Source · Select Committees · Public Accounts Committee
Recommendation 7
7
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 pool approximately every three years. The NDA accepted that this leak is its “single biggest environmental issue”. However, the witnesses told us that the radioactive particles are “contained” in the soil and do not pose a risk to the public.9 They also told us that they–and the site’s regulators–believe that the best way of 4 C&AG’s report, paras 13, 3.17, Figure 8 5 C&AG’s report, paras 1, 16, 3.7 6 C&AG’s report, Figure 7 7 Committee of Public Accounts, Nuclear Decommissioning Authority: risk reduction at Sellafield, Sixty–Fifth Report of session 2017 –2019, HC 1375, 31 October 2018 8 C&AG’s report, Figure 8 9 Qq 52–55 9 addressing the leak is to focus on emptying the silo.10 Sellafield Ltd expects that the silo will largely be emptied at some point between 2054 and 2059, which is 8–13 years later than it expected in 2018.11
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.
Government Response
Accepted
HM Government
Accepted
The government agrees with the Committee’s recommendation. Recommendation implemented The Department for Energy Security and Net Zero has recently heightened its oversight of the performance of the Nuclear Decommissioning Authority (NDA) and, in turn, Sellafield. The department, supported by UK Government Investments (UKGI), exercises oversight of the NDA through a set of frameworks and systems including: • Delegation of Accounting Officer requirements from DESNZ to the NDA Chief Executive Officer (CEO) with Accounting Officer responsibilities, in line with the corresponding HM Treasury settlement letter. • Annual priorities letter issued to the NDA Chair and CEO to set out the department’s expectations. • Annual performance review focusing on performance against annual targets. • Monthly governance and sponsorship meetings. • A cadence of senior civil service and Ministerial meetings. • Through robust scrutiny of programmes and projects through the department’s Portfolio and Investment Committee (PIC). PIC spends around 28% of time on NDA-related cases. • ‘Deep dives’ into specific areas of interest. • Attendance at NDA’s performance reviews of its operating companies. • Regular site visits. Since January 2025, the department has increased its direct oversight by implementing a new governance structure. • Previously run by UK Government Investments (UKGI), the department’s Principal Sponsor now chairs monthly performance meetings. UKGI has responsibility for overseeing operational and safety performance including monitoring performance against annual targets. • The department has assumed responsibility from UKGI for overseeing major project and commercial/contract performance. • UKGI maintains oversight of corporate and financial performance across areas such as health and safety, key targets, operations, culture, people, and risk. • Strengthened the focus of the Senior Civil Service and Ministerial meetings to focus on quarterly performance against the annual targets. • Instituted a reporting cadence of monthly to senior officials and quarterly to Ministers. Within this financial year, 2025-26, the department will: • Initiate a review of the revised governance structure to ensure it maximises effectiveness.