Torness nuclear power station
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| Torness nuclear power station | |
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  Torness nuclear power station shown within Scotland |
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| OS grid reference | |
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| Fuel: | Nuclear 1,364 MW |
| Commissioned: | 1988 |
Torness nuclear power station was the last of the United Kingdom's second generation nuclear power plants to be commissioned. Construction of this facility began in 1980 for the then South of Scotland Electricity Board (SSEB) and it was commissioned in 1988. The station consists of two Advanced gas-cooled reactors (AGR) capable of producing a peak rating of 1364 MWe.
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[edit] Location
Torness nuclear power station is located approximately 30 miles east of the city of Edinburgh at Torness Point near Dunbar in East Lothian, Scotland. It is a local landmark, highly visible from the main A1 road and East Coast Main Line railway.
[edit] History
After extensive discussions with the local planning authority and more than twenty other interested organisations, the SSEB sought approval of the Secretary of State for Scotland in 1973 for Torness as a site for a nuclear power station. A public exhibition was held at Dunbar in February 1974 to explain the Board’s proposals, and in June 1974, a public inquiry was held. The SSEB submitted designs for four types of reactor then being considered by HM Government for the next stage of the UK civil nuclear programme: the Advanced Gas-cooled Reactor (AGR), the Steam Generating Heavy Water Reactor (SGHWR), the Light Water Reactor (LWR) and the High Temperature Reactor (HTR). In February 1975, the Secretary of State for Scotland granted the SSEB statutory consent for the location of future nuclear power stations and, after review of the four alternative reactor types, consent was given on 24 May 1978 for construction of the AGR station. Construction began in 1980. Torness was the last of the United Kingdom’s second generation nuclear power plants to be commissioned (25 May 1988) and is the sister station of Heysham Stage II being of nearly identical design.
Upon deregulation of the United Kingdom’s electricity generation market it passed to the state-owned Scottish Nuclear, now part of British Energy.
[edit] Plant design
The station was designed by NNC, a company created from the gradual amalgamation of five consortia that were formed in the 1950s and 1960s to build the UK's commercial nuclear power stations. At the time of writing, NNC is now AMEC NNC. The graphite-moderated, gas-cooled design was proven at the WAGR – the Windscale experimental AGR facility and is a significant evolution of the Magnox reactor designs. The entire UK commercial reactor programme shares a common heritage with, and was built on operating experience gained from the early PIPPA reactors at Calder Hall and Chapelcross and prior to that, the Windscale piles.
[edit] Technical details
The technical details below can be found in the public domain in a cutaway diagram of Heysham II and Torness in Nuclear Engineering International publication in 1982 and in SSEB pamphlet MCS/JT/PR4901/5M/12.79.
| General | |
| Number of units | 2 |
| Moderator | Graphite |
| Primary Coolant | Carbon dioxide (CO2) |
| Reactor thermal power (full load) | 1650 MWth |
| Electrical output (full load) | 660 MWe (GEC turbine alternator) |
| Electrical output (plated T/A maximum) | 700 MWe |
| Gross thermal to electrical conversion efficiency | 41.9% |
| Unit electrical consumption | 45 – 50 MWe |
| Control rods | 89 |
| Gas circulators | 8 × 4.8 MWe (Howden) |
| Gas circulator speed | Up to 2,970 rpm |
| Mass flow per circulator | 550 kg/s |
| Pressure Vessel | |
| Internal diameter | 20.25 m |
| Internal height | 21.87 m |
| External diameter | 31.86 m |
| Fuel | |
| Fuel enrichment | 3 – 4% 235U |
| Fuel channels per reactor | 332 |
| Weight of uranium per reactor | 113.5 Te |
| Number of fuel elements per channel | 8 |
| Weight of fuel element | 83.7 kg |
| Weight of uranium per element | 42.7 kg |
| Average power per fuel channel | 5.5 MWth |
| Mean fuel discharge irradiation | 30 – 35 GWd/Te |
| Dwell time | 6 – 7 years |
| Gas (Primary Coolant) | |
| Coolant gas pressure | 40 bar |
| Bulk gas core inlet temperature (T1) at full power | 290°C |
| Bulk gas core inlet temperature (T2) at full power | 650°C |
| Steam (Secondary Coolant) | |
| Steam side inlet pressure | 210 bar |
| Steam side outlet pressure | 160 bar |
| Economiser inlet temperature | 155°C |
| Evaporator outlet temperature | 350°C |
| Superheater steam flow | 500 kg/s |
| Reheater outlet temperature | 540°C |
| Reheater inlet pressure | 42 bar |
| Reheater outlet pressure | 40 bar |
| Reheater steam flow | 461 kg/s |
| Cooling Water/Condenser | |
| Condenser vacuum | 38 – 45 mBar BP |
| Average cooling water flow (sea water) at full load | 25 million gallons/hour |
| CW Inlet (summer, typical) | 10°C |
| CW Outlet (summer, typical) | 20°C |
| CW Inlet (winter, typical) | 3°C |
| CW Outlet (winter, typical) | 13°C |
[edit] Operating experience and incidents
Details of incidents are published on the internet site of the Health and Safety Executive in its quarterly statements of nuclear incidents at nuclear installations (see http://www.hse.gov.uk/nuclear/quarterly-stat/) and quarterly inspection reports for each nuclear licensed site. These include:
[edit] Shutdown of both units due to drumscreen blockage by seaweed – August 2006
Complete blockage by seaweed of the main cooling water intake drum-screens is an initiating event considered in the Station Safety Report (SSR). The event resulted in supplies of main cooling water being lost for a period. As a consequence, water supplies to the reactor seawater (RSW) system, which provides a safety role, were lost for a time on one reactor and restricted on the other. The station responded to the event by shutting down both reactors within 70 minutes of receiving the first indication of impaired main cooling water flow and provided adequate post trip cooling.
[edit] Unplanned power excursion – December 2005
An unplanned power increase on Reactor 2 at Torness during the night shift of 30 December 2005. Operators responded to the event by taking corrective action to restore normal core reactivity levels. Station and Company investigations identified that improvement to the training of operators covering reactivity fundamentals is appropriate.
[edit] Catastrophic failure of a gas circulator – May 2002
This was thought, from forensic evidence, to be linked to the development of an unexpected fatigue related crack in part of the impeller. In August, another gas circulator on the other Torness reactor showed signs of increasing vibration and was promptly shut down by the operators. Its subsequent disassembly revealed a fully developed fatigue related crack in a similar position to the first failure, but the prompt shutdown had prevented consequential damage.
[edit] Crash of an RAF Tornado Near the Site - November 1999
In November 1999 an RAF Panavia Tornado crashed into the North Sea less than 1 km from the power station following an engine failure. The UK Ministry of Defence commended the two crew members for demonstrating "exceptional levels of airmanship and awareness in the most adverse of conditions"; they ensured that the Tornado was clear of the power station before abandoning the aircraft.
[edit] See also
- Nuclear power in the United Kingdom
- Energy policy of the United Kingdom
- Energy use and conservation in the United Kingdom
- Pete Roche
- List of places in East Lothian
[edit] External links
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