Chapelcross nuclear power station
Encyclopedia
Chapelcross was a Magnox
nuclear power plant
located near the town of Annan
in Dumfries and Galloway
in south west Scotland
. It was the sister plant to Calder Hall
in Cumbria
, England
, both commissioned and originally operated by the United Kingdom Atomic Energy Authority.
The primary purpose of both plants was to produce weapons-grade
plutonium
for the UK's nuclear weapons programme
, but they also generated electrical power for the National Grid.
in the Annandale and Eskdale district within the Dumfries and Galloway
region of south west Scotland
. The nearest hamlet is Creca.
in Cumbria
, England
. Construction was carried out by Mitchell Construction
and was completed in 1959. The primary purpose was to produce plutonium
for the UK's nuclear weapons programme
(see WE.177
). Electricity was always considered to be a by-product.
The Chapelcross Works was officially opened on 2 May, 1959 by the Lord Lieutenant of Dumfries
shire, Sir John Crabbe. It was initially owned and operated by the Production Group of the United Kingdom Atomic Energy Authority
(UKAEA) until the creation of British Nuclear Fuels Limited (BNFL
) in 1971 by an act of Parliament. The site then operated in conjunction with Calder Hall
under the banner of BNFL’s Electricity Generation Business (EGB) until rebranding, relicensing and restructuring of the various nuclear businesses operated by HM Government under the umbrella legal entity of BNFL
took place in April 2005.
Chapelcross had four Magnox
reactors capable of generating 60 MWe of power each. The reactors were supplied by the UKAEA and the turbines by C.A. Parsons & Company.
Ownership of all of the site’s assets and liabilities was transferred to The Nuclear Decommissioning Authority
(NDA), a new regulatory body created as a result of The Energy Act of 2004. The site was then operated under the two-tier Site Management Company/Site License Company (SMC/SLC) model by British Nuclear Group
’s Reactor Sites business as SMC and Magnox
Electric Ltd as the SLC. In June 2007, EnergySolutions LLC bought the Reactor Sites Management Company Ltd (consisting of two operational divisions, Magnox North and Magnox South) from British Nuclear Group
.
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 NII to permission final defuelling: the engineering work is being carried out by BNS Nuclear Services (Formally Alstec).
Generation ceased in June 2004.
(HSE) granted consent to carry out decommissioning projects at Chapelcross under the regulations to Magnox Electric Ltd on 26 September 2005. The first visible sign of decommissioning
was controlled demolition at 09.00 BST on 20 May 2007 of the four natural draught concrete cooling tower
s of the same hyperboloid design as conventional inland power station
s such as Didcot
, Drax, Ferrybridge
and Fiddlers Ferry
. The explosions were designed to remove a section of the cooling towers’ shells. Approximately two thirds of the circumference and two thirds of the shell legs were removed by the blasts, causing a controlled collapse of each tower. The charges were fired sequentially, reducing the 300 ft (91.4 m) high towers to an estimated 25,000 tons of rubble in less than 10 seconds. Those at Calder Hall
were demolished on 29 September 2007.
Some local people (including site employees) were opposed to the obliteration of such a proud symbol of the region’s industrial heritage and contribution to the local economy and national defence. The towers were considered a local landmark
that could be seen from a distance of up to fifty miles 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.
moderated
, carbon dioxide
cooled nuclear reactor
s 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 MW(e) but progressively uprated to 30 MW(e) as the reactor thermal output was uprated to nominally 265 MW(th).
Reactor 1 had the same core design as Calder Hall
(i.e. unsleeved), but the fuel channels of Reactors 2, 3 and 4 were fitted with graphite
sleeves to allow the bulk moderator to run some 80°C hotter to limit the effects of in-service graphite
damage due to irradiation
. Two of the reactors were used to produce tritium
for the UK’s strategic nuclear deterrent and therefore required enriched uranium
fuel to offset the neutron
absorbing effect of the lithium
target material.
processing plant (CXPP) and new flask handling facility (FHB). The part of the site referred to as north site consists of legacy buildings including aircraft hangars, a graphite
handling laboratory and a large building that originally housed some 10,000 drums of yellow Magnox Depleted Uranium (MDU) trioxide
arising from reprocessing
at Sellafield
.
