ML16064A020

License Amendment Request for a Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replacement, LAR No. 2015-08

ML16064A020
Person / Time
Site:	Oconee
Issue date:	02/26/2016
From:	Batson S Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LAR 2015-08, ON-2016-021
Download: ML16064A020 (49)

Text

DUKE scott L.

Batson FkIFD(~YVice President ENERGY°Oconee Nuclear Station Duke Energy ONOIVP I7800 Rochester Hwy Seneca, SC 29672 o: 864.873.3274 f~864.873. 4208 Scott.Batson@duke-energy.corm ON-201 6-021 10 CFR 50.90 February 26, 2016 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 License Amendment Request for a Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replacement License Amendment Request (LAR) No. 2015-08 In accordance with 10 CF..R 50.90, Duke Energy Carolinas, LLC (Duke Energy) proposes to amend Renewed Facility Operating License Nos. DPR-38, DPR-47, and DPR-55 for ONS Units 1, 2, and 3, respectively. This LAR proposes to add a temporary Completion Time to Technical Specification (TS) 3.8.1 Required Action (RA) C.2.2.5 to allow sufficient time to replace the stator on each Keowee Hydro Unit (KHU).

The Keowee hydroelectric station has been in service since 1971. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The generator pole rewinds were completed in February 2014 and August 2014 for each KHU.

Duke Energy currently plans to replace the generator stator on each KHU starting in January 2019.

The current TS 3.8.1 RA C.2.2.5 maintenance provision requires the KHU and its required overhead emergency power path to be restored to operable status within 45 days of discovery of an initial inoperability when Condition C is entered due to an inoperable KHU if not used for that KHU in the previous 3 years. This 45-day time period is not sufficient to allow the KHU generator stator replacement work to be performed. As such, Duke Energy proposes to add a temporary Completion Time to RA C.2.2.5 that would allow 55 days to restore an inoperable KHU due to stator replacement to be used once for each KHU. The proposed changes are similar to those previously reviewed and approved to support the KHU generator pole rewinds.

The NRC approved a 62-day Completion Time for the generator pole rewind work by NRC letter dated January 8, 2014. During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the Request for Additional Information (RAI) questions from the previous LAR for the generator pole rewind work to facilitate NRC review.

As such, Enclosure 1 of this LAR addresses the RAI questions from the previous LAR RAI responses where appropriate.

I ^/)

Nuclear Regulatory Commission License Amendment Request No. 2015-08 February 26, 2016 Page 2 An evaluation of the proposed temporary change is provided in Enclosure 1. A No Significant Hazards Consideration Evaluation and the Environmental Impact Analysis are also included in. Enclosure 2 provides a list of the regulatory commitments made in this submittal.

The marked up and revised Technical Specification pages are provided in Attachment 1 and 2, respectively. The marked up and revised TS Bases pages are provided in Attachments 3 and 4, respectively. The TS Bases pages are provided for information only.

In accordance with Duke Energy administrative procedures and the Quality Assurance Program Topical Report, the proposed TS changes have been reviewed and approved by the Plant Operations Review Committee. Additionally, a copy of this LAR is being sent to the State of South Carolina in accordance with 10 CFR 50.91 requirements.

Duke Energy requests approval of the proposed LAR by October 31, 2017. Implementation of these changes will not result in an undue risk to the health and safety of the public. The Oconee Updated Final Safety Analysis Report has been reviewed and no changes are necessary to support this LAR.

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

I declare under penalty of perjury that the foregoing is true and correct. Executed on February 26, 2016.

Sincerely, Scott L. Batson Vice President Oconee Nuclear Station

Enclosures:

1. Evaluation of Proposed Change

2. Regulatory Commitments Attachments:

1. Marked up Technical Specification Pages

2. Revised Technical Specification Pages

3. Marked up Technical Specification Base Pages

4. Revised Technical Specification Bases Pages

Nuclear Regulatory Commission License Amendment Request No. 2015-08 February 26, 2016 Page 3 cc w/Enclosures and Attachments:

Ms. Catherine Haney U. S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. James R. Hall, Senior Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852 Mr. Jeffery A. Whited, Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 B1A Rockville, MD 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Site Ms. Susan 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 1 EVALUATION OF PROPOSED CHANGE

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016

Subject:

License Amendment Request for a Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Keowee Stator Replacement

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION

3. TECHNICAL EVALUATION

4. RISK INSIGHTS

5. REGULATORY EVALUATION

6. ENVIRONMENTAL CONSIDERATION

7. REFERENCES

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 1 1.0

SUMMARY

DESCRIPTION This License Amendment Request (LAR) proposes to add a temporary Completion Time to Technical Specification (TS) 3.8.1 Required Action (RA) C.2.2.5 to allow sufficient time to replace the generator stator on each Keowee Hydro Unit (KHU).

The Keowee hydroelectric station has been in service since 1971'. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The generator pole rewinds were completed in February 2014 and August 2014 for each KHU.

Duke Energy currently plans to replace the generator stator on each KHU starting in January 2019.

Currently, TS 3.8.1 IRA C.2.2.5 requires the KHU and its required overhead emergency power path to be restored to operable status within 45 days of discovery of an initial inoperability when Condition C is entered due to an inoperable KHU if not used for that KHU in the previous 3 years.

This 45-day time period is not sufficient to allow the KHU generator stator replacement work to be performed. As such, Duke Energy proposes to add a temporary Completion Time to RA C.2.2.5 that would allow 55 days to restore an inoperable KHU due to stator replacement to be used once for each KHU.

