[ RadSafe ] outdoor low dose rate measurements

[Ted de Castro]

It depends on the instrument of course but also on how large you expect 
the elevated area to be and how fast the walk is.

I could easily discern this for narrow fields - "beams" < inch across - 
with a pancake GM at  the "standard" 2 inches per minute - I routinely 
have to determine < 0.05 with a background of ~0.015 when surveying a 
large cabinet - 4'x4'x8'.

Much faster - NO WAY.

That would be a mighty slow walk.  A brisk walk is 4 mi/hr - ~70 
inches/sec if I calculated correctly - so it would be an EXCEEDINGLY 
SLOW walk - unless the elevated field covers a large area.

Using a larger area detector will of course increase the sensitivity - 
but also the background.  Still the stats would be better.



On 4/3/2013 12:39 PM, JOHN.RICH at sargentlundy.com wrote:
> Radsafers
>
> I just finished a calculation that's going to require a minimally trained
> individual (not a radworker)  to notice the difference between 0.03
> mrad/hr and 0.13 mrad/hr on a handheld meter while walking around an
> outdoor storage area. I'm stressing that this is a calculated result
> because it's the maximum calculated difference. The minimum calculated
> difference is between 0.02 mrad/hr to 0.04 mrad/hr. Actual dose rates
> should fall somewhere in between.
>
> Is this a reasonable expectation, or is it asking too much of an outdoor
> walk-around with a hand held meter?  BTW, I have no idea what the radon
> conditions are.
>
> thx in advance  - -jmr
>
> John Rich
> 312-269-3768
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