Blast Radius of a Nuclear Bomb?

Depends on the kiloton, the operational nukes in the world arsenals range for .3 to 500 kilotons, the Hiroshima nuke was around the 15 kiloton range. In the 60s, the Soviets build a 1,000k monster, but it has since been deactivated. The following site calculates the radius impact damage to the cities of Reno, Salt Lake City, San Francisco, Seattle, Tampa, Tucson and, of course, Washington, DC:

This interactive tool is intended to give an idea of the devastating blast effects of ground-level, shallow subsurface, and low-altitude nuclear weapon detonations. It is relevant to traditional nuclear weapons, potential terrorist attacks, and next generation nuclear weapons such as "Bunker Busters" or "Robust Nuclear Earth Penetrators" (RNEPs).

http://www.fas.org/programs/ssp/nukes/nuclear_weapon_effects/nuclearwpneffctcalc.html?formAction=297&contentId=367

Books on the Nuclear War