Nothing humans do is "clean", so you always have to read the word in context. In the sixties the alternative would've been coal which in comparison is less clean.
I don't think so. What would be "clean" energy for you? Renewables also take considerable resources to build. I assume you weigh nuclear waste very heavily, but I don't believe it to be such a serious problem. There is not that much highly radioactive waste being produced. I prefer renewables over nuclear because I think that in the end they'll be cheaper while being okay for the environment. But I would be very easily convinced that nuclear energy has a smaller environmental footprint.
