91-763: Chapelcross nuclear power station is a former Magnox nuclear power station undergoing decommissioning. It is located in Annan in Dumfries and Galloway in southwest Scotland, and was in operation from 1959 to 2004. It was the sister plant to the Calder Hall nuclear power station plant in Cumbria , England; both were commissioned and originally operated by the United Kingdom Atomic Energy Authority . The primary purpose of both plants
182-537: A heat exchanger to generate steam to drive conventional steam turbine equipment for power production. The core is open on one end, so fuel elements can be added or removed while the reactor is still running. The dual-use capability of the magnox design led to the UK building up a large stockpile of fuel-grade (reactor-grade) plutonium, with the aid of the B205 reprocessing facility . The low-to-interim burnup feature of
273-403: A 25 or 100-year decommissioning strategy should be adopted. After 80 years short-lifetime radioactive material in the defuelled core would have decayed to the point that human access to the reactor structure would be possible, easing dismantling work. A shorter decommissioning strategy would require a robotic core dismantling technique. The current approximately 100-year decommissioning plan
364-591: A License Instrument would be granted by the Nuclear Installations Inspectorate (NII) to permit final defuelling: the engineering work was carried out by BNS Nuclear Services (formally Alstec). Generation ceased in June 2004. The Health and Safety Executive (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
455-424: 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
546-604: A few dozen reactors of this type were constructed, most of them in the UK from the 1950s to the 1970s, with very few exported to other countries. The first magnox reactor to come online was Calder Hall (at the Sellafield site) in 1956, frequently regarded as the world's first commercial nuclear power station, while the last in Britain to shut down was Reactor 1 in Wylfa (on Anglesey ) in 2015. As of 2016 , North Korea remains
637-402: A large number of fuel channels . Uranium fuel was placed in aluminium canisters and pushed into the channels in the front, pushing previous fuel canisters through the channel and out the back of the reactor where they fell into a pool of water. The system was designed to work at low temperatures and power levels and was air-cooled with the help of large fans. Graphite is flammable and presents
728-495: 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. By December 2012, three of
819-506: A loose-fitting magnox shell and then pressurized with helium . The outside of the shell was typically finned in order to improve heat exchange with the CO 2 . Magnox alloy is reactive with water, which means it cannot be left in a cooling pond after extraction from the reactor for extended periods. In contrast to the Windscale layout, the magnox design used vertical fuel channels. This required
910-445: A new beryllium -based cladding, but this proved too brittle. This was replaced by a stainless steel cladding, but this absorbed enough neutrons to affect criticality, and in turn required the design to operate on slightly enriched uranium rather than the magnox's natural uranium, driving up fuel costs. Ultimately the economics of the system proved little better than Magnox. Former Treasury Economic Advisor, David Henderson , described
1001-465: A non-oxidising covering to contain fission products. Magnox is short for mag nesium n on- ox idising. This material has the advantage of a low neutron capture cross-section, but has two major disadvantages: Magnox fuel incorporated cooling fins to provide maximum heat transfer despite low operating temperatures, making it expensive to produce. While the use of uranium metal rather than oxide made reprocessing more straightforward and therefore cheaper,
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#17327832621161092-431: A quarter of UK's generating needs. Although Sir John Cockcroft had advised the government that electricity generated by nuclear power would be more expensive than that from coal, the government decided that nuclear power stations as alternatives to coal-fired power stations would be useful to reduce the bargaining power of the coal miners' unions, and so decided to go ahead. In 1960 a government white paper scaled back
1183-476: A serious safety risk. This was demonstrated on 10 October 1957 when Unit 1 of the now two-unit site caught fire. The reactor burned for three days, and massive contamination was only avoided due to the addition of filtering systems that had previously been derided as unnecessary " follies ". As the UK nuclear establishment began to turn its attention to nuclear power , the need for more plutonium for weapons development remained acute. This led to an effort to adapt
