ML13171A295

Request for Additional Information Regarding Amendment Application for a Revision to the Technical Specification on the Emergency Power System

ML13171A295
Person / Time
Site:	Oconee
Issue date:	06/26/2013
From:	Boska J Plant Licensing Branch II
To:	Batson S Duke Energy Carolinas
Boska J 301-415-2901
References
TAC ME9022, TAC ME9021, TAC ME9023
Download: ML13171A295 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 26, 2013 Mr. Scott L. Batson Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 SUBJECT OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3, REQUEST FOR ADDITIONAL INFORMATION REGARDING AMENDMENT APPLICATION FOR A REVISION TO THE TECHNICAL SPECIFICATION ON THE EMERGENCY POWER SYSTEM (TAC NOS. ME9021, ME9022, AND ME9023)

Dear Mr. Batson:

By letter dated June 27, 2012, Duke Energy Carolinas, LLC (Duke), submitted an application to the Nuclear Regulatory Commission (NRC) for a proposed amendment for the Oconee Nuclear Station, Units 1, 2, and 3, which would revise the Technical Specification on the emergency power system. The application is in the NRC's Agencywide Documents Access and Management System under Accession No. ML12181A312 The revision would permit each of the two emergency power system generating units (Keowee Hydro Units) to be out of service for up to 75 days on a one*time basis for major maintenance work.

The NRC staff is reviewing the submittal and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI) The NRC staff requests that a response to the RAI be provided within 30 days of the date of this letter.

S. Batson If you have any questions, please call me at 301-415-2901.

Sincerely,

()LV.~

Uft,n P. Boska, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION (RAil REGARDING PROPOSED AMENDMENT TO TECHNICAL SPECIFICATIONS ON THE EMERGENCY POWER SYSTEM DUKE ENERGY CAROLINAS LLC OCONEE NUCLEAR STATION UNITS 1 2 AND 3 DOCKET NOS. 50-269, 50-270 AND 50-287 By letter dated June 27, 2012, Duke Energy Carolinas, LLC (Duke), submitted an application to the Nuclear Regulatory Commission (NRC) for a proposed amendment for the Oconee Nuclear Station, Units 1, 2, and 3, which would revise the Technical Specification (TS) on the emergency power system. The application is in the NRC's Agencywide Documents Access and Management System under Accession No. ML12181A312. The revision would permit each of the two emergency power system generating units (Keowee Hydro Units) to be out of service for up to 75 days on a one-time basis for major maintenance work. The Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has the following questions:

Question 1 The lAR stated in Section 4.0, Risk Insights:

The justification for the TS Completion Time (CT) extension is based on the deterministic evaluation in Section 3.0. To supplement this evaluation and to gain insights concerning the proposed plant configuration, Duke Energy performed a risk assessment. The findings of the risk assessment confirm that the risk impact with adding an additional Completion Time of 75 days to restore an inoperable KHU due to generator pole rewind work is insignificant. The relevant criteria are Core Damage Frequency (CDF) and Large Early Release Frequency (LERF). The increase in either of these metrics resulting from the addition of a new 75-day Completion Time to restore an inoperable KHU due to major maintenance is estimated to be insignificant.

Regarding the above stated risk assessment, please respond to the following questions:

• Concerning the risk assessment performed to gain insights in Section 4.0 of the Oconee lAR dated June 27, 2012, related to the proposed one-time 75-day TS CT, please discuss the basis for your conclusion(s) on risk insights (i.e., risk impact with additional75-day CT is insignificant). Provide your key assumptions used to derive your conclusion.

• What duration was used for the single Keowee Hydro Unit (KHU) outages? Were dual KHU outages considered as part of the single KHU outage risk assessment? If dual KHU outages were considered, how many hours of dual KHU outages were considered for the risk assessment?

• When a single KHU outage is entered, how is it ensured that the other KHU will maintain its high reliability to start and run?

Enclosure

• There may be times when a dual KHU outage is entered, for example to drain the penstock and isolate a single KHU, followed by bringing back one KHU for a period of time, and then re-entering a dual KHU outage to recover the KHU undergoing maintenance. What steps are taken to ensure that the KHU which is brought back to service between dual KHU outages does not have degradation in its reliability to start and run?

• Regarding the Safe Shutdown Facility (SSF) during a dual KHU outage and a single KHU outage, are there differences in the way the SSF is ready to be used if needed (e.g., in the deployment of the SSF)? If so, please discuss the differences.

• During KHU outages, are there any planned actions in the event of a heightened likelihood of a loss of offsite power and/or Lee Combustion Turbine power source (such as tornado warnings, severe weather)?

• During KHU outages, are there any planned actions to ensure availability and reliability of the emergency feedwater system?

Question 2 Please provide the proposed KHU generator field pole rewind outage schedule for both KHU (MS Project or equivalent is acceptable) which includes the identification of all periods of time when one or both KHU are inoperable in accordance with TS up to completion of all work and both KHU restored to operable.

• ML13171A295 *via email OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/EEEB/BC(A) NRR/LPL2-1/BC NRR/LPL2-1/PM RMathew NAME JBoska SFigueroa (sf)* (GMatharu for) RPascarelli JBoska DATE 06/20/13 06/21/13 06/25/13 06/26/13 06/26/13