The number was just to illustrate the point (but I'm pretty sure the actual probability, if modern technology taken into the account, is lower than that). Also take into the account that neither of those events, no matter how much media coverage they've got, in the end didn't affect that many people outside those locations. Chernobyl did scare us in Eastern Europe, but those effects would be way smaller if it wasn't for the dysfunctional Soviet political system that first tried to hide it, so it was a very unique event unlikely to happen ever again. US had the 3 miles island accident, which was a huge thing when I was a kid, and now it's almost forgotten.