RE: dose rate from plane source

["Cook, Lew (LCOO)" <LCOO@chevron.com>]

Tad Blanchard wrote:
"I was always under the impression that if you were far enough away from a
plane source you could consider it a "point" source."  

That is true for distances much greater than the dimensions of the source.
Here, the source is considered infinite.

I deal with contaminated ground a lot and came up with a way of
understanding what I was dealing with.

As a simple-minded intuitive helper, I imagine myself on the surface of the
sun in an air-conditioned asbestos suit. The radiation (light) level is very
high. If I climb a ladder, it still is just as bright. If I move in my
spaceship to a distance of 1000 miles, it is still as bright. At a million
miles it is starting to decrease in brightness, but only slightly. As I move
away to the distance of the earth, then the brightness is dropping off as
1/r squared.

When dealing with a uniformly contaminated area, I can get an idea of its
size by raising the detector as high as I can hold it. If the radiation
level drops off considerably, I know the contaminated area is small. If the
level doesn't change, I know it is probably a large area.

Lew
     http://home.pacbell.net/cookl/



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