Palo Verde provides the following response: Palo Verde uses the DMC-2000S electronic dosimeters and they are biased by 1.07 (+7%). Our ED to TLD comparison by total dose is routinely +/- 2%. Management is fully aware of how close the dose is by both systems and that the only dose we get back during outages is in multi-pack incremental recording. Over the years, we have performed numerous TLD/ED studies of all of the individual results and have very stringent criteria for their comparisons. With these reviews, we have refined the ED bias to where it is today. As of yet, we have not seen any changes in ED to TLD data based on Steam Generator and Rx Head replacements, or from the power up-rate.
One of our "advantages" is that, with an outage every six months, and six-month monitoring cycles, we never have a low total dose personnel cycle. Each read cycle contains outage man-rem exposure totals. So with our TLD LLD of only 5 mrem, and minimal doses incurred by personnel in the PA when EDs are not worn but TLDs are, the TLDs and EDs do match very well. And we are very pleased with the accuracy, rather than any extra conservatisms. Seth. ********************************************************************** Seth J. Kanter, CHP, RPT Sr. Health Physicist Palo Verde Nuclear Generating Station Mail Sta. 7397 5801 S. Wintersburg Rd. Tonopah, AZ 85354 Phone (623) 393-3130 Fax (623) 393-2487 Unless otherwise noted, all opinions are my own Liviu Librescu ********************************************************************** From: [email protected] [mailto:[email protected]] On Behalf Of Courtenay, Christopher C Sent: Tuesday, December 14, 2010 12:37 PM To: [email protected] Subject: Powernet: Electronic Dosimeter Bias Duke Energy would like to know the following: 1. Do you bias your EDs to over-respond in the field? 2. What bias do you apply if you do? (5%, 10%, etc) 3. Have you noticed a change in ED response due to changing plant conditions (Co58/Co60 ratio changes due to Zinc injection, etc) or specific jobs (weld overlay, alloy 600, etc)? Point of reference - Duke uses the DMC2000S from Mirion. Chris Courtenay Engineer, Duke Energy 980-875-5005 "To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be." --- NOTICE --- This message is for the designated recipient only and may contain confidential, privileged or proprietary information. If you have received it in error, please notify the sender immediately and delete the original and any copy or printout. Unintended recipients are prohibited from making any other use of this e-mail. Although we have taken reasonable precautions to ensure no viruses are present in this e-mail, we accept no liability for any loss or damage arising from the use of this e-mail or attachments, or for any delay or errors or omissions in the contents which result from e-mail transmission.
