By rosebell
The contract was awarded by the Civil Works Alliance (CWA) and covers an initial three-year design programme, followed by seven years of design support during construction.
Amentum will lead the design alongside Jacobs, which will provide major tunnelling design support, and ADDA, responsible for 3D reinforced concrete detailing.
Design scope covers three offshore tunnels
The contract includes the design of three 3.5km offshore cooling water tunnels, marine shafts, tunnel-to-shaft connections, intake and outfall structures, onshore galleries and connections to the main civil works.
The scope also incorporates a fish return system designed to protect marine wildlife as part of the cooling water infrastructure.
The tunnels will form a critical component of the marine system supplying cooling water to Sizewell C’s two 1.6GW nuclear reactors. Once operational, the power station is expected to require a substantial daily cooling water flow, equivalent to approximately 4,200 Olympic-sized swimming pools.
Hinkley Point C experience to inform design
Amentum previously led the equivalent marine and tunnelling design scope for Hinkley Point C in Somerset. The company plans to apply lessons from that project to improve design efficiency and reduce construction risks at Sizewell C.
Loren Jones, Amentum senior vice president, said the company would draw on its nuclear design experience and build on lessons learned at Hinkley Point C.
Retaining the same specialist design partners is also intended to support continuity and optimise the design process across the two nuclear projects.
The Civil Works Alliance comprises Balfour Beatty, Bouygues Travaux Publics, Laing O’Rourke and project developer Sizewell C Ltd.
Tunnel segment manufacturing preparations advance
Preparations for the marine tunnelling works are also progressing. In September, Sizewell C announced planning approval for a tunnel segment manufacturing facility at Avonmouth, near Bristol.
The facility is expected to manufacture approximately 38,500 precast concrete tunnel lining segments, alongside marine tunnel head components. These will be transported to Suffolk by rail and sea, and the facility is expected to support up to 400 jobs.
Sizewell C will comprise two European Pressurised Reactor (EPR) units with a combined generating capacity of 3.2GW. The project is adopting much of the design and construction approach used at Hinkley Point C.