1274-437: A turbine to generate electricity, or as process heat in the nearby Windscale works, was seen as a kind of free by-product of an essential process. The Calder Hall reactors had low efficiency by today's standards, only 18.8%. The British government decided in 1957 that electricity generation by nuclear power would be promoted, and that there would be a building programme to achieve 5,000 to 6,000 MWe capacity by 1965,
1365-533: Is Creca. Chapelcross was the sister plant to Calder Hall 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 , for weapons including the WE.177 series. Electricity was always considered to be a by-product. Both Chapelcross and Calderhall were the only nuclear power stations built as part of
1456-561: Is a dense yellow powder 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 upgraded the fabric of the building and the original drums were overpacked into stainless steel drums and dispatched to Capenhurst for long-term storage. During routine defuelling activities on Reactor 3,
1547-403: Is a key element of the design. In magnox, the neutrons are moderated in large blocks of graphite . The efficiency of graphite as a moderator allows the magnox to run using natural uranium fuel, in contrast with the more common commercial light-water reactor which requires slightly enriched uranium . Graphite oxidizes readily in air, so the core is cooled with CO 2 , which is then pumped into
1638-504: Is a serious issue even when, as in this event, BNFL had advised NII that there had been no release of radiological activity. 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
1729-399: Is called Safestore. A 130-year Deferred Safestore Strategy was also considered, with an estimated cost saving of £1.4 billion, but not selected. In addition the Sellafield site which, amongst other activities, reprocessed spent magnox fuel, has an estimated decommissioning cost of £31.5 billion. Magnox fuel was produced at Springfields near Preston ; estimated decommissioning cost
1820-643: 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 Polaris and Trident strategic nuclear weapon systems from about 1980 until 2005. This was achieved by neutron bombardment of lithium target material, with
1911-583: Is governed by a ten-member board, and is accountable to Parliament through the Department for Work and Pensions (DWP) in matters of finance, governance and non-nuclear health and safety. Nick Baldwin CBE, former chief executive of Powergen (now E.ON UK ) was appointed part-time interim chair of the ONR on its formation, resigning as a non-executive director of Scottish and Southern Energy . On 21 February 2019,
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#17327832621162002-414: Is £371 million. The total cost of decommissioning magnox activities is likely to exceed £20 billion, averaging about £2 billion per productive reactor site. Calder Hall was opened in 1956 as the world's first commercial nuclear power station, and is a significant part of the UK's industrial heritage. The NDA is considering whether to preserve Calder Hall reactor 1 as a museum site. All
2093-491: The CEGB and operated on commercial fuel cycles. However Hinkley Point A and two other stations were modified so that weapons-grade plutonium could be extracted for military purposes should the need arise. In early operation it was found that there was significant oxidation of mild steel components by the high temperature carbon dioxide coolant, requiring a reduction in operating temperature and power output. For example,
2184-521: The Latina reactor was derated in 1969 by 24%, from 210 MWe to 160 MWe, by the reduction of operating temperature from 390 to 360 °C (734 to 680 °F). The Nuclear Decommissioning Authority (NDA) announced on 30 December 2015 that Wylfa Unit 1 – the world's last operating Magnox reactor – was closed. The unit had generated electricity for five years longer than originally planned. Two units at Wylfa were both scheduled to shut down at
2275-453: The advanced gas-cooled reactor (AGR) with the explicit intention of making the system more economical. Primary among the changes was the decision to run the reactor at much higher temperatures, about 650 °C (1,200 °F), which would greatly improve the efficiency when running the power-extracting steam turbines . This was too hot for the magnox alloy, and the AGR originally intended to use
2366-494: The fuel rods inside the reactor. Like most other generation I nuclear reactors , the magnox was designed with the dual purpose of producing electrical power and plutonium-239 for the nascent nuclear weapons programme in Britain . The name refers specifically to the United Kingdom design but is sometimes used generically to refer to any similar reactor. As with other plutonium-producing reactors, conserving neutrons
2457-478: The 57 by 23 metres (187 by 75 ft) facility, which can store 700 waste packages for 120 years. Magnox Magnox is a type of nuclear power / production reactor that was designed to run on natural uranium with graphite as the moderator and carbon dioxide gas as the heat exchange coolant. It belongs to the wider class of gas-cooled reactors . The name comes from the magnesium - aluminium alloy (called mag nesium n on- ox idising), used to clad