The proposed changes and commitments are similar to those previously reviewed and approved to support the KHU generator pole rewinds. The differences are as follows:

55-day Completion Time for stator outage versus 62-day for pole rewind outages;

• The TS will require the Protected Service Water (PSW) system to be verified operable prior to entering the extended completion time and that no discretionary maintenance or testing will be allowed on the PSW system. Note that we only credited the ability to align PSW power to the Standby Shutdown Facility (SSF) for the pole rewind LAR as the PSW modification was in progress at the time.

Note 3 to the 45-day Completion Time is modified to only require a one year waiting period after stator replacement for planned work versus all work.

• The SSF will be continuously staffed during dual KHU outages when the penstock is dewatered versus during any dual KHU outage.

During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the Request for Additional Information (RAl) questions from the previous LAR for the generator pole rewind work to facilitate NRC review. As such, Enclosure I of this LAR addresses the RAl questions from the previous LAR RAl responses, where appropriate.

This work will be controlled by a Critical Activity Plan (CAP), which will require Plant Operations Review Committee approval. The work will be categorized as a planned overhaul activity relative to reporting unavailable Performance Indicator hours in accordance with Nuclear Energy Institute (NEI) 99-02, Revision 6 (Reference 1).

An evaluation of the safety impact of the proposed temporary change is provided in the Section 3.0, Technical Evaluation, below. A No Significant Hazards Consideration Evaluation and the Environmental Impact Analysis are also included in Section 5.0 and 6.0, respectively. The marked up and revised Technical Specification pages are provided in Attachment 1 and 2, respectively. The marked up and revised TS Bases pages are provided in Attachments 3 and 4, respectively. The TS Bases pages are provided for information only.

Duke Energy requests approval of the proposed LAR by October 31, 2017.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 P~age 2 2.0 DETAILED DESCRIPTION 2.1 Technical Specification Change Description Duke Energy proposes to replace the existing expired 62-day Completion Time for an inoperable KHU that was used for the Keowee field pole rewind work with a one-time 55-day Completion Time for TS 3.8.1 RA C.2.2.5 applicable only to generator stator replacement. The associated Notes are revised accordingly. A new expiration date of September 30, 2021, has been added in place of the expired date. Additional requirements are added to require verification that the Protected Service Water (PSW) System is operable prior to entering the extended Completion Time and to preclude discretionary maintenance or testing on the PSW System. Note that work on the PSW System had not been completed when the LAP, to support the Keowee field pole rewind work was approved. The revised Completion Time and associated notes are as follows:

AND

-~NOTE-

1. No discretionary maintenance or testing allowed on SSF, PSW, EFW and essential AC Power Systems.

2. Only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021.

3. Only applicable if the SSF, PSW, and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

55 days from initial inoperability when Condition due to an inoperable KHU if entered to perform generator stator replacement work.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 3 Required Action 0.2.2.3 Note will be revised to change "field pole rewind" work to "stator replacement" work as follows:

-~NOTE----

Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work.

This note is needed to allow use of the 60-hour dual KHU outage to disassemble and reassemble the KHU and return it to a functional condition. Without this note, entry into Condition L would be required and only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> (The note to Required Action L allows a 12 delay prior to starting the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Completion Time clock when entered for the purposes of restoring the KHU undergoing maintenance) would be allowed to restore the KHU and its required underground path or only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21, EPSL Keowee Emergency Start Function.

Revise Note 2 and 3 that modifies the 45-day Completion Time of TS 3.8.1 Required Action C.2.2.5 to replace "field pole rewind" with "stator replacement" as follows:

-NOTE-.........

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not applicable during generator stator replacement work.

3.

Not applicable until 1 year after the KHU is declared OPERABLE following generator stator replacement work for planned work.

Note 2 is retained to avoid using up the 45 day Completion Time concurrent with the new 55-day Completion Time and will provide some time to allow Duke Energy to perform emergent maintenance work should the need arise. Note 3 imposes a one year waiting period for planned work.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 4 2.2 Reason for the Proposed TS Change The Keowee hydroelectric station has been in service since 1971. A history of Keowee hydro station major maintenance was provided in a Duke Energy letter to the NRC dated November 26, 2013 (Reference 2). This letter provided a supplement to the LAR submitted to support the generator pole rewinds performed on each KHU in 2014. The need for major refurbishment work within the generator, including generator field pole rewinds and generator stator replacement, was identified during a March 2009 generator inspection. The generator pole rewinds were completed in February 2014 and August 2014, for KHU-2 and KHU-1, respectively.

Duke Energy requested and received a license amendment that provided a one-time 62-day Completion Time to allow this work activity to be performed with the ONS units at power. Duke Energy plans to replace the generator stator on each KHU starting in January 2019. Duke Energy factored in the lessons learned from the generator pole rewind work during development of the generator stator replacement schedule. Duke Energy also evaluated options available to shorten the TS out of service time for a KHU undergoing stator replacement and selected the option that provides the shortest out of service time to minimize the period of inoperability.

However, this option still results in required TS out of service time that exceeds the current 45-day Completion Time of TS 3.8.1 Required Action C.2.2.5 by 10 days thus requiring a TS change to allow the work to proceed. A detailed schedule for the stator replacement is provided in Section 2.4 below. This schedule provides the basis for the proposed one-time 55-day Completion Time.

