[ RadSafe ] Multiple Source, Radon-222 Plumes

Dan W McCarn hotgreenchile at gmail.com
Thu Sep 10 11:11:07 CDT 2009

Hi Jim:

Actually, the amount of radon probably released per liter is greater than
that for an ISR mining operation since that tends to remain pressurized.
The spraying probably does an excellent job of air-stripping.  There will
also be release of the other alpha emitters - But then, when central pivot
systems use such vast quantities of water, sometimes with quite substantial
source terms, it becomes clear that there will be a significant release.

Dan ii

Dan W McCarn, Geologist
7 Likely Place
Santa Fe, NM 87508-5938
+33.(0). (Mobile - France)
+33.(0). (Skype - France)
+1-505-240-6872 (Skype - New Mexico) 
HotGreenChile at gmail.com (Private email)

-----Original Message-----
From: Jim Otton [mailto:jkotton at usgs.gov] 
Sent: Thursday, September 10, 2009 08:51
To: 'Dan W McCarn'
Subject: RE: [ RadSafe ] Multiple Source, Radon-222 Plumes


Once again radon sources surprise me.  I've been tracking the variety of
sources for over 20 years and I had not thought about center-pivot
irrigation systems as a significant source.  

Jim Otton

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Dan W McCarn
Sent: Thursday, September 10, 2009 8:31 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Multiple Source, Radon-222 Plumes

Dear Group:


Does anyone have a Gauss-Plume code or other suggestion (meteorological
model) to calculate the air concentrations and dose from multiple point
sources of radon?  I've been considering writing a code using multiple
sources and a typical wind rose to estimate the concentration / dose.  The
ground surface is extremely flat in every direction over the entire area.


Actually, the number of points may be as large as 7,500 from central-pivot,
spray-type irrigation systems and the release "point" is actually the center
of a large central-pivot irrigation system.  The average concentration of
Ra-222 in the groundwater is about 2-4,000 picoCuries / L and the annual
water use is on the close order of 1.2x10^12 L based on the historical
record of consumptive water demand for the produced crops.


Lowest concentration is about 2,000 pCi/L and the highest may be perhaps
0.1-0.5 million pCi/L, since there is a uranium feature involved (based on
other, similar uranium deposits) - a regional redox controlled, roll-front
about 60 km long.  Based on data from a similar "control" deposit, total
alpha activity in water could be up to 1 million pCi/L in the roll-front.


I am assuming that the fine, misting spray will cause the release of most of
the radon. The area involved is about 180,000 Hectares with several modest
sized towns.


That's about 1 million acre feet of water per annum..


1.2x10^12 L * 3000 pCi/L = about 3600 Ci annual release, if I've done my
math correctly.


Dan W McCarn, Geologist
7 Likely Place

Santa Fe, NM 87508-5938

+33.(0). (Mobile - France)

+33.(0). (Skype - France)
+1-505-240-6872 (Skype - New Mexico) 
 <mailto:HotGreenChile at gmail.com>  <mailto:HotGreenChile at gmail.com>
HotGreenChile at gmail.com (Private email)


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