Sizewell C nuclear power station

Sizewell C
Company type	Joint venture
Industry	Nuclear power
Founded	2012
Founder	EDF Energy, China General Nuclear Power Group (CGN)
Headquarters	Sizewell, Suffolk, England, United Kingdom
Area served	United Kingdom
Key people	Nigel Cann (Managing Director)
Products	Electricity generation
Owner	UK Government (44.9%), La Caisse (20%), Centrica (15%), EDF (12.5%), Amber Infrastructure (7.6%)
Parent	EDF Energy (majority partner)

The Sizewell C nuclear power facility involves constructing a 3,200MWe power station featuring two EPR units close to the village of Sizewell in Suffolk, England. Originally, the project was a joint venture between EDF Energy holding 80% and China General Nuclear Power Group (CGN) with 20%. However, in 2022, the UK Government acquired CGN's share, resulting in an equal partnership with EDF at 50%, which is anticipated to reduce to under 20% following external investments.

On 22 July 2025, the final investment decision confirmed the UK Government’s ownership at 44.9%, alongside stakeholders including La Caisse, Centrica, EDF, and Amber Infrastructure. The plant is expected to generate approximately 7% of the United Kingdom’s electricity supply.

Preparatory work at the site commenced in 2023, with comprehensive construction scheduled to start in 2024 and projected to continue for nine to twelve years. The timeline is influenced by advancements at Hinkley Point C, a comparable EDF Energy development. Each reactor is planned for operation over a six-decade lifespan.

On 10 June 2025, the government announced a capital injection of £14.2 billion into the project, with total construction expenses estimated at £38 billion as of mid-2025.

History

In 2008, the UK government resolved that new nuclear plants should be established on existing sites to replace outdated reactors. By 2010, Sizewell was selected as one of eight potential locations for new development. EDF Energy proposed building two EPR reactors at Sizewell in November 2012.

Following discussions between the UK and China in 2015, agreements were reached to develop Sizewell C alongside Hinkley Point C and Bradwell B; however, financing for Sizewell remained uncertain until after construction began on Hinkley Point C. On 21 October 2015, EDF Energy and China General Nuclear Power Group (CGN) formalized their partnership for Sizewell and Bradwell projects, with EDF holding an 80% share during development and CGN owning 20%.

After engaging local stakeholders, EDF submitted a development consent order application in May 2020, forecasting the creation of around 25,000 jobs and committing to allocate 70% of investment within the UK. The design was largely based on Hinkley Point C to capitalize on prior experience and cost efficiencies. By June 2020, EDF sought financial backing from the UK government through mechanisms such as the Regulated Asset Base (RAB) model or potential equity participation due to construction-related risks.

In June 2020, EDF applied to the Office for Nuclear Regulation (ONR) for a licence authorizing construction and operation of Sizewell C—a critical regulatory milestone. In September that year, Suffolk County Council raised concerns about potential impacts on local communities and the environment, urging enhanced mitigation strategies. EDF responded by proposing substantial adjustments to minimize Heavy Goods Vehicle traffic through increased use of rail and sea transport and by expanding fen meadow habitats to boost biodiversity. A public consultation followed in November 2020.

By October 2020, reports suggested imminent government approval for Sizewell C, reaffirming support for new nuclear projects after Horizon Nuclear Power withdrew from other sites. Interest in government investment increased following faster-than-expected progress at Hinkley Point C’s second reactor, which lowered perceived risks.

The UK energy white paper published in December 2020 outlined ambitions for a net zero transition and initiated talks with EDF regarding investment in at least one new power station before 2024. Meanwhile, CGN was reported to be planning an exit from the project.

On 20 July 2022, the Secretary of State granted planning permission via a Development Consent Order. Although briefly reviewed amid government budget reductions in November 2022, Chancellor Jeremy Hunt confirmed that construction would continue with contracts signed shortly thereafter. Due to national security concerns related to China’s involvement, the UK Government acquired CGN’s stake for over £100 million late in 2022, leaving ownership divided between EDF and the UK Government.

Official construction began on 15 January 2024, marking a key milestone in advancing Sizewell C’s development.

