Re: Smear Collection Efficiency

["tom_dixie" <tom_dixie@MSN.COM>]

Randy,



Nice work, now that you have a basis (or perceived basis) for collection

efficiency for activity on smears maybe something will be done with that.

The 'rule of thumb' that you have identified is an unused rule.



For example, if it was used, a smear that collected an activity of say

20,000 dpm would indicate a surface activity of 20,000/.1 or 200,000 dpm

over the area that the smear was rubbed.  However, it is recorded as 20,000

dpm over that area (usually 100 square cm).



10% is also what the Navy used when I first qualified as a rad tech.

However, the 'loose surface activity' was never determined using this

factor.  It is real and should be used, any idea why it isn't?



There was also some indication (back in the early 70's) that for larger

areas the smear would be less effective in collection and for some surfaces,

like concrete, the smear (paper) would disintegrate.  Or in some cases would

become a medium for transfer of activity to clean areas from contaminated.



There are many caveats to the use of this collection efficiency.  The smear

must remain whole, the pressure over the smear surface must be uniform, the

surface activity must be reasonably homogenious, etc.



It is obvious that smears do not collect 100% of the activity on a surface

(otherwise the surface would be clean) but the current method of surface

activity determination simply leads people to believe that surfaces are

cleaner than they are.



Tom O'Dou, CHP, RRPT

tom_dixie@msn.com



- ----- Original Message -----

From: "Redmond, Randy R. (RXQ) " <RXQ@Y12.doe.gov>

To: <radsafe@list.vanderbilt.edu>

Cc: "'William R Horne/HRW/CC01/INEEL/US'" <HRW@INEL.GOV>; "'Scott Davidson'"

<bsdrp@YAHOO.COM>; "'Lavera, Ron'" <RLavera@ENTERGY.COM>

Sent: Friday, March 30, 2001 12:19 PM

Subject: Smear Collection Efficiency





> Many thanks to those who responded to my inquiry.  10% for the smear

> collection efficiency appears to be the "rule-of-thumb".  Found a report

> (RADSAFE Archives) with some actual test data.

>

>

>

http://ww2.packardinst.com/packard/ecom/pcatalog.nsf/ec5d943f415be302852568c

> 2005e6eb3/ff6d3af15d0faeb6852568c30062da4a?OpenDocument   - Test Data

>

>

http://www.google.com/search?q=cache:romulus.ehs.uiuc.edu/cgi-bin/lwgate/RAD

>

SAFE/archives/radsafe9501/Subject/article-180.html+%22collection+efficiency%

> 22+and+swipe+OR+smear&hl=en

>

> www.epa.gov/radiation/marssim/docs/revision1/apph.pdf  - do a search for

> "collection efficiency"

>

> Randy Redmond

> BWXT Y-12 L.L.C.

> Y-12 National Security Complex

> Radiological Control Organization

> Email:  rxq@Y12.doe.gov

> Phone:  865-574-5640

> Fax:  865-574-0117

>

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