But is yield really the best measure of the destructiveness of a nuclear weapon? Just because it makes a bigger "boom" doesn't mean it's necessarily more dangerous.
Let me explain. In all the MAD projections, the astronomical casualty counts come from "nuclear fallout," not from the bang provided by the bomb. So how much fallout are we talking about?
Well, just take Hiroshima/Nagasaki and compare them with, say Three Mile Island or Chernobyl.
The bombs used on Japan held about 150 lbs of Uranium/ 15 lbs of Plutonium respectively. I believe a modern bomb has about twice that much.
When Chernobyl melted down, the single reactor that melted down had
180 TONS of nuclear fuel.
We would NEVER see this amount of fallout even during the worst case scenario of a nuclear war. And while Chernobyl is still contaminated, Three Mile Island is basically fine, and here's a picture of Chernobyl today:
Also, it's been widely documented that wildlife has almost completely returned to the site. In other words, nature has taken over the area again and is cleaning itself up.
Oh, and only 30 people died in the Chernobyl explosion.