2548-737: The ACR-1000 and ESBWR were subsequently withdrawn from the assessment for commercial reasons, leaving the EPR and AP1000 as contenders for British new nuclear builds. Assessment of the AP1000 was suspended in December 2011 at Westinghouse's request, awaiting a firm UK customer before addressing issues raised by the assessment. In 2012 Hitachi purchased Horizon Nuclear Power , announcing intent to build two to three 1,350 MWe Advanced Boiling Water Reactors (ABWR) on both of Horizon's sites. The GDA
2639-434: The AGR programme as one of the two most costly British government-sponsored project errors, alongside Concorde . Source: The first magnox reactors at Calder Hall were designed principally to produce plutonium for nuclear weapons . The production of plutonium from uranium by irradiation in a pile generates large quantities of heat which must be disposed of, and so generating steam from this heat, which could be used in
2730-651: The GDA process for the Hualong One (HPR1000) started, and successfully finished in February 2022. The ABWR GDA process completed successfully in December 2017. In 2020, the GDA process was updated to be more suitable for small modular reactors and advanced nuclear technologies. A three step process was introduced: On 1 April 2022, the GDA Step 1 of the 470 MWe Rolls-Royce SMR started. Step 2 will begin once
2821-476: The Nimonic springs used contained cobalt, which became irradiated giving high gamma level when removed from the reactor. Additionally, thermocouples were attached to some elements and needed to be removed on fuel discharge from the reactor. The dual-use nature of the magnox design leads to design compromises that limit its economic performance. As the magnox design was being rolled out, work was already underway on
Chapelcross nuclear power station - Misplaced Pages Continue
2912-722: The ONR on a statutory basis at a later date. The ONR was formed from the merger of the HSE's Nuclear Directorate (the Nuclear Installations Inspectorate, the Office for Civil Nuclear Security and the UK Safeguards Office) and — from 1 June 2011 — the Department for Transport 's Radioactive Materials Transport Team. Legislation to establish the ONR was included in the Energy Act 2013 , and it
3003-526: The Reactor Sites Management Company Ltd (RSML, consisting of two operational divisions, Magnox North and Magnox South) from British Nuclear Group. RSML subsequently became Magnox Ltd and is now a wholly-owned subsidiary of the NDA. 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
3094-665: The Secretary of State for Work and Pensions announced that Mark McAllister would succeed Baldwin as Chair of the Board. Mark McAllister began his five-year appointment as ONR Chair on 1 April 2019. The ONR Board oversees the operation of the Chief Executive Officer (CEO) and the Chief Nuclear Inspector (CNI). John Jenkins, who was CEO from 2013 to 2015, resigned from his post on 28 February 2015 and
3185-614: The UK's gas reactor fleet to use cooling towers as a heat sink as opposed to using the sea. The Chapelcross Works was officially opened on 2 May 1959 by the Lord Lieutenant of Dumfriesshire , 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
3276-693: The UK's magnox reactor sites (apart from Calder Hall) are operated by Magnox Ltd , a subsidiary of the NDA. Reactor Sites Management Company (RSMC), a NDA Site Licence Company (SLC), originally held the contract to manage Magnox Ltd on behalf of the NDA. In 2007, RSMC was acquired by American nuclear fuel cycle service provider EnergySolutions from British Nuclear Fuels . On 1 October 2008, Magnox Electric Ltd separated into two nuclear licensed companies, Magnox North Ltd and Magnox South Ltd. Magnox North sites Magnox South sites In January 2011 Magnox North Ltd and Magnox South Ltd recombined as Magnox Ltd . Following procurement and management issues with
3367-402: The UK's nuclear weapons and required enriched uranium fuel to offset the neutron absorbing effect of the lithium target material. 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, tritium processing plant (CXPP) and new flask handling facility (FHB). The part of
3458-542: 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
3549-399: The basic Windscale design to a power-producing version that would also produce plutonium. In order to be economically useful the plant would have to run at much higher power levels, and in order to efficiently convert that power to electricity, it would have to run at higher temperatures. At these power levels, the fire risk is amplified and air cooling is no longer appropriate. In the case of
3640-434: The blasts, causing a controlled collapse of each tower. The charges were fired sequentially, reducing the 300 ft (91 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 a symbol of the region's industrial heritage. The towers were considered
