Nuclear fallout/blast radius?

Uranium turn in small particles with its half time.And in first second very big amount other elements decay too with its halftimes.U238 it is 2 billion years so it cool hardly but other elements are not.So must be forbidden zone for a while.Very danger cloud after blow and its trace.Never such zone become habitable.It is rule.There is time changing that everlasting too(clock two times will be changing with crossing this area.) Mind of people will be some stuff (out).Excuse for out of theme.