Select committee: Public Accounts Committee

Conclusion 3

28th Report - Decommissioning Sellafield Published 4 Jun 2025 Addressed to HM Treasury
Conclusion (the committee's words)
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 billion more, and be delivered many years later than Sellafield Ltd expected in 2018, the last time this Committee examined Sellafield. Sellafield has a poor track record of delays and cost overruns, but the NDA reassured us in 2018 that cost forecasting is improving while the Department believed that the estimates of those costs have begun to stabilise. Nevertheless, there are some signs that a corner may finally have been turned. Sellafield Ltd is now working with a group of contractors in a different way, which places more emphasis on planning. As a result, most of the projects that have started more recently are being delivered in line with their business cases. However, one of Sellafield’s more recent major projects, the Replacement Analytical Project (RAP) has been managed very poorly indeed. When Sellafield Ltd ‘paused’ RAP last year, it was expected to cost up to £1 billion more than originally approved while new plutonium analysis capabilities would be at least 5 years late. Sellafield Ltd now believes that it can cut this gap to around one year and save money by converting a different building instead. However, £127 million spent on RAP will have been wasted. 4 recommendation As it carries out more detailed planning for future provision of Analytical Services, Sellafield Ltd should write to the Committee at a suitable point (but within six months) to update us on: • when it expects to be able to carry out the plutonium analysis the site will require (and what level of confidence it has in this estimate); • how much it expects to spend on the projects it has decided to carry out instead of the Replacement Analytical Project; and • what assessment it has made of the costs and value for money of mainta

From: Public Accounts Committee, 28th Report - Decommissioning Sellafield (HC 363), 4 June 2025

Government response

Latest Treasury Minutes progress report to the Committee of Public Accounts on the Twenty-eighth Report of Session 2024-26

The government responded to the whole report on 4 June 2026 (deadline 4 August 2025).

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Treasury minutes: Government response to the Committee of Public Accounts on the Twenty-eighth report from Session 2024-26

Published 18 September 2025.

Summary written by Accountability Index from the government's response. It is not the government's own words.

The government says it agrees with each of the Committee's recommendations covered in this extract, with target implementation dates ranging from December 2025 to March 2027, though some are already implemented and some publication details remain to be settled.

  • On oversight (recommendation 1), the government agrees and describes the recommendation as implemented. Since January 2025 the department's Principal Sponsor chairs monthly performance meetings, and a review of the revised governance structure will be initiated within 2025-26.
  • On medium-term targets (recommendation 2), the government agrees, with a target date of March 2027. Work "is required to establish how and then when this information would be made public", and DESNZ will commission an independent, externally led review of the NDA Group by end-2025.
  • On asset management (recommendation 4), the government agrees and says the recommendation is implemented. It states that "Solely increasing the productivity of maintenance teams misses the demands" of the site's complex asset picture.
  • On long-term cost scenarios (recommendation 5), the government agrees, with a target date of December 2026. It says "It will be necessary to agree the mechanism and timing, including what is published".

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