I'm well aware of the 25MT monsters the Soviets made. That has NOTHING to do with subsequent radioactivity. You're full of crap, especially in the case of Nagasaki, which was a plutonium bomb.
Baseless fears, ignorance, and apathy are the biggest killers when it comes to surviving nuclear war. My suggestion is that you consult a reliable source: Nuclear War Survival Skills, by Cresson Kearney. It's free online, but the book is worth the money. Your life may depend upon it.
Have you ever contemplated the long term effects down wind from a 25MT bomb detonated at a depth of about 200 feet in the Persian Gulf?
And let’s not forget the courageous Russian workers who while wearing white paper suits refined plutonium by HAND.