Setting aside the argument of whether nuclear power should be used or not, the big question right now is where to store the waste material for the next million years. https://www.cnn.com/2019/11/30/europe/germany-nuclear-waste-grm-intl/index.html For those that know more than I do, what would be the logistical problems with launching it into space? Maybe not today, but in the next couple of decades when we should have some bigger, cheaper launch vehicles. (and I realize that "cheaper" is a very relative term). Of course though, we might just upset some alien civilization if it comes crashing down on their heads, but I suspect mankind will not even be around by then.