Re: Powernet: Calibration of neutron survey meters

[Roger . Schanzenbach]

Joe:

I note section 5.1 of ANSI N323A-1997 requires "A calibration source or sources should provide a radiation dose sufficient to reach the full scale of any instrument to be calibrated." Also, standard industry (power plant) practice is referencing to moderated Cf.  

I am not aware of any moderated Cf sources delivering more than a few hundred mRem/hr, whereas the ASP-1/ NRD reads up to 100,00 mRem/hr.   Therefore, it is not physically possible to meet the current standard, or calibrate all scales without some form of electronic transfer.  Having seen more than a few power plants, I can tell you it is common practice to calibrate some scales of this instrument with a pulser.  While not meeting the ANSI standard, you can at least say you are no worse than your contemporaries

The ASP-1 technical manual section "Calibration to Detectors" 2.e.6 anticipates this condition somewhat:  "If radiation exposures sufficiently high enough to do...are not available, set the dead time switches to the nominal amount given for the detector."   I recall a more detailed description in the Eberline PRM-7 technical manual, but do not have it anymore.

SONGS calibrates this instrument at 8, 80, and 800 mrem/hr with a neutron calibrator, and pulses the other three scales.

Roger Schanzenbach
HP Technical Support
San Onofre Nuclear Generating Station
(949) 368-9580






From:        "Danek, Joe" <joe.da...@fpl.com>
To:        "powernet@hps1.org" <powernet@hps1.org>, "Danek, Joe" <joe.da...@fpl.com>
Date:        07/12/2012 01:05 PM
Subject:        Powernet: Calibration of neutron survey meters
Sent by:        owner-power...@hps1.org

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For ASP1/NRD’s (?) neutron survey meters, calibration currently sent to a vendor for annual calibration. The vendor's neutron source allows for calibration up to 200 mrem/hr. For the higher range, up to 1000 mrem/hr, electronic pulse calibration is performed. Please provide responses for;
1). What do you do for calibrations, and particularly at the higher range?
2). Is electronic pulse calibration an acceptable practice ?
3). In addition to ANSI N323-1978 & ANSI N323A-1997, can you list any other reference documents, and in particular for use of electronic pulse calibrations?
 
Thank you,
Joe Danek
Corporate RP
Florida Power & Light / NextEra Energy
joe.da...@fpl.com
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