ML13217A002

Additional Information Regarding License Amendment Request to Clarify the Application of the 45-day Completion Time of Technical Specification 3.8.1 Required Action C.2.2.5 License Amendment Request No. 2012-14, Supplement 2

ML13217A002
Person / Time
Site:	Oconee
Issue date:	07/26/2013
From:	Batson S Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13217A002 (6)

Text

DU.KE Scott L. Batson ENERGY. Vice President Oconee NuclearStation Duke Energy ONOIVP 17800 Rochester Hwy Seneca, SC 29672 o: 864.873.3274 f 864.873.4208 Scott.Batson@duke-energy.com 10 CFR 50.90 July 26, 2013 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC Oconee Nuclear Station (ONS), Units 1, 2, and 3 Docket Numbers 50-269, 50-270, and 50-287 Additional Information Regarding License Amendment Request to Clarify the Application of the 45-day Completion Time of Technical Specification 3.8.1 Required Action C.2.2.5 License Amendment Request (LAR) No. 2012-14, Supplement 2 On October 30, 2012, Duke Energy Carolinas, LLC (Duke Energy) submitted a License Amendment Request (LAR) requesting the Nuclear Regulatory Commission (NRC) approve a Technical Specification (TS) change to allow the 45-day Completion Time of TS 3.8.1 Required Action C.2.2.5 to be applied cumulatively over a 3-year time period for each Keowee Hydro Unit (KHU). By letter dated June 17, 2013, the NRC requested Duke Energy to submit additional information associated with the LAR. Duke Energy responded to this request by letter dated July 16, 2013. During conference calls with NRC staff on July 9 and July 11, Duke Energy agreed to provide additional information to address the risk significance of dual KHU outages.

The enclosure provides the requested information. This license amendment is needed to allow work associated with the Protected Service Water (PSW) System tie-in to the KHU emergency power to proceed on schedule. This work is scheduled to begin on September 3, 2013; therefore, approval no later than August 15, 2013, is requested. There are no new commitments being made as a result of this letter.

If there are any additional questions, please contact Boyd Shingleton, ONS Regulatory Affairs, at (864) 873-4716.

www.duke-energy.com

Nuclear Regulatory Commission License Amendment Request No. 2012-14, Supplement 2 July 26, 2013 Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on July 26, 2013.

Sincerely, Scott L. Batson Vice President Oconee Nuclear Station Enclosure Response to NRC Request for Additional Information

Nuc*par Regulatory Commission License Amendment Request No. 2012-14, Supplement 2 July 26, 2013 Page 3 cc w/

Enclosure:

Mr. Victor McCree, Regional Administrator U. S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. John Boska, Senior Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8G9A Rockville, MD 20852 Mr. Ed Crowe Senior Resident Inspector Oconee Nuclear Site Ms. Susan E. Jenkins, Manager Radioactive & Infectious Waste Management Division of Waste Management South Carolina Department of Health and Environmental Control 2600 Bull St.

Columbia, SC 29201

ENCLOSURE Duke Energy Response to NRC Request for Additional Information (RAI)

EncIpsure - Duke Energy Response to NRC RAI License Amendment Request No. 2012-14, Supplement 2 July 26, 2013 Page 1 Background Information NRC requested Duke Energy to respond to 8 RAI questions by letter dated June 17, 2013. During phone calls to discuss Duke Energy responses to the RAI questions on July 9 and 11, 2013, NRC continued to express concern that allowing the 45-day Completion Time of Technical Specification (TS) Required Action C.2.2.5 to be applied cumulatively over a three year period versus one time over a three year period will result in an additional number of extended dual Keowee Hydro Unit (KHU) outages. Duke Energy's response to RAI 8, which was intended to address this concern, proposed to restrict the cumulative time allowed in dual KHU outages by adding a second Completion Time to TS 3.8.1 Required Action H.2 that restricts the time allowed in Condition H over a three year period to 240 cumulative hours when in the 45 day Completion Time of RA C.2.2.5. This is equivalent to the maximum time that could be incurred during one continuous 45-day outage for each KHU with two 60-hour dual KHU outages (one to isolate a KHU for maintenance and one to restore a KHU from maintenance). Limiting the dual KHU outage time in this manner precludes increasing the duration of dual KHU outage time over what is currently allowed.

The NRC Staff acknowledged that the proposed change limits the time in a dual KHU outage but indicated that NRC would like to get an understanding of the risk significance of these dual KHU outages and asked Duke Energy to calculate the Incremental Conditional Core Damage Probability (ICCDP) and Incremental Conditional Large Early Release Probability (ICLERP) incurred due to 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> of dual KHU outage time over a three year period. Duke Energy agreed to perform this calculation using a method identified as acceptable by NRC Staff.

Summary of PRA results The risk evaluation was conducted for the dual KHU outage configuration using the following assumptions:

" Maintenance unavailability values for all plant systems were set to zero for all plant systems except for Keowee.

• The tornado initiating event frequency was set to zero and the weather-related Loss of Offsite Power (LOOP) initiating frequency was reduced to reflect risk management actions that preclude entering a dual KHU outage when the potential for severe weather exists during the outage period. This assumption is based on administrative controls and risk management plans that require review of the weather forecast prior to the beginning of the dual KHU outage and do not allow the outage to begin if any weather conditions are predicted that could adversely affect the availability of offsite power from the switchyard.

" Operator actions in the Probabilistic Risk Assessment (PRA) model to align backup power from transformer CT5 following a LOOP event were removed from the model. These actions are not required during the Keowee outages because the Standby Buses will be energized from a Lee Combustion Turbine (LCT) using a dedicated transmission line as required by TS 3.8.1 Condition H.

• Seismic events were neglected from the analysis.

- Encl9sure - Evaluation of Proposed Change License Amendment Request No. 2012-14, Supplement 2 July 26, 2013 Page 2 The analysis results determined that a total dual KHU unit outage time of 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> (10 days) corresponds to an ICCDP of approximately 6E-08. Approximately half of this risk contribution was due to LOOP initiating events and half from fire-related events. When this unavailability is averaged over a 3 year period, the equivalent ICCDP is 2E-08 which represents an insignificant impact on average annual plant risk.

The ICLERP value was not specifically computed. However, it was concluded that the ICLERP impact is also insignificant given that the Large Early Release Frequency (LERF) is a subset of the Core Damage Frequency (CDF) and that the ICCDP value is very low.