RE: Absorption Properties of Wood

[Eric Bickel <BBRE069@barms036.b-r.com>]

The only rule that applies to absorption of radionuclides in wood is that 
there are no rules.  Wood, being an biological product varies greatly both 
within and by species.  Previous personal experience with deconning wood 
found that the majority of the contamination could be removed from solid 
stock by planing.  Plywood had significant absorption at the edges and 
tended to only absorb activitity on the surface layer.  The glues between 
the plywood layers being waterproof seemed limit further absorption.  We 
were almost never successful in deconning wood to release levels.  Best 
practice is to seal the wood and plane the surface to remove the gross 
level, reseal and reuse until it became too thin.

Cost for deconning wood quickly becomes a factor and it does not compress 
well.  Incineration is by far the best disposal reduction alternative.  Good 
luck
 ----------
From: radsafe
To: Multiple recipients of list
Subject: Absorption Properties of Wood
Date: Tuesday, March 4, 1997 4:23PM

I need information regarding the absorption properties of wood with
radionuclides.  I have a large numbe of wood pallots and plywood, (mostly
pine) that need to be surveyed and released if possible.  Contaminants here
are primarily Tc-99, Uranium 234,235,238, and small amounts of Np-237 and
Th-230. The questions I need answers to are as follows:

1.How deep into the wood will the radionuclide be absorbed?

2.Do the radionuclides concentrate in the wood or would you expect to see
more contamination on the surface than what has been absorbed into the wood?

3.Is there any calculation or rule of thumb that can be used to determine
"If you have X1 dpm/100 cm2 contamination on the surface, then you will
have X2 dpm at Y inches into the wood"

Please respond to vcz@cosmail5.ctd.ornl.gov

Thank you,

Tom Carver
Health Physicist
Lockheed Martin Energy Systems