I would like to present a qualified disagreement with John and Jim for this specific case of WBC QA/QC.
I agree with Jim's comments that from a diagnostic standpoint more peaks are better and low energy peaks could be useful. But modern Ge systems are quite reliable and a competent spectrum reviewer can identify most all common failure modes by simply looking at the WBC spectrum and result. My disagreement is using Eu-152 as the primary QC source in a program designed to prove to outsiders that the plant working environment has been safe. A very important purpose of the WBC QA program is to prove to an outside observer [regulator, litigant] that the system was operating properly when it is in use in the normal mode - i.e. to count people. That requires the same nuclide library and analysis process be in place during the QC count as is used for people counts. With NaI systems [e.g. FastScan] putting Eu152 in the People library is asking for trouble. Yes with HPGe systems you could get away with it - although it can cause problems if there is also Co-57 in your library. So unless you have Eu-152 in your plant inventory in sufficient concentrations as to have a meaningful contribution to internal body activity, it should not be in the people library. NOTE: John at Oyster Creek perhaps could soon be in that category as neutrons + concrete make Eu-152. Even of one chooses to use Eu-152 as a check source you should track each of several lines separately, not simply nuclide activity which is normally the weighted average of all lines. Eu-152 is a very practical and useful source for calibrations [energy, FWHM, efficiency], although there are some quirks for NaI systems that must be avoided. But we use it routinely for that purpose. However we only supply and recommend Co-60 and Cs-137 as the standard check source for our WBC products. Those two nuclides in a QC program demonstrate to an outside observer [generally non-technical] the consistent stability of the system when measuring two of the major potential dose contributors in NPPs. That is a far easier task than convincing a skeptical non-technical observer [think lawyer] why a non-NPP nuclide is relevant and especially why a different library is relevant. While I am on a roll, a proper QC program should have all 3 elements included: 1] check source counts to show that positive activity will be measured reliably; 2] blank counts to show that the measurement system does not falsely report activity in the sample when a sample is not present; and 3] Duplicates to demonstrate the reproducibility of real samples [people]. Those are the elements that Quality Control experts will look at as evidence of the validity of the results. Fortunately today modern NPP internal doses are so low and WBCs are so reliable that this interesting technical discussion does not have significant dose consequences - but it could have expensive litigation consequences if not done properly. Have fun frazier Frazier Bronson CHP Scientific Director Meriden Technologies - Canberra 800 Research Parkway Meriden CT 06450 USA [email protected] From: Powernet [mailto:[email protected]] On Behalf Of McCarthy, John:(GenCo-Nuc) via Powernet Sent: Wednesday, January 9, 2019 12:08 PM To: [email protected]; [email protected] Cc: McCarthy, John:(GenCo-Nuc) Subject: Re: [Powernet] Benchmark - WBC Check Source I used 152Eu in the mid 80's with Pilgrim's HPGe WBC. Jack McCarthy, DCHP Decommissioning Health Physics Oyster Creek 609.971.4764 From: Powernet <[email protected]> On Behalf Of Jim Key via Powernet Sent: Wednesday, January 09, 2019 11:31 AM To: [email protected] Cc: Jim Key <[email protected]> Subject: Re: [Powernet] Benchmark - WBC Check Source Eu-152 would be the preferred source. HPIG energy response is slightly non-linear so the lower energies from Eu-152 are advantageous. Also, the lower energy peaks provide resolution info that can be useful in recognizing signal noise. Jim Jim Key Key Solutions, Inc. 4350 Big Springs Road, Lebanon, TN 37090 615-453-3712 (Office) [email protected]<mailto:[email protected]> 413-403-9805 (e-Fax) From: Powernet <[email protected]<mailto:[email protected]>> On Behalf Of Holmes, Stephen J:(GenCo-Nuc) via Powernet Sent: Wednesday, January 9, 2019 5:35 AM To: [email protected]<mailto:[email protected]> Cc: Holmes, Stephen J:(GenCo-Nuc) <[email protected]<mailto:[email protected]>> Subject: [Powernet] Benchmark - WBC Check Source This benchmark is primarily for those of you using a Germanium based whole body counter...I welcome feedback from everyone, however Questions (with Ginna info) 1. What WBC system are you using? Mirion/Canberra Accuscan-II with dual HPGe detectors 1. What nuclides/peaks are you using to perform your routine QC checks? Cs-137/Co-60 source. The 662 and 1332 peaks are used for QCC. We are in need of a new source and are considering Eu-152 (122 keV and 1408 keV peaks) 1. Have you changed this source in recent history? If so, why and did you encounter any issues when you changed sources? No, but Mirion has recommended we consider changing to Eu-152 1. Have you been challenged by a regulator/auditor on the source you are choosing to use? We have not. Benefit of the Co-60/Cs-137 mixture is that we are directly validating two key nuclides each time we do a QC check. Benefit of Eu-152 is ability to validate the lower end of the energy spectrum during QC checks. Eu-152 will also have a longer working life. Thanks Stephen J Holmes, CHP Rad Prot Tech Support Manager [email protected]<mailto:[email protected]> 315-791-3577 | 845-476-0796 (mobile) [cid:[email protected]] R.E. Ginna Nuclear Power Plant 1503 Lake Rd Ontario, NY 14519 This Email message and any attachment may contain information that is proprietary, legally privileged, confidential and/or subject to copyright belonging to Exelon Corporation or its affiliates ("Exelon"). 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