Not sure I agree with #1. Nuclear power had a super utopian vibe going for a good couple of decades. Nuclear power plant orders only started to decline in the early 70's. https://en.wikipedia.org/wiki/Atomic_Age
I don't think you can entirely discount the effects of 20 years of Cold War existential threat, accompanied by duck-and-cover videos and the like. People were terrified and fascinated by nuclear technology - this is the era of Godzilla, and of mutant superheroes. Yes, there was a utopian vibe as well, courtesy of a concerted propaganda campaign [1] - but when the eco-movement kicked off in the 70s, nuclear was right in the firing line. That didn't spring from nowhere - it was decades of accumulated fear finding an expression.
[1] https://en.wikipedia.org/wiki/Atoms_for_Peace