[ RadSafe ] Fwd: Radon Progeny affinity for Iron Oxide (rust)
JPreisig at aol.com
JPreisig at aol.com
Thu Sep 12 12:12:35 CDT 2013
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.
In a message dated 9/12/2013 1:04:08 P.M. Eastern Daylight Time,
achris1999 at gmail.com writes:
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.
---------- 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>
I am inquiring if there has been a study or report that supports the
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.
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