Sizewell C benefits from lessons learned and captured from HPC and other EPRs around the world.
In the next phase at Hinkley Point C, contractors will need to co-ordinate their work as they install complex cabling and pipework in the power station’s 2,500 rooms. This phase is known as the MEH phase (Mechanical, Electrical and HVAC – heating, ventilation and air conditioning).
This co-ordination was a challenge at Flamanville 3 and contractors effectively competed to get access to the spaces.
Experience at Taishan has shown the benefits of bringing contractors into a single organisation where collaboration is incentivised and skills and expertise shared. At Hinkley Point C, this organisation is known as the ‘MEH Alliance’ and brings together Altrad, Balfour Beatty Bailey, Cavendish Nuclear and Doosan Babcock into a single entity. The alliance will also create new industrial capacity and jobs by manufacturing specialist pipework in Britain.
The design of a nuclear power station is complex and thousands of parts need to fit together first time. For example 235,000 tonnes of steel reinforcement bars have to be set in concrete. At Flamanville 3 design clashes happened after different design drawings came together for the first time during construction. This meant steel bars were in the way of components like the anchor plates used to carry cables. Many of the 1,000 plates took up to a week to install rather than a few minutes.
At Hinkley Point C full 3-D modelling brings all the design drawings together in one place and cuts outs clashes. It allows workers to carry the full and fixed design on a tablet computer. This has been used before for pinch points in major UK projects but it has never before been used on this scale. The first concrete pour of the common raft at HPC has been achieved without any clashes.
Equipment for nuclear projects needs to undergo stringent qualification to ensure it meets the exacting standards demanded by the industry and UK regulator. In addition most equipment is adapted for a particular power station’s design. Replication cuts out these one-off costs for follow-on equipment orders.
At Hinkley Point C, there are four 3,600 KWe ‘blackout’ diesel generators to provide power in an emergency. Qualification costs were £10m and design and project management costs were £13m. This work does not need to be fully repeated at Sizewell C – saving more than one third of the £63m costs incurred at Hinkley Point C.
Replication benefits – instrument and control systems
There are two key computerised ‘instrumentation and control’ systems at Flamanville 3. One system controls the power station and the other is a safety system that is designed to manage significant plant safety events.
A third non-computerised back-up safety system is being installed at Hinkley Point C. This requirement originated from the Generic Design Assessment (GDA) process for the EPR reactor design. The third system had to be designed, developed, tested and qualified before it can be approved for use in the UK.
There was a huge cost of developing this new platform. However if the same technology is used at Sizewell C this cost does not need to be repeated, leading to a substantial saving.
Replication benefits – stable design
Changing or creating designs for a nuclear power station is expensive and involves huge amounts of documentation. Replicating a design approved for the UK context at Sizewell C saves this work from being repeated or significantly altered.
For example, the Generic Design Assessment for the EPR in the UK took 850,000 hours of work and is a 6,000 page document. The basic design of the EPR in the UK is made up of 100,000 documents and the detailed ‘execution design’ is one million documents. Qualification of parts adds to this amount of regulatory and design documentation. Not changing the design at Sizewell C means that these documents do not need to be created again and design work is not repeated. That delivers savings in time and money.
Source: Sizewell C Project update, February