Sellafield and Thorp

The largest and most famous of the UK's nuclear installations, with an incredibly chequered history of accidents, cancer and cover-ups.

Sellafield, Windscale, Thorp - Botch, Bungle and Cover-up.

Sellafield - the name alone is enough to fill the nuclear industry and regulators with dread. For more than 60 years the site next to the village of Seascale in Cumbria has witnessed the worst excesses of a nuclear industry in studious denial of its effects on human health and the environment. Botch, bungle and cover-up remains its mantra.

Sellafield profile

Sellafield is the name of a nuclear site, close to the village and railway station of Seascale, operated by Sellafield Ltd, but owned since 1 April 2005 by the Nuclear Decommissioning Authority. Previously Sellafield was owned and operated by BNFL.

Sellafield houses the Thorp nuclear fuel reprocessing plant and the Magnox nuclear fuel reprocessing plant. It is also the site of the remains of Calder Hall Magnox nuclear power station — the world's first commercial nuclear power station, which is now being decommissioned, as well as some other older nuclear facilities.


Sellafield was originally a Second World War Royal Ordnance Factory, ROF Sellafield that, with its sister factory, ROF Drigg, at Drigg, produced TNT. After the war, the Ministry of Supply adapted the Sellafield site to produce nuclear weapons materials, principally plutonium. Construction of the nuclear facilities commenced in 1947 and the site was renamed "Windscale" to avoid confusion with the Springfields uranium processing factory near Preston.

Over the years the site has been the focus for the UK nuclear industry and now houses 200 nuclear facilities and 60% of the UK's nuclear liabilities. These have included plutonium production facilities, fuel plants, Magnox reactors and fuel reprocessing plants.

The Windscale Piles

Following the decision for the UK to develop its own nuclear weapons, Sellafield was chosen as the location of the plutonium production plant. The Windscale Piles consisted of a graphite core cooled by air. Each pile contained almost 2000 tonnes of graphite, and measured over 24 feet high by 50 feet in diameter. Fuel for the reactor consisted of rods of uranium metal, approximately 1-foot long by one inch in diameter, and clad in aluminium

The Windscale fire
control rods in windscale

The Windscale Piles were shut down following a fire in Pile 1 on 10 October 1957 which destroyed the core and released an estimated 750 terabecquerels (TBq) (20,000 curies) of radioactive material into the surrounding environment, including Iodine-131, which is taken up in the body by the thyroid. Consequently milk and other produce from the surrounding farming areas had to be destroyed.

A huge cloud of steam transported radioactive particles and gases up into the air. The radioactive cloud drifted southward with the prevailing winds over most of England and continued into Europe.

Fifty-four Workers at the Sellafield facility itself were exposed to radiation doses 150 times higher than the prescribed dose limit, while many who lived nearby were exposed to radiation doses 10 times higher than the maximum lifetime doses.

Following the fire Pile 1 was unserviceable, and Pile 2, although undamaged by the fire, was shut down as a precaution.

The Prime Minister at the time, Harold MacMillan, suppressed all technical information concerning the accident. He feared that the conclusions of the accident report - that the accident occurred as a consequence of operator negligence and poor instrumentation, as well as the accident report's reference to an earlier accident in 1952 - would adversely affect the population’s confidence in the nuclear energy programme, postponing the development of British nuclear weapons. Macmillan declared that complete openness about the accident would jeopardise national security

Pile 1 still contains about 15 tonnes of highly unstable uranium fuel, and final completion of the decommissioning is not expected until at least 2037.

First Generation Reprocessing Plant

This reprocessing plant was built to extract the plutonium from spent fuel as part of the effort to build the UK's atomic weapons.

Calder Hall Nuclear Power Station

Calder Hall was the world's first commercial nuclear power station. The design was codenamed PIPPA (Pressurised Pile Producing Power and Plutonium) by the UKAEA to denote the plant's dual commercial and military role. It closed in March 2003 after nearly 47 years.

The four Calder Hall cooling towers were demolished by controlled explosions in September 2007.

Windscale Advanced Gas Cooled Reactor (WAGR)

The Windscale Advanced Gas Cooled Reactor (WAGR) was a prototype for the UK's second generation of nuclear reactors - the Advanced gas-cooled reactor or AGR, which followed on from the Magnox stations. The WAGR golfball is, along with the Pile chimneys, one of the iconic buildings on the Windscale site. It was shut down in 1981.

The Magnox Reprocessing Plant

In 1964 the Magnox reprocessing plant came on stream to reprocess spent nuclear fuel from the UK's Magnox reactors. Over the 30 years from 1971 to 2001 the plant has reprocessed over 35,000 tonnes of Magnox fuel, with 15,000 tonnes of fuel being regenerated. Magnox fuel is reprocessed because it corrodes if stored underwater, and routes for dry storage have not yet been developed.


Highly Active Liquor Evaporation and Storage (HALES) is a department at Sellafield. It conditions nuclear waste streams from the Thorp and MAGNOX reprocessing plants, prior to transfer to the Windscale Vitrification Plant (WVP).

