Re: lifespan of a nuclear facility, it really depends on the facility and regulatory culture. They'll often be missing basic things you'd expect like HAVING WRITTEN PROCEDURES, and instead you just rely on a bunch of crotchety 65 year olds that are incapable of training replacements who are imminently retiring (or dying of covid). Then they leave the facility and it goes into triage mode, where a serious failure will probably result in the facility just being shuttered. In my experience, the auditors that look into these kinds of things can't possibly understand an entire facility because the facilities are so complex and they're only there for a couple weeks a year, which means that tons of things slip through the cracks.