The problem with nuclear energy (besides the scale issues, of which I agree with Jaime Frontero on) is that we have to figure out a secure way to store the waste that is beyond any time scale we can reasonably envision. Because of this, we essentially are creating incredibly toxic management problems for societies that we have no idea of. I believe it is an unfair burden for future generations to have to deal with, when we do not know what their capacity to deal with it will be, just so we can have more energy now.