Thermal Oxide Reprocessing Plant (THORP)

THORP opened in 1994. It processes spent nuclear fuel from nuclear reactors and separates the uranium and plutonium (which can be reused in mixed oxide fuel (MOX)) from the radioactive waste which is treated and stored at the plant. Its role was to not only reprocess UK oxide fuel but also to reprocess foreign fuel, which would be imported from as far afield as Japan. This caused, and has continued to cause, no small amount of controversy and heralded the start of a catastrophically expensive and inherently dubious project. The plant cost £2.8bn to build.

The policy of shipping in highly radioactive waste from across the world has been repeatedly criticised on the grounds of safety and terrorism prevention. From Fiji to the Isle of Man campaigners and politicians have sought to limit the shipments.

The 2005 Thorp Leak
Thorp Plant

On April 19, 2005 83,000 litres of radioactive waste was discovered to have leaked in the Thorp reprocessing plant from a cracked pipe into a huge stainless steel-lined concrete sump chamber. Metal fatigue was blamed but reports of a culture of complacency soon surfaced after it emerged that discrepancies in the flow of material through the pipes had been recorded but subsequently ignored.

The leak which closed the plant had been going on for nine months before it was detected. British Nuclear Group's (BNG) Board of Inquiry into the THORP accident has stated that there is a risk that the plant could fail again, even if the Board of Inquiry recommendations are implemented.

The HSE report into the incident concluded: An underlying cause was the culture within the plant that condoned the ignoring of alarms, the non-compliance with some key operating instructions, and safety related equipment which was not kept in effective working order for some time, so this became the norm. In addition, there appeared to be an absence of a questioning attitude, for example, even where the evidence from the accountancy data was indicating something untoward, the possibility of a leak did not appear to be considered as a credible explanation until the evidence of a leak was incontrovertible.

Following a detailed investigation by the Nuclear Installation Inspectorate, HSE brought a prosecution against BNGSL. On 8 June 2006, BNGSL pleaded guilty before Whitehaven Magistrates to charges of breaching three conditions attached to the Sellafield site licence granted under the Nuclear Installations Act 1965. On 16 October 2006, BNGSL was fined £500,000 plus costs of over £67,000 at Carlisle Crown Court

Thorp re-opened briefly but closed again in January 2008 after a vital piece piece of machinery failed. This embarrassing turn of events comes at a time when nuclear unions are pushing for a second Thorp plant to be built

The Vitrification Plant

The Windscale Vitrification Plant, which seals high-level radioactive waste in glass was opened in 1991. In it, liquid wastes are mixed with glass and melted in a furnace, which when cooled forms a solid block of glass. These blocks are then moved to to an air-cooled storage facility.

This storage consists of 800 vertical storage tubes, each capable of storing ten containers. The total storage capacity is 8000 containers, and 2280 containers had been stored by 2001.

The Sellafield MOX Plant

The Sellafield MOX Plant was completed in 1997. MOX fuel, is a blend of plutonium and natural or depleted uranium. This behaves similarly to the enriched uranium feed for which most nuclear reactors were designed. MOX fuel is an alternative to Low enriched uranium (LEU) fuel used in the light water reactors which predominate in nuclear power generation. MOX also provides a means of using excess weapons-grade plutonium (from military sources) to produce electricity.


Sellafield directly employs around 10,000 people and is one of the two largest, non-governmental, employers in West Cumbria (along with BAE Systems at Barrow-in-Furness), with approximately 90% of the employees coming from West Cumbria.

Accidents, Leaks, Releases and Dumping

The site has a remarkable record of producing radioactive pollution. Between 1950 and 2000 there have been 21 serious incidents or accidents involving some off-site radiological releases that merited a rating on the International Nuclear Event Scale, one at level 5, 5 at level 4 and 15 at level 3.

INES Scale diagram

In a rush to build the ‘British Bomb’ safety concerns were sidelined and a culture of marine dumping developed. Moreover, during the 1950s and 1960s there were protracted periods of known, non-accidental, discharges to the atmosphere of plutonium and irradiated uranium oxide particulates.
Until the mid-80s, waste was diluted and discharged into the Irish Sea and it remains one of the most contaminated in the world.

It is estimated that 200kg of plutonium has been deposited in the sediments of the sea while fish and cattle also test positive for high levels of isotopes of caesium and technetium.

A side effect of the Thorp reprocessing business is the continued build up of low and intermediate level nuclear waste produced from processing other country’s waste fuel. In theory a radiological equivalent of HLW is shipped out of the country in exchange. The UK, like every other nuclear country, still lacks long-term storage facilities for High Level Waste.

Below are some of the major scandals that have dogged the plant over the years:
MOX Plant Output Pitiful

In spite of costing £470m the Sellafield MOX Plant has produced almost nothing since it was opened in 1997. Criticised at the time for being uneconomic it was originally predicted to have an annual throughput of 120 tonnes of fuel. In March 2008, the energy minister, Malcolm Wicks, admitted in response to a parliamentary question that it had managed only 2.6 tonnes in any one 12-month period between 2002 and 2006-07. Wicks described the Sellafield Mox plant (SMP) as being based on "largely unproven technology".

