Chapelcross nuclear power station
Chapelcross Nuclear Power Station | |
---|---|
Country | Scotland |
Coordinates | 55°00′57″N 3°13′34″W / 55.0157°N 3.2261°W |
Status | Decommissioning in progress |
Construction began | 1955 |
Commission date | 1959 |
Decommission date | 2004 |
Owner(s) | Nuclear Decommissioning Authority |
Operator(s) | Magnox Ltd |
Thermal power station | |
Primary fuel | Unenriched Uranium |
Cooling towers | 4 (demolished 2007) |
Power generation | |
Units operational | 4 x 60 MWe (1959–2004) |
Make and model | C.A. Parsons & Company UKAEA |
External links | |
Commons | Related media on Commons |
grid reference NY217697 |
Chapelcross nuclear power station is a former
The site is being decommissioned by Nuclear Decommissioning Authority subsidiary Magnox Ltd. The station's four cooling towers were demolished in 2007. The reactors are spent-fuel free and are currently undergoing dismantlement of primary loop equipment such as heat exchangers and hot gas ducts. Once complete, the reactors will enter a care and maintenance stage to allow radiation levels to decline before the reactors themselves are demolished.
Location
Chapelcross occupies a 92-hectare (230-acre) site on the location of former World War II training airfield, RAF Annan, located 3 km (1.9 miles) north east of the town of Annan in the Annandale and Eskdale district within the Dumfries and Galloway region of south west Scotland. The nearest hamlet is Creca.
History
Chapelcross was the sister plant to
The Chapelcross Works was officially opened on 2 May 1959 by the
Chapelcross had four
Ownership of all of the site's assets and liabilities was transferred to the
Several significant events in 2001 persuaded BNFL to upgrade the fuel routes of both Calder Hall and Chapelcross to near modern standards at a cost of tens of millions of pounds, to guarantee that a License Instrument would be granted by the
Generation ceased in June 2004.
Decommissioning and the cooling towers
The
Some local people (including site employees) were opposed to the obliteration of a symbol of the region's industrial heritage. The towers were considered a local landmark that could be seen from a distance of up to 50 miles (80 km) in good weather conditions. British Nuclear Group and the NDA prioritised conventional demolition over deplanting and post-operational clean-out (POCO) of the nuclear facilities on the site. A large part of the shell of tower 1 managed to resist the explosives despite having a visible bulge that resulted from a construction anomaly.[4]
By December 2012, three of the four reactors had been defuelled.[5] Defuelling was completed in February 2013.[6]
Removal of most buildings is expected to take until 2023–2024, followed by a care and maintenance phase from 2024 to 2089. Demolition of reactor buildings and final site clearance is planned for 2089 to 2095.[7]
Plant design
The plant design was essentially the same as Calder Hall, comprising four 180 MWth graphite moderated, carbon dioxide cooled nuclear reactors fuelled by natural abundance uranium (0.71% 235U) enclosed in magnesium-alloy cans, the principal difference being in plant layout. Since Chapelcross was commissioned from the outset as a four-reactor site (the option for a further four reactors was not exercised) rather than separate two-reactor sites as at Calder 'A' and 'B' stations, the site layout was more compact. There is a single turbine hall housing all eight turbines, which were originally rated at 23 MWe but progressively uprated to 30 MWe as the reactor thermal output was uprated to nominally 265 MWth.
Reactor 1 had the same
Layout and facilities
The south part of the site consists of a modular administration building, four reactor buildings, turbine hall, maintenance workshops, stores, fuel element cooling pond building,
Liquid effluent is disposed of via a 5 km (3.1 miles) long pipeline to the Solway Firth. All environmental discharges are subject to an annual discharge authorisation which is regulated by the Scottish Environment Protection Agency (SEPA).
Chapelcross produced tritium for the
Operating experience and incidents
Single channel fuel clad melt (May 1967)
Fuel in a single channel in Reactor 2 that was loaded with fuel elements under evaluation for the commercial reactor programme experienced a partial blockage, attributed to the presence of graphite debris (see
Fatal accident (ca. 1978)
BNFL was fined £200 in 1978 for a fatal accident at Chapelcross.[8]
Boiler shell defect (June 1997)
Cracks associated with brackets in Heat Exchanger 6 on Reactor 2 were discovered during routine ultrasonic testing. Metallurgical examination of samples of the defect showed that:
- It originated during fabrication in the workshop and prior to an over-pressure test of 2.35 times the design pressure (a loading significantly in excess of a modern pressure vessel code requirement).
- There was no evidence of in-service fatigue crackgrowth.
