[ RadSafe ] Multiple Source, Radon-222 Plumes

Dan W McCarn hotgreenchile at gmail.com
Thu Sep 10 09:30:51 CDT 2009

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)

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