[ RadSafe ] Fwd: Radon Progeny affinity for Iron Oxide (rust)

[JPreisig at aol.com]

Radsafe:
 
      Use of plastic scintillators in high energy  neutron dosimetry is 
described in Patterson and Thomas' book on Accelerator  Health Physics (at the 
end of the book).  The plastic scintillator used in  this manner usually has 
a coating of white paint on it, and during neutron  irradiation the paint 
apparently absorbs radon and/or daughters.  During  counting of the plastic 
scintillator, multiple counts in time must be made to  remove, subtract off 
or account for these radon/daughters.
 
      Joe Preisig
 
 
 
 
 
 
In a message dated 9/12/2013 1:04:08 P.M. Eastern Daylight Time,  
achris1999 at gmail.com writes:

Douglas

I cannot cite you a study or report, right off, but  I can tell you,
from experience, that this is so.  What's more, the  metal does not
have to be rusty.  With the right atmospheric  conditions, painted
objects, such as trucks and automobiles, will also give  spurious alpha
counts due to the accumulation of radon daughters.   Actually, plastics
and neoprene can too.

The saving grace is that  radon (Rn-222) progeny are gone in a few
hours; the same is not true of  thoron (Rn-220) daughters, where you
get actual ingrowth of longer  half-lived progeny.

Cheers
cja
---------- Forwarded message  ----------
From: dcoble tds.net <dcoble at tds.net>
Date: Thu, Sep  12, 2013 at 11:58 AM
Subject: [ RadSafe ] Radon Progeny affinity for Iron  Oxide (rust)
To: "The International Radiation Protection (Health Physics)  Mailing
List" <radsafe at health.phys.iit.edu>
Dear RadSafers,
I  am inquiring if there has been a study or report that supports the  
theory
that Radon Progeny has an affinity for certain types of metal e.g.,  (rusty
steel, galvanized steel, etc.)?  If so, can someone point me in  the right
direction or provide me a copy of the study or report?
Most  field Technicians in the environmental remediation arena are familiar
with  or have experienced at some point increased low level alpha counts
with  hand held instrumentation when trying to release metal objects  for
unrestricted use.  I personally have experienced it when surveying  steel.
Painted portions would be at or below background while rusty  sections of
the same piece of steel would produce alpha counts from 2 to 10  times
background.  Considering free air background ranged from 0 to 2  cpm.
Historical assessment of the area the steel came from revealed no  known
reason for the metal to be contaminated.  Surveys of the metal  were
required due to decommissioning plans or site specific procedures and  were
established to be conservative.  Additionally, resurveys or the  same area 2
or 3 days later would not indicate the presence of alpha  emitters.  This
leads me to believe that the culprit is Radon  Progeny.
Thanks in advance for any help that you may provide.
Douglas  Coble,
RRPT
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