2.3 Description of Keowee Stator Replacement Original construction of the Keowee generators was performed by assembling both the stator and rotor components in the powerhouse, thus avoiding transfer through the shipping bay of preassembled components. This method of assembly was common at the time of construction (circa 1970). The generators are identical and provide on-site emergency power for Duke Energy's Oconee Nuclear Station (ONS).

Recent generator evaluations have concluded that the Keowee generator stator core and coils are reaching their end of life and require replacement. Initial planning studies indicated that traditional "in-place" disassembly and installation of replacement core and coils would require a lengthy outage for each unit (approximately 120 days). Duke Energy plans to use modern advancements in hydroelectric generator stator replacement practices based on successful pre-assembly of stators outside the confines of the powerhouse to facilitate a much shorter KHU outage, as described below.

The stator replacement will utilize a location remote to the powerhouse to perform the generator stator pre-builds. Prior to transport of the new stator to the powerhouse, the existing stator will be removed in one piece from the generator pit and transported out of the powerhouse. The existing stator will be wrapped and sealed due to probable presence of lead paint and asbestos then transported to the remote location. The new stator complete with core and windings will be transported to the shipping bay, lifted by the powerhouse overhead crane, and installed into the generator pit.

Precise operation of the powerhouse crane is required for rotor or stator lifts immediately adjacent to its companion component under limited clearances. The powerhouse crane is critical to outage activities. The crane was overhauled prior to the 2014 Keowee rotor pole replacement

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 5 rewind outages. This recent overhaul will continue to ensure reliable operation during the generator stator outages. The existing powerhouse roll-up door is 20 feet (ft) wide and will not accommodate transport of the 37.5-ft-diameter stator. As such, the building entrance will be widened to approximately 40 ft.

The stator pre-build location will be remote from the powerhouse yet reasonably close and at nearly the same elevation as the powerhouse due to transport considerations. The stator pre-build structure will be climate-controlled and supported on a reinforced concrete slab approximately 60 ft wide by 75 ft long, providing sufficient working space to maximize efficiency.

2.4 Keowee Stator Replacement Schedule The schedule for the 55-day generator stator replacement outage is derived as follows:

2 days - generator isolation and preparation for rotor and stator lifts 2 days - dual KHU outage; key inhibit operable KHU generator, lower intake gate to dewater KHUs, perform rotor sweep, remove generator rotor, install shaft locking device on KHU under repair, raise head gate and restore remaining KHU to OPERABLE status.

25 days - remove outer cooler covers and piping, install lifting devices for old stator, lift old stator onto heavy hauler and transport to temporary storage location, clean and inspect sole plates (7 day contingency to repair concrete if necessary), transport new stator from Stator Assembly Building, lift new stator into the generator, set stator to permanent location, perform electrical testing (3 days contingency to jumper coils due to coil failure) 2 days - dual KHU outage; key inhibit operable KHU generator, lower intake gate, remove shaft locking device, install generator rotor, perform rotor sweep, weld sole plates to sole plate adapters, raise head gate and restore remaining KHU to OPERABLE status 24 days - stator cleanup, install stator ancillary equipment (e.g., coolers, cooler piping),

install generator upper bracket, assembly closeout, generator restoration, balance runs (contingency, only if necessary), KHU operability checks.

Schedule Contingency 1 day contingency has been included prior to the start of each dual KHU outage to account for schedule delays caused by delayed entry into each dual KHU outage for severe weather. Duke Energy has committed to not enter a dual KHU outage if severe weather is forecast to occur during the dual KHU outage.

3 days of contingency has been added to account for schedule delays caused by severe weather (icing, high humidity, rain) that would preclude transport of the old stator from the Keowee Hydro-station or transport of the new stator from the temporary structure to the Keowee Hydro Station.

7 days of contingency has been added to the schedule to allow time to repair concrete should cracking or other damage be discovered after old stator has been removed from the generator. In order to mitigate this, risk limited inspection of the stator foundation will be performed prior to stator replacement.

3 days of contingency has been added to allow time to repair any coils that are damaged during transport and installation of the new stator in the Keowee Hydro Station.

2 days contingency has been added to account for time lost due to replacement of broken drills/taps that may occur during the drilling and tapping of the stator upper bracket.

1 day has been added for balance shots, if required, on the rotor after installation.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 6 This work will be controlled by a Critical Activity Plan, which will require Plant Operations Review Committee approval. The work will be categorized as a planned overhaul activity relative to reporting unavailable Performance Indicator hours in accordance with NEI 99-02, Revision 6.

3.0 TECHNICAL EVALUATION

3.1 System Descriptions 3.1.1 AC Power System The Oconee Nuclear Station (ONS) AC Power System consists of the offsite power sources (preferred power) and the onsite standby power sources, Keowee Hydro Units (KHUs). This system is designed to supply the required Engineered Safeguards (ES) loads of one unit and safe shutdown loads of the other two units and is so arranged that no single failure can disable enough loads to jeopardize plant safety. The design of the AC Power System provides independence and redundancy to ensure an available source of power to the ES systems.

The Keowee Hydro Station contains two units rated 87,500 kVA each, which generate at 13.8 kV.

The KHU turbine generators are powered through a common intake by water taken from Lake Keowee. Upon loss of power from the Oconee generating unit and 230 kV switchyard, power is supplied from both KHUs through two separate and independent routes. The underground emergency power path is from one KHU through the underground feeder circuit, transformer CT-4, the CT-4 output breakers (SK breakers), standby bus and the standby breakers (S breakers). The overhead emergency power path is from the other KHU through the startup transformer and the startup breakers (E breakers).

