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Hinkley Point C: The renaissance of the UK nuclear industry

29 November 2012

The Government has made it clear that large-scale investment is urgently needed in the UK’s energy infrastructure to meet the challenges of replacing ageing plant, moving towards low carbon sources of power and improving the security of our energy supplies. New nuclear power has been identified as an important part of this investment, and the most advanced nuclear project to date in the UK is EDF Energy’s proposed new build at Hinkley Point C in Somerset.

Artist’s impression of the completed Hinkley Point C nuclear power station. The project will employ up to 25,000 people over the course of construction, with 5,600 people on site at peak
Artist’s impression of the completed Hinkley Point C nuclear power station. The project will employ up to 25,000 people over the course of construction, with 5,600 people on site at peak

In January 2008, the UK government gave the go-ahead for a new generation of nuclear power stations to be built, and by October 2010 identified eight sites it considered suitable for new facilities. Electricité de France (EDF) was one of the first to pick up the baton, proposing large capacity power plants at both Hinkley Point in Somerset and Sizewell in Suffolk designed to contribute 13% of the UK’s electricity by the early 2020s.

EDF, 85% owned by the French Government, bought British Energy and its fleet of eight existing UK nuclear power stations (including Hinkley B and Sizewell B) in February 2009 for £12.4 billion. British Energy was renamed EDF Energy Nuclear Generation and teamed up with UK energy group Centrica to set up an 80:20 owned joint venture, NNB (Nuclear New Build) Generation Company, to design and build the proposed new nuclear plants.

EDF will use Areva NP's EPR design, the evolutionary descendant of the Framatome N4 and Siemens Power Generation Division KONVOI reactors. These have a net power output of 1,650 MW and other nuclear power stations at Flamanville in France, Olkiluoto in Finland and Taishan in China are already being built to this design.

Key development milestones at Hinkley Point C included the start of site preparation work in February 2012 after permission from the local authorities and agreement in January 2012 on a package of mitigation.

After three years of community consultation, EDF Energy submitted its application for a Development Consent Order to build and operate Hinkley Point C in October 2011. The Planning Inspectorate completed its examination on 22 September and is expected to make its recommendation later this year.

Contracts signed to date include a £100 million-plus contract to Kier Bam for work to prepare the site, and in June, EDF announced Laing O’Rourke/Bouygues TP as the preferred bidder for the £2 billion civils contract.

Following four years of work by EDF and Areva, in December 2011 the joint regulators (Office for Nuclear Regulation and Environment Agency) issued interim design acceptance confirmation for the EPR Pressurized Water Reactor (PWR), describing this themselves as a major milestone in the process. Working with AREVA, the ONR and the EA, EDF says it hopes to close out the design acceptance process by the end of 2012.

The next milestone, the most important of all, will be EDF Energy’s final decision on whether to go ahead with the £10bn plus investment at Hinkley, expected to be taken by the end of March 2013. This will be largely dependent on the price to be paid per megawatt-hour (MWh) generated at the plant, which is currently under negotiation with the Government.

The Hinkley site

The first thing that strikes the visitor to the Hinkley Point site is the large area set aside for the new power station. Its 1x2km footprint dwarfs the combined area of the adjacent existing nuclear facilities, the first-generation Hinkley A and second-generation Hinkley B stations.

Recent safety enhancements at Hinkley B are designed to extend its operational life to 2023. These include the introduction of flexible boron control rods that can be pushed into the core even if some of the graphite bricks that line the reactor have
Recent safety enhancements at Hinkley B are designed to extend its operational life to 2023. These include the introduction of flexible boron control rods that can be pushed into the core even if some of the graphite bricks that line the reactor have

The Hinkley A Magnox station came on stream in 1965 with a capacity of 500MW and was closed in 1999. Defuelling finished in 2004, and it is currently undergoing decommissioning with up to 500 staff still working on site. The planned interim completion date is 2015 with a care and maintenance regime subsequent to that up until final decommissioning in 2110.

The Hinkley B Advanced Gas Reactor (AGR) station started generating in 1976 and output for the whole of 2010 is estimated at 6.4 TWh. It has a capacity of 1,250MW but is currently generating around 70% of full output to extend its service life. It employs 550 full-time staff and 200 contractors.