3731-485: The building programme to 3,000 MWe, acknowledging that coal generation was 25% cheaper. A government statement to the House of Commons in 1963 stated that nuclear generation was more than twice as expensive as coal. The plutonium credit which assigned a value to the plutonium produced was used to improve the economic case, although the operators of the power stations were never paid this credit. Once removed from
Chapelcross nuclear power station - Misplaced Pages Continue
3822-524: The complete gas circuit, are much lower. In all, 11 power stations totalling 26 units were built in the United Kingdom where the design originated. In addition, one was exported to Tōkai in Japan and another to Latina in Italy. North Korea also developed their own magnox reactors, based on the UK design which was made public at an Atoms for Peace conference. The first magnox power station, Calder Hall ,
3913-495: The contract, Magnox Ltd will become a subsidiary of the NDA in September 2019. Nuclear Installations Inspectorate The Office for Nuclear Regulation (ONR) is the regulator for the nuclear industry in the United Kingdom. It is an independent statutory corporation whose costs are met by charging fees to the nuclear industry. The ONR reports to the Department for Work and Pensions , although it also worked closely with
4004-487: The costs of the magnox programme. Later reviews criticised the continuing development project by project instead of standardisation on the most economical design, and for persisting with the development of a reactor which achieved only two export orders. A retrospective evaluation of costs, using a low 5% discount rate on capital, estimated magnox electricity costs were nearly 50% higher than coal power stations would have provided. The magnox reactors were considered at
4095-409: The day after the designer, Westinghouse, filed for Chapter 11 bankruptcy because of $ 9 billion of losses from its nuclear reactor construction projects, mostly the construction of four AP1000 reactors in the U.S. On 21 September 2015 Energy Secretary Amber Rudd announced that a Chinese designed nuclear power station was expected to be built at Bradwell nuclear power station . On 19 January 2017
4186-508: The design of submarine nuclear power plants or nuclear weapons, and does not regulate security or transport of MOD nuclear materials. ONR responsibility includes assessing the response systems for nuclear weapon accidents at HMNB Clyde and RNAD Coulport , in Argyll , Scotland. Since about 2013 the ONR has given the two major Atomic Weapons Establishment (AWE) sites enhanced regulatory attention due to "safety and compliance concerns, and
4277-539: The design) would not cause large-scale fuel failure as the Magnox cladding would retain the bulk of the radioactive material, assuming the reactor was rapidly shutdown (a SCRAM ), because the decay heat could be removed by natural circulation of air. As the coolant is already a gas, explosive pressure buildup from boiling is not a risk, as happened in the catastrophic steam explosion at the Chernobyl accident . Failure of
4368-475: The differences between the stations; for example, nearly every power station used a different design of magnox fuel element. Most of the magnox builds suffered time overruns and cost escalation. For the initial start up of the reactor neutron sources were located within the core to provide sufficient neutrons to initiate the nuclear reaction. Other aspects of the design included the use of flux shaping or flattening bars or controls rods to even out (to some extent)
4459-564: The dome, connected through piping. Although there were strengths with this approach in that maintenance and access was generally more straightforward, the major weakness was the radiation 'shine' emitted particularly from the unshielded top duct. The magnox design was an evolution and never truly finalised, and later units differ considerably from earlier ones. As neutron fluxes increased in order to improve power densities problems with neutron embrittlement were encountered, particularly at low temperatures. Later units at Oldbury and Wylfa replaced
4550-576: The end of 2012, but the NDA decided to shut down Unit 2 in April 2012 so that Unit 1 could continue operating in order to fully utilize existing stocks of fuel, which was no longer being manufactured. The small 5 MWe experimental reactor, based on the magnox design, at Yongbyon in North Korea , continues to operate as of 2016 . Magnox is also the name of an alloy —mainly of magnesium with small amounts of aluminium and other metals—used in cladding unenriched uranium metal fuel with
4641-587: The first reactor had been in use for nearly 47 years. The first two stations (Calder Hall and Chapelcross ) were originally owned by the UKAEA and primarily used in their early life to produce weapons-grade plutonium , with two fuel loads per year. From 1964 they were mainly used on commercial fuel cycles and in April 1995 the UK Government announced that all production of plutonium for weapons purposes had ceased. The later and larger units were owned by