The standby buses can also receive power from either one of two combustion turbine generators at the Lee Steam Station through a dedicated 100 kV transmission line, transformer CT-5, and both CT-5 output breakers (SL breakers). The 100 kV transmission line can be supplied from a Lee combustion turbine (LCT) and electrically separated from the system grid and offsite loads.

The limiting capacity available from any of the multiple sources of AC power is 22.4 MVA (limited by either CT-4 or CT-5 transformer capacities).

3.1.2 Emergency Feedwater: (EFW) System The EFW system automatically supplies feedwater to the steam generators to remove decay heat from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply. The EFW pumps take suction through suction lines from the upper surge tank (UST) and condenser hotwell and pump to the steam generator secondary side through the EFW nozzles. The steam generators function as a heat sink for core decay heat. The heat load is dissipated by releasing steam to the atmosphere from the steam generators via the main steam relief valves (MSRVs) or atmospheric dump valves (ADVs). If the main condenser is available, steam may be released via the Turbine Bypass System and recirculated to the condenser hotwell.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 7 3.1.3 Standby Shutdown Facility (SSF)

The SSF is designed as a standby system for use under certain emergency conditions. The SSF includes a dedicated power system. The SSF provides additional defense-in-depth protection for the health and safety of the public by serving as a backup to existing safety systems. The SSF is provided as an alternate means to achieve and maintain the unit in MODE 3 with average RCS temperature >_ 5250F (unless the initiating event causes the unit to be driven to a lower temperature) following fire, turbine building flood, and station blackout (SBO) events. The SSF is designed in accordance with criteria associated with these events. The SSF Auxiliary Service Water System is credited as a backup to Emergency Feedwater due to lack of tornado missile protection for the EFW System. In addition, the SSF may be activated as necessary in response to events associated with plant security. The SSF requires manual activation and can be activated if emergency systems are not available.

3.1.4 Protected Service Water (PSW) System The PSW system provides a diverse means to achieve and maintain safe shutdown by providing secondary side decay heat removal, reactor coolant pump seal cooling, primary system inventory control, and RCS boration for reactivity management during certain plant scenarios that disable the 4160 V essential electrical power distribution system.

The PSW system is not an Engineered Safety Feature Actuation System (ESFAS) and is not credited to mitigate design basis events as contained in UFSAR Chapters 6 and 15. No credit is taken in the safety analyses for PSW system operation following design basis events. The Protected Service Water (PSW) system is designed as a standby system for use under emergency conditions. The PSW system provides added "defense in-depth" protection by serving as a backup to existing safety systems. The PSW system is provided as an alternate means to achieve and maintain safe shutdown conditions for one, two or three units following postulated scenarios that damage essential systems and components normally used for safe shutdown.

3.2 Diversity and Defense-In-Depth of ONS Electrical System ONS can receive offsite power from multiple offsite sources that approach from the north, southwest, southeast, and east. Either of two LCTs can provide power to the safety related electrical buses at ONS. During the single KHU outage, the remaining KHU will be available to provide power via the underground emergency power path with capability to align to the overhead emergency power path. The LCTs are located to the southeast of ONS and can provide power via an isolated power path (electrically isolated from the grid) to the ONS standby buses via Transformer CT5. This transformer is located on the opposite side of the station from the 230 kV switchyard. Either of two Jocassee Hydro Units can be electrically separated from the grid and aligned directly to provide power to the 230 kV switchyard Yellow Bus to power safe shutdown loads. The Jocassee Hydro Units are located north of ONS while the LCTs are located in the opposite direction, southeast of ONS.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 8 3.3 Current Technical Specification Requirements The following is required by existing TS 3.8.1 Action C prior to exceeding the 72-hour Completion Time of Required Action C.2.1:

1) Energize both standby buses using a Lee Combustion Turbine.

2) Suspend KHU generation to the grid except for testing.

3) Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE.

4) Verify by administrative means that other electrical TS Limiting Conditions for Operation (LCOs) (3.8.3, 3.8.6, 3.8.8) and instrumentation TS LCOs (3.3.17, 3.3.18, 3.3.19, and 3.3.21 ) are fully met.

5) Verify alternate power source capability by performing SR 3.8.1.16.

With both standby buses energized from an LCT via an isolated power path, a high degree of reliability for the emergency power system is provided. In this configuration, the LCT is serving as an emergency power source. Suspending KHU generation reduces the number of possible failures which could cause loss of the underground emergency power path. Verifying that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE provides additional assurance that offsite power will be available and that the KHU and its required underground emergency power path are available. Verifying the other electrical power system LCOs and emergency power switching logic (EPSL) LCOs are met increases the probability, even in the unlikely event of an additional failures, that the DC power system and the 120 VAC Vital Instrumentation power panelboards will function as required to support EPSL, power will not be lost to ES equipment, and the EPSL will function as required.

Verifying alternate power source capability by performing SR 3.8.1.16 confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable.

3.4 Additional Requirements Imposed by Proposed TS Change The proposed TS change will also require that TS LCOs 3.7.5, "Emergency Feedwater (EFW)

System," 3.7.10, "Protected Service Water (PSW) System," and 3.10.1, "Standby Shutdown Facility (SSF)," be administratively verified as met prior to exceeding the 72-hour Completion Time of Required Action C.2.1. This increases the probability, even in the unlikely event of an additional failure that these risk significant systems will function as required to support their safety function. The proposed 55-day Completion Time is modified by three notes. The first note states no discretionary maintenance or testing is permitted on SSF, PSW, EFW and essential AC power systems. The second note states that the 55-day Completion Time is only applicable one time for each KHU due to generator stator work and provides an expiration date of September 30, 2021.

