28th Report - Decommissioning Sellafield

Select Committee
Public Accounts Committee HC 363 4 June 2025
Report Status Government responded
Conclusions & Recommendations 32 items (9 recs)
Source View on Parliament website
Government Response (AI assessment · 31 of 32 classified)
Accepted 28
Acknowledged 2
Not Addressed 1
Government response
Treasury minutes: Government response to the Committee of Public Accounts on the Twenty-eighth report from Session 2024-26 · published 18 Sep 2025
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Recommendations & Conclusions

32 results
2 Recommendation Accepted
Publish medium-term targets for Sellafield's key decommissioning activities and report annual progress.
Recommendation
The targets set for Sellafield Ltd neither support DESNZ and the NDA in holding it to account for poor performance, nor allow Sellafield Ltd to demonstrate it is making meaningful progress towards addressing the site’s hazards. In recent years, Sellafield … Read more
Government Response Summary
The government agrees, stating the NDA will develop a consistent planning approach, deliver revised whole-life, 20-year, and 5-year operating plans, and define medium-term milestones. The NDA will also set out actions for achieving a decommissioned site, with progress reported annually. DESNZ will commission an independent review of the NDA Group by end-2025.
HM Treasury
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3 Conclusion Accepted
Require Sellafield Ltd to update Committee on plutonium analysis and alternative project costs.
Conclusion
Sellafield’s ability to deliver its largest projects on time and budget is still too variable. While there are some recent signs of improvement, Sellafield continues to repeat old mistakes. Four of the largest projects at Sellafield will collectively cost £1.15 … Read more
Government Response Summary
The government agrees, stating Sellafield Ltd will provide an update on future analytical capability plans within six months (December 2025) and a further update once the Outline Business Case for Special Nuclear Material capability is completed (June 2026), including a delivery schedule and confidence level.
HM Treasury
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4 Conclusion Accepted
Require Sellafield Ltd to explain actions addressing deteriorating asset condition and maintenance team productivity.
Conclusion
The failure of the Replacement Analytical Project illustrates the need to improve asset management at Sellafield. Sellafield is frequently in a race against time to complete work before assets (such as buildings or equipment) reach the end of their life … Read more
Government Response Summary
The government agrees and states the recommendation has been implemented. Sellafield Ltd has sent a letter outlining its asset management approach, including a targeted Asset Management Intervention launched in 2022, whose outcomes will be embedded into business-as-usual operations.
HM Treasury
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5 Conclusion Accepted
Publish financial model scenarios to reduce NDA estate lifetime decommissioning costs, including funding constraints.
Conclusion
DESNZ is not doing enough to ensure that long–term value for money is achieved from decommissioning the Sellafield site. The cost of decommissioning Sellafield continues to grow – notwithstanding the billions spent on the site every year. The NDA’s tight … Read more
Government Response Summary
The government agrees and commits that scenario planning will be undertaken by the NDA and Sellafield Ltd, focusing on the impact of different funding levels. This will be generated alongside an update to the current mission plan, with further work needed to define the mechanism and timing for publication.
HM Treasury
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6 Recommendation Accepted
Publish bullying/harassment prevalence, staff survey results, and reporting effectiveness metrics in NDA Annual Report.
Recommendation
The NDA and Sellafield Ltd still have more to do to build a culture where all employees feel able to raise concerns and report poor behaviour. The exceptionally hazardous nature of many of Sellafield’s activities means that it is imperative … Read more
Government Response Summary
The government agrees that the NDA will publish an annual "People" report containing staff survey results, Speak Up data, and other cultural health metrics. The report will consider breaking down results by Operating Company and demographics, guided by confidentiality, and will include relevant safety reporting data.
HM Treasury
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1 Conclusion Accepted
Committee took evidence on the decommissioning of the Sellafield site.
Conclusion
On the basis of a report by the Comptroller and Auditor General, we took evidence from the Department for Energy Security and Net Zero (the Department), the Nuclear Decommissioning Authority (the NDA) and Sellafield Ltd on the decommissioning of the … Read more
Government Response Summary
The government agrees and states the recommendation has been implemented, detailing existing oversight frameworks and a recently implemented new governance structure by DESNZ and UKGI. Within 2025-26, the department will initiate a review of this revised governance structure.
HM Treasury
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7 Conclusion Accepted
Magnox Swarf Storage Silo's radioactive leak persists, with emptying delayed significantly until 2054-2059.
Conclusion
We heard from the NDA that the Magnox Swarf Storage Silo is “the most hazardous building in the UK”. It has been leaking radioactive water into the ground since 2018–we calculated, at current rates, enough to fill an Olympic–size swimming … Read more
Government Response Summary
The government agrees and states the recommendation is implemented, detailing how the Department for Energy Security and Net Zero has recently heightened its oversight of NDA and Sellafield through new governance structures, increased meeting cadences, and shifting responsibilities from UKGI. The department will also review the effectiveness of this revised governance structure in 2025-26.
