[ RadSafe ] Advection / Diffusion of Radon through Media

Dan W McCarn hotgreenchile at gmail.com
Thu Aug 21 14:32:28 CDT 2008

Hello Group:

What I'm really fishing for transport equations for diffusion / advection including 
time and decay or some papers / pubs that describe the mechanisms.

Dan ii

Dan W. McCarn, Geologist; 3118 Pebble Lake Drive; Sugar Land, TX 77479; USA 
Home: +1-281-903-7667; Austria-cell:  +43-676-725-6622
HotGreenChile at gmail.com   mccarn at unileoben.ac.at   UConcentrate at gmail.com

From: "Dan W McCarn" <hotgreenchile at gmail.com>
To: "'Radsafe'" <radsafe at radlab.nl>
Sent: Wednesday, August 20, 2008 7:18 PM
Subject: [ RadSafe ] Advection / Diffusion of Radon through Media

> Hello:
> Perhaps this has been done somewhere before:  How does one go about
> estimating that component of radon that emanates from a granite or other
> material? There are several factors that I can think of:
> 1 - Nature of uranium mineralization: a) contained within minerals e.g.
> zircon, monazite; biotite and b) epigenetic mineralization via solutions
> precipitating U minerals in pore spaces and fractures.  Most granites show
> secular equilibrium in the uranium series.  Is this a macroscopic or
> microscopic property?  Does the 5 MeV or so recoil dislodge the radon that
> far away from the origin in a mineral grain? Since granites are massive
> rock
> bodies, emanation of radon and subsequent decay would / could occur within
> the same granite, except near the margins.
> Does the accumulation of alpha decays e.g. U-238, Th-234, U-234, Th-230,
> Ra-226 ⇒ Rn-222 make it more accessible to mobilization? Because U-234 is
> more easily leachable than U-238 (Wyoming Basins, Kazakhstan), this
> suggests
> to me that the Ra-226 has been fairly well dislocated prior to decay to
> Rn-222.
> 2 - Dual porosity matrix - the nature of the permeability associated with
> fractures or porous fractions of a material vs. that portion that is
> contained within a mineral grain.  I can imagine that if the rock was
> porous
> / permeable enough to be an aquifer, that the radon would advect at the
> same
> rate as the water.  This is borne-out by borehole measurements in and near
> sandstone U deposits.
> 3 - Distance to a surface (e.g. fracture or actual surface of material)
> Empirically, does a 1 or 2 cm slab of uniform composition granite emanate
> at
> the same rate per unit surface area as a 10 cm slab?
> Dan ii
> Dan W. McCarn, Geologist; 3118 Pebble Lake Drive; Sugar Land, TX 77479;
> HotGreenChile at gmail.com   UConcentrate at gmail.com
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