re: Earth's atmosphere
We can pin the blame game on both equally. But another factor was, I believe, a very real diminishing intellectual capacity of the nuclear industry.
If we had some of the early pioneers still working on the waste problems during the eighties, they would have worked their tail off until they came up with a workable solution. But by then most of the brainpower was gone or seriously graying.
I'm convinced we would have a much better nuclear reaction to use as well, something between fission and fusion.