If you plan to use a factor to convert from counts to uCi you need to be VERY aware of the fact that the conversion factor will change appreciably from place to place within the plant and sometimes within a system within the plant. The significant changes that may occur in isotopic mix, especially when trans-uranics may be present, can have a major impact to the total dose an individual accumulates per each "mR/h" indicated on the meter.
... Mine and mine alone ...
Ron LaVera
lavera.r@nypa.gov
-----Original Message-----
From: Bult, James [mailto:james.bult@msfc.nasa.gov]
Sent: Friday, September 18, 1998 9:12 AM
To: Multiple recipients of list
Subject: RE: Need conversion from mrad/h to dpm/100 cm^2; beta and alpha
D
A conversion factor that we used very successfully in my days at
Browns Ferry was 1 mRad/hr per about 22,000 dpm. The way this was
accomplished was taking an open window contact dose rate on the smear, and
multiplying the result by 100,000 to convert to dpm. The beta correction
factor on each ion chamber was determined individually, but they were all in
the area of 4.5. The answer is roughly 1.8E6 dpm/100cm2 assuming it was a
standard 100cm2 smear.
The folks at the plant would be your best source of info on your
airborne activity questions.
Jim Bult, RRPT
NASA MSFC RSO
> ----------
> From: Strom, Daniel J[SMTP:daniel.j.strom@pnl.gov]
> Reply To: radsafe@romulus.ehs.uiuc.edu
> Sent: Thursday, September 17, 1998 5:48 PM
> To: Multiple recipients of list
> Subject: Need conversion from mrad/h to dpm/100 cm^2; beta and alpha
> DACs
>
> Power reactor folks,
>
> I have a couple of questions on power reactor outage operations.
>
> 1. NRC Info notice 97-36, June 20, 1997 describes an incident in the fuel
> transfer canal at Haddam Neck. Removable beta-gamma contamination is
> given as
> "80 mrad/hr." I need an estimate of the conversion from mrad/hr to
> dpm/100
> cm^2, and the variability in or range of this estimate (i.e., "1 mrad/hr
> is
> within a factor of 2 of 5E6 dpm/100 cm^2 95% of the time." I'd also like
> to
> learn about what affect this conversion, e.g., age of fission products,
> whether
> it's fission or activation, etc.
>
> 2. In the same notice, the airborne radioactivity levels were quoted as
> "0.8
> DAC beta and 24 DAC alpha." What would these DACs be? Probably a
> plant-specific value for the kind of stuff they usually find, but I'd like
> to
> know the isotope mix, the assumptions (D, W, Y mix, particle size), etc.,
> that
> are used for this kind of DAC. How do you calculate results in DACs? X
> dpm
> beta-gamma per m^3 is Y DAC, and Z dpm alpha per m^3 is W DAC?
>
> Thanks in advance for your help.
>
> - Dan Strom
>
> The opinions expressed above are my own, and have not been reviewed or
> approved
> by Battelle, the Pacific Northwest National Laboratory, or the U.S.
> Department
> of Energy.
>
> Daniel J. Strom, Ph.D., CHP
> Risk Analysis and Health Protection, K3-56, Pacific Northwest National
> Laboratory
> Battelle Boulevard, P.O. Box 999, Richland, WA 99352-0999 USA
> (509) 375-2626 fax: (509) 375-2019 daniel.j.strom@pnl.gov
>
>
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