H-bomb aim that led to disaster

The chimney was the first of two to be built at Windscale (Sellafield) to service reactors which were used solely for making weapons-grade plutonium for Britain's nuclear weapons programme

This week marks the 60th anniversary of the worst nuclear accident in British history – an incident which spread panic among Lancashire’s farmers, fishermen and tourism industry. Jessica Hay looks back:

In the aftermath of the Second World War people feared a third and atomic weapons were seen as the best deterrent.

Archive image of workers constructing the two Windscale pile chimneys in the late 1940s

Countries around the world raced to develop their own nuclear capability as a result of the Cold War’s arms race in the 1950s.

Following early collaboration with American scientists, Britain was forced to develop its own capability following the US Congress signing of the McMahon Act, which prohibited the sharing of atomic secrets with other countries.

An existing munitions factory at Windscale, in west Cumbria, was chosen as the location to produce the plutonium needed for a hydrogen bomb and the site became a nuclear facility.

But on the night of October 10, 1957, Pile 1 at Windscale, now known as Sellafield, caught fire during a routine maintenance exercise called a Wigner release.

Archive image of workers constructing the two Windscale pile chimneys in the late 1940s

Thousands of workers at the site, including men from Lancashire, were told to “carry on as normal”.

From the outside there were no flames and no smoke, leaving locals unaware of the unfolding drama.

Inside, however, it was a different story.

Workers had a difficult decision to make and by the morning of Friday,

Lancashire Post of October 11, 1957 reporting the Windscale fire

October 11, it was decided they would have to try to put the fire out with water, a move which carried the risk of a devastating explosion, but there was little choice.

As the water went in, the air supply to the reactor was turned off to combine a lack of oxygen with the gallons of water.

The calculated gamble worked and the fire was eventually put out.

In the days which followed, a cloud which carried potentially hazardous radiation drifted across the whole north west and radioactive dust was estimated to have been deposited as far south as Preston and over the Pennines to Leeds.

Nobel Prize-winning scientist Sir John Cockcroft installed the filter gallery at the top of the Windscale chimney, which caught around 95 per cent of the radioactive dust and prevented catastrophic consequences after the fire of October 1957

Ranking in severity at level five out of a possible seven on the International Nuclear Event Scale, it is clear now how dangerous the situation was. Indeed, before the Chernobyl disaster of April 1986, the Windscale fire was the world’s worst nuclear accident.

Tapes taken from an inquiry into the incident, which were heard for the first time in a BBC film, revealed why politicians played down the severity of the accident.

They also revealed how warnings from scientists, who pointed out that it was possible an accident could happen due to the safety margins of the radioactive materials inside the reactor continuously eroding, were ignored.

But politicians at the time instead decided to increase demands on Windscale to produce material for development of a hydrogen bomb.

Subsequent inquiries revealed how political aspirations ultimately brought on the disaster and then blamed the workers, the true heroes of Windscale.

However, a book made up of interviews with 100 people who worked there or lived nearby revealed the truth of how the accident unfolded.

Sheep grazing outside Sellafield (formerly Windscale) nuclear power plant in Cumbria, December 1983.

Mary Johnson, who was born on the farm which was compulsorily bought to become the site of Sellafield, reveals in the book Sellafield Stories how her father

had no choice in the matter and that she wished the nuclear business “hadn’t come”.

She is quoted as saying: “You kept quiet. But you know you were scared stiff really. Those who were working there... didn’t want to be seen against the thing.”

The landmark appearance of the two 125m tall ventilation chimneys was cemented by nuclear pioneer and Windscale chief engineer John Cockcroft, who insisted that filters be added to the chimneys. As construction was well under way at this point, they were installed to the top of the structures, giving the

chimneys their unique

shape.

Despite being known locally as ‘Cockcroft’s follies’, they proved their value with the fire in Windscale reactor 1 in 1957.

It was the filter at the top of the Windscale Chimney 1 which prevented this disaster from becoming a catastrophe, by limiting the amount of

radiation released into the environment.

Radioactive dust did escape, but the filters caught about 95 per cent of it.

The blaze burned for three days and even though there were no fatalities in the fire, some of the radioactive material released travelled to the north-east before a north-westerly wind carried the emissions over southern Cumbria and the neighbouring county of Lancashire.

Those who lived in the Ribble Estuary in Lancashire were exposed to the highest level of whole body exposures as a result of external radiation from Sellafield discharges.

It is believed that some deaths in the UK, and elsewhere in Europe, could have been attributed to the release of the radioactivity.

In 1979, 22 years later, scientists at Manchester University discovered a rise in leukaemia deaths in Lancaster, Preston, Blackpool and Burnley, however, it was not proved this rise could be solely attributed to the radiation released from the Windscale fire.

Everything surrounding the plant was affected, even after assurance was given by a health official that the accident wouldn’t have an affect on livestock and that there would be no reason to fear any in the future.

Indeed, in the days after the blaze a dairy cow from a farm close to Windscale was taken to the Manchester studios of Granada TV to be milked on air and the resulting produce tested with a Geiger counter.

Yet farmers in the district were left worried as cows in the surrounding countryside had been contaminated by eating grass which had become covered with the radioactive dust and a total of 730 individual farms were affected in Lancashire.

As a precaution, milk from the surrounding area was destroyed and a ban was put on the milk sales from 100 farms.

The restriction was imposed because the level of radio-iodine found in the milk was six times the permissible amount.

These measures had the effect of helping to reduce the potential impact of the accident on public health. Yet it was clear to see that the Windscale Fire disaster changed many people’s views on the nuclear industry.

An inquiry into the fire blamed the accident on a combination of human error, poor management and faulty instruments.

And in the aftermath of the blaze the sprawling facility closed both reactors and the chimneys were no longer used.

The 1957 fire was a wake-up call for the nuclear industry.

It led to vast operational and technological improvements in nuclear reactor design, technology, licensing and regulation, which have stood the test of time.

The Office for Nuclear Regulation is the country’s nuclear regulator and its predecessor organisations were founded in the aftermath of the fire and recognised that regulation needed to be more robust.

Over the years since the fire, the nuclear industry’s relationship with its regulators has developed, and is now represented by a new body. Formed in spring 2014, G6 is made up of representatives from Sellafield Ltd, ONR, the Environment Agency, the Nuclear Decommissioning Authority, the Department of Energy and Climate Change and UK Government Investments.

The aim of the group

is to work together to safely and securely accelerate hazard and risk reduction at Sellafield.

Now the chimneys are being pulled down piece by piece, starting with the demolition of the diffuser, which will start in early 2018, and should take a little under two years to complete.

Following this, the full chimney will be decommissioned by April 2022.

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