Generally, we use an alpha-only instrument operating on the alpha voltage plateau. That way there is essentially no beta interference - the precise quantifying of which, for a calculated compensation, is tricky & very instrument and radionuclide mix dependent. The detector type will determine the gamma interference. For example, Ludlum's 43-93 has a relatively thin zinc-sulfide doped plastic that has a very low gamma interaction.
A gas-proportional instrument (e.g., Tennelec XLB, Protean WPC-9550, etc.) equipped with a guard detector and operated on the alpha voltage plateau will do about as good as you reasonably can. Not many count room leads are going to be happy with you putting a smear that contaminated in a sample-changer instrument as it will likely contaminate the instrument. A 15 rad/hr beta smear is going to be a challenge. At that level, a portable instrument and a sample holder/jig should provide sufficient results. David Brehm Sr. Radiological Engineer Radiation Protection - Fort Calhoun Station Omaha Public Power District FC-3-1 9610 Power Lane, Blair, NE 68008 Office: 402.533.6045 Cellular: 402.237.9840 [email protected]<mailto:[email protected]> From: Powernet [mailto:[email protected]] On Behalf Of Hood, Eric via Powernet Sent: Tuesday, June 05, 2018 12:55 PM To: '[email protected]' <[email protected]> Cc: Hood, Eric <[email protected]> Subject: [Powernet] Alpha Determination Phishing = #1 threat to OPPD Is this a phishing email? - Look again! This email is from [email protected]<mailto:[email protected]> - do you know them? Use the "Report it" button if you think this is a phishing email. ________________________________ During our last S/G outage diaphragm alpha levels were not determined due to beta/gamma being too high(actual around 15R/hr) to count for alpha . We did not have an alpha frisker available. How does anyone else count for alpha with high beta/gamma? [STP Logo] Eric G. Hood Staff Health Physicist - ALARA (361)972-7928
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