ML12227A357
| ML12227A357 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 07/30/2012 |
| From: | Repko R Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-08-220, IR-08-009 | |
| Download: ML12227A357 (4) | |
Text
Duke REGIS T. REPKO Duke Vice President
- Energy McGuire Nuclear Station Duke Energy MGOI VP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078 980-875-4111 980-875-4809 fax regis. repko@duke-energy. com July 30, 2012 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555
Subject:
Duke Energy Carolinas, LLC (Duke Energy)
McGuire Nuclear Station, Units 1 and 2 Docket No. 50-369, 50-370 Supplemental Response to Request for Additional information regarding a Revision to Commitment in Response to Notice of Violation EA-08-220 (NRC Inspection Report Nos. 05000369/2008009 and 05000370/2008009)
By letter dated December 7, 2009, McGuire responded to an NRC request for additional information dated November 6, 2009. Enclosure 2 of the December 7, 2009 response discussed the scope of three modifications being developed to address Operable but Degraded Nonconforming (OBDN) conditions associated with the Nuclear Service Water System (NSWS) strainer backwash function. The letter also discussed the schedule of activities to be completed and why those activities represented the first available opportunity to restore compliance.
Please find attached a supplemental response to modification #3 as described in Enclosure 2 of the December 7, 2009 submittal and supplemented July 28, 2011.
This submittal contains no new regulatory commitments.
Please direct any questions you may have in this matter to Rick Abbott at (980) 875-4685.
Regis T. Repko Attachment www.duke-energy com
U. S Nuclear Regulatory Commission July 30, 2012 Page 2 cc:
V. M. McCree, Regional Administrator U. S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 J. H. Thompson McGuire Project Manager U. S. Nuclear Regulatory Commission Mail Stop 8 H4A 11555 Rockville Pike Rockville, MD 20852-2738 John Zeiler U. S. Nuclear Regulatory Commission Senior Resident Inspector McGuire Nuclear Station
Attachment of the December 7, 2009 letter stated, in part:
"To address the operable but degraded non-conforming condition McGuire is in the process of developing three modifications for the Nuclear Service Water System (NSWS). The three modifications are described as follows:
- 1. The first modification includes the addition of an assured air source to the backwash inlet valves to allow the NSWS Strainers to automatically back wash for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> into a loss of Instrument air (VI) event. This will remove the time critical operator actions required to operate the back wash supply inlet valve during the potential loss of VI event.
- 2. The second modification re-routes the backwash return piping to provide a less restrictive flow path for backwash return to the Ground Water (WZ) sump via manual operator actions.
- 3. The third modification installs a new Nuclear Safety Related backwash discharge pump to the NSWS Return Header for each train of the NSWS. This phase ensures there will be no depletion of the SNSWP by routing the discharge back to the back wash source of water."
1-Assured Air to Strainer Backwash Inlet AOV completion in August 2010 Modification #1, Assured Air Source to Strainer Backwash Inlet Air Operated Valve, is complete. Safety-related air provided by accumulators will provide the motive force to the NSWS strainer backwash supply valves upon a loss of non-safety related instrument air system (VI). Safety-related air from accumulators provides additional time for continued automatic valve operation before any manual action utilizing the bypass valve is required. The completion of this modification has eliminated previous reliance on time critical operator actions necessary to initiate strainer backwash in the event of loss of VI concurrent macro-fouling event.
2 - Pipe from Strainer Backwash to WZ Sump completion in July 2011 Modification #2, Pipe from NSWS Strainer Backwash to WZ (Ground Water Drainage System) Sump, is complete. The strainer backwash discharge flow path to the WZ sump has been modified including installation of a basket to collect debris from the strainer backwash outlet to the WZ sump. Manual discharge flow from the NSWS Strainer to the WZ sump is provided by a branch line off the backwash pump suction line.
Attachment 3 - Backwash pump discharging to the NSWS System Return Header completion in December 2012 Modification #3 is complete with the exception of installing flow elements with flange taps to provide backwash supply flow indication. Installation of flow elements with flange taps will enhance monitoring but is not necessary to resolve the OBDN condition associated with removing debris from the NSWS Strainer and discharging to the NSWS return header. The installation of safety related NSWS strainer backwash pumps has resolved the flow design deficiency associated with backwash discharge to the NSWS return header. Therefore, the December 7, 2009 letter is revised to eliminate the installation of flow elements with flange taps from the scope of modification #3. The completion of modifications 1, 2 and 3, as described herein, has resolved the OBDN condition associated with the NSWS Strainer Backwash System and the NSWS Strainers are in full compliance with the current licensing basis.