Nuclear waste is not as dangerous as you think. One, its contained within a very small area (which increases its lethality but substantially decreases your risk of exposure). Two, some waste products decay alpha particles which are basically harmless unless consumed. Three, some waste products have short half-lives which increases their risk in the short term but substantially decreases their risk over a 500 year period. Four, most deaths from nuclear waste would be slow and probabilistic (e.g. 18% increase cancer risk for an individual with high exposure) whereas deaths from some other power source would be immediate and devastating (e.g. flood, destruction of habitat).

I don't mind hydro. I don't particularly like the habitat destruction but they provide tons of clean power and tons of fresh water. But those dams have to be maintained for those 500 years. A collapse of a dam is pretty catastrophic.