RE: Low Levels Environmental

["Beekman, Marsha" <Beekmam@wipp.carlsbad.nm.us>]

Benny,
It is hard to say for sure just what number to use.  It would depend upon
what you are doing with the data.  The number is probably less than the MDA
for the instrument so the MDA is not really a valid number.

Maybe we can get together and see if we can come up with an approach to the
number.

Marsha L. Beekman  MS 452-06
Westinghouse Government Environmental
Services Company, LLC
P.O. Box 2078
Carlsbad, NM 88220
(505) 234-8495
Fax:  (505) 234-8298
beekmam@wipp.carlsbad.nm.us

> ----------
> From: 	Hooda, Benny
> Reply To: 	radsafe@romulus.ehs.uiuc.edu
> Sent: 	Thursday, September 30, 1999 9:01 AM
> To: 	Multiple recipients of list
> Subject: 	Low Levels Environmental
> 
> Hi,
> I need peer opinion on very low levels of environmental activity where the
> results reported are mostly negative concentrations. The DOE/EH 0173T,
> "Environmental Regulatory Guide for Radiological Effluent Monitoring and
> Environmental Surveillance" , section 7.3.4, states that less- than-
> detectable values and negative values have to be included in the data
> evaluations, and assigning zero, detection limit, or some in between value
> would "severely" bias the resulting estimates and should be avoided.
> Therefore, I have been including these negative values in the statistical
> analyses. However, I am being asked to use the MDA instead of negative
> values. What's your input?
> 
> Secondly, NCRP 50, section 4.5.4, says that plutonium presently in the
> environment is mostly Pu-239, (or definitely higher than Pu-238) so if the
> concentration of Pu-238 reported by the laboratory is about three times
> higher than Pu-239 (with no other known source) then after investigation
> and
> all other sample results below detection limit, it can safely be concluded
> that it was an "analytical artifact". Are there any suggestion on what to
> call these kind of anomalous results because " analytical artifact" does
> not
> sound right to some people, as well as, is this "flawed logic"?
> Thanks for your help. 
> 
> "Sometimes deepness is a surface. If that weren't true, we would have no
> need for mirrors"( by Ray Bradbury).
> 
> 
> -/-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ 
> Benny Hooda
> Westinghouse Electric Corporation
> WIPP
> P.O.Box 2078 M/S 910-20
> Carlsbad, NM 88221
> (505)234-8932 Voice
> (505)885-0974 Fax
> Hoodab@WIPP.Carlsbad.NM.US
> /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ /-/ 
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