The worst nuclear accident in British history (and the first serious one in all of Mankind's history) was remembered on BBC 1's Monday late night documentary: "Windscale: Britain's Biggest Nuclear Disaster". It happened 50 years ago, on the night of 10 October 1957, when Pile 1, a graphite moderated and air cooled nuclear reactor for the production of military nuclear materials at the Windscale (now Sellafield) facility overheated and caught fire (see photos of both piles and schematic of these reactors here). Only 50 years after the facts is it now becoming clear that there was a rather major cover-up by the Macmillan government to absolve itself from responsibility and lay the blame at the door of the plant's operators.
The accident, which caused an estimated 240 cancers but which could have had a far, far worse outcome, has to be understood against the backdrop of the Cold War and Britain's bid to gain ascendancy at the top nuclear table. Not content with having achieved A bomb status, Britain feverishly sought partnership with the US for its H bomb project. And an upcoming ban on nuclear tests, to which Britain was about to subscribe, would mean it would soon become impossible to develop a testable (H) weapon and convince the US that Britain would be a suitable partner to share its H bomb technology secrets with.
And so a race against time began, which involved stepping up the production of Tritium (a vital component of hydrogen bombs) by a factor of 500 % to meet the demands for bomb development. An early British H bomb test that failed to reach the 1 megaton threshold didn't really help the situation much either.
Britain thus found herself steaming ahead to meet unrealistic Tritium production quota with two reactors that by today's standards would be considered ramshackle, to say the least.
The exact cause of the accident remains, predictably perhaps, the subject of some controversy. For those who are interested in the technical details, I would say that going by the BBC documentary, Wikipedia's account of events, from detection of the fire to final extinguishing, appears a fairly accurate portrayal. At the time of the enquiry, blame was laid at the operators' door for initiating repeated so-called "Wigner releases" (although in an attempt to compromise, inadequate plant instrumentation was also blamed). But today's version of events acknowledges that the Macmillan government's initial blame game was more inspired by the fear that if American Congress had learnt that the fire was essentially the result of a reckless attempt to build the H bomb in record time, they would possibly have vetoed Eisenhower and Macmillan's plans for nuclear cooperation.
The story of those heady days when a disaster was averted from becoming a true catastrophe is well worth remembering, if only to avoid a future repeat. It's also to be noted that the mostly successful containment of the extremely dangerous radio nuclides (reaction by-products) was largely due to the incorporation of a particular design feature, the chimney filters, which almost didn't make it into the final design...