The third note states that the Completion Time is only applicable if the SSF, PSW, and EFW Systems are administratively verified OPERABLE prior to entering the extended Completion Time. By limiting the performance of discretionary maintenance or testing there is improved defense-in-depth. Discretionary maintenance is optional, therefore, only required preventative maintenance to ensure equipment reliability and required TS or Selected Licensee Commitment (SLC) surveillance testing will be planned on SSF, PSW, EFW, and essential AC Power Systems during the extended Completion Time. In addition, no discretionary maintenance or testing will be planned on 230 kV switchyard equipment where human error could contribute to the likelihood of a Loss of Offsite Power (LOOP). Any emergent maintenance or testing identified as required for

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 9 these systems during the extended Completion Time will be appropriately reviewed to ensure that their performance will not add undue risk. In accordance with System Operations Management Procedure 02-02, "Operations Roles in the Risk Management Process," (Reference 4) selected plant equipment will be posted as "protected" to ensure that no persons inadvertently enter the area of the equipment. This equipment includes, but is not limited to, the 230 kV switchyard and main transformer yards, the essential switchgear rooms, and the SSF, PSW, EFW, and essential AC Power Systems. Station personnel will verify once per shift that the above compensatory measures remain in place.

The essential AC Power System encompasses equipment and risk significant systems associated with normal AC power availability as well as offsite power. Oconee has multiple available sources of electrical power to an ONS unit. These include the following:

1. The Oconee Unit Generator to Auxiliary Transformer (IT, 2T, 3T),

2. 230kV Switchyard to Startup Transformer (CT1, CT2, CT3),

3. Keowee Overhead Power Path through PCB-9,

4. Keowee Underground Power Path through CT-4, and

5. Lee Steam Station through CT-5.

The EFW System automatically supplies feedwater to the steam generators to remove decay heat from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply. ONS also takes credit for recovery actions of EFW (cross connect from another unit) to avoid using the SSF. The SSF Auxiliary Service Water System is designed to provide a backup supply of water to the steam generators in the event of a total loss of all main and emergency feedwater. The SSF emergency procedure has entry conditions for the SSF on unavailability of EFW. The PSW system provides a diverse means to achieve and maintain safe shutdown by providing secondary side decay heat removal, reactor coolant pump seal cooling, RCS primary inventory control, and RCS boration for reactivity management following scenarios that disable the 4160 V essential electrical power distribution system.

During the KHU outages, the protocol for work coordination and communication will be consistent with that established in the Nuclear Switchyard Interface agreement and the Nuclear Switchyard Operating Guidelines currently in place. Oconee will minimize risk through proper coordination between the plant and the Transmission Control Center (TCC). Transmission Coordinators at the TCC routinely communicate transmission matters such as system configurations, work at other sites, line switching and work being performed by site personnel that may have an effect on the nuclear plant. Transmission communicates to the Oconee Switchyard Coordinator or designee any planned operations of site equipment that could have an impact at ONS. Notification of planned activities requires a fourteen week lead-time. This lead-time is necessary for risk analysis on activities that may impact reliability of offsite power to ONS. Similarly, the Oconee Switchyard Coordinator or Work Control personnel notify the TCC of plant risk changes that increase the plant's sensitivity to offsite power status. This notification will be a prerequisite in the Critical Activity Plan for the planned maintenance activity. As part of the Critical Activity Plan for this work activity, the Work Control Center is to notify the TCC and the System Operating Center to take action to ensure grid reliability and minimize risks (e.g., minimize non-critical maintenance work affecting ONS ties in surrounding power paths and substations).

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 10 3.5 Backup Power for Emergency Power System a)

Currently Required by Technical Specifications The proposed TS change for the generator stator replacement work credits a LCT as a backup power source to the inoperabie KHU to support the one-time 55-day Completion Time to maintain the defense-in-depth design philosophy of the electrical system to meet its intended design function. ONS TS 3.8.1 Required Action C.2.2.1 requires a LCT to be energizing both standby buses via an isolated power path within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time of Required Action C.2.2.5. ONS TS Condition H requires a LCT to be energizing both standby buses via an isolated power path prior to entry into a dual KHU outage. During the planned extended outages, the remaining KHU is required by TS 3.8.1 to be operable and aligned to the underground emergency power path with capability to be manually aligned to the overhead emergency power path. Both required offsite power sources are required to be verified operable by TS 3.8.1 Required Action C.2.2.3 within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time of Required Action C.2.2.5. The proposed TS change requires that the SSF, PSW, and Emergency Feedwater (EFW) Systems be administratively verified operable with 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time and does not permit discretionary maintenance or testing on the SSF, PSW, EFW and essential AC power systems. Consistent with the LAR for generator field pole rewind work, Duke Energy commits to prohibit discretionary maintenance on the offsite power system (230 kV Switchyard) during the extended Completion Time for generator stator replacement work and to maintain operability of required offsite circuits at all times (note that this is also a TS requirement). Duke Energy will use a Critical Activity Plan (CAP) for the generator stator replacement outages and include similar risk mitigation strategies to those that are currently used in CAPs for scheduled dual KHU outages. The CAP will also include requirements to notify the Transmission Control Center and System Operating Center to take action to ensure grid reliability and minimize risks.

b)

Additional Backup Power Sources Duke Energy will provide an additional backup power source and implement risk reduction measures to ensure safe shutdown should a loss of all station power occur during the generator stator replacement work. Duke Energy will use a nearby hydro unit (Duke Energy's Jocassee Hydroelectric Station) as an additional backup power source to provide additional defense-in-depth for the electrical power system at ONS. A Jocassee Hydro Unit can be black-started, aligned and dedicated to ONS via a power path isolated from the grid in accordance with approved procedures in approximately one hour.