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#17327832621164732-537: The four reactors had been defuelled. Defuelling was completed in February 2013. 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. 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% U) enclosed in magnesium - alloy cans,
4823-431: The fuel canisters were left in the reactor as long as possible, while for plutonium production they were removed earlier. The complicated refuelling equipment proved to be less reliable than the reactor systems, and perhaps not advantageous overall. The entire reactor assembly was placed in a large pressure vessel. Due to the size of the pile, only the reactor core itself was placed within the steel pressure assembly, which
4914-434: The fuel shells to lock together end-to-end, or to sit one on top the other to allow them to be pulled out of the channels from the top. Like the Windscale designs, the later magnox reactors allowed access to the fuel channels and could be refuelled while operating . This was a key criterion for the design because its use of natural uranium leads to low burnup ratios and the requirement for frequent refuelling. For power use,
5005-400: 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
5096-577: 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). A small amount of Magnox depleted uranium (MDU) leaked from some corroded mild steel drums due to rainwater ingress and leaching. MDU
5187-423: The magnox design, this led to the use of carbon dioxide (CO 2 ) as the coolant. There is no facility in the reactor to adjust the gas flow through the individual channels whilst at power, but gas flow was adjusted by using flow gags attached to the support strut which located into the diagrid . These gags were used to increase flow in the centre of the core and to reduce it at the periphery. Principal control over
5278-442: The need to reprocess fuel a short time after removal from the reactor meant that the fission product hazard was severe. Expensive remote handling facilities were required to address this danger. The term magnox may also loosely refer to: The Nuclear Decommissioning Authority (NDA) is responsible for the decommissioning of the UK magnox power plants, at an estimated cost of £12.6 billion. There has been debate about whether
5369-459: The neutron flux density across the core. If not used, the flux in the centre would be very high relative to the outer areas leading to excessive central temperatures and lower power output limited by the temperature of the central areas. Each fuel channel would have several elements stacked one upon another to form a stringer . This required the presence of a latching mechanism to allow the stack to be withdrawn and handled. This caused some problems as
5460-528: The now-defunct Department of Energy and Climate Change . The establishment of the ONR followed a 2008 review conducted on behalf of the Government into the regulation of the UK civil nuclear industry, recommending the creation of a single industry-specific regulator. The ONR was created on 1 April 2011 as a non-statutory agency of the Health and Safety Executive (HSE), with the Government intending to put
5551-586: The only operator to continue using magnox style reactors, at the Yongbyon Nuclear Scientific Research Center . The magnox design was superseded by the advanced gas-cooled reactor , which is similarly cooled but includes changes to improve its economic performance. The UK's first full-scale nuclear reactor was the Windscale Pile in Sellafield . The pile was designed for the production of plutonium-239 which
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#17327832621165642-426: The operational gas temperatures to 360 °C (680 °F), much lower than desirable for efficient steam generation. This limit also meant that the reactors had to be very large in order to generate any given power level, which was further amplified by the use of gas for cooling, as the low thermal capacity of the fluid required very high flow rates. The magnox fuel elements consisted of refined uranium enclosed in
5733-438: 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
5824-424: The reaction rate was provided by a number (48 at Chapelcross and Calder Hall) of boron -steel control rods which could be raised and lowered as required in vertical channels. At higher temperatures, aluminium is no longer structurally sound, which led to the development of the magnox alloy fuel cladding. Unfortunately, magnox is increasingly reactive with increasing temperature, and the use of this material limited
5915-472: The reactor design would become responsible for changes to US regulatory classifications after the US–UK reactor-grade plutonium detonation test of the 1960s. Despite improvements to the design in later decades as electricity generation became the primary operational aim, magnox reactors were never capable of competing with the higher efficiency and higher fuel burnup of pressurised water reactors . In total, only
