I'd get a source with the normal Canberra energy lines and then add Am-241 to see the true performance before rather than deciding based upon our opinion poll. You can share a performance graph like the one below that doesn't have Am-241. I don't have such a neat graph and would like to see one... Maybe it's on the Canberra Coffee cup that I can't seem to find...
Glen Vickers Exelon Corp RP Technical Lead, CHP 815-216-2723 (work/cell) From: Vickers, Glen:(GenCo-Nuc) Sent: Sunday, March 30, 2014 6:59 AM To: [email protected] Subject: RE: Quick Whole Body Counter Benchmark 1. Do you include Am-241 as one of the standard nuclides in your WBC Library? No. Cal goes down to 88 keV. Very significant changes in slope and concavity <250 keV. Most difficult part of NaI energy and FWHM cal. A couple channels off and you may not ID at all. Look at your efficiency curves on a linear instead of log scale and you'll see just how much the monitor performance changes over a narrow energy range. Have not put Am-241 in library recently and turned on MDAs to see how high Am-241 LLD would be, but it may be higher than your dosimetry action level for in-vitro samples. Just because I didn't see it, I wouldn't think I'm okay. If I did see it, it's probably a false ID and then you're chasing a ghost. I'd include alpha based upon work area smears and air samples. 2. Is Am-241 part of your mixed gamma calibration source (do you calibrate the 59 keV energy line)? Canberra multi-energy line sources typically start at 88 keV. Look at the graph below and look at the detector response, The change in response is nearly infinite and not how we typically select detectors. We try to pick detectors with minimal change in response over an energy range. It's clear in this case that the slope of the response at 60 keV is the most extreme I've seen. I'm thinking Canberra would say the same if they were looking at the same data. 3. What type of Whole Body Counter do you use (e.g. Canberra Fastscan, Canberra Accuscan, etc)? Canberra Fastscan NaI, recently purchased Accuscan with Germanium detector, but haven't played with it yet. Germanium Accuscan is a very nice unit with very good resolution. I don't have a response graph for the germanium yet to review like the one below. Check out the calibration graphs below for the Fastscan NaI and see where Am-241 would fall. The answer to the test question is no, if it asks if this is a good detector for 60 keV... You also see why they have 3 energy lines down low to try to describe the performance in this region of extreme change. The lower three energy lines are always the most difficult for energy and FWHM cal and the ANSI precision and bias calcs... [cid:[email protected]] Glen Vickers Exelon Corp RP Technical Lead, CHP 815-216-2723 (work/cell) From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Holmes, Stephen J:(GINNA) Sent: Tuesday, March 18, 2014 3:36 PM To: [email protected]<mailto:[email protected]> Subject: Powernet: Quick Whole Body Counter Benchmark Hello all, quick benchmark on WBC Operation and Calibration: 4. Do you include Am-241 as one of the standard nuclides in your WBC Library? 5. Is Am-241 part of your mixed gamma calibration source (do you calibrate the 59 keV energy line)? 6. What type of Whole Body Counter do you use (e.g. Canberra Fastscan, Canberra Accuscan, etc)? Thanks, -Steve Stephen J Holmes, CHP, PE Principal Plant Health Physicist, RE Ginna NPP [email protected]<mailto:[email protected]> 585-771-3577(main); 845-476-0796 (cell) This e-mail and any attachments are confidential, may contain legal, professional or other privileged information, and are intended solely for the addressee. If you are not the intended recipient, do not use the information in this e-mail in any way, delete this e-mail and notify the sender. -EXCIP
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