The Jocassee Hydro Station contains four units rated 195 MW each. All four units generate at 14.4 kV, which is then stepped up to 230 kV. The Jocassee Hydro Station has a similar switchyard layout to ONS. It has a 230 kV and 525 kV switchyard, both in a breaker-and-a-half configuration connected via an auto-transformer. In the unlikely event that all other power sources (Offsite Grid, KHU Overhead, KHU Underground, and CT5) are unavailable, and ONS is experiencing a Station Blackout, the Emergency Operating Procedure will be entered. When all power sources are confirmed to be unavailable, the following steps will be taken at ONS to dedicate a Jocassee Unit via the Jocassee Black Line:

1) Transmission Control Center (TCC) is informed of the following "Jocassee Hydro is needed to power ONS and 230 kV Yellow Bus has been separated from the Grid."

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 11

2) Jocassee Black Line is isolated.

3) When notified by the TCC that Jocassee Black Line is energized, PCB 15 (Jocassee Black Line Yellow Bus Tie) is closed. (This energizes the Yellow Bus and each ONS unit's startup transformer.)

To address the additional risk incurred to ONS during a dual KHU outage, Duke Energy will provide a temporary diesel generator at the Keowee Hydro Station to allow recovering the remaining operable but dewatered KHU within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. This recovery time is consistent with the required 4-hour station blackout coping duration for ONS. The temporary diesel generator allows recovery of the KHU by providing power to operate Keowee Hydro Station electrical auxiliaries, the intake gate hoist to provide water to the remaining available KHU, and the powerhouse crane to set the locking beam in place should the rotor be in transit. Note the rotor is removed/replaced during the dual KHU outages; the stator is removed/replaced after the dual KHU outages.

Additionally, the Fant 100 kV line or a KHU can be aligned to the SSF via the Protected Service Water (PSW) system should the SSF diesel generator (DG) fail to start and run. This provides additional contingency for failures of transformer CT5 and Keowee power paths and allows realignment of these sources to PSW and the SSF. The SSF and PSW provide alternate means of maintaining safe shutdown for all three ONS units until power can be restored to ONS.

c)

Action that will be Taken if Backup Power Sources Become Unavailable TS 3.8.1 Required Action C.2.2.1 requires a LCT to be energizing both standby buses via an isolated power path within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and within one hour from subsequent discovery of a deenergized standby bus. If the transmission line fails or the LCTs cannot be started and aligned to energize the standby buses within one hour then entry into TS 3.8.1 Condition M is required and all three ONS units are required to be placed in MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 5 within 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />. Should the Jocassee Hydro source become unavailable during the Keowee generator stator replacement outages, the Critical Activity Plan will require immediate action to restore the Jocassee Hydro source to available status.

3.6 Alternate Methods of Maintaining Safe Shutdown The following systems/equipment can be used to maintain all three ONS units in a safe shutdown condition should a loss of all station power occur until power can be restored:

Turbine Driven Emergency Feedwater Pump capable of feeding steam generators, SSF operable and capable of providing alternate shutdown capability, PSW System operable and capable of providing alternate shutdown capability, and Onsite diesel-driven feedwater pump capable of feeding steam generators.

A station blackout would result from the loss of all offsite power, the loss of the LCT energizing the standby buses, and the loss of the remaining KHU. Should this occur, emergency power will be restored within one hour by starting the second LCT and aligning to the standby buses, or starting one of the Jocassee Hydro Units and aligning to the Yellow Bus in the 230 kV switchyard.

Should the remaining KHU be inoperable due to being dewatered during one of the two dual KHU outages, a temporary DG located at the KHS will be used to restore the KHU within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 12 3.7 Standby Shutdown Facility (SSF) Ability to Mitigate Station Blackout The SSF houses stand-alone systems that are designed to maintain the plant in a safe and stable condition following postulated emergency events that are distinct from the design basis accidents for which the plant systems were originally designed. The system provides additional defense-in-depth protection for the health and safety of the public by serving as a backup to existing safety systems. As such, the SSF provides an alternate means to achieve and maintain MODE 3 with an average Reactor Coolant temperature _Ž 525°F (RCS cold leg temperature

_< 555°F and RCS pressure - 2155 psig) following postulated fire, turbine building flooding, and station blackout (SBO) events, and is designed in accordance with criteria associated with these events.

Loss of all other station power does not impact the SSF's capability to mitigate each event. The SSF is also credited as the alternate AC (AAC) power source and the source of decay heat removal required to demonstrate safe shutdown during the required four hour station blackout coping duration. The SSF is capable of maintaining all three ONS units in a safe shutdown condition for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following a fire, turbine building flood, or station blackout event.

3.8 Keowee Reliability The KHUs have been > 99% reliable. Below is a calculation of recent reliability of the KHUs based on number of starts versus the number of failures.