6006-422: The reactor shutdown system to rapidly shut down the reactor, or failure of natural circulation, was not considered in the design. In 1967 Chapelcross experienced a fuel melt due to restricted gas flow in an individual channel and, although this was dealt with by the station crew without major incident, this event had not been designed or planned for, and the radioactivity released was greater than anticipated during
6097-415: The reactor thermal output was uprated to nominally 265 MWth. 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 80 °C (144 °F) hotter, to limit the effects of in-service graphite damage due to irradiation . Two of the reactors were used to produce tritium for
6188-454: The reactor, the used fuel elements are stored in cooling ponds (with the exception of Wylfa which has dry stores in a carbon dioxide atmosphere) where the decay heat is transferred to the pond water, and then removed by the pond water circulation, cooling and filtration system. The fact that fuel elements can only be stored for a limited period in water before the magnox cladding deteriorates, and must therefore inevitably be reprocessed , added to
6279-503: The reactors will enter a care and maintenance stage to allow radiation levels to decline before the reactors themselves are demolished. 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
6370-530: The reactors. For example, the most exposed members of the public living near Dungeness magnox reactor in 2002 received 0.56 mSv , over half the International Commission on Radiological Protection recommended maximum radiation dose limit for the public, from direct shine alone. The doses from the Oldbury and Wylfa reactors, which have concrete pressure vessels which encapsulate
6461-422: The site in all directions would be less than six times the 10-degree limits. Planning permission constraints would be used to prevent any large growth of population within five miles. In the older steel pressure vessel design, boilers and gas ducting are outside the concrete biological shield. Consequently, this design emits a significant amount of direct gamma and neutron radiation , termed direct shine , from
6552-409: 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 depleted uranium trioxide arising from reprocessing at Sellafield . In the mid-2010s, the NDA removed and shipped all of the depleted uranium drums from Chapelcross to Sellafield. Liquid effluent
6643-536: The site's assets and liabilities was transferred to the Nuclear Decommissioning Authority (NDA), a new regulatory body created by the Energy Act 2004 . The site was then operated under the two-tier Site Management Company/Site License Company (SMC/SLC) model, with British Nuclear Group 's Reactor Sites business as SMC and Magnox Electric Ltd as the SLC. In June 2007, EnergySolutions bought
6734-408: The station design. Despite the belief in their inherently safe design, it was decided that the magnox stations would not be built in heavily populated areas. The positioning constraint decided upon was that any 10-degree sector would have a population less than 500 within 1.5 miles (2.4 km), 10,000 within 5 miles (8.0 km) and 100,000 within 10 miles (16 km). In addition population around
6825-411: The steel pressure vessels with prestressed concrete versions which also contained the heat exchangers and steam plant. Working pressure varies from 6.9 to 19.35 bar for the steel vessels, and 24.8 and 27 bar for the two concrete designs. No British construction company at the time was large enough to build all the power stations, so various competing consortiums were involved, adding to
6916-487: The time to have a considerable degree of inherent safety because of their simple design, low power density, and gas coolant. Because of this they were not provided with secondary containment features. A safety design principle at the time was that of the "maximum credible accident", and the assumption was made that if the plant were designed to withstand that, then all other lesser but similar events would be encompassed. Loss of coolant accidents (at least those considered in
7007-592: The timescales and resources have been agreed. Although the ONR is primarily a civil regulator, the ONR Defence Programme regulates military nuclear and conventional safety across a number of licensed and non-licensed nuclear sites, which are operated for the Ministry of Defence (MOD) nuclear defence capability. This is carried out under a complex legal regime, in conjunction with MOD’s Defence Nuclear Safety Regulator (DNSR). The ONR does not influence
7098-563: 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 Atomic Weapons Establishment at Aldermaston via secure road convoys. Because of its involvement in the nuclear weapons programme, the site was not subject to international safeguards until 1998. Fuel in a single channel in Reactor 2 that
