The problem with trotting out the Banqiao Dam as proof of the dangers of hydroelectric is that it was a dual-purpose dam built to prevent downstream flooding as well as providing power, and it failed due to mismanagement of the flood control aspect. So even if nuclear power had existed at the time, and even if the idea of building a nuclear power plant with the same quality of engineering used in the dam wasn't a utterly terrifying idea that would make Chernobyl look safe, not using hydroelectic power wouldn't have solved the problem. The dam would still have been built and those hundred thousand people would still have died due to dam failure, all that would changed is that nuclear proponents couldn't point to their deaths as proof nuclear is the safer option.