KEOWEE RELIABILITY (3+YRS) - 6/2012-11/2015 The calculation of the Keowee Units' Reliability is depicted below:

Baseline Data (06/01/12 - 11/30/15)

Total KHU Start/Load Run Demands for KHU-1 667 Total KHU Start/Load Run Demands for KHU-2 629 KHU-1 Failures (06/01/12 - Present)

1. 10/2013 - Guide Bearing Oil low level actuated and locked in causing a Normal Lockout on KI and prevented an Emergency Start

2. 5/2015 - Proportional valve failure in the KHU-1 governor caused an Emergency Lockout of KHU-I.

3. 6/2015 - KHU-1 Emergency lockout due to human performance error during Troubleshooting in GCS cabinet.

KHU-2 Failures (06/01/12 - Present)

1. 8/2013 - KHU-2 86E2 Lockout due to 86E2X relay chatter

2. 9/2013 - KHU-2 86E2 Lockout due to 86E2X relay chatter

3. 6/2014 - Keowee Main Transformer Lockout 86T tripped rendering the Keowee Overhead Power Path inoperable. Failure was determined to be an adverse interaction during maintenance in the ACB-2 cabinet.

4. 1/2015 - Keowee Main Transformer Lockout 86T and Emergency Lockout 86E2 were received after a failure of the Y-relay in the ACB-2 circuit.

5. 3/2015 - Gen#2 Bearing Oil Level Hi and Unit#2 Normal Lockout were received on KHU-2.

With the Bearing Oil Level Hi locked in, KHU-2 was unavailable for Emergency Start.

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 13 RELIABILITY CALCULATION:

Reliability = 1 - (Total Failures / Total Start(Load Run) Demands)

Total Start/Load Run Demands Total Failures Reliability KHU-1 667 3

0.9955 KHU-2 629 5

0.9921 3.9 Lee Combustion Turbine Reliability Duke Energy replaced the original three Lee Combustion Turbines with two new LCTs in January 2007 to improve LCT reliability. The new LCTs have been > 98% reliable. Below is a calculation of the reliability of the LCTs based on number of starts versus the number of failures.

LCT RELIABILITY ('-9 YRS)

The calculation of the LCT Reliability is depicted below:

1/2007 - 11/30/2015 Total LCT Start/Load Run Demands for 7C 627 Total LCT Start/Load Run Demands for 8C 635 RELIABILITY CALCULATION:

Reliability = 1 - (Total Failures I Total Start (Load Run) Demands)

Total Start/Load Run Demands Total Failures Reliability LCT starts failures reliability 7C 627 6

0.9904 (99.0%)

8C 635 8

0.9874 (98.7%)

By letter dated December 14, 2012, in response to an NRC RAI question (RAI 6) related to the LAR submitted to support the Keowee pole rewinds performed in 2014, Duke Energy provided; a description of activities being performed to prepare the LCTs for the pole rewind outages, the latest LCT testing and summary of test results performed to comply with TS 5.5.19 (LCT Testing Program), available test results and associated maintenance records for at least five years, and identified any failures that resulted in the loss of a LCT. The following information updates the response to that question.

The LCT's and Lee/Central Power path are maintained to nuclear standards and have a robust preventive maintenance (PM) program. Gas turbine inspections were completed in 2015 while the engines were at General Electric (GE). During the turbine refurbishment, GE found some parts on the turbine outside of tolerances and they were replaced. Electrical generator inspections were performed on both generators in 2013. No issues were found during the generator inspection.

Internal water wash of the turbines is performed in the Spring and Fall of each year. This ensures the engine efficiency is maintained at its highest level. Annual boroscope inspections are performed on both LCT's to provide early detection of any internal degradation. Boroscope inspections have been performed annually since installation of the LCT's and no internal issues exist. Gas turbine inspections consist of all maintenance items outlined by the original equipment manufacturer (OEM) which are listed in LM6000 Service Letter 6000-05-03, "Preventative Maintenance and Servicing Checks." Electrical generator inspections are per Oconee Nuclear

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 14 Station prescribed maintenance strategy and include normal electrical tests and inspections such as winding insulation test, shaft ground inspections, excitation tests and inspections.

In the latter half of 2015 both LCTs were serviced by General Electric (GE) to fix items identified in GE service bulletins. Service Bulletins 220 (Reference 4) and 225 (Reference 5) identified a lack of oil flow through the Inlet Gearbox (IGB) which can increase spline wear and lead to disengagement of the IGB from the high pressure compressor (HPC) rotor shaft, resulting in high core speed on startup, fluctuating core speed at power, and the inability to restart the gas turbine following a shutdown. Service Bulletin 236 (Reference 6) identified a potential problem with Compressor Rear Frame (CRF) tubing wear. Thermal stresses and vibration may cause the clamp to move off the wear sleeve and against the single wall section of the ORE tube. Vibration then causes the clamp to wear into the tube causing it to leak.

The Mark 6e control system has been updated with S6 software and trips have been changed from 1/2 logic to 2/2 logic to prevent unnecessary trips due to due to false indications from the sensors and to increase reliability.

A Lee CT load bank test was successfully completed in December 2014. This testing proved the Lee CTs can meet all Oconee loads without the gas compressors operating.

TS Section 5.5.19a verifies an LCT can energize both standby buses using the 100KV line electrically separated from system grid and offsite loads every 12 months. This testing was last performed on November 2, 2015, with all acceptance criteria met. Additionally, the requirements of this action are met each time a LCT is aligned to ONS which typically occurs a few times each year.

