Sizewell C reuse of Hinkley tunnel segment site: logistics and design notes for engineers
Reviewed by Joe Ashwell
First reported on The Construction Index
30 Second Briefing
Sizewell C has secured planning approval to manufacture pre-cast concrete tunnel segments and tunnel heads at the former Hinkley Point C facility in Avonmouth, 10 km from Bristol city centre, for installation in marine tunnels at the Suffolk nuclear plant. Components will be shipped by sea to support the project’s commitment to move 80% of materials by rail and sea, reducing heavy vehicle movements around the site. Early works are underway, with 55 CWA staff and 86 supply chain workers on site, and full production targeted for 2028, leveraging existing Hinkley Point C infrastructure and teams.
Technical Brief
- Early works currently support 55 Civil Works Alliance staff on site, including two apprentices.
- A further 86 supply chain workers are already mobilised at Avonmouth for enabling and set-up activities.
- Planning approval is conditional, with full-scale segment and tunnel head production not expected before 2028.
- Leveraging HPC’s off-site prefabrication experience is expected to de-risk safety, quality, cost and schedule performance.
Our Take
The 80% rail-and-sea materials target at Sizewell C aligns with the recently commissioned Green Rail Route freight link, signalling that heavy precast elements from Avonmouth are likely being planned around rail paths rather than HGV capacity on Suffolk roads.
Re-using the Hinkley Point C tunnel segment facility for Sizewell C extends the life of a specialised nuclear precast supply chain, which our database shows is already being deepened by modular accommodation and long-term FM contracts on the Suffolk project.
With production at Avonmouth pencilled in for 2028, the Civil Works Alliance’s current 55-strong workforce and small apprentice intake suggest this is still an early ramp-up phase, giving contractors time to refine QA and logistics before peak nuclear civils demand at Sizewell C.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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