The current most ubiquitous US nuclear weapon deployed is the W78 nuclear weapon with a yield of 350kt which has a total fireball of .63KM and a 5PSI which collapse most residential buildings up to 4.95KM this is with a airburst detonation which is better against large areas but ineffective against hardened targets. The ground destruction of a surface detonation is signifgantly reduced in area of affect. The majority of radiation is gone by 2 weeks and it must also be kept in mind that with there being less nuclear weapons 5550 and Russia 6,257 with only 1588 nuclear weapons of Russia deployed on various launch methods well the US has 2021 warheads deployed. The likelihood of nuclear war is quite low and would not be as destructive as many people believe due to lower yields and with the reduction in nuclear weapons yield and numbers they would be used predomintally on military targets. I would also like to state that "MAD" is not a actual true doctrine and it was just a excuse for the Kennedy admin to cut civil defense nuclear bunker funding to fund the Vietnam war.