But I can't compare the risk posed by a dam and the risk posed by a nuclear fission plant.
One is an instant and relatively local disaster, the other is a long term and wide-spread (before containment) pita.
However, I suspect that dams are much harder to turn into a catastrophe than nuclear plants. While for a nuclear plant you just have to disable the cooling and move all the fuel rods all the way outside of the boron dampener and keep it this way for enough time to overheat, for a dam you would have to throw a really huge lot of explosives on it to physically destroy its concrete. There are several types of dams too, some of which are probably as strong as a natural hill.
About spent fuel: there are probably many reasons (that I don't know) why the actively-cooled-pools are not all in the middle of deserts, but right now they are just next to the plants. Of course we could put them on the Moon too, I would consider it a definitive solution (for this part of the problem).