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

[Chris Alston]

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