Also, since it seems some people are making some assumptions about nuclear bombs...
- nuclear bombs don't vaporize stuff. Even when dropped in the middle of a city they leave rubble
- The actual "explosion" part of a nuke is only a hundred meters or so at best. The "blast radius" is a giant shockwave made of air
- "Blast radius" does not mean everything inside said radius is vaporized, it's how far a shockwave travels before ceasing to be meaningful
If you were on the other side of a mountain when a nuke went off, it wouldn't reach you in the slightest. The heat blast wouldn't penetrate, the shockwave would ricochet off the side, and the fallout would be blocked.