John, Our contractors procedure has this guidance:
* Count smears for 2-minutes in an alpha counter such as the SAC-4. 1. Calculate the activity in units of dpm by dividing the net cpm by the instrument efficiency; normally found on the side of the instrument or performance test log. * When the beta activity on the smear is >25,000 cpm, then count with a field instrument such as the AC-3 Alpha Scintillation Detector. Stevie Vaughan DA Oversight Mgr., RP, Chem., Enviro., & Waste San Onofre Nuclear Generating Station T. 949-368-7788 | M. 949-683-4151 5000 Pacific Coast Hwy, San Clemente, CA, 92672 [cid:[email protected]] From: Powernet [mailto:[email protected]] On Behalf Of Diehl, John via Powernet Sent: Sunday, October 21, 2018 1:20 AM To: '[email protected]' <[email protected]> Cc: Diehl, John <[email protected]>; Billings, Dewayne <[email protected]> Subject: (External):[Powernet] How do you count for Alpha when beta-Gamma activity is greater than your limits for count room equipment? How do other nuclear plants count smears for alpha when the beta-gamma contamination levels are greater than your limits for counting in scalers or tennelecs or other counting device? (e.g. >100,000 dpm/100cm2) Do you allow technicians to take a smear of a smear? Do you allow technicians to cut smears to reduce activity? Thanks John Diehl, CHP South Texas Project Health Physics
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