ML13045A307
| ML13045A307 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 02/04/2013 |
| From: | Capps S Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC ME8118, TAC ME8119 | |
| Download: ML13045A307 (5) | |
Text
d.,
Duke Energy STEVEN D. CAPPS Vice President McGuire Nuclear Station Duke Energy, MGO1VP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078 980-875-4805 980-875-4809 fax Steven. Capps@duke-energy. corn February 4, 2013 10 CFR 50.90 U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 ATTENTION: Document Control Desk
SUBJECT:
Duke Energy Carolinas, LLC (Duke Energy)
McGuire Nuclear Station, Units 1 and 2 Docket Nos. 50-369 and 50-370 Response to Request for Additional Information Regarding License Amendment Related to Revising Technical Specification 3.7.7, "Nuclear Service Water System" (TAC Nos. ME8118 and ME8119)
By letter dated February 22, 2012 Duke Energy requested a license amendment to revise the McGuire Nuclear Station (MNS) Technical Specifications (TS) for Limiting Condition for Operation (LCO) 3.7.7, "Nuclear Service Water System" (NSWS). The License Amendment Request (LAR) will allow the use of the NSWS Pump discharge crossover valves and associated piping to cross-connect Unit 1 and Unit 2 NSWS Trains to mitigate a Loss of Service Water (LOSW) event at MNS Unit 1 or 2.
By electronic mail dated January 03, 2013, the Nuclear Regulatory Commission (NRC) staff requested additional information needed to complete their review of the proposed LAR. The enclosed document provides Duke Energy's response and contains no new regulatory commitments.
Pursuant to 10 CFR 50.91, a copy of this LAR is being sent to the designated officials of the State of North Carolina.
If there are any questions or if additional information is needed, please contact Mr. R. E. Abbott at (980) 875-4685.
Steven D. Cap s Enclosure www. duke-energy corn
U.S. Nuclear Regulatory Commission February 4, 2013 Page 2 xc: with enclosure:
V. M. McCree Regional Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 J. Zeiler NRC Senior Resident Inspector McGuire Nuclear Station J. H. Thompson (addressee only)
NRC Senior Project Manager (McGuire)
U.S. Nuclear Regulatory Commission Mail Stop 0-8 G9A Washington, DC 20555-0001 W. L. Cox III, Section Chief North Carolina Department of Environment and Natural Resources Division of Environmental Health Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1645
U.S. Nuclear Regulatory Commission February 4, 2013 Page 3 Steven D. Capps affirms that he is the person who subscribed his name to the foreqoing statement, and that all the matters and facts set forth herein are true and correct to the best of his knowledge.
Steven D. Capps,'VicLI Pesident, McGuire Nuclear Station Subscribed and sworn to me:
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4.L ENCLOSURE Responses to Request for Additional Information
Subject:
License Amendment Request to Revise Technical Specification 3.7.7, "Nuclear Service Water System" dated February 22, 2012.
NRC Request for Additional Information:
"The U. S. Nuclear Regulatory Commission (NRC) staff requests that the licensee provide the following additional information to support the review of this LAR:
Generic Letter (GL) 91-13 (ADAMS Accession No. 9109160253) requested information from affected licensees regarding their review of the proposed TS changes relating to the loss of service water (LOSW) event at their plant sites (including McGuire 1 and 2). The licensee provided a letter, dated February 27, 1992 (ADAMS Accession No. 9203020311), to the NRC staff indicating that no TS changes were needed due to McGuire I and 2 having both a Containment Ventilation Water (RV) system as well as the Standby Shutdown Facility (SSF) to provide adequate backup cooling water in the event of LOSW The NRC staff accepted the licensee response by letter dated July 15, 1992 (ADAMS Accession No. 9207220396).
However, the LAR proposes to add a note to TS 3.7.7 which would allow the sharing unit to donate one train of service water to the affected unit for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. There is no discussion of the RV or SSF being used as backup cooling water systems prior to utilizing the manual crosstie between the service water systems of both units. This would appear to contradict the licensee's assessment provided in its letter February 27, 1992.
The NRC staff requests that the licensee clarify whether both the RV and/or SSF will continue to be used as the initial backup cooling water sources in the event of the LOSW, prior to utilizing one of the sharing unit's service water trains. If not, the licensee should also explain how will it continue to meet its conditions in response to GL 91-13, which were previously accepted by the NRC staff"
Response
The proposed LAR stated, in part, "Cross-connecting service water trains between units will complement existing unit-specific actions currently specified for LOSW'. The LAR did not describe existing unit-specific actions or how cross-connecting service water trains would complement these actions. Steps to mitigate a LOSW event are prescribed in abnormal procedure (AP) which currently includes steps to recover a unit designated NSWS train, and if necessary, align the Containment Ventilation Cooling Water (RV) system to provide cooling water. These actions are intended to restore cooling water to the affected unit's NSWS essential header. Current AP guidance also provides steps to activate the SSF standby makeup pump.
This step reduces the consequences of LOSW. Specifically, in the event cooling water cannot 1
be restored to the NSWS essential header and charging motor temperature cannot be maintained with RV, action to align the SSF standby makeup pump is necessary to prevent a possible Reactor Coolant Pump seal Loss of Coolant Accident (LOCA). Although this step does not restore cooling water to the NSWS essential header, it does mitigate a potential consequence.
Following NRC approval of the proposed LAR, McGuire will revise AP guidance to include steps to cross-connect NSWS Trains between units as an additional mitigation alternative to restore cooling water to the affected unit's NSWS essential header. The proposed LAR described a LOSW as a "failure of both NSW trains to provide required flow(s) to the essential service water header." Existing AP guidance to restore cooling water to the NSWS essential header using unit specific NSWS Trains and RV will continue to precede steps that will share one of the non-affected unit's two available NSWS trains. As described above, activating the SSF is a unit-specific action that protects against component failure; however, it does not restore service water to the essential header. Consequently, actions to align the SSF may or may not be taken prior to sharing one of the non-affected unit's redundant NSWS trains. In this regard, the AP guidance following NRC approval of the LAR will be consistent with the "Bases for Resolution" section of McGuire's response to GL 91-13 as docketed in the letter dated February 27, 1992 (ADAMS Accession No. 9203020311). As stated:
"McGuire has several design and operational features which reduce the consequences resulting from a loss of RN event. First, the RN System at McGuire can receive backup cooling flow from the RV System. This system is aligned to the RN non-essential header but can deliver adequate flow to the RN essential loads. The RV System contains three 3200 gpm pumps which will start automatically on low RN System pressure. Second, McGuire has an independent backup system, the SSF, which contains a dedicated makeup pump to supply injection flow to the NC pump seals. The Loss of RN procedure directs the operators to (i) ensure that the RV System is providing sufficient flow, (ii) align to the other unit's RN System through the system crosstie if insufficient RN flow exists, and (iii) activate the SSF if all seal cooling is lost."
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