A campaign group has written to the National Audit Office (NAO) calling for a review of the government’s value assessment for the controversial Sizewell C nuclear power station.
Campaign group Together Against Sizewell C (TASC) has written to the audit office calling for a review of the government’s value-for-money assessment, which underpinned £8bn of public spending on the nuclear power station.
It claims there has been a lack of transparency over the government’s audit of spending on the nuclear project, which unlocked billions of pounds of subsidies before a final investment decision (FID) has been made.
“TASC have considerable concerns about the decision making at this pre-FID stage of the project due to the risk to public finances and the lack of transparency regarding the VfM assessment which is being used to justify the current funding,” Chris Wilson wrote on behalf of the campaign group.
The group previously raised concerns around the spiralling costs of the project in a separate letter to the government’s energy department last April.
“It is worth recalling that when EDF first proposed Sizewell C, they budgeted the costs to get to FID to be £458 million,” the campaign group said in its latest letter to the NAO.
“With a £2.5 billion spend by the previous Tory government, £5.5 billion authorised by this government under the Devex Scheme and an estimated £700 million invested by EDF, the cost of getting to FID is approximately 1,900% of the original budget.”
‘Staggering’ underbudgeting
TASC called the underbudgeting by French energy supplier EDF “staggering”. According to its registration document in 2020, EDF had “planned to pre-finance the development up to its share of an initial budget of £458 million”.
“There has been no explanation as to why these costs are so astronomically higher than the original estimate, how such increases have been justified and how much more public funding is likely to be assigned to what many observers are calling ‘Labour’s HS2’,” it said in the letter.
“Assessment of the true costs of the project could lead to Sizewell C failing the value for
money assessment,” the campaign group added.
The group’s letter to the NAO follows Ecotricity founder Dale Vince’s plea to chair of the Treasury’s new Office for Value for Money, David Goldstone, in December, asking him to review plans to develop the new nuclear power project in Suffolk.
In the Labour donor’s letter, he warned that the nuclear power station “will saddle consumers with higher bills long before it delivers a single unit of electricity”.
The Sizewell C project was not expected to reach a final investment decision until the government’s spending review in June, though campaign group TASC said in its letter, citing a report for the scheme, that it may not take place for another year.
‘Proceeding by stealth’
Addressed to Gareth Davies, comptroller and auditor at the NAO, campaign group TASC described the nuclear power station as “a risky project proceeding by stealth with no transparency regarding Value for Money (VfM)”.
Echoing Labour donor Vince’s concerns, Wilson wrote: “The Sizewell C DCO was approved based on an estimated capital cost of £20 billion, but with announcements that the sister project at Hinkley Point C is estimated to cost (at current prices) £46 billion and in the knowledge that the Sizewell site is a more difficult site to develop, it is not credible to suggest, as one of the developer’s joint managing directors did in 2024, the cost to build Sizewell C remains at £20 billion.”
The campaign group raised “considerable concerns” about the decision-making process in granting government subsidies for nuclear project Sizewell C at this early stage, citing “the risk to public finances and the lack of transparency”.
The Department for Energy Security and Net Zero published details of the development expenditure subsidy scheme in late summer 2024, authorising a £5.5 billion subsidy, the first £1.2bn tranche of which was allocated to the project in September.
“If the project does not go ahead, the writing off of billions worthlessly invested and the cost of remedial work to make good the damage Sizewell C has caused to East Suffolk will largely fall on the public purse,” the campaign group said.
‘Wholesale environmental vandalism’
The letter added that “TASC are not aware that ground testing has even started for the area that will be covered by the hard coast sea defences”.
Last month, a separate campaign group Theberton and Eastbridge Action Group on Sizewell (TEAGS) lost a legal challenge against the Sizewell C nuclear plant in the High Court, which claimed the project’s licence did not include adequate sea defences, a concern following the 2011 Fukushima disaster.
TASC said developments amount to “wholesale environmental vandalism, especially when the project still lacks a final design of the all-important sea defences and while the nuclear site’s ground stabilisation trials are incomplete”.
It warned that the “safety case currently being assessed” by the Office for Nuclear Regulation is “materially different from the project that was approved” regarding overland floor barriers and should be reviewed by the energy secretary.
The campaign group said: “Sizewell C is proposed to be sited on one of Europe’s fastest eroding coastlines, yet there is still no final design of the sea defences required to keep it safe from the effects of climate change, so there is no guarantee that the Office for Nuclear Regulation (ONR) will be satisfied that the site can be kept safe for its full lifetime i.e. until the late 2100s.
“The future need for a final design of the sea defences, including the flood risk
implications of the 20-year extension to the site lifetime.”