Sizewell nuclear power stations

Infobox UK power station
static_

static_image_caption=Sizewell nuclear power stations
os_grid_reference=TM001087
latitude=52.215
longitude=1.61972
country=England
region=East of England
shire_county=Suffolk
operator=British Energy (Sizewell B)
fuel=Nuclear
fuel_capacity=1,195MWe (Sizewell B)
opened=1995 (Sizewell B)

There are two nuclear power stations located near the small fishing village of Sizewell in Suffolk, England. Sizewell A, with two Magnox reactors, is now in the process of being decommissioned, while Sizewell B has a single pressurised water reactor and is the UK's newest nuclear power station. A third twin-unit EPR reactor is planned .

The imposing buildings of the two power stations provide an unmistakable landmark on the Suffolk coast. Surrounded by fields and separated by a shingle beach from the North Sea, the site is less than two miles from the town of Leiston. The site was chosen because of its proximity to the north sea, which provided a plentiful supply of cooling water for the steam turbine condensers, and its suitable geology, which could support the mass of the two power stations structures.

Sizewell formerly ran a popular visitor programme, whereby the public could take guided tours through the turbine hall and around the reactor area of Sizewell A, as well as around the Sizewell B site. It had a small science museum type visitors' centre.

izewell A

Building work on Sizewell A began on 1 April 1961. The Midlands Project Group of the Central Electricity Generating Board (CEGB) planned and managed the project. The main contract was awarded to British Nuclear Design and Construction Ltd (BNDC) a consortium backed by English Electric, Babcock & Wilcox and Taylor Woodrow. The initial budget was £56 million, but due to inflation this figure rose to £65 million. Unit 1 was commissioned on 21 March 1966, and Unit 2 on 15 September. When Sizewell A was completed, it was Britain’s fastest constructed nuclear power station.

Sizewell A consisted of two 1000 MWt Magnox reactors, producing a total electrical power output of 420 MWe. The power station was shut down on 31 December 2006. [ [http://www.neimagazine.com/story.asp?sectionCode=76&storyCode=2043403 Night falls on Sizewell A] , "Nuclear Engineering International", 2 April 2007] During its 40 year operational lifetime, it had produced 110 TWh of electricity, which would have been sufficient to meet the domestic needs of England and Wales for 6 months. The power station had an impeccable safety record. The Nuclear Decommissioning Authority (NDA) is responsible for placing contracts for the decommissioning of Sizewell A, at a budgeted cost of £1.2 billion.

izewell B

Sizewell B is the UK's only commercial Pressurised Water Reactor (PWR) power station, and is operated by British Energy. It was built and commissioned between 1987 and 1995, the main civil engineering contractor being John Laing plc [ [http://www.nce.co.uk/events/british_construction_industry_awards__best_of_the_best.html British Construction Industry Awards] ] . The 'nuclear island' at SXB is based on a Westinghouse '4-loop' plant known as SNUPPS (Standard Nuclear Unit Power Plant System) initially designed in the 1970s and used at Wolf Creek and Callaway but with additional redundancy and diversity in the safety systems, and other modifications such as the addition of a passive Emergency Boration System. The containment design was not based on SNUPPS however, but was designed by NNC in conjunction with Bechtel.

The Wolf Creek and Callaway plants each use single half speed, 1,800 rpm, steam turbine-alternator sets to convert the steam produced from the heat generated in the reactor into about 1,200 MWe of electricity at the US grid frequency of 60Hz. Such large turbo-alternator sets were not available in the UK at the time Sizewell B was designed. So that orders could be given to UK manufacturers, and to avoid project risk in dealing with what were at the time newly designed very large turbo-alternator sets, Sizewell B uses two full speed, 3,000 rpm, nominal 660 MWe turbo-alternator sets similar to those used at Drax coal fired power station, and at the last of the AGRs Heysham 2, but adapted to cope with the wetter steam conditions produced by the PWR steam supply system. PWR steam supply systems produce saturated steam at lower temperature and pressure than the dry superheated steam produced by AGR reactors or coal fired power stations, and the high and intermediate pressure stages of the steam turbines have to be designed cope with this.

First announced in 1969 as an Advanced Gas-cooled Reactor (AGR) based power station, [The Times Thursday, Oct 30, 1969; pg. 5; Issue 57704; col A ] and then in 1974 as a Steam Generating Heavy Water Reactor (SGHWR), Sizewell B was eventually announced as a PWR power station in 1980. [The Times, Thursday, Oct 02, 1980; pg. 5; Issue 60739; col A ] The initial design submissions to the CEGB and NII were based on the design of the Trojan plant at Portland, Oregon. [The Times, Saturday, Jul 30, 1977] [The Times, Thursday, Apr 23, 1981] Designed by Westinghouse, construction of Trojan began in 1970 and was completed in 1975. Westinghouse continued to develop the design they had used for the Trojan plant into the SNUPPS design, built first at Callaway, and SNUPPS was adopted as the basis for the design approved by the CEGB in October 1981. [The Times, Saturday, Oct 24, 1981]

Before construction commenced, the design of Sizewell B was subjected to a detailed safety review by the Nuclear Installations Inspectorate (NII), and a lengthy public inquiry. The Pre-Construction Safety Case was submitted to the NII in August 1981. The public inquiry was held between 1982 and 1985, and took over 16 million words of evidence, a record at the time. The chairman of the inquiry, Sir Frank Layfield, reported in early 1987 that, subject to a satisfactory safety case, there were no substantive reasons why the project should not proceed. The Nuclear Installations Inspectorate accepted the Pre-Construction Safety Case and issued a licence to proceed with construction in August 1987.

