A while ago I was reading something about Hiroshima and Nagasaki. If I remember it correctly, when we deployed the nuclear weapons, it was predicted that the area would be uninhabitable for something like 70 years. However, the areas were resettled withing something like 30 days, as background radiation levels had returned to near normal by then. In the article, no explanation for this discrepancy was given.

So, can someone explain to me why the radiation levels dropped so quickly? Was it because the weapons were not as efficient as we had expected?

And would our current nuclear weapons perform in the same way, or have we improved their function/efficiency?

Interesting question

Magic

I'm guessing it was confusion between long-lived and short-lived fission product daughters.

Everything I've ever read about Manhattan and Trinity implies that these guys really didn't know much about the real character of the "dragon."  Hell, there were some involved who thought that a free atmosphere nuclear detonation would result in global scorching (IOW they thought the sky would burn).

Quoted: Magic

Were you a nuke?

Proud veteran of RP "Magic" and the "I believe" button.

Quoted: I'm guessing it was confusion between long-lived and short-lived fission product daughters. Everything I've ever read about Manhattan and Trinity implies that these guys really didn't know much about the real character of the "dragon."  Hell, there were some involved who thought that a free atmosphere nuclear detonation would result in global scorching (IOW they thought the sky would burn).

I've heard that when the Soviets detonated the 50 mt TSAR BOMBA, scientists were seriously afraid of earth's entire atmosphere igniting!

The main reason those areas are still inhabitable is that both weapons were air-burst.  If they had been ground-burst, people wouldn't be living there.

tag.