Davis-Besse is on its first full cycle of adding depleted zinc (5 ppb). Approximately one year into the process. We increased monitoring in our reactor coolant letdown areas and reactor coolant sample sinks. We did not observe any increase in dose rates and have since reverted to normal routine survey frequencies. We are in progress of down sizing our process filters. Started out at 2 micron and have since decreased to 1 micron.
Harry M provided some excellent insights. Pay attention to RCS cobalts. DB monitors soluble and insoluble Co 58. I know that many do not. At one point in the cycle, the insoluble replace the soluble as the higher fraction of the two....had us concerned so we sent data to EPRI and met with them. Conclusion was that our response was similar to most others, but not all. As discussed earlier, we have not detected any adverse changes. Since that time, the two components have switch, with the particulate fraction on a downward trend. Good luck. Douglas L. Noble Manager - Radiation Protection Davis-Besse Nuclear Power Station (419) 321-7780 office (419) 304-0068 cell From: "Barber, Jerry" <[email protected]> To: "[email protected]" <[email protected]> Date: 03/02/2013 03:34 PM Subject: Powernet: Zn Injection - Initial Increases in Dose Rates Sent by: [email protected] We are about to start injecting Zn at Robinson (finally!) which is a 3 loop Westinghouse PWR. In addition to placing more ARMs at locations along CVCS components and piping, we are also looking at any changes to our routine surveillances that should be implemented. For those plants that still have folks around who can remember back when they first started Zn injection: · Did you have any dose rate ?surprises?? If so, where? · Did you change the frequency of any routine radiological surveillances? Jerry Barber - RP Supervisor - Field Operations Robinson Nuclear Plant 843-857-1496 Work 843-861-2524 Cell [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.
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