Japan bet that they wouldn't have an earthquake over, what, 7.8? I forget what the nuclear plants were engineered to withstand. Life is risk management.

I agree with others, though, that the TSA should know, to a reasonably high degree of certainty, what the maximum dose of radiation will be from any given scan. But what can you expect from an organization that judges success by the number of water bottles and nail clippers confiscated...