I take it you've read Command and Control [1]? A great, if worrying read on exactly that subject. It's luck, not judgement that something really terrible hasn't happened yet.
Along the same lines: a whistleblower's account of problems in the UK's "Trident" nuclear defense program from 2015: https://wikileaks.org/trident-safety/
[1] - https://en.wikipedia.org/wiki/Command_and_Control_(book)