there is a huge cost with getting them up and running but the amount of red tape to get approval is unreal and it probably the biggest issue. there have been 40 plants that have been canceled in as many years stateside due to a mix of costs, fear and of course government regulations changing (most of the canceled projects happened after TMI-2.) the US's newest plant took nearly 43 years to start producing power and cost nearly $6b. our last plant to open before that was 20 years ago (at the same location too.)My brother was a Nuclear Engineer. Interesting bit of trivia though, turns out nuclear energy isn't all that great and self-sustaining. The actual cost to engineer the plants, build them, secure them, perform maintenance on them, exceeds the potential cost-benefit of nuclear power in the first place. This is one big reason why we haven't made any new plants in a long time. It's not because of hippies or satan, in the long term cost it just doesn't really work out.