Liquid effluent
is disposed of via a 5 km 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 Polaris
and Trident
strategic nuclear deterrents from about 1980 until 2005. This was achieved by neutron
bombardment of lithium
target material and the tritium gas extracted in the Chapelcross Processing Plant (CXPP). This facility was managed by BNFL
on behalf of the Ministry of Defence
(MoD). The material was transferred to Aldermaston
via secure road convoys. Because of involvement in the defence programme, the site was not subject to international safeguards until 1998.
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.
that is less radiologically toxic than naturally occurring uranium but chemotoxic
in a similar manner to lead
. Owing to its high density
and low solubility
, it does not tend to disperse far and dry spills are easy to clean up. This material was stored at the larger sites, including Capenhurst
in mild steel drums. BNFL has upgraded the fabric of the building and the original drums are being overpacked into stainless steel
drums and dispatched to Capenhurst
for long-term storage.
The event revealed shortfalls in the safety of the refuelling operation and the licensee took the immediate step of halting all refuelling operations 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).
. Metallurgical examination of samples of the defect showed that:
). The fuel overheated and the Magnox
cladding failed, causing contamination to be deposited in one region of the core. The reactor was restarted in 1969 after successful clean-out operations and was the final reactor to cease operation in February 2004.
Magnox
Magnox is a now obsolete type of nuclear power reactor which was designed and is still in use in the United Kingdom, and was exported to other countries, both as a power plant, and, when operated accordingly, as a producer of plutonium for nuclear weapons...
nuclear power plant
Nuclear power plant
A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...
located near the town of Annan
Annan, Dumfries and Galloway
The royal burgh of Annan is a well-built town, red sandstone being the material mainly used. Each year in July, Annan celebrates the Royal Charter and the boundaries of the Royal Burgh are confirmed when a mounted cavalcade undertakes the Riding of the Marches. Entertainment includes a...
in Dumfries and Galloway
Dumfries and Galloway
Dumfries and Galloway is one of 32 unitary council areas of Scotland. It was one of the nine administrative 'regions' of mainland Scotland created in 1975 by the Local Government etc. Act 1973...
in south west Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. It was the sister plant to Calder Hall
Sellafield
Sellafield is a nuclear reprocessing site, close to the village of Seascale on the coast of the Irish Sea in Cumbria, England. The site is served by Sellafield railway station. Sellafield is an off-shoot from the original nuclear reactor site at Windscale which is currently undergoing...
in Cumbria
Cumbria
Cumbria , is a non-metropolitan county in North West England. The county and Cumbria County Council, its local authority, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbria's largest settlement and county town is Carlisle. It consists of six districts, and in...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, both commissioned and originally operated by the United Kingdom Atomic Energy Authority.
The primary purpose of both plants was to produce weapons-grade
Weapons-grade
A weapons-grade substance is one that is pure enough to be used to make a weapon or has properties that make it suitable for weapons use. Weapons-grade plutonium and uranium are the most common examples, but it may also be used to refer to chemical and biological weapons...
plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
for the UK's nuclear weapons programme
Nuclear weapons and the United Kingdom
The United Kingdom was the third country to test an independently developed nuclear weapon, in October 1952. It is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, which the UK ratified in 1968...
, but they also generated electrical power for the National Grid.
Location
Chapelcross occupies a 92 hectare site on the location of former World War II training airfield, RAF Annan, located 3 km north east of the town of AnnanAnnan
-People:* Kofi Annan, , former Secretary-General of the United Nations * Kojo Annan, , Kofi Annan's son* Noel Annan, Baron Annan, was a member of the House of Lords and British academic...
in the Annandale and Eskdale district within the Dumfries and Galloway
Dumfries and Galloway
Dumfries and Galloway is one of 32 unitary council areas of Scotland. It was one of the nine administrative 'regions' of mainland Scotland created in 1975 by the Local Government etc. Act 1973...
region of south west Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. The nearest hamlet is Creca.
History
Chapelcross was the sister plant to Calder HallCalder Hall
Calder Hall can refer to -* Calder Hall Magnox nuclear power station at Sellafield* Calder Hall...
in Cumbria
Cumbria
Cumbria , is a non-metropolitan county in North West England. The county and Cumbria County Council, its local authority, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbria's largest settlement and county town is Carlisle. It consists of six districts, and in...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. Construction was carried out by Mitchell Construction
Mitchell Construction
Mitchell Construction was once a leading British civil engineering business based in Peterborough.-History:The business was founded by F.G. Mitchell in London in 1933 as an offshoot of Mitchell Engineering, his engineering business. In 1940 the Company moved to Peterborough because of the...
and was completed in 1959. The primary purpose was to produce plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
for the UK's nuclear weapons programme
Nuclear weapons and the United Kingdom
The United Kingdom was the third country to test an independently developed nuclear weapon, in October 1952. It is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, which the UK ratified in 1968...
