Sellafield - accounts - Parliament

First Annual Report of the Chair of the Committee of Public Accounts.

(Paras 55&56) We were informed that the estimated cost of decommissioning
the site was £136 billion, an increase of 18.8% since March 2019. When the
previous Committee last took evidence on Sellafield in 2018, the nine major
projects that were underway then were between them delayed by 165 months
and expected to cost £913 million more than originally budgeted. However,
the Committee heard that the combined costs of four of these projects are
now expected to cost £1.15 billion more than when the previous Committee
reported. Each of these four projects will also be delayed further by
between 58 and 129 months each. Sellafield Ltd has begun retrieving
hazardous waste from the site, and in the longer term, this waste will be
stored in an underground offsite Geological Disposal Facility (GDF) capable
of storing the waste for thousands of years. However, the Committee found
that the opening date of the GDF has slipped from 2040 to the late 2050s.
For every decade of delay, additional buildings could need to be
constructed to accommodate short-term storage of the waste at a cost of
£500–760 million. As well as the serious implications for the value for
money of the project, this delay makes the ambition to completely
decommission the Sellafield site in the next hundred years even more
challenging. In addition to this, in August the GDF project was rated red
in its Delivery Confidence Assessment by NISTA, meaning “successful
delivery of the project appears to be unachievable.” DESNZ has since
acknowledged that the NDA is “undertaking some replanning to mitigate
risks and support ongoing progress” across all of its programmes,
including the GDF. We will be following any further developments closely
over the coming months.

 House of Commons 15th Oct 2025

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