Exelon does corrections for both smears and air samples. Our process has you either determine the instrument efficiency with a source that simulates self-absorption (such a Mylar covered standards or a simulated filter paper) or if an electro-deposited standard is used, factor in a 30% sample attenuation by multiplying the measured (electro-deposited) efficiency by 0.7.
This is in part based on an article by Robert McFarland titled “Determination of Alpha-Particle Counting Efficiency for Wipe-Test Samples”, Radioactivity & Radiochemistry Vol. 9, No. 1, 1998. I prefer the having the self-absorption included in the efficiency as it is less numbers for RPTs to remember and/or plug in to a calculator. I would always recommend smear corrections. You could justify lower self-absorption factors if you used a membrane filter (e.g., 5 µm PTFE) but they are much more expensive. Jeffrey J. Cady, MS, CHP, RRPT Radiation Protection Manager Exelon Generation - Braidwood Generating Station 35100 South Route 53 Braceville, IL 60407-9619 Office: 815-417-2700│Cell: 208-360-9480 │Pager: 815-767-6133 Email: [email protected]<mailto:[email protected]> From: Holmes, Stephen J:(GenCo-Nuc) Sent: Friday, December 11, 2015 11:13 AM To: Lee, Sun G.; [email protected] Subject: [powernet] RE: Alpha air sample self-absorption factor Ginna calibrates using a NIST traceable impregnated filter source to account for alpha self-absorption. Stephen J Holmes, CHP, PE Sr Radiation Protection Technical Specialist [email protected]<mailto:[email protected]> 315-791-3577 (desk) 845-476-0796 (mobile) [cid:[email protected]] R.E. Ginna Nuclear Power Plant 1503 Lake Rd Ontario, NY 14519 From: Lee, Sun G. [mailto:[email protected]] Sent: Friday, December 11, 2015 11:06 AM To: [email protected]<mailto:[email protected]> Cc: Lee, Sun G. Subject: [powernet] Alpha air sample self-absorption factor The Perry Nuclear Power Plant would like to know: 1 – Do you have a site specific Alpha air sample self-absorption factor? 2 – If yes, what is the value? 3 – Was the value based upon site testing or other means? 4 – Please provide contact information if answering “yes”: Thank you. Sun Lee, CHP Perry Nuclear Power Plant Technical Support 440-280-5039 Work 440-465-8030 Cell Email: [email protected]<mailto:[email protected]> ________________________________ ________________________________ The information contained in this message is intended only for the personal and confidential use of the recipient(s) named above. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this document in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify us immediately, and delete the original message. 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"). This Email is intended solely for the use of the person(s) to which it is addressed. If you are not an intended recipient, or the employee or agent responsible for delivery of this Email to the intended recipient(s), you are hereby notified that any dissemination, distribution or copying of this Email is strictly prohibited. If you have received this message in error, please immediately notify the sender and permanently delete this Email and any copies. Exelon policies expressly prohibit employees from making defamatory or offensive statements and infringing any copyright or any other legal right by Email communication. Exelon will not accept any liability in respect of such communications. -EXCIP
