Britain’s worst nuclear disaster: the Windscale fire of 1957

Yet it remains one of the lesser-known entries in the list of worst-ever nuclear accidents. This might be because the British government severely downplayed the seriousness of the fire or perhaps it’s because Windscale, in the end, was not as bad as it could have been.

Thankfully, the true nightmare scenario is contained to Atomfall, a new videogame set in a post-apocalyptic Lake District in an alternate 1960s in which the Windscale disaster was much worse.

Windscale before the fire

The site – known today as Sellafield, which is currently in the century-long process of being decommissioned – had been built in the 1940s, when countries were eager, often impatient, to get going with making nuclear power or nuclear bombs. Windscale was intended for the latter, with two reactors set to produce plutonium for Britain’s atomic weapons program.

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The reactors, known as ‘piles’, had been constructed in relatively quick time, with Pile No. 1 going operational by the end of 1950 and Pile No. 2 following in 1951. They were made up of a graphite core with uranium rods, which would be air-cooled through two 125-metre-tall chimneys.

The Cockcroft Follies

Despite a number of concerns about design flaws coming out during the construction phase – related chiefly to overheating and the possibility of fires – political pressure mounted to get Windscale working with all expediency.

But Sir John Cockcroft, who led the Windscale project, was suitably alarmed at the likelihood that, if a fire did break out, uranium dust would be released out of the chimneys and into the atmosphere. He demanded that filters be added.

They were an expensive and time-consuming addition – since construction on the chimneys had begun, the filters had to be placed at the top rather than the base – leading many in Britain’s nuclear program to consider them a needless waste. The filters became known as Cockcroft’s Follies.

As it turned out, those acts of folly would become life-savers.

How did the Windscale fire start, and what happened?

On 7 October 1957, a routine heating procedure of Pile No. 1, called a Wigner release, was carried out. It soon became clear that not everything was going smoothly: two attempts at the procedure were made, and still results indicated that temperatures in the reactor were climbing but not falling again, as was supposed to happen.

By 10 October, detectors showed that there had been a radiation release in the chimney. Initially, this was thought to be an issue with one of the uranium rods, which was not too serious as it was nothing that had not happened before. The decision was made to turn up the cooling fans.

What really happened, however, was that the uranium was on fire, and had been for two days. The fans were therefore helping to fan the flames.

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Several Windscale employees, headed by Tom Tuohy, the deputy works manager, risked their lives by personally inspecting what they could of the reactor. Even in protective gear, they could have been blasted with a fatal dose of radiation.

Attempts to put out the fire failed. These included trying to get the molten fuel cartridges (which held the uranium rods) out of the core and into the cooling pond by having men in radiation suits push them with scaffolding poles. Hoses were also rigged up to shoot water at the reactor, despite the risk of a hydrogen reaction that, in turn, would cause an explosion.

By the early hours of 11 October, more than 10 tons of uranium were ablaze, and temperatures reached 1,300 degrees Celsius (2372 degrees Fahrenheit).

As a final resort, Tuohy ordered all cooling and ventilating air to be shut off in the hope that this would suffocate the fire. Throughout, he continued to make inspections of the reactor, until eventually he could see that his plan was successful and the flames had died out.

Aftermath of the accident

In the history of nuclear accidents, only two have earned the top ranking on the International Nuclear and Radiological Event Scale (INES), which classifies the seriousness of events on a scale out of 7. These are the explosion at Chernobyl, Soviet Union, in 1986 and the earthquake-caused disaster at Fukushima, Japan, in 2011, both scoring level 7. The Windscale fire ranked level 5, the same as the partial meltdown of Three Mile Island, US, in 1979.

During the fire, radioactive material was released into the air and blown over Britain and Europe, most significantly the radioisotope iodine-131 and some of the extremely hazardous polonium-210 estimated to have directly resulted in more than 200 cases of cancer.

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Yet the death toll could easily have been much higher, if not for the filters on the chimney. The nicknamed Cockcroft’s Follies did their job effectively and stopped much more radiation from escaping. The response of Windscale employees to the fire was also deemed to be “prompt and efficient and displayed considerable devotion to duty”, according to the initial report into the accident.

A government cover up

Since this was a military site producing weapons-grade plutonium, little news about the fire made it to the public, and men like Tuohy did not receive the full recognition that their efforts deserved.

The British government under Harold Macmillan did put a ban on the sale of milk produced in a 200-square mile area around Windscale for a month, having discovered that the cows had been exposed to iodine-131. But no evacuation was ordered and the prime minister, Harold Macmillan, demanded that the report be heavily censored. It would be over 30 years before it was published in full.

The Kyshtym nuclear disaster

The Windscale fire was not actually the only nuclear accident of 1957. Less than two weeks earlier, an explosion at the nuclear fuel processing plant in Mayak, in the Soviet Union, caused radioactive material to disperse over thousands of square miles.

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The Kyshtym disaster remained the third worst nuclear accident in history, ranked as level 6 on the INES, although its status as a military site meant that the Soviets did not even admit there had been a problem for years.

How does the videogame Atomfall compare to the real events?

If the damage had been worse, say if Cockcroft’s Follies had not been there, the fire of 1957 could have led to a huge area, the whole Lake District perhaps, being out of bounds, similar to the exclusion zone around Chernobyl. That is the setting imagined by the videogame, Atomfall.

Atomfall is set five years after a far-worse version of the accident, where players have to survive in the quarantine zone. In truth, it draws more on sci-fi than history – with irradiated monsters and killer bees, and 1950s-style robots – but it is an unnerving glimpse at what the stakes were with the Windscale fire of 1957, Britain’s worst nuclear disaster.