Record-breaking concrete pour at Hinkley

Materials World magazine
6 Aug 2019

Hinkley Point C nuclear power plant breaks the record for the largest concrete pour in the UK. Ceri Jones reports.

Hinkley Point C secured the record for the largest ever continuous concrete pour in the UK on 28 June 2019. The event dwarfed the previous record of 5,500m3, set in 2010 during the building of the Shard in London. Located in Somerset, Hinkley Point C nuclear power plant has now completed the construction of its base in a project that took six months.

The milestone, known as J-zero, took 240 hours to pour 9,000m3 of concrete, which reached up to 4m-thick in places and was reinforced with 5,000 tonnes of Welsh steel. The area made up the last of five segments that form the criss-cross foundation of the external nuclear reactor buildings. With the concrete in place and the first of two reactor bases complete, works will start on the overground elements, including the permanent building that will house the European pressurised reactor. Construction of the second reactor base is estimated to be quicker due to lessons learned, and should hit J-zero by June 2020.

A solid foundation

Hinkley Point C civil engineering works, including concrete production, are being managed by BYLOR – the joint venture project of France’s Bouygues TP and UK firm Laing O’Rourke.

During the 10-year site construction, the plant will use an estimated total of 1.2 million cubic tonnes of concrete. ‘Every batch of concrete must be exactly the same and must comply with the stringent quality standards laid down by the Office for Nuclear Regulation,’ said Head of Nuclear Operations, Stewart Cameron, at Hanson UK, which supplied the raw materials to BYLOR.

‘Trials of the mix design for Hinkley Point C took three years of development and testing to ensure concrete of the required quality can be produced consistently right,’ he added.

More records are likely, as the project includes the setup of the world’s biggest crane, the Sarens SGC 250, which will be used to prefabricate parts of the nuclear buildings, and the world’s largest turbine is currently under construction at GE.

Setting records

Hinkley Point C is slated to be operational by the mid-2020s with a 60-year lifespan. It will have a power capacity of 3.2GWh, which will supply 7% of the UK’s energy mix, representing six million homes. Crucially, the plant will also offset nine million tonnes of carbon emissions every year.

The UK’s goal of reaching net-zero carbon emissions by 2050 officially came into law on the same day. To mark the occasion, Parliamentary Under Secretary of State, Minister for Business and Industry (BEIS), Andrew Stephenson, visited the site to meet apprentices from the National College for Nuclear. ‘This is a huge achievement for Hinkley Point C and a major milestone for the UK’s nuclear newbuild industry, which – as a low-carbon electricity source – is key to meeting our ambitious target of net-zero emissions by 2050,’ he said.

UK nuclear has been treading water in recent years, due to controversies on all fronts, and concerns about the safety of nuclear power in general, criticism of the £20bln cost of Hinkley Point C, financial problems encountered by operators, contractors and investors, and the collapse of similar projects including Wylfa in Wales. Despite this, the J-zero milestone was a positive marker for UK nuclear and the Confederation of British Industry (CBI) used the opportunity to press the government for clarity on its commitment to nuclear energy.

In a letter to Secretary of State for BEIS, Greg Clark, the CBI said nuclear has an ‘important role’ in reaching low-carbon energy ‘at the right price’. It also called for greater support of foreign investment models and funding for large and small modular nuclear reactor setups, as well as support for other low-carbon energy formats including onshore wind power.

‘Business is right behind the need for the UK to have a net-zero economy by 2050 and build on our global leadership in cutting greenhouse gas emissions,’ CBI said. ‘Firms want to see a whole host of stable, long-term policies enacted, from building new nuclear power stations to scaling-up carbon capture and storage technology and infrastructure, that send markets a robust signal – the UK is open for green business, and is a world leader in tackling climate change.’