- The material in which the crack was located was different from that specified in the design. Similar material was also identified in other heat exchangers, and no additional cracks of structural significance were revealed during comprehensive inspections. The NII considered the material to be adequate and within the bounds of the heat exchanger safety case.[9][10]
Exposure of workers to an irradiated fuel element (first quarter 2001)
During refuelling operations on Reactor 2, an irradiated fuel element failed to release from the grab which holds an element while it is withdrawn from a reactor. Routine methods were used to release the grab. However, the irradiated fuel element snagged during the operation and was lifted out of its shielding, resulting in the operators on the pile cap being exposed to the intense radiation being emitted from the irradiated fuel element. Personnel responded quickly, and the radiological dose they received was small.
The event revealed shortfalls in the safety of the refuelling operation and the licensee took the immediate step of halting all refuelling while it investigated the event and reviewed the safety of the equipment. The NII investigated the event and judged that it was due to inadequate design and operation of the equipment.
The incident was classified as Level 1 (anomaly) on the International Nuclear Event Scale (INES).[11]
Leak of Magnox depleted uranium trioxide (July 2001)
A small amount of
Dropped basket of irradiated fuel elements (July 2001)
During routine defuelling activities on Reactor 3, a basket containing 24 low-rated irradiated Magnox fuel elements fell a few feet within the discharge machine onto the door at the top of the fuel discharge well. Remote TV camera inspections revealed that twelve of the elements had fallen just over 80 ft (24 m) down the discharge well into a water-filled transport flask at the bottom. The NII initiated an investigation because dropping irradiated fuel elements is a serious issue even when, as in this event, BNFL had advised NII that there had been no release of radiological activity.[13]
Charge pan movement relative to the core (September 2001)
Because of known shrinkage of the graphite moderator bricks in the core due to in-service irradiation effects, some of the steel charge pans on top of them had become dislocated from their design position in the interstitial channel and were suspended from the Burst Can Detection (BCD) pipework. This was most prevalent in Reactor 1 because of the different core design to Reactors 2, 3 and 4. BNFL were unable to make an adequate safety case or effect an economic repair and therefore, Reactor 1 did not return to power from its annual outage in August 2001. The core of Reactor 4 was repaired but this reactor did not return to power after the repair.[12]
Interim storage facility
An interim storage facility for storing intermediate level radioactive waste from Chapelcross came into operation in 2021. Construction began in 2014 of the 57 by 23 metres (187 by 75 ft) facility, which can store 700 waste packages for 120 years.[14]
See also
- Nuclear weapons and the United Kingdom
- Nuclear power in Scotland
- Nuclear power in the United Kingdom
- Energy policy of the United Kingdom
- Energy use and conservation in the United Kingdom
References
- ISBN 978-0-571-14985-8
- ^ a b "Nuclear Power Plants in the UK - Scotland and Wales". Industcards.com. Archived from the original on 19 July 2009. Retrieved 24 December 2012.
- ^ Convention on Nuclear Safety Questions Posted To United Kingdom in 2005 Seq. No. 16 Archived 19 July 2013 at the Wayback Machine HSE 2005
- ^ Nuclear cooling towers demolished BBC News, 22 May 2007
- ^ "Chapelcross nuclear plant reaches defuelling milestone". BBC Online. 24 December 2012. Retrieved 24 December 2012.
- ^ "Chapelcross nuclear plant sees final fuel rods removed". BBC Online. Retrieved 27 February 2013.
- ^ "The 2010 UK Radioactive Waste Inventory: Main Report" (PDF). Nuclear Decommissioning Agency/Department of Energy & Climate Change. February 2011. Archived from the original (PDF) on 25 March 2012. Retrieved 22 May 2012.
- ^ House of Commons written answers 5 May 2000
- ^ Nuclear Safety Newsletter, Issue 14 Archived 11 June 2007 at the Wayback Machine HM Nuclear Installations Inspectorate, October 1997
- ^ Nuclear Safety Newsletter, Issue 15 Archived 24 September 2006 at the Wayback Machine HM Nuclear Installations Inspectorate, February 1998
- ^ "Statement of nuclear incidents at nuclear installations". United Kingdom Health and Safety Executive. Archived from the original on 21 February 2014. Retrieved 6 January 2008.
- ^ a b "Chapelcross - Quarterly Report for 1 July 2001 to 30 June 2002". HM Nuclear Installations Inspectorate. Archived from the original on 2 December 2008. Retrieved 6 January 2008.
- ^ "An investigation into a dropped fuel element incident at Chapelcross Nuclear Power Station" (PDF). HM Nuclear Installations Inspectorate. Archived from the original (PDF) on 25 June 2006.
- ^ "Chapelcross ISF receives first container of waste". World Nuclear News. 14 May 2021. Retrieved 17 May 2021.
External links
- Official website archived in February 2008