Anti-nuclear activists have been amazingly successful in their attempts to conflate nuclear power with nuclear explosions. But of course the two are not mutually inclusive. You just have to take a deep breath and think about it for a moment. Sure, a nuclear meltdown is a terrifying prospect but it's nothing compared to a bloody mushroom cloud!
But thinking calmly is the last thing the activists want people to do. Journalists cooperate with them in achieving this aim because many of them are greenies themselves. Also, constantly beating up the threat of a catastrophic outpouring of radioactive material sells a helluva lot more papers.
That's why there's been such a weird fixation on the potential nuclear threat over the actual quake disaster in Japan. It's also why you see articles like this one, the title of which is very revealing: "Why Japan embraced nuclear power after suffering the atomic bomb".
Short answer: Because they're not the same thing. And doing so made economic sense.