HM Treasury
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8 Recommendation Accepted
Sellafield Ltd consistently misses waste retrieval and vitrification targets since 2020 due to various issues.
Recommendation
Since 2020, Sellafield Ltd has missed most of its operational targets for retrieving waste, and turning liquid waste into a glass–like substance (both of which reduce the hazard the waste poses).12 It told us that the COVID–19 pandemic had had … Read more
Government Response Summary
The government accepted the recommendation, stating the NDA will develop a consistent strategic planning approach by March 2027, unifying plans across the estate and delivering revised whole-life, corporate, and operating plans with clear milestones. Additionally, DESNZ will commission an independent review of the NDA Group by end-2025.
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9 Recommendation Accepted
Plutonium management at Sellafield shows improvement, with long-term strategy to reduce risks by 2060.
Recommendation
The Department, NDA and Sellafield Ltd have all taken actions to improve the management of the plutonium stored at Sellafield since the previous Committee expressed concerns about this. The previous Committee raised then the lack of a long–term strategy for … Read more
Government Response Summary
The government accepted the recommendation, stating Sellafield Ltd will provide an update on future analytical capability plans by December 2025 and a further update with a delivery schedule upon Outline Business Case completion for Special Nuclear Material capability by June 2026.
HM Treasury
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10 Conclusion Accepted
Sellafield Ltd consistently underperforms against strategic waste processing targets, impacting wider site cleanup plans.
Conclusion
Sellafield Ltd has–in conjunction with the NDA and the Office for Nuclear Regulation–set a ‘strategic tolerance’ for completing key activities. It described this to us as the date “we really want to hit”, to ensure that the site is fully … Read more
Government Response Summary
The government agrees, stating the NDA will develop a consistent planning approach for all operating companies, delivering revised whole-life, corporate, and operating plans by March 2027. Additionally, DESNZ will commission an independent review of the NDA Group by end-2025 to assess strategic planning, project delivery, and financial management.
HM Treasury
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11 Conclusion Accepted
Sellafield Ltd plans significant acceleration of waste retrieval, requiring substantial capability development over next few years.
Conclusion
Sellafield Ltd has shown that it is technically possible to retrieve waste from all of its oldest ponds and silos.25 The plan to make the site less hazardous assumes that it will be able to significantly accelerate the speed it … Read more
Government Response Summary
The government agrees, stating the NDA will develop a consistent planning approach for all operating companies, delivering revised whole-life, corporate, and operating plans by March 2027. Additionally, DESNZ will commission an independent review of the NDA Group by end-2025 to assess strategic planning, project delivery, and financial management.
HM Treasury
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12 Recommendation Accepted
Efficient waste retrieval demands constant iteration, strong performance culture, and sophisticated, transparent target setting.
Recommendation
We explored with the witnesses what Sellafield Ltd needs to do to reach the point where retrieving waste becomes an efficient, routine activity. As well as installing the right equipment, they emphasised the importance of “constant iteration” – addressing problems … Read more
Government Response Summary
The government accepted the recommendation, stating the NDA will develop a consistent strategic planning approach by March 2027, unifying plans across the estate and delivering revised whole-life, corporate, and operating plans with clear milestones. Additionally, DESNZ will commission an independent review of the NDA Group by end-2025.
HM Treasury
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13 Conclusion Not Addressed
Major project delays and costs at Sellafield significantly escalated since 2018 due to poor planning.
Conclusion
When it last took evidence on Sellafield, the previous Committee was told that major project delivery was improving.32 The NDA told it that “cost forecasting is improving” while the Department said that “for the first time now, the estimates of … Read more
Government Response Summary
The government response does not directly address the committee's finding of increased costs and delays for major projects, instead citing a 2024 NAO report that noted positive progress in more recent projects and praised the Programme and Project Partners model.
HM Treasury
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14 Conclusion Acknowledged
Recent major project delivery at Sellafield shows tangible signs of improvement, with several projects on track.
Conclusion
DESNZ told us that it nevertheless believes that “there is some tangible evidence on improvement” and that “the overall direction of travel on project delivery is improving at the site”.36 Four of the five major projects which have been approved … Read more
Government Response Summary
The government acknowledges the positive progress in major project delivery at Sellafield, referencing the NAO report and the positive contributions of the Programme and Project Partners (PPP) model.
HM Treasury
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15 Conclusion Acknowledged
New Programme and Project Partners (PPP) model improves major project delivery at Sellafield.
