The Sizewell C nuclear project has reached financial close, unlocking full-scale construction of the £38 billion development after securing a £5.5 billion debt package with 13 major banks. This milestone makes Sizewell C the first nuclear power project globally to be financed through private investors under the UK’s Regulated Asset Base (RAB) model — the same framework used for landmark infrastructure such as Heathrow Terminal 5 and the Thames Tideway Tunnel. The RAB structure allows the project to earn regulated revenue during construction, reducing financing costs and helping lower consumer energy bills. The UK government estimates that the model could save households about £30 billion over the plant’s operational life compared with traditional financing approaches.

Located in Suffolk, the two-reactor plant will generate enough low-carbon electricity to power six million homes for at least six decades, reinforcing Britain’s energy security and climate commitments. Sizewell C’s construction is expected to cost roughly 20% less than the similar Hinkley Point C project, with savings driven by shared supply chains and efficiencies gained from experience. More than 10,000 people will work on the site, including 1,500 apprenticeships, while around 70% of the project’s value is set to flow to UK businesses — marking one of the country’s largest ever investments in clean energy infrastructure.

The project’s civil construction phase is being advanced by a diverse and highly skilled workforce, with firms such as Balfour Beatty leading major early works on-site. Backed by both public and private investment, construction activity is accelerating as the project moves toward its targeted completion later in the decade.

Civil Works Alliance with Three Major Construction Firms Formed

Reported on July 2, 2025 – Sizewell C has partnered with three of the industry’s top construction companies – Balfour Beatty, Laing O’Rourke, and Bouygues Travaux Publics – through a new Programme Alliance Agreement to provide the central civil engineering work on the new Suffolk nuclear power station. They have merged as the Civil Works Alliance (CWA), who will provide the project’s backbone infrastructure.

The partnership unites the three contractors and Sizewell C as a single delivery team. Over the duration of the 8-year civil works programme, the CWA is expected to employ between 3,000 and 4,000 workers.

Scope of Work

The Civil Works Alliance will oversee several critical components of the project, including:

• Enabling and earthworks
• Marine and tunnelling work, including three 3-kilometre-long undersea tunnels
• Main civils construction for the Nuclear and Conventional Islands, Heat Sink, and Balance of Plant
• Permanent roads and utility network ancillary works

All three companies are already deeply involved in major UK and international infrastructure projects, including their current roles at Hinkley Point C, where they’ve been instrumental in restarting nuclear construction in the country.

CWA Executives Pledge Quality, Safety, and Value in Sizewell C Delivery

Nigel Cann, Joint Managing Director of Sizewell C, emphasized the advantages of having experienced partners:

“With this agreement, we’re entrusting the civil works to three companies with proven expertise in meeting nuclear-grade construction standards. The progress seen between the first and second reactor units at Hinkley Point C shows how much has been learned. Together with our alliance partners, we’ll build on that momentum at Sizewell C—delivering both high value for consumers and a project the UK can take pride in.”

As an entirely embedded member of the Alliance, Sizewell C will be a ‘Client Participant’ and employ a Target Outturn Cost (TOC) methodology. This is designed to facilitate cost control, transparency, and partnership working for all partners.

Balfour Beatty Group Chief Executive, Leo Quinn, also reflected on national importance of the project:

“Sizewell C is a key step forward in the UK’s pursuit of energy independence and a net-zero future. We’re proud to bring our experience from Hinkley Point C into this alliance, reaffirming our role in delivering complex nuclear infrastructure and supporting the UK’s low-carbon transition.”

Laing O’Rourke’s Group CEO, Cathal O’Rourke, echoed the sentiment:

“Our work at Hinkley has equipped us to take on Sizewell C with the same focus on safety, quality, and productivity. I’m proud to see Laing O’Rourke contributing to a project that will help make cleaner, more affordable energy a reality for Britain.”

Jean-Philippe Trin, Deputy CEO of Bouygues Construction, highlighted the project’s alignment with global energy goals:

“Sizewell C reflects our broader commitment to expanding low-carbon energy solutions. It builds on the knowledge and capabilities we’ve developed through decades of involvement in large-scale nuclear initiatives.”

Progress and Future Outlook

Initial construction began in January 2024 and the scheme has already met its first targets on time and budget. The Sizewell C site will employ approximately 10,000 people at its peak, with tens of thousands of additional jobs created across the UK wider supply chain.

Earlier on, the UK Government used Sizewell C to describe the country’s new “golden age” of nuclear growth. It restated £14.2 billion of investment over the next five years. A Final Investment Decision, reached on July 22, 2025 also confirmed private sector backers who will be supplying the project’s long-term funding.

Sizewell C Civil Works Alliance – Project Factsheet

Project Overview

Sizewell C’s Civil Works Alliance (CWA) formed through a Programme Alliance Agreement with three leading construction companies will deliver the main civil engineering works for the new nuclear power station in Suffolk.

Civil Works Alliance Partners

• Balfour Beatty
• Laing O’Rourke
• Bouygues Travaux Publics
• Sizewell C (Client Participant)

Key Project Details

Timeline & Workforce

• Programme Duration: 8 years
• CWA Workforce: 3,000 – 4,000 workers
• Peak Site Employment: 10, 000+ workers
• Construction Start: January 2024

Scope of Work

The Civil Works Alliance will deliver:

• Enabling and earthworks
• Marine and tunnelling activities (including three 3km undersea tunnels)
• Main civils construction for Nuclear and Conventional Islands
• Heat Sink and Balance of Plant (BoP) infrastructure
• Ancillary works (permanent roads and utility networks)

Financial Framework

• Delivery Model: Target Outturn Cost (TOC) approach
• Government Investment: £14.2 billion over five years
• Final Investment Decision: July 22, 2025

Also Read: The UK to Develop Eight Additional Nuclear Power Plants