Response from Diablo Canyon. From: Miller, Clint Sent: Tuesday, February 05, 2013 9:27 AM To: [email protected] Cc: [email protected] Subject: Powernet: RCS Filters Importance: High
Douglas, At Diablo Canyon we currently use 0.1u absolute pore size filters in RCS letdown, Seal Water injection and Seal water Return filter vessels. Originally our plant had 25u nominal filters in these vessels except Seal Water Injection which was 5u Nominal. We reduced pore size one step at a time to prevent overwhelming radwaste with high activity filters they could not handle, store, process or ship. A smaller size filter would be installed in a vessel and if it didn't D/P in 3 months we stepped down another pore size. Our results were that we could have jumped from the course pore size down to 2u in one step. Going below 2u we did generate more filters. If you are not using macroporous (filtration) resin in your shut down clean up bed, you will likely mimic our experience. As we stepped down from 2u to 1u we had several filters D/P before 3 months had passed. Only after getting a 3 month run did we down size to 0.45u and then to 0.1u. I'd suggest you obtain a spent filter transfer cask, if you don't have one already and line up a filter HIC or shielded drums so that radwaste has a place to put spent filters should they D/P quickly. We had our fix it now team assigned to replace the filters and procedures in place for each vessel prior to ever stepping down a filter pore size. If you have use the macroporous resins [Purolite 501P, 5070 or PRC 0-1] in CVCS, you might be able to step down from 2u to 1u with no added filter generation. We did find that once we reduced size below 1u we started seeing C-14 in the off-site Lab filter samples. In order to limit Greater than Class C generation the submicron filters might have to be removed prior to D/P to limit the amount of C-14 on the filters. Good Luck, Clint Miller 805-545-4582 ________________________________ From: Sewell, Linda Sent: Tuesday, February 05, 2013 8:53 AM To: Miller, Clint Subject: FW: Powernet: RCS Filters Importance: High Hi Clint, Can you answer this. I will forward on. Linda From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of [email protected]<mailto:[email protected]> Sent: Tuesday, February 05, 2013 7:57 AM To: [email protected]<mailto:[email protected]> Subject: Powernet: RCS Filters Importance: High Davis-Besse is considering lowering the micron size of the RCS letdown filter from 2 micron to 1 microns. Requesting industry information regarding the micron size of RCS filters used at your station (on-line). Thanks Douglas L. Noble Manager - Radiation Protection Davis-Besse Nuclear Power Station (419) 321-7780 office (419) 304-0068 cell ----------------------------------------- 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. PG&E is committed to protecting our customers' privacy. To learn more, please visit http://www.pge.com/about/company/privacy/customer/
