Windscale fire

October 10, 1957 -
A fire in the Windscale plutonium production reactor (later called Sellafield) north of Liverpool, England, spread radioactive iodine and polonium through the countryside and into the Irish Sea. Livestock in the immediate area were destroyed, along with 500,000 gallons of milk. At least 30, and possibly as many as 1,000, cancer deaths were subsequently linked to the accident. The event, known as the Windscale fire, was considered the world's worst nuclear accident until the Three Mile Island accident in 1979. (Then both were dwarfed by the Russian Chernobyl disaster in 1986.) PM Harold Macmillan ordered the disaster hushed up. (video from BBC report.)