Here is simple risk assessment formula that I think should be used in determining the catastrophe failure possibilities of a nuclear power plant. Simply take the number of planets humans inhabit and subtract 1. That's the only acceptable error rate that the world will accepted in the future after this catastrophe.
Find a way to meet that goal (and I know you can do it), and you can all quit your public works jobs and go back to building nuclear power plants, IMO.
I guess I don't understand your equation. According to the world population clock, at 23:02 UTC on 3/15/2011 the world population was 6,905,991,023. According to your formula, if I subtract 1 from this total, I get 6,905,991,022. Are you saying that an error rate of 6,905,991,022 is "acceptable"? That seems pretty high to me, based on 30+ years experience in engineering, in private, public, and academic jobs. Better to use the historical nuclear industry average for LWR technology: zero fatalities, zero injuries among the general population.
Did you know that they discovered a naturally-occurring nuclear reactor? Clumps of uranium happened to settle together underground, and water flowed through it to moderate, and voila, there was a nuclear core underground, cranking out the heat and xenon. There were 16 sites which ran for a few hundred thousand years, producing 100kw of heat on average.
Completely natural, completely uncontained. I think our planet can tolerate man-made nuclear reactors carefully constructed and judiciously managed.