[Pollster1]

Figure if it is a fission devise that all dead within 1 mile at the minimum.

Even that would be an accomplishment for an improvised or low-tech device. Unless they have connections in high places within a sophisticated nuclear country . . .

. . . fission yields would be quite limited, and there would be survivors within a mile of ground zero. Akiko Takakura survived at three hundred meters from ground zero in Hiroshima, and Tsutomu Yamaguchi survived both Hiroshima and Nagasaki within 3 km from ground zero both times (either very lucky to survive or very unlucky to be visiting Hiroshima on the wrong day and then back at his job in Nagasaki, despite his burns, later that week).

Add tritium - correctly - and all bets are off. But where would they get the detailed technical knowledge; theory is not enough. It's not like high government officials in the United States government would mishandle Top Secret . . . um . . . never mind.

[PIF]

Survivors - count them on the fingers of one hand or maybe both or throw in a few toes not many more.

All dead does for rough purposes - no need to get someone’s hope up. I think the questioner was hoping that somehow he lived far enough away from a possible target zone and that none of his family or property would be effected.