Also consider ED angular dependency. The EDs we use (DMC-2000s) are known to under-respond by about 20% if the source is from an angle greater than about 75 degrees from the front face.
1. Have you ever seen higher TLD results for a majority of workers on any particular job(s)? If so, which one(s)? In our most recent outage, the workers we used EDEX/mulitbadging dosimetry for tended to have higher dose recorded on the DLRs than the EDs estimates 2. Have you ever required that the TLD and ED be kept together (for example in a bag) for a particular job to eliminate placement differences? When we do EDEX/multibadging we attach the ED to the DLR and put them in a bag -Steve Stephen J Holmes, CHP, PE Sr. Plant Health Physicist, CENG-RE Ginna NPP [email protected] 585-771-3577 From: [email protected] [mailto:[email protected]] On Behalf Of Bullard, William (Bill) Sent: Friday, July 12, 2013 12:27 PM To: '[email protected]' Subject: Re: Powernet: Higher TLD Dose Trend. STP had a similar issue with first PZR nozzle weld overlays. -As I recall we concluded a hardened photon spectra from the large amount of shielding we used or some small ED/TLD placement differences. On 2nd unit for same job we required a special ED/TLD holder on a lanyard that ensured the two devices were close together. My recollection is that change dialed it in to our normal bias. From: Haynes, Larry E [mailto:[email protected]] Sent: Friday, July 12, 2013 10:23 AM To: [email protected] <[email protected]> Cc: Haynes, Larry E <[email protected]> Subject: Powernet: Higher TLD Dose Trend. Duke saw this issue as well on the same mod at McGuire. I don’t think we can say with 100% certainty that we nailed the cause, but after testing with TLD/ED pairs we came to the conclusion that the avg. photon energy in the work areas had shifted more towards Co-60 due to zinc injection. The EDs (DMC-2000) under respond in this energy range which resulted in the correlation delta. We discovered this after the first outage working on the mod and RWP review showed that the correlation issue was related to the craft that had work many hours on the sump mod. Subsequent outage work and testing lead us to this conclusion. Chris Whitener at McGuire would be a good contact. 980-875-4039. Larry From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Liesl K Germann Sent: Tuesday, July 09, 2013 2:17 PM To: [email protected]<mailto:[email protected]> Subject: Powernet: Higher TLD Dose Trend. Hello All, At Millstone, we recently discovered a trend where a majority of individuals working on our ECCS sump strainer cover installation had TLD doses higher than the ED estimates (ICES #305595). A couple follow-up questions: 3. Have you ever seen higher TLD results for a majority of workers on any particular job(s)? If so, which one(s)? 4. Have you ever required that the TLD and ED be kept together (for example in a bag) for a particular job to eliminate placement differences? Thanks! Liesl Liesl Germann Health Physicist Millstone Power Station Rope Ferry Road Waterford, CT 06385 860-447-1791 Ext. 6511 CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you. 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