(see WE.177
WE.177
WE.177 was the last air-delivered tactical nuclear weapon of the British Armed Forces. There were three versions; WE.177A was a boosted fission weapon, while WE.177B and WE.177C were thermonuclear weapons...
). Electricity was always considered to be a by-product.
The Chapelcross Works was officially opened on 2 May, 1959 by the Lord Lieutenant of Dumfries
Lord Lieutenant of Dumfries
This is a list of people who have served as Lord-Lieutenant of Dumfries.*William Douglas, 4th Duke of Queensberry 17 March 1794 –1797*Charles Montagu-Scott, 4th Duke of Buccleuch 17 November 1797 – 20 April 1819...
shire, Sir John Crabbe. It was initially owned and operated by the Production Group of the United Kingdom Atomic Energy Authority
United Kingdom Atomic Energy Authority
The United Kingdom Atomic Energy Authority is a UK government research organisation responsible for the development of nuclear fusion power. It is an executive non-departmental public body of the Department for Business, Innovation and Skills and was formerly chaired by Lady Barbara Judge CBE...
(UKAEA) until the creation of British Nuclear Fuels Limited (BNFL
BNFL
British Nuclear Fuels Limited was a nuclear energy and fuels company owned by the UK Government. It was a former manufacturer and transporter of nuclear fuel , ran reactors, generated and sold electricity, reprocessed and managed spent fuel , and decommissioned nuclear plants and other similar...
) in 1971 by an act of Parliament. The site then operated in conjunction with Calder Hall
Calder Hall
Calder Hall can refer to -* Calder Hall Magnox nuclear power station at Sellafield* Calder Hall...
under the banner of BNFL’s Electricity Generation Business (EGB) until rebranding, relicensing and restructuring of the various nuclear businesses operated by HM Government under the umbrella legal entity of BNFL
BNFL
British Nuclear Fuels Limited was a nuclear energy and fuels company owned by the UK Government. It was a former manufacturer and transporter of nuclear fuel , ran reactors, generated and sold electricity, reprocessed and managed spent fuel , and decommissioned nuclear plants and other similar...
took place in April 2005.
Chapelcross had four Magnox
Magnox
Magnox is a now obsolete type of nuclear power reactor which was designed and is still in use in the United Kingdom, and was exported to other countries, both as a power plant, and, when operated accordingly, as a producer of plutonium for nuclear weapons...
reactors capable of generating 60 MWe of power each. The reactors were supplied by the UKAEA and the turbines by C.A. Parsons & Company.
Ownership of all of the site’s assets and liabilities was transferred to The Nuclear Decommissioning Authority
Nuclear Decommissioning Authority
The Nuclear Decommissioning Authority is a non-departmental public body of the United Kingdom formed by the Energy Act 2004. It came into existence in late 2004, and took on its main functions on 1 April 2005...
(NDA), a new regulatory body created as a result of The Energy Act of 2004. The site was then operated under the two-tier Site Management Company/Site License Company (SMC/SLC) model by British Nuclear Group
British Nuclear Group
Sellafield Ltd is a nuclear decommissioning Site Licence Company controlled by Nuclear Management Partners Ltd, its designated Parent Body Organisation...
’s Reactor Sites business as SMC and Magnox
Magnox
Magnox is a now obsolete type of nuclear power reactor which was designed and is still in use in the United Kingdom, and was exported to other countries, both as a power plant, and, when operated accordingly, as a producer of plutonium for nuclear weapons...
Electric Ltd as the SLC. In June 2007, EnergySolutions LLC bought the Reactor Sites Management Company Ltd (consisting of two operational divisions, Magnox North and Magnox South) from British Nuclear Group
British Nuclear Group
Sellafield Ltd is a nuclear decommissioning Site Licence Company controlled by Nuclear Management Partners Ltd, its designated Parent Body Organisation...
.
Several significant events in 2001 persuaded BNFL
BNFL
British Nuclear Fuels Limited was a nuclear energy and fuels company owned by the UK Government. It was a former manufacturer and transporter of nuclear fuel , ran reactors, generated and sold electricity, reprocessed and managed spent fuel , and decommissioned nuclear plants and other similar...
to upgrade the fuel routes of both Calder Hall
Calder Hall
Calder Hall can refer to -* Calder Hall Magnox nuclear power station at Sellafield* 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 NII to permission final defuelling: the engineering work is being carried out by BNS Nuclear Services (Formally Alstec).
