IN Brief:
- PERI UK has delivered a bespoke formwork solution for Hinkley Point C’s reactor domes.
- The system supports complex curved concrete pours around 45m above ground without relying on conventional through-ties.
- Digital modelling, prefabrication, and redesigned platform systems helped accelerate installation on the second reactor unit.
PERI UK has delivered a bespoke formwork solution for the reactor domes at Hinkley Point C, supporting one of the most technically demanding concrete construction phases on the Somerset nuclear project.
The company has been involved at Hinkley Point C since 2017, with its latest work focused on the formation of the reactor domes. Each unit has an inner and outer dome layer. At Unit 1, the inner layer was completed at the end of 2025, while the outer dome pour began at the start of 2026.
The dome geometry required a flexible formwork system capable of supporting concrete works across a structure that curves in several directions at once. PERI selected its VARIO formwork for the main dome works and fabricated 199 bespoke panels for the package.
Earlier transition sections from the vertical reactor walls up to level 13 used RUNDFLEX circular wall formwork before the works moved fully into dome curvature. As the structure changed shape, the formwork had to adapt without compromising load transfer, access, or pour quality.
The working environment was especially constrained. The formwork had to operate around 45m above ground level and support substantial construction loads without traditional through-ties. Dense reinforcement and post-tensioning ducts within the reactor structure prevented conventional tying methods from being used.
PERI’s engineers developed a non-standard system combining SCS Starter Brace, 550 Strongbacks, and load-bearing SB platforms suspended horizontally around the reactor building perimeter. A special 45-degree anchor adapter transferred concrete loads back into the structure in the absence of ties.
The SB platforms were also reconfigured for the project. Normally used vertically for single-sided wall construction, they were adapted at Hinkley to create platforms approximately 5m wide for the curved concrete pour. Those platforms had to support formwork, fresh concrete pressure, equipment, and live operative loads while maintaining safe working conditions at height.
The design process moved from 2D engineering drawings into 3D CAD and digital modelling so the team could test how formwork, platforms, reinforcement, anchors, and surrounding structures interacted. Because the configuration sat outside standard system parameters, PERI developed a full structural model to verify loads, connections, and anchor forces.
Digital modelling then fed directly into site execution. Dense rebar grids and embedded components left limited tolerance for anchor positions, and slight deviations required elements of the system to be redesigned during construction. Lessons from Unit 1 were applied to Unit 2, where the full platform solution was installed in under a fortnight.
Prefabrication helped reduce programme pressure and limit complex assembly at height. Many components were assembled before delivery, allowing faster installation once on site and reducing the amount of work required around the dome perimeter.
The package shows how temporary works have become a core engineering discipline on major infrastructure schemes. On projects such as Hinkley Point C, formwork is not simply selected late in the programme; it is designed around permanent works geometry, reinforcement strategy, load transfer, site safety, and installation methodology.
That same integration pressure is visible across large transport assets, including HS2’s Washwood Heath operational hub, where buildings, control systems, maintenance facilities, and rail infrastructure have to come together as a single working asset. At Hinkley, the equivalent challenge sits inside the reactor structure, where formwork, reinforcement, concrete, post-tensioning, and access systems must align within tight tolerances.
As nuclear, rail, water, and energy projects become more technically demanding, temporary works suppliers with digital design capability and close site integration are taking a larger role in delivery certainty. Hinkley’s reactor dome works provide a clear example of that shift, with bespoke engineering used to solve constraints that standard systems alone could not handle.