Timeline

Phase	Status	Completion Date
Community consultation statement	Finalized	2012
Initial consultation phase	Finalized	6 February 2013
Revised community consultation statement	Finalized	November 2016
Second consultation phase	Finalized	3 February 2017
Third consultation phase	Finalized	29 March 2019
Fourth consultation phase	Finalized	27 September 2019
Evaluation of Stage 4 feedback	Finalized	-
Submission of application	Finalized	24 June 2020
Decision on development consent	Finalized	20 July 2022
Commencement of groundworks	In Progress	15 January 2024
Final Investment Decision (FID)	Finalized	22 July 2025
Main construction phase	Pending	-
Operational phase	Pending	-

Construction

The construction and commissioning period for Sizewell C is projected to span between nine and twelve years. EDF expects this project to benefit from notable reductions in both time and costs when compared to its closely related counterpart, Hinkley Point C. The estimated expenditure for construction, including inflation and contingency allowances, was reported as £20 billion in 2020. This figure reflects a 25% increase over the £16 billion estimate (in 2012 prices) for Hinkley Point C, primarily due to inflation adjustments applied to approximately 80% of the latter’s costs.

Financing

By mid-2025, Sizewell C’s projected budget had escalated to £38 billion, surpassing earlier forecasts of £20–30 billion. Initially, EDF Energy and CGN held ownership stakes of 80% and 20%, respectively. EDF has sought financial backing from the UK government through mechanisms such as the Regulated Asset Base (RAB) model or direct equity investment, with the objective of reducing their financial risk.

In 2020, a coalition comprising 32 UK nuclear supply chain firms publicly supported the RAB approach, which transfers initial capital recovery to consumers via their energy bills. EDF submitted an application for a construction licence in June of that year. Following Hitachi’s exit from the Wylfa Newydd project due to funding challenges, EDF’s CEO appealed to the Treasury for a definitive strategy on nuclear project financing.

Towards the end of 2020, negotiations commenced with the UK government potentially acquiring a stake in Sizewell C amid CGN’s possible withdrawal. In January 2022, the government contributed £100 million toward project development. By March that year, an agreement was reached whereby both the UK government and EDF would each hold a 20% share, with infrastructure investors and pension funds expected to finance the remaining 60%. Additional financial resources were allocated to support local projects associated with Sizewell C and the East Anglia Array.

In August 2022, cost estimates were reported at £20 billion, including £1.7 billion from taxpayers and a consumer surcharge under the RAB framework; Barclays was engaged to secure further investment. The government increased its ownership stake to 50% for £679 million in November 2022.

By early 2023, EDF anticipated reducing its ownership below 20%, with cost projections fluctuating between £20 billion and £35 billion. In September of that year, private investors were invited by the government to submit bids, accompanied by an additional £511 million allocation for development and site preparation.

January 2024 saw a further government commitment of £1.3 billion aimed at infrastructure necessary for construction ahead of the final investment decision (FID). In August, up to £5.5 billion was made accessible through the Sizewell C Development Expenditure Subsidy Scheme; subsequent Autumn Budget provisions allocated £2.7 billion for ongoing development through fiscal years 2025–26.

By December 2024, managing director Nigel Cann indicated that five investors were actively engaged in bidding processes with FID anticipated in 2025. Early reports in 2025 suggested potential costs nearing £40 billion; however, representatives from EDF and government officials disputed these figures. Meanwhile, the French state auditor recommended that EDF reduce its financial exposure on Hinkley Point C before advancing further.

In June 2025, the UK government announced a capital investment of £14.2 billion as part of the spending review covering 2026–2030, forecasting creation of approximately 10,000 jobs and electricity supply sufficient for six million households. The FID was expected during summer that year.

The final investment decision was formalized on 22 July 2025. The UK government acquired a 44.9% stake; other shareholders include La Caisse (20%), Centrica (15%), EDF (12.5%), and Amber Infrastructure (7.6%). A proposed £5 billion debt guarantee from Bpifrance supports commercial borrowing alongside additional backing from the National Wealth Fund.

Equity and debt financing exceed base construction costs to accommodate potential overruns. The RAB funding structure incentivizes suppliers to manage costs effectively by limiting returns if overruns occur, thereby mitigating taxpayer risk. With an estimated construction cost of £38 billion—representing a saving of roughly one-fifth compared to Hinkley Point C—the model is projected to increase consumer energy bills by only about £1 per month while delivering annual savings of approximately £2 billion to the electricity system once operational.

Opposition groups

Groups opposing Sizewell C include organizations like Together Against Sizewell C (TASC) and Stop Sizewell C.

In September 2019, TASC initiated a judicial review contesting East Suffolk Council's approval for preparatory activities, which involved removing 229 trees and demolishing structures at the Sizewell B location. They argued that the council's decision was unlawful and that the environmental impact had been underestimated. However, in September 2020, the High Court dismissed TASC’s challenge, describing the habitat loss as "minor" and "not significant."

