Good point Sandy. Also, now the dosimeter responds significantly more than your general area dose rates set with an ion chamber; as much as 20-25% depending on the energy of course. The end result - dealing with dose rate alarms because your ED over-responds so much to the true dose rate in an area.
From: [email protected] [mailto:[email protected]] On Behalf Of Perle, Sandy Sent: Monday, November 28, 2011 2:49 PM To: [email protected] Subject: Re: Powernet: RE: period TLD-ED dose discrepancy criteria Setting a PED as much as 25% high is a problem all by itself. One obvious issue is that the device that is primarily used for dose control may have to be used for dose of record if the primary dosimeter can't be used to assign the official dose. Also consider how a high setting would be explained on the event of a litigation. Attorney could have a field day! Sandy Perle Sent from my iPhone On Nov 28, 2011, at 4:38 PM, "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> wrote: Scott, We studied this situation earlier last year to find what appeared to be "best practice." Found little formal guidance. What I recommend is what we found at some high-performing benchmark plants: 1. PEDs are biased to ensure aggregate PED dose is greater than TLD dose. (Most plants are today biasing PEDs 15-25% high.) The target is for PEDs to read (in aggregate) 0-5% above TLDs. 2. When TLDs (now OSL dosimeter for us) are processed we resubmit CRE data to INPO PIC to correct reported PED overestimate. and 3. If PED total dose is outside 0-5% over OSL total dose, shoot PEDs again to to adjust the bias. Mark Lewis Health Physics Division Manager San Onofre Nuclear Generating Station (D1N) Work: (949) 368-7687 [email protected]<mailto:[email protected]> From: "Huneycutt, Scott" <[email protected]<mailto:[email protected]>> To: "'[email protected]<mailto:[email protected]>'" <[email protected]<mailto:[email protected]>> Date: 11/28/2011 01:04 PM Subject: Powernet: RE: period TLD-ED dose discrepancy criteria Sent by: [email protected]<mailto:[email protected]> ________________________________ Linda , You are correct, The question was focused on the total site Record dose versus the total site estimated dose for a wear period. What is considered unacceptable? From what I have seen so far, and thank you all so far for your responses, there is little formal guidance or procedures at most sites. There are evaluations done, but mostly informally. Scott Huneycutt Radiation Protection 763.295.1380 ________________________________ From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Sewell, Linda Sent: Monday, November 28, 2011 2:50 PM To: '[email protected]<mailto:[email protected]>' Subject: Powernet: RE: period TLD-ED dose discrepancy criteria Hi, If I think I understand your question, the answer for Diablo Canyon is yes, but only informally. As part of my review of the ED-TLD comparisons for each wear period I also look at the aggregate total period dose and ensure that it is reasonable compared to previous periods. I also plot all data and that information is also very useful for total system health purposes. Linda Linda M. Sewell, CHP Principal Health Physicist Pacific Gas & Electric Company Diablo Canyon Power Plant MS 119/1/117 PO Box 56 Avila Beach, CA 93424 P: 805.545.4315 | F: 805.545.2618| [email protected]<mailto:[email protected]> From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Huneycutt, Scott Sent: Sunday, November 27, 2011 11:39 AM To: '[email protected]<mailto:[email protected]>' Cc: Huneycutt, Scott Subject: Powernet: period TLD-ED dose discrepancy criteria There are recommendations and criteria for performing investigations when an individual's TLD or DRD period results are greater than 100 mrem and differ by more than 25%. Does your site have an acceptance criteria for total period dose for the site? What difference between total site TLD and Estimated dose is considered unacceptable? If so, what is the basis for your criteria? Thank you, Scott Huneycutt Xcel Energy | Responsible By Nature Senior Health Physicist Monticello Nuclear Generating Plant 2807 West County Road 75, Monticello, MN 55362 P: 763.295.1380 F: 763.295.1225 E: [email protected]<mailto:[email protected]> ________________________________________________ XCELENERGY.COM<http://www.xcelenergy.com/> Please consider the environment before printing this email ----------------------------------- Powernet - a service of the Health Physics Society Power Reactor Section Powernet archives at http://www.mail-archive.com/[email protected]/ Reply to: [email protected]<mailto:[email protected]> If Questions, contact Mike Russell, CHP at [email protected]<mailto:[email protected]>
