Without really getting into the how I'd know part
I can assure everyone modern day nuclear weapons are every bit as bad as you may imagine.
Chernobyl was a bad deal and although the wildlife thrives (Due to a lack of pressure from humans) to eat a diet of meat from there would pretty much insure death by thyroid or some other similar cancer.
I don't know about the fraudulent Hiroshima and Nagasaki attacks, but I can say that nuclear bombs do some pretty marvelous stuff. Take a look at either city and you'll see an amazing place. Very modern, vibrant, beautiful. Makes one wish someone would nuke Washington DC. Think about how nice that place would be in a few decades!