Actually, the airburst was 580 meters off the ground for Hiroshima. People at ground zero were 580 meters from the bomb. Some of them did survive, if barely.
Just to translate, 580 meters = 1902.4 feet
So the "0 - 1000 93.0%" figure is actually something like "1902 - 2902 from the blast produced 93% mortality". Which is the same as saying there were survivors half a mile away from the blast point.
Based on the science, I'd say that anything in the same zone of bomb would not exist after the blast - except as radioactive dust. When "Other 10%" includes "being converted to a shadow on a building" assigning stress levels just doesn't work. If the piece of land you're standing on becomes part of a glass crater your chances for survival are zero.
Now for the one time nukes were mentioned in the books:
Morgan, a man who made a life out of killing magical threats, wouldn't have just said "Well, that nuke probably killed a semi-divine creature. Yes, it's of the status of maybe an angel or minor god, but I'll just assume that it was taken out because I'm known for assuming that things always work out for the best." No, Morgan strikes me as the type who would have checked the results in great detail. Even if somehow he had forgotten to, the Merlin would have poured the council's resources into finding out if that thing was dead or not.
Why? Because knowledge is power and the current Merlin strikes me as someone who would want to know how to kill semi-divine things. I wouldn't be surprised if in the DV those missing nukes aren't where people think they are (they are in riverbeds in the real world) but in the hands of the White Council serving as their god killer weapons.
Which is more or less my reasoning for Morgan being right when he said the nuke killed one of them. Looking at the stats in Our World, instant death for that thing would mean instant death for most godlings.
Richard