There's been a fair amount of worry the last couple days about the situation with several nuclear reactors which were hit by the earthquake and tsunami in Japan. The difficulty is, of course, that most reporters know nothing about nuclear energy or physics, and there is a tendency (in TV news in particular) to focus on whichever "experts" are most exciting. Combine that with the fact that when most people near the word "nuclear" they picture a mushroom cloud and it's easy to produce hysteria.
While the events at the Fukushima plant reactors are serious, they also underline how many layers of redundancy and safety measures are built into modern nuclear power plants. There's a good blog post by an MIT engineer (expanded and corrected by the Nuclear Science and Engineering department as MIT) which covers the basics of how this type of reactor works, what happened to the reactors at this plant which are having problems, and what the relevant dangers are. I'd strongly recommend this post over most mainstream media coverage. Members of the Nuclear Science and Engineering department have continued posting additional updates on the topic at this blog.