In the four years before 2002, the plant had produced annual figures respectively of 2.3 tonnes, 0.3 tonnes, 0 tonnes and 0 tonnes. British Nuclear Group (BNG), which operates the site, said a range of improvements were being made to the facility but it admitted that the 2007-08 period had again seen production disrupted by various problems.

The SMP was designed to make new fuel from the recycled uranium and plutonium recovered from used nuclear fuel, which had been reprocessed by the nearby thermal oxide reprocessing plant (Thorp) at Sellafield.

Attempts to open the main SMP facility led to high court challenges by Greenpeace and Friends of the Earth, which argued that the government's decision to allow BNG's parent group, BNFL, to proceed with opening the facility was unlawful under European law. The Irish government also took unsuccessful legal action to stop the SMP opening over concerns about radioactive effluent from the plant polluting the Irish Sea.

Organ Retention Scandal

In 2007 it was alleged that tissue from 65 dead nuclear workers had been removed without permission from their relatives. The issue is currently under investigation by an official inquiry led by the QC Michael Redfern.

MOX Fuel Quality Scandal

The MOX Demonstration Facility was a small-scale plant to produce commercial quality MOX fuel for light water reactors. Until 1999 it produced fuel for Swiss, German and Japanese reactors, at which point it was discovered that staff had been falsifying quality insurance data on the MOX fuel since 1996.

A Nuclear Installations Inspectorate (NII) investigation found systemic failures of management in the plant, concluding that: "the level of control and supervision [of workers] had been virtually non existent."

BNFL had to compensate a Japanese nuclear plant customer while its Chief Executive John Taylor grudgingly resigned after the NII published its results.

The Beach Incident

In 1983 an accidental discharge at Sellafield led to strandings of radioactive material along several Cumbrian beaches. BNFL were subsequently fined £10,000 while a scientific survey raised new questions over discharges when 25% of the material found didn’t appear to have been released in the accidental event they were investigating.

Leukaemia Clusters

In the 1990s, the Committee on Medical Aspects of Radiation in the Environment (COMARE) found an excess of leukaemia and non-Hodgkin's lymphoma (NHL) near nuclear installations including Sellafield, AWE Burghfield and UKAEA Dounreay. All of which process nuclear materials. Depending on which statistics are quoted, the excess represents up to a tenfold increase in the number of cases expected on the basis of conventional dose/risk models.

Ireland and Norway Object

Both governments have been deeply concerned by the activities at Sellafield and the subsequent contamination of their waters. The Irish governments have repeatedly made formal complaints about the pollution it produces and now have an agreement whereby the Radiological Protection Institute of Ireland and the Irish police force (An Garda Síochána) are now allowed access to the site.

Norway remains deeply concerned about the levels of technetium found in their waters whose source is the Sellafield site. Water samples off the Norwegian coast show increases of up to 10 times background in isotopes of technetium and other radioactive materials.

Both governments are actively seeking the closure of the facility.

Missing Plutonium

On February 17, 2005, the UK Atomic Energy Authority reported that 29.6 kg (65.3 lb) of plutonium, enough to make seven nuclear bombs, was unaccounted for in auditing records at the Sellafield nuclear fuel reprocessing plant.

British Nuclear Group blamed the discrepancy on dodgy paperwork rather than a physical loss of nuclear materials. IAEA regulations allow a discrepancy of up to 1% at reprocessing plants as the product rarely matches the feed. This allowed the issue to be quietly dropped without a satisfactory conclusion.

Financial Liability Bailout

As the Parliamentary recess began in summer 2008, few noticed the indemnity rushed through parliament - under emergency rules - that relieved the firms decommissioning Sellafield of any financial liabilities should they cause an accident. As the firms URS Washington, Areva and Amec danced with joy, dreaming of their cut of the £6.5bn decommissioning contract for Europe's largest nuclear installation, others were left wondering why the British taxpayer should foot yet another payout to corporate interests.

Such was Energy Minister Malcolm Wickes's excitement at the deal, he neglected to leave a copy of the deal in the Commons library, a rather blatant breach of Parliamentary procedure and a move guaranteed to reduce any scrutiny of the plan. It was the last step in the privatisation of Sellafield's clean up and as with the banking system, it is the public who will be left to deal with the toxic debts while the corporations walk away, cash trousered.


Cumbrians Opposed to a Radioactive Environment (CORE):
World Information Service on Energy (WISE):
Sellafield Ltd:
UK Atomic Energy Authority:
Nuclear Decommissioning Authority:


  • HSE Report on 2005 Thorp Leak (310 Kb - Format pdf)
    This report covers the investigation by HSE into the circumstances of the leak of highly radioactive product liquor inside a cell of the THORP plant at Sellafield. The leak was reported to the HSE on 20 April 2005.
    PDF logoThis document is in PDF format and can be read using Acrobat Reader.
Powered by PhPeace