RE: 120-ml and tool monitor

[Glen.Vickers@ucm.com]

Shouldn't the "probability of detection" be 1.7 sigma, which would equate to
95% confidence?  We use the 95% confidence level to be consistent with the
quality levels of our formal Ge unconditional release counts.  We use this
level of confidence for all free-release monitors.

Glen Vickers
Braidwood Nuclear Power Station


> -----Original Message-----
> From:	William E. Cox [SMTP:COXWX@naesco.com]
> Sent:	Thursday, April 20, 2000 11:16 AM
> To:	Multiple recipients of list
> Subject:	Re: 120-ml and tool monitor
> 
> 
> 
> Typically, these monitors are set up with a point source efficiency to
> monitor
> loose surface contamination on materials.  Some facilities have done
> shielding
> calculations and bounded cases where these monitors are even used to look
> for
> internal comtamination.
> 
> There is nothing to say that one could not set one of these up with an
> efficiency for a liquid geometry.  Based on my experience I estimate you
> could
> achieve about a 1e-5 uCi/ml (2700 dpm total) MDA for Cs-137 in a 120ml
> sample
> within the units maximum 100 second count time.  This assumes a four
> detector
> SAM9 unit in a <10uR/hr background using a Prob of Det of 1S and a Prob of
> False
> Alarm of 2.4S.  Therefore it could be done but you may not be able to meet
> your
> ODCM specified values.  Obviously some specific application testing would
> be
> required and some assumptions made about the average gamma mix.  Mark
> Deacon at
> Bicron/NE could tell you who is doing this.
> 
> Bill Cox
> Seabrook Station HP
> coxwx@naesco,com
> 
> 
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