Sizewell B was calculated to be economically viable at a 5% discount rate and was approved financially on that basis. The project was managed by the CEGB Sizewell B Project Management Team, who declared that it was completed on time and to budget, the final out turn cost being £2,030 million. The original rating was for a thermal power of 3,444 MWth and gross electrical output of 1,250 MWe, which after house load of 62 MWe gave a net output to the grid of 1,188 MWe, equivalent to 8.7 TWh in the year of 2005. It was uprated by 1% in 2005 with a thermal power of 3,479 MWth and an electrical output of 1,195 MWe, though this is dependent on seawater temperature.

As with many other PWRs, Sizewell 'B' operates on an 18-month operating cycle, i.e. at or near 100% output continuously for around 17 months, followed by a month's shutdown for maintenance and refuelling.

Sizewell B was designed for a commercial life of 40 years — i.e., to around 2035 — but similar stations elsewhere have been granted extensions to 60 years.

A distinctive white hemisphere envelopes the outer shell of the twin-walled Containment building that protects the pressurised water reactor and its steam generators.

On 27 May 2008, the Sizewell B plant had its first unplanned shutdown for over three years, cutting off its supply to the National Grid. cite web | url=http://news.bbc.co.uk/1/hi/uk/7422817.stm | title=Sizewell nuclear plant shut down | publisher=BBC News | date=2008-05-27 | accessdate=2008-05-27 ] A British Energy spokesman said that the fault involved conventional equipment at the plant rather than any part of the nuclear reactor.

izewell C

Since the recent proposed sale of British Energy to Électricité de France (EDF), plans for a further twin-unit reactor to be built at Sizewell look increasingly positive and EDF are said to be beginning planning for new reactors in earnest. cite web | url=http://www.world-nuclear-news.org/NN_New_dawn_for_UK_nuclear_power_2409081.html | title=New dawn for UK nuclear power | publisher=WNN | date=2008-09-24 | accessdate=2008-09-25 ] Sizewell already has a connection agreement in place for a new nuclear power plant to be built. [ cite web | url=http://www.newenergyfocus.com/do/ecco.py/view_item?listid=1&listcatid=32&listitemid=1723 | title=EDF confirms £12.5bn offer for British Energy | publisher=New Energy Focus | date=2008-09-24 | accessdate=2008-09-25 ] The government revealed that the 1600 MWe projected units, to be called Sizewell C, would, together with the planned units at Hinkley Point, contribute 13% of UK electricity in the early 2020s. EDF plans to use Areva's EPR design for any new build reactors in the UK; the design of reactors currently being built in Finland and France.

References

ee also

* Nuclear power in the United Kingdom
* Energy policy of the United Kingdom
* Energy use and conservation in the United Kingdom
* List of nuclear reactors

External links

* [http://www.britishnucleargroup.com/content.php?pageID=275 British Nuclear Group, Sizewell A]
* [http://www.british-energy.com/pagetemplate.php?pid=96 British Energy — Sizewell B]
* International Atomic Energy Agency power station performance data: [http://www.iaea.org/cgi-bin/db.page.pl/pris.ophis.htm?country=GB&site=SIZEWELL%20A&refno=10A&opyear=2020 Sizewell A1] , [http://www.iaea.org/cgi-bin/db.page.pl/pris.ophis.htm?country=GB&site=SIZEWELL%20A&&refno=10B&opyear=2020 Sizewell A2] , [http://www.iaea.org/cgi-bin/db.page.pl/pris.ophis.htm?country=GB&site=SIZEWELL%20B&refno=24&opyear=2020 Sizewell B]
* [http://www.nda.gov.uk/About_the_NDA--Locations--Sizewell_A--Sizewell_A_-_Overview_of_NDA's_Draft_Strategy_(966).aspx?pg=966 Sizewell A - Overview of NDA's Draft Strategy]
* [http://www.bbc.co.uk/suffolk/content/image_galleries/sizewell_b_tour_gallery.shtml Gallery: Sizewell B] from the BBC
* " [http://news.bbc.co.uk/1/shared/spl/hi/pop_ups/05/sci_nat_living_with_sizewell_b/html/1.stm Living with Sizewell B] " and " [http://news.bbc.co.uk/1/hi/england/suffolk/4316424.stm Sizewell B given 10 more years] " from BBC News