I've always thought the negatives of nuclear were less economic than other factors (though the high fixed capital costs might be an unattractive model in some cases). The worst case scenario for a nuclear accident is pretty frightening to a lot of people. While it may be true that overall fossil fuels are more dangerous in the long run, people tend to overvalue spectacular, high profile failures.

In addition, one negative of nuclear I don't see come up on HN very often, is that nuclear power plants pose an extra risk in regards to nuclear proliferation and terrorism concerns. I do think that some of the recent decline of nuclear is, in part, geopolitical. You don't see groups of nations banding together to stop another nation from building a coal plant.