Are telling us of the nagasaki case?
Cuz current nukes are beyond that and we have no idea how catastrophic they can be. and we atleast 100x the nuke we threw on japan.
I am talking about normal nukes.
Their blast raidus would vary depending on how much KT detonation they have.
But nukes impacts are limited to cities.
Biggest nuke till now have blast radius upto 3km - instant death
And, first degree burns upto 15-18 kms
A nuke don't have impact on whole country unless you are talking about small ones like Vatican