Generation ceased in June 2004.
Decommissioning and the cooling towers
The Health and Safety ExecutiveHealth and Safety Executive
The Health and Safety Executive is a non-departmental public body in the United Kingdom. It is the body responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare, and for research into occupational risks in England and Wales and Scotland...
(HSE) granted consent to carry out decommissioning projects at Chapelcross under the regulations to Magnox Electric Ltd on 26 September 2005. The first visible sign of decommissioning
Nuclear decommissioning
Nuclear decommissioning is the dismantling of a nuclear power plant and decontamination of the site to a state no longer requiring protection from radiation for the general public...
was controlled demolition at 09.00 BST on 20 May 2007 of the four natural draught concrete cooling tower
Cooling tower
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or in the case of closed circuit dry cooling towers rely...
s of the same hyperboloid design as conventional inland power station
Power station
A power station is an industrial facility for the generation of electric energy....
s such as Didcot
Didcot Power Station
Didcot Power Station refers to a combined coal and oil power plant and a natural-gas power plant that supply the National Grid. They are situated immediately adjoining one another in the civil parish of Sutton Courtenay, next to the town of Didcot in Oxfordshire , in the UK...
, Drax, Ferrybridge
Ferrybridge power station
The Ferrybridge power stations refers to a series of three coal-fired power stations situated on the River Aire in West Yorkshire, England. The first station on the site, Ferrybridge A power station, was constructed in the mid-1920s, and was closed as the second station, Ferrybridge B power...
and Fiddlers Ferry
Fiddlers Ferry Power Station
Fiddlers Ferry Power Station is a coal fired power station located in Cheshire in North West England, which is capable of co-firing biomass. It is situated on the north bank of the River Mersey between the towns of Widnes and Warrington. Opened in 1971, the station has a generating capacity of...
. The explosions were designed to remove a section of the cooling towers’ shells. Approximately two thirds of the circumference and two thirds of the shell legs were removed by the blasts, causing a controlled collapse of each tower. The charges were fired sequentially, reducing the 300 ft (91.4 m) high towers to an estimated 25,000 tons of rubble in less than 10 seconds. Those at Calder Hall
Calder Hall
Calder Hall can refer to -* Calder Hall Magnox nuclear power station at Sellafield* Calder Hall...
were demolished on 29 September 2007.
Some local people (including site employees) were opposed to the obliteration of such a proud symbol of the region’s industrial heritage and contribution to the local economy and national defence. The towers were considered a local landmark
Landmark
This is a list of landmarks around the world.Landmarks may be split into two categories - natural phenomena and man-made features, like buildings, bridges, statues, public squares and so forth...
that could be seen from a distance of up to fifty miles in good weather conditions. British Nuclear Group
British Nuclear Group
Sellafield Ltd is a nuclear decommissioning Site Licence Company controlled by Nuclear Management Partners Ltd, its designated Parent Body Organisation...
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.
Plant design
The plant design was essentially the same as Calder Hall comprising four 180 MW(th) graphiteNuclear Graphite
Nuclear graphite is any grade of graphite, usually electro-graphite, specifically manufactured for use as a moderator or reflector within nuclear reactors...
moderated
Neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....
, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
cooled nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s fuelled by natural abundance uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
(0.71% 235U) enclosed in magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
-alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
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 MW(e) but progressively uprated to 30 MW(e) as the reactor thermal output was uprated to nominally 265 MW(th).
Reactor 1 had the same core design as Calder Hall
Calder Hall
Calder Hall can refer to -* Calder Hall Magnox nuclear power station at Sellafield* Calder Hall...
(i.e. unsleeved), but the fuel channels of Reactors 2, 3 and 4 were fitted with graphite
Nuclear Graphite
Nuclear graphite is any grade of graphite, usually electro-graphite, specifically manufactured for use as a moderator or reflector within nuclear reactors...
sleeves to allow the bulk moderator to run some 80°C hotter to limit the effects of in-service graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
damage due to irradiation
Irradiation
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to...
. Two of the reactors were used to produce tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
for the UK’s strategic nuclear deterrent and therefore required enriched uranium
Enriched uranium
Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...
fuel to offset the neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
absorbing effect of the lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
target material.
