The consequences of this incident seem to have become much more widespread than anyone could have imagined. On October 7, 1957, in the county of Cumbria in the northwest of England, a fire broke out at the Windscale nuclear power station, now renamed Sellafield.
The accident is classified as level 5 on the INES international nuclear event scale (International Nuclear Event Scale) ranging from 0 to 7.
At the roots of drama
Windscale power station was the first nuclear power station built in Great Britain. Of the two reactors, the first is designed to process uranium. But at the time of the accident, it was used for a different purpose: the cartridges were loaded with a mixture of uranium and lithium. The “thermocouples” which are usually responsible for controlling the temperature of the reactor were not in an arrangement adapted to this configuration.
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On October 7, operators noticed that the reactor was heating up abnormally. Strong bursts of energy occur, risking inflammation of the graphite. In physics, this is the Wigner effect. To counter this phenomenon, the operators then decide to initiate an annealing cycle. But against all expectations, instead of heating up, the reactor cools down. The next day, the operation is repeated and this time results in a general warm-up.
Three days later, the operators saw the reactor continuing to heat up and decided to speed up the fans in order to cool it. A titanic error, since without knowing it, they had just fanned the flame which caused the fire. The heat in the reactor was not due to a discharge, as they thought, but to a cartridge that had ignited after cracking. The blowing of the fans only amplified the phenomenon. The fire spread to the other cartridges, without the operators being able to stop it.
Disastrous consequences
The next day, the temperature was estimated at nearly 1,300 degrees. 11 tons of fuel were on fire. A solution presented itself: put out the fire with water. A risky technique, since it is usually not recommended with uranium. This didn’t work. It was not until engineer Tom Tuohy gave instructions to turn off the fans that the fire subsided. Although the reactor was sealed, the fire released a radioactive cloud of iodine-131, which spread throughout England. The population was not evacuated, nor even warned of this incident.
One thing still concerned the health authorities: the milk which could have been contaminated in the surrounding area. In the 500 km2 around the plant, all the milk produced was collected and thrown into the North Sea over several months.
Despite these measures, the Windscale fire had serious health consequences. Of the 238 people examined, 128 were contaminated at the thyroid level. Members of the plant’s staff were also contaminated.
More than 25 years later, a journalistic investigation revealed a particularly high rate of childhood cancer in the nearby village of Seascale. In 2007, one estimate claimed that the Windscale Fire caused 240 cases of cancer.
