As World War II was closing down, Japan refused to surrender. The Allies had two choices: either invade with waves of million-man strong forces, causing horrendous casualties and destruction for both sides, or use the new superweapons originally made to use against NAZI Germany. These were two atomic fission bombs, one made from deadly radioactive uranium-235 isotopes, the other from even more deadly plutonium-239. As history records, both bombs were dropped when Japan rejected overtures of surrender.
Neither bomb was very well designed, as this was uncharted territory, and there were very few test devices, since the amount of available weapons grade material was precious limited. They were perhaps 10-15% efficient, so most of the radioactive material in the bombs, as well as the huge lead casings of the bombs, became vaporized and scattered across the land near the targets, and in fact the entire globe. This was deadly stuff, highly radioactive and toxic metals. But the Japanese were determined to reclaim the land, even though the advice from numerous scientists was that these areas would be radioactive wastelands, contaminated for centuries and uninhabitable.
Well, they worked like crazy to clean away the fallout, and today both cities are safe, wonderfully rebuilt and thriving. I'm not too worried about what people write and think in fear. In time, no matter what happens, these reactors will be dealt with, Fukushima will be safe, and we'll come up with some other scare, true or false, to worry about.