The original lifetime expiry date was 2006 and there has already been a life extension to 2016. EDF Energy is currently preparing to submit a further case to extend the life of its AGRs to the Office for Nuclear Regulation with a likely average extension of seven years, which would take Hinkley B through to 2023. The station’s graphite cores and boilers are still in good condition and £37m was recently spent on upgrades, so the company is obviously confident an extension will be granted.

In comparison, the two EPR units at the C station will generate 3,300MW, making it by a long way the largest capacity nuclear power station in the UK. C will have roughly the same height profile as B, even though the reactors will be roughly a third smaller in size, because their turbine halls will be much larger.

Hinkley C will employ 900 staff when operational, 700 full-time staff and 200 contractors.

A 13.5m sea wall will protect the site from flooding, a feature whose design was strengthened and heightened following the Fukushima disaster in Japan last year. Inland from this will be the two nuclear units and their ancillary facilities, and further inland construction and support facilities. Much of the latter will be restored to their natural state after construction is completed.

EDF Energy has undertaken extensive geological tests to ensure the site is safe, on top of those that were carried out in 1990 in support of the proposal to build a sister PWR to Sizewell B on the site, which was subsequently scrapped. There are some faultlines in Somerset that are well known, but none of any significance. 

Large water intake and outfall pipes will also be routed up to 2.5km out into the Bristol Channel, far further than those of the existing B station.

The company has received permission to construct a temporary jetty to receive construction materials by sea. Because of the large tidal range in the Bristol Channel, the second biggest in the world, it will have to go out a long way from shore.

There will also be a wharf at Combwich nearby. Large indivisible loads will be imported through here, including fabricated parts for the reactor. Major sub-assemblies will be made in France by Areva with some major forgings from China, and Rolls-Royce will supply some parts following an agreement signed in early 2012.

Site remediation has included extensive works to rid the site of asbestos
Site remediation has included extensive works to rid the site of asbestos

Safety features

Key to the success of the power station will be the safety of its EPR reactors. Enhancements include shorter outages for refuelling and maintenance, major improvements in materials protection capacity, improved layout of potentially radioactive systems and components, and optimisation of radiation shielding thicknesses according to maintenance operations.

Enhanced safety features include:

* Four separate safeguard buildings. 

* Four major safety sub-systems or trains, each capable of fulfilling the two essential safety functions in any situation -- stopping the nuclear reaction and cooling the reactor. Each safety system is physically separated from the others and two of them are aircraft crash-resistant. They are located in separate parts of the plant and have their own protection features. This overcomes the risk of simultaneous failure of all the safety systems due to internal or external events, such as fire or the impact of a large aircraft.

* Leaktight containment. An extremely robust leaktight containment around the reactor includes both a metal liner which would prevent any external radioactive release but also an annular area inside the dual-wall containment where any residual radioactive elements would be filtered. The containment is designed to withstand high pressures and temperatures, even during severe accidents leading to core meltdown and reactor vessel failure.

Severe accident mitigation features include:

* Corium retention area. In the highly unlikely event of core meltdown, molten core (or corium) escaping from the reactor vessel would be collected and contained in a specially-design corium area at the bottom of the reactor containment building. It would then be cooled with water from an in-containment storage tank.

External hazard protection measures include:

* Aircraft crash protection, from both high-speed military jet or large commercial aircraft. The containment building, which houses the most sensitive buildings, is particularly robust. The upper part comprises two walls with an inner pre-stressed concrete housing, steel liner and outer reinforced concrete shell. The outer shell protects the inner walls and structures from direct impact and resulting vibration, and covers the reactor building, the used fuel building, two of the four safeguard buildings and the main control room. The two other safeguard buildings and the diesel buildings are geographically separated, so they cannot both be impacted at the same time.

*Earthquake resistance. To withstand severe earthquakes, the entire nuclear island stands on a single reinforced concrete base and the height of the buildings has been minimised.

Radiation exposure

Exposure to radioactivity for plant personnel will be very low, in most cases lower than background radiation levels. Areva NP says a priority objective in the EPR design is to reduce the target collective radioactive dose by more than 50% on the average rate in nuclear plants operating in OECD countries, which is already on a par with natural background radiation.

