Amazingly, no one seemed to know. That was the situation until two years ago when I published the first paper (1.8 MB PDF) to estimate the risk.
My analysis showed that relying on nuclear weapons is as risky as living in a town surrounded by thousands of nuclear power plants. Equivalently, a child born today has at least a 10% chance of not living out his or her natural life, and that child’s odds are probably worse than 50-50. For more details, see http://nuclearrisk.org/email26.php and a later post.
Professor Emeritus of Electrical Engineering