RE: Smear Collection Efficiency

["Stokes, James" <StokesJ@TTNUS.COM>]

 I ain't no expert, but let's take off our shoes for a minute and consider

this:



Can anyone estimate the amount of water in the ocean by smearing the

shoreline?  I don't think so.  Collection efficiency factors are based on

assumptions, as ALL other estimes are.  There will always be a point at

which any survey technique is not appropriate for the circumstances.  Each

type of surface, contaminate, quantity and collection media, will have their

own "rules of thumb".  The US Navy adopted a system that worked well for

them, under the "normal" conditions of surface contamination.  There were

certain jobs that I performed, where it was identified that those

established techniques, did not accurately represent what was actually

there.  Other techniques were used in those circumstances.



In example.  Smears of porous materials will unders estimate the CURRENT

level of loose surface contamination.  But more importantly, if this surface

is subject to mechanical vibration, what was fixed at the time of survey,

will become, and contribute to the loose component later.



Food for the gray matter to consider.



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

From: tom_dixie

To: Redmond, Randy R. (RXQ) ; radsafe@list.vanderbilt.edu

Cc: 'William R Horne/HRW/CC01/INEEL/US'; 'Scott Davidson'; 'Lavera, Ron'

Sent: 3/30/01 5:26 PM

Subject: Re: Smear Collection Efficiency



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/ec5d943f415be302852

568c

> 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+efficie

ncy%

> 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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