RealClearScience - Putting Chernobyl in Perspective: "With the world gripped by fear that the stricken Fukushima Daiichi nuclear power plants may turn into “another Chernobyl,” perhaps it’s worth examining just how bad Chernobyl actually was.
There’s no doubt that the scale of the accident was unequalled, either before, or so far in Japan, since. The Soviet-style nuclear reactor had been built without a containment structure, and when the graphite moderator components caught fire, they spewed more than 400 times more radioactivity into the environment than the atomic bomb dropped on Hiroshima."