EDF highlighted that the judge acknowledged East Suffolk Council’s comprehensive environmental assessment. The report noted that 73% of the trees slated for removal were low-quality plantations with limited ecological value. This loss was to be compensated by planting more than 2,500 young broadleaf and conifer trees, carefully selected to thrive in local conditions.

On 6 October 2020, TASC together with Stop Sizewell C presented a petition bearing over 10,400 signatures to Downing Street, the Treasury, and the Department for Business, Energy and Industrial Strategy. The petition called on the government to abandon Sizewell C due to financial uncertainties and concerns about delayed contributions to net-zero targets until 2040.

Stop Sizewell C serves as the public campaign identity for Theberton and Eastbridge Action Group on Sizewell (TEAGS), which was established in 2013 by residents living near the proposed development site. Initially not opposed to the project, TEAGS adopted its current name after eight years of dialogue with EDF and other stakeholders.

In December 2023, following a legal challenge from TASC over potential environmental harm to the Suffolk coastline, the Court of Appeal upheld the government's approval of the site as lawful.

Subsequently, in May 2024, the Supreme Court refused to hear an appeal, affirming that no arguable legal issue had been presented. Later that year, the High Court rejected TEAGS/Stop Sizewell C’s legal challenge, deeming it "totally without merit" and unlikely to succeed.

Issues surrounding Chinese participation

Apprehensions have been expressed regarding CGN, a shareholder in the consortium owned by the Chinese government, which the United States Department of Commerce has blacklisted due to attempts to obtain advanced U.S. nuclear technology for military purposes.

Following Hitachi's withdrawal from the Wylfa and Oldbury initiatives in September 2020, the UK government reportedly explored the possibility of substituting CGN as an investor and potentially acquiring a stake in Sizewell C.

In 2022, the UK Government declared its intention to buy out CGN’s interest to enable their departure from the project.

Concerns about water usage

Environmental advocates and opponents of Sizewell have raised doubts about whether the plant’s demand for drinking water can be fulfilled without adversely affecting local resources. In 2010, operators of Sizewell A and B—Magnox Ltd and EDF—disclosed daily mains water usage near , along with seawater intake of for cooling purposes. Critics projected that Sizewell C would need an extra of potable water each day, implying EDF might prefer mains supply due to cost benefits compared to desalination. Initially, Essex and Suffolk Water guaranteed a sustainable supply for 25 years should Sizewell C proceed.

Subsequently, Essex and Suffolk Water reversed this assurance, leading EDF to propose a temporary desalination facility for construction water and a permanent pipeline drawing from the River Waveney. This pipeline proposal was suspended in August 2021 when the Environment Agency restricted water abstraction from the Waveney by up to 60%. Essex and Suffolk Water confirmed that current resources would not meet projected demand, including operational needs of Sizewell C, prompting EDF to commit to installing a permanent desalination plant if no alternative supply was found. Kwasi Kwarteng, Secretary of State for Business, Energy and Industrial Strategy, clarified that uncertainty over long-term water provision would not obstruct project approval.

On 8 August 2022, Together Against Sizewell C (TASC), supported by Friends of the Earth, announced intentions to legally contest the development consent order on grounds of unresolved water supply concerns. The Planning Inspectorate had previously indicated that lacking a definitive water strategy would prevent consent under Habitats Regulations. Nevertheless, on 20 December 2023, the challenge was dismissed as the Secretary of State regarded the power station development as distinct from permanent water supply arrangements. TASC’s subsequent appeal was also rejected on 13 May 2024 for failing to present a valid legal argument.

Support for alternative energy sources

Academics including Professor Barrett and colleagues at UCL contend that an integrated approach combining renewable energy technologies, energy storage solutions, hydrogen, and fossil fuels can deliver an equally dependable electricity supply as Sizewell C but at reduced expense.

Local economic effects

The Aldeburgh Town Council has voiced concerns that the elevated salaries offered by Sizewell C are drawing employees away from local businesses reliant on tourism. These enterprises face challenges competing for staff and have previously experienced workforce reductions during the construction phase of Sizewell B.

Archaeological discoveries

In January 2025, Oxford Cotswold Archaeology revealed a collection of 321 remarkably preserved silver coins from the 11th century at the Sizewell C location. These coins, minted between 1036 and 1044 under the reigns of Harold I, Harthacnut, and Edward the Confessor, are believed to be savings concealed during a period of political instability. This significant archaeological find was showcased in Digging for Britain (series 12, episode 1).

External links

Sizewell C planning documentation at National Infrastructure Planning website.