Conclusion
We asked the witnesses to explain what has led to the apparent improvement in how projects are now being delivered. Sellafield Ltd told us that it was now delivering its largest projects in a new way, which it calls ‘Programme … Read more
Government Response Summary
The government acknowledges the positive progress in major project delivery at Sellafield, referencing the NAO report and the positive contributions of the Programme and Project Partners (PPP) model.
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16 Conclusion Accepted
Improved project planning and robust assurance processes contribute to better delivery outcomes at Sellafield.
Conclusion
More generally, the Department and the NDA told us that they believed that there was a much greater focus on ensuring projects were well–planned. ‘Reference class forecasting’ is being used to help ensure that project baselines are realistic, and there … Read more
Government Response Summary
The government reinforces the committee's observations about improved project planning and assurance, citing the 2024 NAO report which noted positive progress in major project delivery and the effectiveness of Reference Class Forecasting and the Programme and Project Partners (PPP) model.
HM Treasury
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17 Conclusion Accepted
NDA and Sellafield Ltd actively share project learning and best practice group-wide.
Conclusion
We asked the NDA and Sellafield Ltd what they were doing to ensure that other projects benefitted from these improvements. Sellafield Ltd told us that it was looking to share learning with those projects which were being delivered under its … Read more
Government Response Summary
The government states that a target focused on improving project and contract delivery by sharing and implementing lessons learned was successfully delivered in 2024-25 and will inform the NDA’s group-wide organizational learning policy.
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18 Conclusion Accepted
Replacement Analytical Project faced significant cost increases and delays due to inadequate planning.
Conclusion
A notable exception to this positive trend is the ‘Replacement Analytical Project’ (RAP) – which Sellafield Ltd now believes should be abandoned.44 This project would have refurbished a laboratory on the site so Sellafield Ltd would be able to continue … Read more
Government Response Summary
The government agrees to provide an update on future analytical capability plans as alternatives to the Replacement Analytical Project by December 2025, and a further update on the Outline Business Case for SNM capability by June 2026.
HM Treasury
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19 Conclusion Accepted
Sellafield Ltd adopted a new, cheaper plan for analytical services despite long-term uncertainties.
Conclusion
Sellafield Ltd now plans to convert a different building to support SRP, and also refurbish the existing building so it can carry on using it until 2040 (whereas RAP had been expected to remain in use until 2070).49 The NDA … Read more
Government Response Summary
The government agrees with the conclusion, stating Sellafield Ltd will provide an update on future analytical capability plans by December 2025. A further update, including a delivery schedule for the Special Nuclear Material capability, will be provided by June 2026 after the Outline Business Case is completed.
HM Treasury
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20 Conclusion Accepted
Significant financial waste on previous projects indicates slow learning of lessons at Sellafield.
Conclusion
The previous Committee criticised the NDA in 2018 for failing to learn the lessons from projects it had cancelled after belatedly realising that there were more cost–effective ways to reduce risk (having spent £586 million of taxpayers’ money on three … Read more
Government Response Summary
The government states that a target focused on improving project and contract delivery by sharing and implementing lessons learned was successfully delivered in 2024-25 and will inform the NDA’s group-wide organizational learning policy.
HM Treasury
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21 Conclusion Accepted
Sellafield's century-long decommissioning plan faces urgent race against ageing assets.
Conclusion
The NDA told us that its plan for decommissioning Sellafield will take around a hundred years, and has three phases. The current phase, focussing on ‘minimising the risk of offsite consequences’ will last until approximately the 2060s; in the next … Read more
Government Response Summary
The government agrees, stating the NDA will develop a consistent planning approach for all operating companies, delivering revised whole-life, corporate, and operating plans by March 2027. Additionally, DESNZ will commission an independent review of the NDA Group by end-2025 to assess strategic planning, project delivery, and financial management.
HM Treasury
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22 Conclusion Accepted
Increasing maintenance backlog and unknown asset conditions negatively impact Sellafield operations.
Conclusion
There is an increasing backlog of maintenance tasks at Sellafield which is affecting the condition of Sellafield’s assets. Sellafield Ltd could not carry out some tasks during the COVID–19 pandemic due to restrictions on working practices to prevent transmission of … Read more
Government Response Summary
The government states the recommendation is implemented, explaining that Sellafield Ltd launched a targeted Asset Management Intervention in 2022 and its outcomes will be embedded into business-as-usual operations.
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23 Conclusion Accepted
Deteriorating asset condition poses acute risks, impeding hazard reduction and future site operations.
Conclusion
We explored with the witnesses the implications of assets’ condition for Sellafield Ltd’s plans to address hazards and clean up the site by 2125 and identified four areas of particular concern. Firstly – poor availability of assets has impeded Sellafield … Read more
Government Response Summary
The government states the recommendation is implemented, explaining that Sellafield Ltd launched a targeted Asset Management Intervention in 2022 and its outcomes will be embedded into business-as-usual operations.