EPR reactors have a number of advanced safety features, including double skinned containment building and four separate safety shutdown systems
EPR reactors have a number of advanced safety features, including double skinned containment building and four separate safety shutdown systems

In an EPR the collective dose should be around 0.4 man-Sievert per reactor per year, considerably lower than the 1 man-Sievert average currently experienced in OECD nuclear plants.

In comparison, in France background radiation varies from 1 to 6 mSv/year, mainly from rocks in the ground. In other parts of the world, doses from natural radioactivity can be much higher. Background radiation in southern India is more than 10 mSv/year, up to 175 mSv/year in some regions of Brazil and up to 300 mSv/year in certain parts of Iran.

Environmental improvements

Enhanced environmental protection features include:

* More efficient use of nuclear fuel: At an average sustained rate of power generation, 17% lower fuel consumption compared with existing 1,300 MW reactors

* A marked reduction in radioactive liquid and gaseous effluent discharge compared with the current best-performing French nuclear power plants (- 30%, excluding carbon 14 and tritium, which remain at the same level as that observed in existing reactors)

* A 30% reduction in the amount of solid radioactive waste produced

Economic enhancements

Drawing on the technologies of the French N4 reactors at Chooz and Civaux and German KONVOI reactors, the EPR is an evolution of existing technologies designed to deliver greater operational flexibility with lower operating costs. 

This evolutionary approach, with full support from the French and German safety authorities, is key to the design of the reactor and builds on feedback from the operation of more than 100 reactors previously built or under construction by Areva.

The EPR will be the most powerful reactor in the world (1,650 MW, compared with the 1,500 MW delivered by the most recent reactors), while also delivering greater efficiency. It has been designed for a 60-year service life, compared with the 30- to 40-year average of most second-generation reactors.

The EPR reactor should be operational for 91% of the time, a much higher percentage than existing reactors. This is essentially down to shorter average refuelling outage durations at equivalent safety levels. Refuelling outages will be cut to 16 days, compared with the 30 to 45 days currently observed at existing plants. This will increase annual power output by 36% compared with reactors currently in operation.

The future

While the safety case seems impressive, whether the EDF Energy can deliver all the economic benefits will be another matter. The Flamanville nuclear power station in France is four years behind schedule, with costs almost double the original budget, and the Olkiluoto EPR plant has also faced problems. 

In an August interview with The Daily Telegraph, EDF Energy chief executive Vincent de Rivaz said: “Clearly there are lessons to be learnt from Flamanville, lessons we are going to take into account in our project in Hinkley.” 

Flamanville started before it was ready, de Rivaz said, “leading to underestimation of cost, underestimation of timetable.”

Certainly, EDF and Areva deserve praise for their willingness to fly the nuclear flag and invest heavily taking the technology forward at a time when many others are falling by the wayside. German energy groups RWE and E.ON pulled out of a separate project to build two nuclear plants in the UK in March after the German Government announced its plans to close down all nuclear plants in the country post-Fukushima, and this baton has now been handed to Hitachi, which plans to develop the sites.

Other candidates to build nuclear power stations in the UK are Hitachi, which was selected in October 2012 to develop the Wylfa (Anglesey) and Oldbury (Gloucestershire) sites, and further ahead Spain’s Iberdrola, which is looking at developing a site in Cumbria.

EDF Energy and Centrica, however, seem totally committed. With site preparation now complete at Hinkley Point C, the partners recently announced that initial consultations would take place on the construction of Sizewell C by the end of this year.

Richard Mayson, Director of Planning and External Affairs for EDF Energy and Centrica’s NNB Generation Company, said: "We are very pleased to signal the start of our formal consultation for Sizewell C. It demonstrates our clear intent to progress our role at the forefront of the UK's nuclear renaissance.

"As well as helping to supply new low carbon electricity for ten million homes, both these projects offer massive employment and economic opportunities for local residents and firms. We now look forward to the planning decision for Hinkley Point C and to working with the communities in Suffolk to develop our proposals at Sizewell."

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