[ RadSafe ] Re: Determining Radon

[TConley at kdhe.state.ks.us]

Frankly, when I first read the question it was obvious this was a case of
wanting to find out about others solutions to a common limitation of this
instrument.  Perhaps its being obvious is due to my operational experience
with these instruments.

The question is about a simple problem with solutions ranging from very
simple to very complicated depending on your budget.  I assume that the
budget for this project is limited and will address the simple and cost
effective solutions.

After a person alarms the monitor, perform a survey using a typical pancake
probe to identify if the cause is from a localized or diffuse source of
contamination.  If localized (< a few square centimeters), then try
removing it with tape or other simple decon method (i.e. washing if it is
on the skin).  If diffuse and uniform its a good bet it is radon and
daughters.  Simply wait 30 minutes and re-survey. If its gone, fine, if not
do a half life calculation and if its less than 45 minutes let the person
go.  I've seen it done both by releasing the person based on the frisker
survey and by making them go back through the PCM.  Either are valid.


>Depending on your budget and your philosophy on personnel release
>methods, you may find an option that will provide some relief for that
>long line of people standing in front of the fan!

Just a note about fans. They make the people think they're doing something
but in reality they are not that effective.  In my previous life we did a
lot of testing using an air shower similar to what is used in clean rooms
and found that it works well for noble gases such as xenon but not for
radon and its daughters.  Presumably, because of the large static charge
created by the alpha particles.  Beta emitters were much easier to remove
with the air shower.

Thomas A. Conley, RRPT, CHP
Section Chief, Radiation and Asbestos Control
Kansas Department of Health and Environment
Phone: (785) 296-1565
email: tconley at kdhe.state.ks.us