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24 Recommendation Accepted
Sellafield decommissioning costs have significantly risen, potentially compromising long-term value for money.
Recommendation
The forecast cost of decommissioning Sellafield has risen considerably since we last reported. It now stands at £136 billion, an increase of 18.8% since March 2019.68 We challenged the witnesses about the adequacy of the NDA’s budget as we are … Read more
Government Response Summary
The government accepted the recommendation, committing to undertake scenario planning by December 2026 to assess the impact of different funding levels on the Sellafield mission and inform group-level strategic planning.
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25 Conclusion Accepted
Funding constraints force difficult decisions, risking long-term costs and facility obsolescence.
Conclusion
The NDA acknowledged that its funding settlement for 2025–26 means “there are difficult decisions to be made about some of the less critical aspects”.70 It subsequently told us that it would ideally “remove risk/ hazard and liability at the earliest … Read more
Government Response Summary
The government agrees to undertake scenario planning by December 2026, focusing on the impact of different funding levels on the Sellafield Ltd mission, to inform an updated mission plan.
HM Treasury
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26 Conclusion Accepted
Department relies on NDA boards for resource allocation; lacks recent greenfield cost analysis.
Conclusion
We explored how the Department, as sponsor, ensures that the NDA and Sellafield Ltd achieve value for money. It told us that it was for the NDA board and the Sellafield board to decide how to allocate resources, within the … Read more
Government Response Summary
The government agrees, committing to undertake scenario planning by December 2026 to improve visibility of the uncertainties linked to Sellafield Ltd's mission, particularly focusing on funding levels. This will be developed alongside an update to the NDA and Sellafield Ltd mission plan.
HM Treasury
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27 Recommendation Accepted
UKGI's role in NDA oversight remains unconvincing and unclear.
Recommendation
The previous Committee questioned whether UK Government Investments (UKGI) ‘is playing any useful role’ – and whether its function could instead be discharged by the Department.78 The Department told us that UKGI did help it hold the NDA to account, … Read more
Government Response Summary
The government stated the recommendation is implemented, explaining that DESNZ has heightened its oversight of the NDA, assumed responsibility for major project and commercial/contract performance from UKGI, and will initiate a review of the revised governance structure in 2025-26.
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28 Conclusion
Geological Disposal Facility project experiences significant delays and slow progress.
Conclusion
The NDA also needs to construct a ‘Geological Disposal Facility’ (‘GDF’) to store waste permanently – including that currently at Sellafield. This project is still at a very early stage: it needs to drill boreholes before it can even start … Read more
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29 Recommendation Accepted
Government must improve valuing whistleblowers, addressing Sellafield mistreatment allegations.
Recommendation
The previous Committee took evidence on how the civil service responds to whistleblowing, and found that the government needs to do more to signal the value of whistleblowers.85 It is particularly important that everyone working on a site as hazardous … Read more
Government Response Summary
The government agrees, stating the NDA has strengthened its Speak Up policy and will publish an annual "People" report by October 2026. This report will include staff survey results and Speak Up data to provide a contextualised view of cultural progress regarding whistleblowing.
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30 Conclusion Accepted
Sellafield believes its safety reporting processes are robust and effective.
Conclusion
Sellafield Ltd told us that it believed it does have a robust process for reporting safety issues as this is one of the conditions of its nuclear site licence. It pointed to the “green rating” it had received the last … Read more
Government Response Summary
The government agrees to publish an annual 'People' report by October 2026, which will contain staff survey results, Speak Up data, and other information to assess corporate culture.
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31 Recommendation Accepted
Sellafield Ltd uses NDAs and makes significant special payments for employment claims.
Recommendation
The Department also considered that workers’ willingness to report safety issues is correlated with their willingness to report other poor behaviour.89 We asked about Sellafield Ltd’s use of non–disclosure agreements–a previous Public Accounts Committee report noted that these agreements have … Read more
Government Response Summary
The government accepted the recommendation, stating the NDA will publish an annual “People” report by October 2026, providing data on staff survey results, Speak Up incidents, and safety culture to enhance transparency and assess corporate culture.
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32 Conclusion Accepted
Sellafield's workplace culture demonstrates improvement through new 'Speak Up' initiatives.
Conclusion
The NAO report recognises that there has been an improvement since 2021 in the number of employees at Sellafield who would recommend it as a great place to work.95 Sellafield Ltd informed us that the most recent survey showed a … Read more
Government Response Summary
The government agrees to publish an annual 'People' report by October 2026, which will contain staff survey results, Speak Up data, and other information to assess corporate culture.
HM Treasury
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