Also, we've seen more things go wrong. When you design a nuclear plant, you need to do a really careful risk analysis. That's why they are so safe. But as tim

Also, we've seen more things go wrong. When you design a nuclear plant, you need to do a really careful risk analysis. That's why they are so safe. But as time progresses, and actual designs meet reality and Murphy's law kicks it, it turns out some of the assumptions are factually incorrect. More elaborate safety requirements are needed to compensate, increasing cost. You can't build a car the way you could 50 years ago, and the same is true for nuclear plants.