In its annual report for 2015-2016, the UK Nuclear Decommissioning Authority (NDA) said the estimated cost of the future clean-up of nuclear sites across the UK is around GBP117bn ($154bn) spread across the next 120 years, down slightly from last year’s estimate of GBP118bn. NDA is responsible for the UK’s civil public sector nuclear estate, encompassing 17 nuclear sites, their liabilities and assets. This includes the first generation of Magnox power stations, various research and fuel facilities and what the NDA says is its “largest, most complex site”, Sellafield. NDA owns the historic sites on the government's behalf and is responsible for deciding how they should be decommissioned. Decommissioning work is carried out by Site Licence Companies, working for the NDA.

"Decommissioning many of these facilities will continue well into the 22nd century. Over this timescale, plans and forecasts will be affected by technology improvements, changes in government policy, economic circumstances and environmental issues," the NDA said. "The figure is updated annually but should be regarded as an informed estimate that depends on assumptions about future developments and lies within a range of possible figures," it added.

NDA said it had achieved more than GBP1bn of commercial income of through contracts for reprocessing and management of used fuels, electricity generation at the Wylfa NPP and “ongoing asset disposal”. There had also been increased savings from “collaborative procurement”, which combines demand in goods and services across the NDA estate, to almost GBP87m, compared with the previous year’s GBP65m savings.

NDA said that over the course of the year, it spent GBP3.1bn in directly addressing “the often complex decommissioning tasks”. According to the report: “The scale of work is compounded by the complexity of many of the critical projects at Sellafield, which are at an early stage in their design and delivery, and therefore inherently uncertain in both the means of physical delivery and cost and schedule of delivery.” NDA’s running cost is GBP41m a year, with income of GBP3m producing a net total of GBP38m.

"At sites where a decommissioning programme is relatively straightforward and the challenges well understood, costs can be calculated with relative confidence and ultimately driven down," NDA said. "This is already happening at the sites of 11 Magnox nuclear power stations – first built during the 1950s to 1970s – as well as the former nuclear research sites at Dounreay, Harwell and Winfrith. At these sites, cost estimates are being reduced by billions of pounds and work accelerated." But the NDA's largest site, Sellafield, "poses levels of complexity and uncertainty that are unique in the global nuclear sector.

Regarding the costs for decommissioning other UK nuclear sites, the private-sector operator EDF Energy will fund decommissioning for the second generation of nuclear power stations, the Advanced Gas-Cooled Reactor (AGR) fleet. Funds for the future decommissioning program are set aside via the Nuclear Liabilities Fund.

NDA CEO and accounting officer John Clarkesaid in the annual report that the past year had brought a number of major developments for the authority, "but perhaps the most significant" were the UK Government's Spending Review, the publication of its latest long-term Strategy and the introduction of new management arrangements at Sellafield.