Re: Survey Instrument calibration frequency

[Christopher_Wend@bedison.com]

Brief summary:

ANSI N323A-1997, section 4.9, says: "Calibration shall be required at least 
annually..." There are also the usual words about calibration after maintenance,
adjustment, etc. that can affect instrument performance. Also words about 
increasing cal. frequency due to extreme op, conditions, hard usage, etc. 
Essentially, there isn't any change (on this issue) from the 1978 version.

NCRP 112, section 2.8 begins with: "Calibration frequencies suggested by various
groups for portable radiological survey instruments vary from once every few 
weeks to once every year, with the most commonly suggested periods between 
calibrations ranging between quarterly and annually." 

ANSI N323A-1997, NCRP 112 and ISO 7503-1 all require daily source response 
checks (NCRP calls it a "performance check"). The source response checks should 
be based on a reference reading, normally established during calibration. 
Acceptance criteria should be +/-20% (ANSI N323A-1997, section 4.8).


I'd be wary about taking your cal. freuency past 1 year. Recommend reviewing the
discussion in NCRP 112, section 2.8. Probably not what you wanted to hear - but 
I hope it helps a little.

My opinion only,

Chris Wend
Sr. Rad Engineer
(508) 830-8158
christopher_wend@bedison.com
magnum8@banet.net
______________________________ Reply Separator _________________________________
Subject: Survey Instrument calibration frequency
Author:  "Jim F. Herrold" <Herrold@uwyo.edu> at Internet
Date:    2/4/99 12:27 PM


Howdy.
     
Reading through Draft NUREG 1556 vol.11 I came across this statement under 
section 8.10.2, RADIATION MONITORING INSTRUMENTS:
     
"Some instruments may only need to be checked periodically for operability 
and response to radiation rather than receive full calibration.  For 
example, Geiger-Mueller (G-M) type survey instruments used to identify 
contamination in laboratories may only need to be checked for ability to 
detect low level contamination."
     
If this is true, it would have a HUGE impact on our calibration program. Is 
anybody else doing this? Does anybody know where the NRC got this guidance? 
Was it from ANSI N323A-1997? I don't have it yet, but am planning to obtain 
one as soon as possible. We have been following the old ANSI N323-1978, and 
don't remember any statements like the one above.
     
We are in the process of renewing our license. Because NUREG 1556-11 is 
still in draft form, the NRC says I can't use it yet. However, if I can find 
another suitable reference for this statement, I could use it.
     
Thanks.
     
Jim Herrold, Radiation Safety Officer 
herrold@uwyo.edu
     
University of Wyoming
Environmental Health & Safety
303 Merica Hall
Laramie, WY 82071-3413
     
(307) 766-3277
     
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