7189-475: Was agreed in April 2013. In August 2014 Westinghouse resumed the AP1000 assessment, after Toshiba and ENGIE purchased NuGeneration and announced plans to develop Moorside Nuclear Power Station with 3 AP1000s. In November 2016 the ONR noted there was a "very large amount of assessment to complete with issues still emerging". On 30 March 2017 the AP1000 successfully completed the GDA process, ironically
7280-441: Was appointed Executive Director of Regulation and Sarah High as Deputy Chief Executive. Additionally, Paul Fyfe was appointed as Director of Regulation Civil Nuclear Security and Safeguards, Jane Bowie was appointed as Director of Regulation for New Reactors, Mike Finnerty was appointed Director of Regulation Operating Facilities, Paul Dicks was appointed Director of Regulation Sellafield, Decommissioning Fuel and Waste and Steve Vinson
7371-592: Was appointed Technical Director. As of 2021 the ONR had about 650 staff and a budget of £95.05 million, which was largely cost-recovered from users, with a 2% grant from the DWP. Following the 2006 Energy review the Nuclear Installations Inspectorate developed the Generic Design Assessment process (GDA), now operated by ONR, to assess new nuclear reactor designs ahead of site-specific proposals. The GDA initially started assessing four designs: However
7462-454: Was bred in multi-week reactions taking place in natural uranium fuel. Under normal conditions, natural uranium is not sensitive enough to its own neutrons to maintain a chain reaction . To improve the fuel's sensitivity to neutrons, a neutron moderator is used, in this case highly purified graphite . The reactors consisted of a huge cube of this material (the "pile") made up of many smaller blocks and drilled through horizontally to make
7553-421: Was controlled demolition at 09:00 BST on 20 May 2007 of the four natural-draught concrete cooling towers , which were of the same hyperboloid design as conventional inland power stations such as Didcot , Drax , Ferrybridge and Fiddlers Ferry . The explosions were designed to remove a section of the towers' shells. Approximately two-thirds of the circumference and two-thirds of the shell legs were removed by
7644-509: Was fined £200 in 1978 for a fatal accident at Chapelcross. 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: 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
7735-555: Was formally launched as an independent statutory corporation on 1 April 2014. ONR’s original mission (as detailed in the DWP/ONR Framework document) was: "To provide efficient and effective regulation of the nuclear industry, holding it to account on behalf of the public". The 2013 Energy Act specified that ONR's five statutory purposes were: Nuclear safety; Nuclear site health and safety; Civil Nuclear security; Nuclear safeguards; Transport of radioactive materials. The ONR
7826-452: 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 failure ). 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. BNFL
7917-562: 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. An interim storage facility for storing intermediate level radioactive waste from Chapelcross came into operation in 2021. Construction began in 2014 of
8008-610: Was replaced by Les Philpott on 1 March 2015 as the Interim Chief Executive. Adriènne Kelbie was appointed Chief Executive and took up the appointment on 18 January 2016. In October 2017 Mark Foy was appointed Chief Nuclear Inspector; he was previously the Deputy Chief Nuclear Inspector. New leadership arrangements commenced on 1 June 2021 which saw Mark Foy become ONR's combined Chief Executive and Chief Nuclear Inspector. Donald Urquhart
8099-454: Was the world's first nuclear power station to generate electrical power on an industrial scale (a power station in Obninsk, Russia started supplying the grid in very small non-commercial quantities on 1 December 1954). The first connection to the grid was on 27 August 1956, and the plant was officially opened by Queen Elizabeth II on 17 October 1956. When the station closed on 31 March 2003,
8190-401: Was then surrounded by a concrete confinement building (or biological shield ). As there was no water in the core, and thus no possibility of a steam explosion, the building was able to tightly wrap the pressure vessel, which helped reduce construction costs. In order to keep the size of the confinement building down, the early magnox designs placed the heat exchanger for the CO 2 gas outside
8281-718: Was to produce weapons-grade plutonium for the UK's nuclear weapons programme , but they also generated electrical power for the National Grid . Later in the reactors' lifecycle, as the UK slowed the development of the nuclear deterrent as the cold war came to a close, power production became the primary goal of reactor operation. 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,
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