Nothing boring about Hinkley Point C’s latest milestone moment
Another key milestone has been achieved at the Hinkley Point C construction site in Somerset, with the completion of the first of three off-shore tunnels needed for the power station’s cooling-water system.
The first Tunnel Boring Machine (TBM), named Mary, reached the end of her 3.5km journey under the Bristol Channel to complete intake tunnel 1 on 9 December 2020.
Roger Frost, Balfour Beatty Project Director, said: “This is a significant achievement - one that marks another step towards the successful delivery of the UK’s landmark nuclear power station, Hinkley Point C. The unrivalled expertise of our people, combined with our state-of-the-art offsite manufacturing facility in Avonmouth, has made it possible for us to break through the first of three off-shore tunnels. I am immensely proud of the commitment everyone has shown.”
The 3.5km-long intake tunnel 1 was mined at a depth of 33m below the Bristol Channel, using one of three TBMs needed for the project. The TBM, named Mary after prominent palaeontologist Mary Anning, was effectively a moving factory operating underground.
As Mary advanced forward she installed concrete rings, each made up of six segments. The tunnel comprises more than 2,300 of these rings, with nearly 14,000 segments needed to complete them. After each ring was placed, the crew then filled the gap behind it with grout. Around 12,000m3 of grout was used in total over the full length of the tunnel.