Nuclear plants can't explode. It's just not possible.
And the reason people are freaking out is because they don't understand how hard it is for a meltdown to occur. On top of that, the media will always jump on a chance to cause fear because it creates more news, which in turn gives them more stories to report. It's a vicious circle, and a rather sickening practice (it's also why I refuse to read, watch, or listen to the news). All these protests will end when people finally pull their heads out of the sand and actually go and attempt to learn about things that they don't fully understand.
That being said, the Japan incident was indeed a close call, bu because of the numerous safeguards, they were able to keep everything under control, and they still do have it under control. There really isn't anything to fear...But let the protesters have their way; they'll find themselves in a quandary when a good 70-80% of the power just doesn't exist anymore.