Also there's Stephen Vincent Benet's short story, "By The Waters of Babylon".
Written in 1937 it was inspired, not by the atomic bomb, but by 1937 bombing of Guernica, in which Fascist military forces destroyed the majority of the Basque town of Guernica during the Spanish Civil War.
You can read it online at
http://www.tkinter.smig.net/Outings/...ts/Babylon.htm