[ RadSafe ] RE: Toxic Countertops

[Geo>K0FF]

I agree. There are two factors at work, the release of gaseous radons/thoron 
and the intrinsic penetrating gamma radiation from the stone itself. The 
source of the
radiation is natural abundance of Th-232, uranium 238 and 235, and their 
decay chains, as well as natural potassium-40 ( K-40).
Ironically, radon daughters are attracted to the electrostatic charge on CRT 
screens, concentrating the lower daughters there. See:
http://www.qsl.net/k0ff/Selectrostatic%20Collection%20of%20Radon%20Daughters,%20by%20George%20Dowell/

My spectrum analysis of granite:

http://www.qsl.net/k0ff/Granite%20Countertop%20Study/Granite%20Counter%20Top.jpg

This natural distribution of U and Th and K-40 reveals the same spectra as 
one would find in any natural rock, more or less, depending on the 
originating locale's geophysical properties. Go to any landscaping yard and 
select a pile of decorative gravel, analyze it, and a similar spectrum will 
be produced.

This vein of inclusions:
http://www.qsl.net/k0ff/Granite%20Countertop%20Study/Slab%20with%20vein.jpg 
is no different in countertop granite as it would be in any other natural 
stone.

To the point, any natural stone or material made from stone that is brought 
into an airtight home will increase the level of gamma radiation as well as 
the level of radons/thoron gas. The extent of the increase depends on the 
nature of the stone and the release of gas depends on the available surface 
area of the isotope/atmosphere interface.

Granite countertops are getting a close review at the moment, but other 
stone products should not be overlooked, such as tile, firebrick, brick, and 
yes, concrete itself. All
of these products contain natural abundances of the normally occurring 
radioactive materials.



Concrete is made from
A) course aggregate<stone, gravel, shells)
 B) fine aggregate <sand>
 C)cement < Portland cement is a complex mixture of minerals>
 D) water.
All of these components may contain some amount of NORM.

A new patent by Henry Liu will allow flyash byproducts from coal fired power 
plants to be made into construction bricks. I am getting samples of the 
bricks and the flyash itself to analyze the radium content of that material. 
These bricks will need to be observed and monitored as to their radiological 
consequences.

My involvement is from a scientific measurement standpoint only and I have 
no opinions on human exposure issues.

George Dowell
NLNL
New London Nucleonics Lab
GEOelectronics at netscape.com






----- Original Message ----- 
From: "Dan W McCarn" <hotgreenchile at gmail.com>
To: "'radsafelist'" <radsafe at radlab.nl>
Sent: Thursday, July 24, 2008 2:24 PM
Subject: RE: [ RadSafe ] RE: Toxic Countertops


> Gentlemen:
>
> It all depends on the permeability of the granite!  Even relatively active
> granites usually have very low primary permeability so radon is retained
> within the mineral grains and rock itself to a great degree.  That's why
> granites are usually in secular equilibrium with all uranium daughters
> because they retain radon until it decays.  Most of the activity measured 
> by
> a scintillation counter comes from the Bi-214 decay at the end of the 
> chain.
> At a larger scale, where granites are fractured and faulted and develop
> significant secondary permeability, is there a good likelihood that radon 
> in
> significant quantities will be fluxed via changes in barometric pressure 
> to
> the surface, and these examples are noteworthy.
>
> But in countertops, chosen to avoid fractures, that is unlikely.  Most of
> the radon would be only from the very near surface.  The radon from deeper
> inside would have virtually no chance of diffusing to the surface.
>
> My opinion only!
>
> Dan ii
>
> Dan W. McCarn, Geologist; 3118 Pebble Lake Drive; Sugar Land, TX 77479; 
> USA
> HotGreenChile at gmail.com   UConcentrate at gmail.com
>
>
> -----Original Message-----