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, tritiumTritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
processing plant (CXPP) and new flask handling facility (FHB). The part of the site referred to as north site consists of legacy buildings including aircraft hangars, a graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
handling laboratory and a large building that originally housed some 10,000 drums of yellow Magnox Depleted Uranium (MDU) trioxide
Uranium trioxide
Uranium trioxide , also called uranyl oxide, uranium oxide, and uranic oxide, is the hexavalent oxide of uranium. The solid may be obtained by heating uranyl nitrate to 400 °C. Its most commonly encountered polymorph, γ-UO3, is a yellow-orange powder.-Production and use:There are three methods...
arising from reprocessing
Nuclear reprocessing
Nuclear reprocessing technology was developed to chemically separate and recover fissionable plutonium from irradiated nuclear fuel. Reprocessing serves multiple purposes, whose relative importance has changed over time. Originally reprocessing was used solely to extract plutonium for producing...
at Sellafield
Sellafield
Sellafield is a nuclear reprocessing site, close to the village of Seascale on the coast of the Irish Sea in Cumbria, England. The site is served by Sellafield railway station. Sellafield is an off-shoot from the original nuclear reactor site at Windscale which is currently undergoing...
.
Liquid effluent
Effluent
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...
is disposed of via a 5 km long pipeline to the Solway Firth
Solway Firth
The Solway Firth is a firth that forms part of the border between England and Scotland, between Cumbria and Dumfries and Galloway. It stretches from St Bees Head, just south of Whitehaven in Cumbria, to the Mull of Galloway, on the western end of Dumfries and Galloway. The Isle of Man is also very...
. All environmental discharges are subject to an annual discharge authorisation which is regulated by the Scottish Environment Protection Agency
Scottish Environment Protection Agency
The Scottish Environment Protection Agency is Scotland’s environmental regulator. Its main role is to protect and improve Scotland's environment...
(SEPA).
Chapelcross produced tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
for the Polaris
UGM-27 Polaris
The Polaris missile was a two-stage solid-fuel nuclear-armed submarine-launched ballistic missile built during the Cold War by Lockheed Corporation of California for the United States Navy....
and Trident
UK Trident programme
The UK Trident programme is the United Kingdom's Trident missile-based nuclear weapons programme. Under the programme, the Royal Navy operates 58 nuclear-armed Trident II D-5 submarine-launched ballistic missiles and around 200 nuclear warheads on 4 Vanguard-class ballistic missile submarines from...
strategic nuclear deterrents from about 1980 until 2005. This was achieved by neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
bombardment of lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
target material and the tritium gas extracted in the Chapelcross Processing Plant (CXPP). This facility was managed by BNFL
BNFL
British Nuclear Fuels Limited was a nuclear energy and fuels company owned by the UK Government. It was a former manufacturer and transporter of nuclear fuel , ran reactors, generated and sold electricity, reprocessed and managed spent fuel , and decommissioned nuclear plants and other similar...
on behalf of the Ministry of Defence
Ministry of Defence (United Kingdom)
The Ministry of Defence is the United Kingdom government department responsible for implementation of government defence policy and is the headquarters of the British Armed Forces....
(MoD). The material was transferred to Aldermaston
Atomic Weapons Establishment
The Atomic Weapons Establishment is responsible for the design, manufacture and support of warheads for the United Kingdom's nuclear deterrent. AWE plc is responsible for the day-to-day operations of AWE...
via secure road convoys. Because of involvement in the defence programme, the site was not subject to international safeguards until 1998.
Operating experience and incidents
All information presented below is in the public domain and external hyperlinked references to official reports and information are included where available.Charge pan movement relative to the core (September 2001)
Because of known shrinkage of the graphiteNuclear Graphite
Nuclear graphite is any grade of graphite, usually electro-graphite, specifically manufactured for use as a moderator or reflector within nuclear reactors...
moderator bricks in the core due to in-service irradiation effects
Neutron-induced swelling
Neutron-induced swelling is the increase of volume and decrease of density of materials subjected to intense neutron radiation. Neutrons impacting the material's lattice rearrange its atoms, causing buildup of dislocations, voids, and Wigner energy...
, 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.
