I appreciate the responses, but I am asking for a very specific answer, please.

I need to know if radiation from each of the damaged reactors can climb straight up into the atmosphere?

Or does the radiation just settle near the ground until it's blown in one direction or another?

Here's why I think this is important.

On July 7th one of the NHK broadcasters let slip that the closest monitoring device installed to any of the reactor buildings was "approximately 1km away". It was not in the text of that press release. He said it. I have a copy of that.

Very recently we received information from NHK that the closest monitoring device was 500 meters away.

There have been no monitoring devices right on the reactor building structures themselves. There has never been any reference or mention of any gathering of daily emmissions radiation levels directly above the reactors.

So it's vital to know whether the reason no such radiation gathering instruments have been/had been placed in such locations was/is because it was/would be pointless. Because the radiation will not/would not travel straight up.

How can they tell how much radiation has been emitted if they do not have the data from measurements directly above the reactor buildings? Unless it's not important.

And that's what I need to know -- is this important? And why or why not? Radiation doesn't climb like a gas? It settles until blown along the ground to one of the monitoring devices 500 metters to one kilometer away?

Thank you.