Re: Stripping Radon From Air Samples

["TOM_DIXIE" <tom_dixie@email.msn.com>]

Robert,

1.  If the major contaminant in the soil is "primarily Pu-239 and Am-241" is
it reasonable to risk allowing intake at the levels in the soil?  The DAC
values for these radionuclides is very low.

2.  What do you mean by immediate area, are on-lookers allowed in the same
area as the excavation?

3.  Is there possibly an occupational exposure to radon and daughters?

4.  Regarding the program, Clay French has an e-mail address listed on the
AAHP - CHP list.

Tom O'Dou
tom_dixie@msn.com



-----Original Message-----
From: Robert Augdahl <augie@macconnect.com>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Saturday, May 09, 1998 4:47 PM
Subject: Stripping Radon From Air Samples


>I need help, I have been looking for a way to strip Radon (and daughters)
>from air samples that I need to count in a relatively quick time frame.
>
>Here's my situation; we are doing soil clean-up activities, the soil
>contains primarily Pu-239 and Am-241, we're running air samplers in the
>area to check for airborne concentrations. We would like to only have the
>personnel in the immediate area wear respirators. In the past we have
>always done air sampling but waited 24hrs to allow for decay before
>counting the sample. This could be a serious delay time if we found we
>had exceeded a 10th of a DAC the previous day.
>
>I have found in Cember 'Intro to Heath Physics' a calculation to strip
>the Rn and Th counts out, but it requires a 20hr delay in counting. Not
>much help. I have been told by some of the old hands that they used to
>have a calculation for doing this but no one remembers it. I don't mind
>if it is a quick and dirty method, I can always count the filter again at
>a later date and get a final number for the records, I just need
>something to show with some certainty that the work area was below a 10th
>of a DAC. Also all the workers will be wearing BZA samplers for dose
>estimations, which are counted after a 24hr decay.
>
>My plan is to run a sampler pulling approx. 5 CFM, start it at the
>beginning of the shift. Change the filter at lunch (about 4hrs) and stop
>(change) at end of shift. The filter changed at lunch I would like to
>count after 2hrs decay, and again after 2 hrs. Using those two counts,
>can I strip the Rn and Th counts out with any degree of certainty?  Would
>some other time frame (that would fit in a single day) work better? The
>filter I change at end of shift could be counted at the start of the next
>day before work began. That should give me enough of a decay time to show
>a count below 10% DAC.
>
>I'm open to any ideas, and would like to hear how its done other places.
>
>On a related note, I have a copy of a program by K. Skrable and C. French
>for a HP-42S calculator that allows the user to count the sample a couple
>of times, enter the info and leave you with only the long lived nuclides.
>The problem I have is I can't for the life of me find how to enter one of
>the program instructions.
>
>The instruction is    J+   it will increment the column pointer in an
>indexed matrix. I can't find anywhere in the owner's manual how to enter
>that command. Anyone familiar with it?
>
>Bob Augdahl
>RRPT
>augie@macconnect.com
>Las Vegas, NV