Dropped basket of irradiated fuel elements (July 2001)
During routine defuelling activities on Reactor 3, a basket containing twenty-four 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 80ft (24.4m) 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.Leak of Magnox depleted uranium trioxide (July 2001)
A small amount of Magnox Depleted Uranium leaked from some corroded mild steel drums due to rainwater ingress and leaching. MDU is a dense yellow powderUranium trioxide
Uranium trioxide , also called uranyl oxide, uranium oxide, and uranic oxide, is the hexavalent oxide of uranium. The solid may be obtained by heating uranyl nitrate to 400 °C. Its most commonly encountered polymorph, γ-UO3, is a yellow-orange powder.-Production and use:There are three methods...
that is less radiologically toxic than naturally occurring uranium but chemotoxic
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
in a similar manner to lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
. Owing to its high density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
and low solubility
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...
, it does not tend to disperse far and dry spills are easy to clean up. This material was stored at the larger sites, including Capenhurst
Capenhurst
Capenhurst is a village and civil parish in the unitary authority of Cheshire West and Chester and the ceremonial county of Cheshire, England and located on the Wirral Peninsula to the south west of the town of Ellesmere Port...
in mild steel drums. BNFL has upgraded the fabric of the building and the original drums are being overpacked into stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
drums and dispatched to Capenhurst
Capenhurst
Capenhurst is a village and civil parish in the unitary authority of Cheshire West and Chester and the ceremonial county of Cheshire, England and located on the Wirral Peninsula to the south west of the town of Ellesmere Port...
for long-term storage.
Exposure of worker to an irradiated fuel element (First Quarter 2001)
During refuelling operations on Reactor 2, an irradiated fuel element failed to release from the grab (this is used to hold 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 operations 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
International Nuclear Event Scale
The International Nuclear and Radiological Event Scale was introduced in 1990 by the International Atomic Energy Agency in order to enable prompt communication of safety significance information in case of nuclear accidents....
(INES).
Boiler shell defect (June 1997)
Cracks associated with brackets in Heat Exchanger 6 on Reactor 2 were discovered during a routine ultrasonic inspectionUltrasonic inspection
In ultrasonic testing , very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to characterize materials...
. Metallurgical examination of samples of the defect showed that:
- (a) 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 vesselPressure vesselA pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.The pressure differential is dangerous and many fatal accidents have occurred in the history of their development and operation. Consequently, their design,...
code requirement). - (b) there was no evidence of in-service fatigue crack growth.
- (c) 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.
Fatal accident (ca. 1978)
Response reference 120714 in House of Commons Hansard written answers for 5 May 2000 (pt 5) shows that BNFL was fined £200 in 1978 for a fatal accident at Chapelcross.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 fuel element failureFuel element failure
A fuel element failure is a rupture in a nuclear reactor's fuel cladding that allows the nuclear fuel or fission products in the form of dissolved radioisotopes or hot particles to enter the reactor coolant or storage water....
). The fuel overheated and the Magnox
Magnox
Magnox is a now obsolete type of nuclear power reactor which was designed and is still in use in the United Kingdom, and was exported to other countries, both as a power plant, and, when operated accordingly, as a producer of plutonium for nuclear weapons...
cladding failed, causing contamination to be deposited in one region of the core. The reactor was restarted in 1969 after successful clean-out operations and was the final reactor to cease operation in February 2004.
See also
- Nuclear weapons and the United KingdomNuclear weapons and the United KingdomThe United Kingdom was the third country to test an independently developed nuclear weapon, in October 1952. It is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, which the UK ratified in 1968...
- Nuclear power in ScotlandNuclear power in ScotlandNuclear power contributes about half of Scotland's electricity. The current Scottish National Party government elected in 2007 however has a 'no new nuclear power strategy'. This position is at odds with UK government policy which in January 2008 announced the go-ahead for new nuclear power...
- Nuclear power in the United KingdomNuclear power in the United KingdomNuclear power currently generates around a sixth of the United Kingdom's electricity. As of 2011, the United Kingdom operates 19 nuclear reactors at nine locations...
- Energy policy of the United KingdomEnergy policy of the United KingdomThe current energy policy of the United Kingdom is set out in the Energy White Paper of May 2007 and Low Carbon Transition Plan of July 2009, building on previous work including the 2003 Energy White Paper and the Energy Review Report in 2006...
- Energy use and conservation in the United KingdomEnergy use and conservation in the United KingdomEnergy use in the United Kingdom stood at 3,894.6 kilogrammes of oil equivalent per capita in 2005 compared to a world average of 1,778.0. In 2008, total energy consumed was 9.85 exajoules - around 2% of the estimated 474 EJ worldwide total...
- Radioactive wasteRadioactive wasteRadioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...