scottish Government, Welsh Government and Northern Ireland Department of Agriculture, Environment and Rural Affairs, May 2024. UK policy framework for managing radioactive substances and nuclear decommissioning. [Accessed 18 August 2026] ↩ ↩² ↩³