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| Fig. 1: Cooling process of the Windscale Piles. (Source Wikimedia Commons) |
Located in the northwest coast of England (Sellafield, Colombia), the Windscale Piles were built as part of the British post-war atomic bomb project. The piles became operational in October of 1950 and were intended to be active for 5 years but served for 7 until the Windscale Fire in 1957. [1] The accident occurred in the morning of October 10th, 1957, during a planned procedure to release stored Wigner energy form the graphite core of Pile 1. Temperatures in the core continued to rise and increasing levels of radioactivity were discovered in the cooling air discharge and in on-site samples. After flooding the core with water, it was evident that both graphite and uranium fuel elements had been involved in a fire. [2]
The release of Wigner energy was the ninth anneal of Pile No. 1. If released in an uncontrolled manner, Wigner energy would lead to higher localized temperatures and potentially culminate in a fire. [3] The Windscales Piles were susceptible to inadequacies of temperature control because of how the energy was released. As shown in Fig. 1, the Windscale Piles used large volumes of air to contain the temperatures of the flammable graphite and uranium. Wigner energy was a complex subject that was not fully understood, and the accident occurred when energy was released at an accelerated of a rate. [2] This led to failure in one or two of the channels of fuel, thus oxidizing its contents and eventually leading to the fire. [1]
About 18.6 PBq of radioactivity were released into the atmosphere, of which the most important components were 1.8 PBq of I-131 and 42 TBq of Po-210. [2] Although evacuation was not deemed necessary, reports after the release suggested a transfer of I-131 into food, especially milk. On October 12th, the distribution of milk was banned in the surrounding 207 km and later extended to 518 km. [2] Although there were no lasting health effects for surrounding villages, or the clean-up crew, the Windscale Fire was the worst nuclear accident in Great Britain's history.
© Ben Hallock. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] M. J. Crick and G. S. Linsley, "An Assessment of the Radiological Impact of the Windscale Reactor Fire, October 1957," Int. J. Radiat. Biol. 46, 479 (1984).
[2] S. Jones, "Windscale and Kyshtym: A Double Anniversary," J. Environ. Radioactiv. 99, 1 (2008).
[3] R. Wakeford, "The Windscale Reactor Accident - 50 Years On," J. Radiol. Prot. 27, 211 (2007).
