On April 26, 1986, a routine systems test of the number four reactor of the Chernobyl Nuclear Power Plant (near Pripyat, in the Ukraine) caused a power surge – and an attempt at a manual shutdown caused a second, larger surge, which in turn led a series of explosions, leading to a large fire. The smoke from this fire spread over large portions of Europe, from the Soviet Union to the Atlantic coast.
The disaster – alongside the Fukushima reactor event of 2011 – is the worst nuclear accident in history. Estimates of the resulting deaths vary, with 31 to 64 deaths being directly attributed to the disaster, and hundreds of thousands of deaths since then being attributed to secondary effects. A large area around the reactor has been evacuated (and remains so today), including the entire town of Pripyat, and the environmental effects are likely to remain for another century at least.
Freakonomics — Clutch
Mrs. O — The Dresden Dolls