Canada-based AtkinsRéalis has secured a five-year framework agreement to remain the civil works design partner for the Sizewell C NPP in Suffolk, England. The framework agreement was signed directly with Sizewell C Ltd, the project delivery company developer backed by the UK Government, and energy developer EDF (Électricité de France). AtkinsRéalis operates as a key delivery partner alongside the project’s Civil Works Alliance (CWA), which includes major construction firms Balfour Beatty, Laing O’Rourke, and Bouygues Travaux Publics.
Sizewell C will build two 1,630 MWe EPR (Evolutionary Power Reactor) units, directly copying the design of its sister site, Hinkley Point C in Somerset. This allows the team to reuse engineering plans, transfer skilled workforce, and reduce construction risks. The construction budget is estimated at £38bn ($50bn). There are currently over 2,000 on-site workers, ramping up to an expected peak of 8,000 personnel.
The project is the first majority UK-owned nuclear power station in more than three decades. Following the Final Investment Decision (FID) in July 2025, the financing is split among public and private investors under a Regulated Asset Base (RAB) model. The UK Government is the largest shareholder with 44.9%. Institutional Investor La Caisse holds 20.0%, UK energy company Centrica 15.0%, project supplier & nuclear operator EDF12.5% and private investor Amber Infrastructure 7.6%.
AtkinsRéalis is providing multidisciplinary design and engineering services across the permanent plant design at Sizewell C, including the conventional island, balance of plant, heat sink buildings and ancillary works. This builds on the extensive role AtkinsRéalis has played to date across planning, consenting and enabling work phases at Sizewell C. AtkinsRéalis will continue bringing both new and established digital tools into the delivery of the civil works programme.
The Sizewell C project uses a structured, five-phase development timeline for its main development site.
- Phases 1&2 – site establishment and earthworks (2024–2026): Formal construction was triggered in January 2024. In July 2025, the FID unlocked full funding. By early 2026, the on-site workforce surpassed 2,000 people. The first bulk engineering train arrived via the operational Sizewell branch line to transport 60% of materials by rail or sea. The current focus is completion of the temporary sea wall, park-and-ride facilities, and groundwork infrastructure.
- Phase 3 – Main Civil Engineering (2026–2029): Heavy civil works will begin, led by the permanent design framework involving AtkinsRéalis. This will involve deep excavation, construction of the nuclear island, and pouring of the first structural concrete.
- Phase 4 – Mechanical and Electrical Installation (Late 2020s–Early 2030s): Installation of the two EPR reactors will take place, as well as fitting of turbines, cooling systems, and electrical grid infrastructure.
- Phase 5 – Commissioning and Commercial Operation (Mid-2030s): This will involve safety testing, fuel loading, and first criticality. Commercial operation target is estimated between 2034 and 2037, depending on design replications from Hinkley Point C.
“AtkinsRéalis has played a significant role in design and engineering management at Sizewell C since 2019, bringing knowledge, experience and learnings from a decade of delivery at Hinkley Point C,” said Joe St Julian, President, Nuclear at AtkinsRéalis. “Our design and engineering teams have pioneered new digital technology and data-led design to streamline schedules, increase certainty and mitigate program risks at Sizewell C. This new agreement renews our commitment to realising the full benefits of replication and unlocking even greater efficiencies through excellence in delivery.”
AtkinsRéalis has over 70 years of global nuclear expertise, delivering nuclear technology products and full-service solutions to nuclear utilities around the world. AtkinsRéalis is the steward of Candu nuclear technology, operating on four continents, and provides advisory and engineering services to other nuclear developers.
