Hinkley Point A nuclear power station

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Hinkley Point A nuclear power station
Hinkley Point Nuclear Power Station.jpg
Hinkley Point A twin reactors on the left. Hinkley Point B on the right
Country England
Location Somerset, South West England
Coordinates 51°12′31″N 3°08′01″W / 51.208739°N 3.133743°W / 51.208739; -3.133743Coordinates: 51°12′31″N 3°08′01″W / 51.208739°N 3.133743°W / 51.208739; -3.133743
Status Decommissioned
Construction began 1957
Commission date 1965
Decommission date 2000
Owner(s) Central Electricity Generating Board
(1965–1989)
Nuclear Electric
(1989–1996)
Magnox Electric
(1996-2005)
Nuclear Decommissioning Authority
(2005-Present)
Operator(s) Magnox Limited
Nuclear power station
Reactor type Magnox
Reactor supplier English Electric
Power generation
Primary fuel Nuclear
Units decommissioned 2 x 250 MWe (Net. 235 MWe) [1]
Nameplate capacity 500 MWe
Website
Magnox Sites
grid reference ST211460

Hinkley Point A nuclear power station is a decommissioned Magnox Nuclear power station located on a 19.4-hectare (48-acre) site in Somerset on the Bristol Channel coast, 5 miles (8 km) west of the River Parrett estuary.

History[edit]

The construction of the power station, which was undertaken by a consortium backed by English Electric, Babcock & Wilcox Ltd and Taylor Woodrow Construction,[2] began in 1957. The reactors and the turbines were supplied by English Electric.[3]

The power station, which is currently being decommissioned, had twin Magnox reactors, each supplying steam to a turbine alternator set which was designed to produce 500 MWe but, after de-rating of the reactor power output due to corrosion concerns, producing 221 MWe.[4]

The design followed the principles established by the Calder Hall nuclear power station, in that it used a reactor core of natural uranium fuel in Magnox alloy cans within a graphite moderator, all contained in a welded steel pressure vessel. The core was cooled by CO2 pumped by six nominal 7,000 hp (5.2MW) gas circulators, which transported the hot gas from the core to the six Steam Raising Units (boilers) via steel ducts. The gas circulators could be driven by induction motors supplied with mains electricity or, when steam was available, dedicated variable speed turbo alternator sets. The design pressure of the gas circuit was 185 psig, and the temperature of the gas leaving the reactor was 378°C, although this was later reduced when the hot CO2 was found to be corroding the mild steel components of the gas circuit more quickly than had been anticipated. Like all Magnox reactors, Hinkley Point A was designed for on-load refuelling so that exhausted fuel elements could be replaced with fresh without shutting down the reactor.

While primarily planned for peaceful electricity generation, Hinkley Point A was modified so that weapons-grade plutonium could be extracted for military purposes should the need arise.[5][6]

Gas circulator design problem[edit]

Hinkley Point A reactors seen from the entrance to Hinkley Point B

In August 1963 during a hot run test on the first reactor, which had not then been loaded with nuclear fuel, problems were encountered due to noise from the single stage axial flow gas circulators. This could be heard up to five miles away, and personnel working at the station had to wear ear defenders. After unexplained drops in the mass flow rate and motor driving current in number 3 and 5 gas circulators, the hot run tests were stopped and the gas circuit opened up. Severe mechanical damage to the blading and diffuser sections of the number 3 and 5 gas circulators was observed. Large sections of the diffusers had broken away, and extensive fatigue cracking was found in the outer tapering shell and central axial cone. Large pieces of the diffuser casing had entered the gas circulator blades and caused heavy impact damage, and large amounts of debris had been transported down the gas duct. The Inlet Guide Vanes (IGVs), which were provided to enable the performance of individual gas circulators to be "trimmed," were found to be extensively damaged, and the rotor blades and outlet guide vanes also had extensive impact and fatigue damage. Large numbers of the nuts and bolts involved had been shaken loose.[7]

The subsequent investigation determined that the noise was caused by interaction between the IGVs and the rotor blades. The sound pressure levels generated by this noise were high enough to cause rapid fatigue failure in gas circuit components, and major re-design of the gas circulators and associated components was required. The IGVs were scrapped and flow straighteners introduced to smooth the flow of gas into the gas circulator intakes. Much pioneering experimental laboratory work on resonance and sound pressure levels was performed at English Electric's Gas Turbine and Atomic Power Division (APD) facilities at Whetstone, Leicestershire, to support the redesign work, and instrumentation to measure stress and sound pressure levels in the gas circuit during testing was developed. The delay caused severe financial difficulties for the consortium and set the construction schedule back; the station began generating electricity two years late in 1965.[8]

Closure[edit]

Both reactors were shut down in April 1999 to carry out reinforcement work following a Nuclear Installations Inspectorate Periodic Safety Review. Reactor 2 was returned to service in September 1999, but shut down on 3 December 1999 because of newly identified uncertainties in the reactor pressure vessel material properties. Because of the cost of remedying these problems, it was announced on 23 May 2000 that Hinkley Point A would be shut down.[9]

Hinkley Point A was one of eleven Magnox nuclear power stations commissioned in the United Kingdom between 1956 and 1971. During its 35 years of operation, Hinkley Point A generated more than 103 TWh of electricity, giving a lifetime load factor against design of 34%.[10]

There are two nuclear power stations at Hinkley Point, the other is Hinkley Point B, operated by EDF Energy. There are also two other power stations nearby at Oldbury and Berkeley on the banks of the River Severn. In October 2013, the UK government announced that it had approved the construction of Hinkley Point C. The plant will be completed in 2023 and remain operational for around 60 years.[11]

References[edit]

  1. ^ "IAEA PRIS". Retrieved 14 Oct 2014. 
  2. ^ Nuclear Development in the United Kingdom
  3. ^ Nuclear Power Plants in the UK
  4. ^ "Nuclear Power Plants in the UK - England". Power Plants Around the World. Retrieved 2010-11-14. 
  5. ^ David Lowry (13 November 2014). "The world's first 'Nuclear Proliferation Treaty'". Ecologist. Retrieved 2 December 2014. 
  6. ^ Reginald Maudling (24 June 1958). "Atomic Power Stations (Plutonium Production)". Hansard. UK Parliament. HC Deb 24 June 1958 vol 590 cc246-8. Retrieved 2 December 2014. the Central Electricity Generating Board has agreed to a small modification in the design of Hinkley Point and of the next two stations in its programme so as to enable plutonium suitable for military purposes to be extracted should the need arise. 
  7. ^ "Investigations into the failure of gas circulators and circuit components at Hinkley Point nuclear power station" Rizk, W and Seymour, D F Proceedings of the Institution of Mechanical Engineers, v179 1964 p627-703
  8. ^ "Hinkley A: 1965". BBC Somerset. BBC. Retrieved 2008-07-05. 
  9. ^ Nuclear Installations Inspectorate (September 2000). Report by HM Nuclear Installations Inspectorate on the results of Magnox Long Term Safety Reviews (LTSRs) and Periodic Safety Reviews (PSRs) (Report). Health and Safety Executive. p. 37 (Appendix E). http://www.hse.gov.uk/nuclear/magnox.pdf. Retrieved 2010-03-21.
  10. ^ "Hinkley Point A - Facts and figures". Magnox Ltd. Retrieved 7 February 2011. 
  11. ^ "UK nuclear power plant gets go-ahead". BBC News. 21 October 2013. Retrieved 21 October 2013. 

See also[edit]