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RE: Smear Collection Efficiency
Glen,
I think you already know the answer to your question below, the answer is
no. If you don't know the area surveyed, how could you quantify an activity
per unit area? However, if you read the post that you replied to, Joel
wasn't talking about a package, he was talking about general surveys in the
work area. He was referring to a technique call a large area wipe (LAW)
which is frequently used (at least in the DoE world) to find contamination
in the work area. Then you go back and quantify the amount of contamination
after you find it with the large area wipe.
To further add to this thread, a survey for "removable" contamination should
be done to approximate the amount of contamination that will be removed
based on the use of the area. Usually this involves a dry smear or swipe
(filter paper) to approximate routine transfer to an individual. However,
if heavy work (or even decontamination) is to be performed in an area, I've
seen surveys for removable contamination performed with wet canvas and even
scotch-bright or steel wool pads. Again, I emphasize that the intent is to
approximate the transfer of contamination from the surface to the worker and
his (or her) equipment based on the activity being performed. And yes, you
have to know the area of the smear or swipe.
If you want to know the total amount of contamination on the surface,
perform a direct survey, not a smear / swipe. That's why (again in the DoE
world) we have limits for "total" and "removable" contamination.
Sorry for stepping on the "soap box", I'll quit now.
David Hyder, CHP
(509) 373-9652
David_S_Hyder@rl.gov
Hanford's Facility Evaluation Board
-----Original Message-----
From: glen.vickers@EXELONCORP.COM [mailto:glen.vickers@EXELONCORP.COM]
Sent: Tuesday, April 03, 2001 10:41 AM
To: baumbaug@NOSC.MIL; alombardo@EARTHSCIENCES.NET;
radsafe@list.vanderbilt.edu
Subject: RE: Smear Collection Efficiency
Question: If you wipe a large area of a package in excess of 100 cm^2
without paying attention to the total area wiped, then how do you know if
the shipper was in violation of contamination limits if you find anything?
glen.vickers@exeloncorp.com
> -----Original Message-----
> From: Joel Baumbaugh [SMTP:baumbaug@NOSC.MIL]
> Sent: Tuesday, April 03, 2001 9:42 AM
> To: Andrew Lombardo; radsafe@list.vanderbilt.edu
> Subject: RE: Smear Collection Efficiency
>
> Radsafers,
>
> I think that we have two different "perspectives" here. Some of us
> are
> looking at "contamination" in an analytical sense - i.e. how much
> contamination is actually there and how do we determine/quantify that
> amount. Others of us are looking at how much contamination is "removable"
>
> - i.e. how much will be transferred from the surface to the person or
> thing
> that comes into contact with it.
>
> When, at my work, I do a survey (not wiping a sealed source/package
> for
> removable contamination but of a "work-surface" in a laboratory), I am
> initially looking for "removable" contamination. I'm looking for
> something
> (anything) which will leave the surface and contaminate something else.
> My
> initial swipes are typically in excess of 100 cm-2 because I'm "looking"
> for "anything" that is radioactive. After (if or when) I find something,
> "THEN" I go back and "quantify" what is there and whether there are other
> aspects of the contamination I should worry about - IS it readily
> removable
> (or even still there), is it an external hazard, should I let it decay in
> place or remove it and HOW to remove it (if necessary), etc., etc. Well,
> I
> don't want to write a book here, but I noticed that while everyone was
> "correct" in what they were saying that it seemed that the group was
> polarizing (with a couple of exceptions) and not really seeing each
> other's
> sides....
>
> Just my 2 cents (and my "own" personal opinion [NOT the U.S.
> Navy's]),
>
>
> Joel Baumbaugh (baumbaug@nosc.mil)
> SSC San Diego
>
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