TS Section 5.5.19b verifies an LCT can supply equivalent of one Unit's LOCA loads plus two Unit's LOOP loads when connected to system every 12 months. This testing was last performed on January 19, 2015, with all acceptance criteria met. The LCT's have a monthly PM (non-TS related) to align each unit to the system grid and load to full power which is well in excess of LOCA/LOOP load requirements.

TS Section 5.5.19c verifies an LCT can provide the equivalent of one Unit's LOCA loads within one hour through 100KV line electrically separated from system grid and offsite loads every 24 months. This last performed on October 31, 2015, with all acceptance criteria met.

The following additional failures have occurred that resulted in a Maintenance Rule Functional Failure (MRFF) of an individual LCT since the December 14, 2012, RAI 7 response. (The redundant LCT and the power path were available during the below MRFFs.)

April 12, 2013 - LOT 8C tripped during system generation from a false "Air Inlet Screen D/P Sensor A Hi" signal. The signal was generated by a short on the circuit board containing the Air Inlet Screen High D/P signal. The short was directly caused by foreign material (stranded wire clippings), that migrated across channels 7, 8, and 9 on the circuit board. All circuit boards in all cabinets on both units were inspected and all wire clippings have been removed.

July 15, 2013 - While generating to the grid LCT 70 shutdown on a false Generator Lube Oil (GLO) Supply Temperature Sensor Al HIHI. The temperature trend showed a momentary

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 15 spike from 144 to 176 degrees F. The software has been updated to require 2 out of 2 for the shutdown to occur during grid operation and Oconee Mode.

September 18, 2013 - LOT 70 tripped while attempting to align to the ONS dedicated line in preparation for KHU outage. Subsequent investigation revealed that a relay (K85A) had been partially dislodged from its socket, most likely during maintenance performed on 9/17/13 in the cabinet in which K85A is located. The relay did not operate when required and triggered a unit lockout and trip. LOT 70 had been successfully started and run prior to the maintenance that was performed in the cabinet. Testing confirmed that the partially dislodged condition of the relay would cause the unit lockout.

November 19, 2013 - An internal fault occurred in the LOT 70 13.8/5kv auxiliary transformer which caused a voltage drop on the 70 480V bus. The control system for LOT 70 detected the voltage drop, interpreted it as a loss of 480V MOO power and initiated a trip of the unit.

The fault was successfully cleared by the 13.8kV feeder breaker that supplies the transformer.

March 4, 2014 - LOT 70 was being started to support grid operation. The start sequence would not complete because SOV-2090 would not operate. This valve is in the fuel system and is used to purge and bleed the system during startup and shutdown. The cause of the failure to operate was mechanical binding. The valve and all similar valves have been replaced and PMs have been established to replace the valves on a 6 year frequency.

February 25, 2015 - While generating to the grid, LOT 80 tripped off due to low lube oil pressure. An algae like material was found in the lube oil pump inlet strainer. The lube oil tanks on LOT 70 and 80 were cleaned. Actions are in place to add biological testing to semi-annual oil analysis and to establish PMs to clean the tanks on a 2 year frequency.

Failures in the LOTs are reviewed to consider the potential extent of condition. Programmatic controls for the LOTs are warranted to ensure availability and reliability are maintained. As such, the LOTs are included in the Selected Licensee Commitments (SLC) Manual and are subject to formal functionality assessments. Duke Energy Administrative Procedure AD-OP-ALL-01 05, Operability Determinations and Functionality Assessments, provides guidance on functionality assessments. Per AD-OP-ALL-Ol105, the formal functionality assessment content includes a required extent of condition section which considers other components, trains, systems, or units affected by the failure. In the December 14, 2012, RAI response, two specific failures were reviewed for common cause/extent of condition if the same components were used in both LOTs.

No additional failures have occurred since then that would require a common cause/extent of condition review.

There have not been any repetitive MRFFs on the LOT system. The LOTs are included in the ONS Maintenance Rule program. This program tracks unavailability and reliability of the LOTs.

Preventive maintenance and performance monitoring are performed on the LOTs to ensure continued equipment reliability. Some of the PMs/Monitoring include:

• An annual major turbine outage, A major 5 year generator outage, although other smaller electrical and generator maintenance PMs are performed on more frequent basis,

• Annual Black Start test, Daily Operator rounds,

Enclosure I - Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 16 Daily phone call with Oconee Operations Control Room for updates on status, equipment concerns, and Selected License Commitment (SLC) 16.8.6, Lee/Central Alternate Power System, is used to log and track the time the LCTs are not available to energize the Oconee Standby Buses.

The SLC Commitment requires two LCTs be available for supplying power to the Oconee Standby Buses through a separated 100 kV power path within one hour of a loss of both On-Site Emergency Power Paths. Requirements for energizing the Oconee Standby Buses are found in TS.

Duke Energy provided a summary of recent (during the past year) failure/outage and any preventative maintenance performed on the 100 kV line, and associated Transformer CT-5 at the Oconee plant in the response to RAI 7 provided by letter dated December 14, 2012, to support approval of the LAR that supported the Keowee generator pole rewind work. One additional failure has occurred since the December 14, 2012, RAl response that resulted in a MRFF of the Lee/Central Power (LCP) System path.

July 17, 2013 - While aligned to ONS, the LCT Switchyard was struck by lightning.

Protective relaying actuated as designed and opened the expected breakers. Power Delivery functional tested CB1 breaker and the breaker operated as expected. The bus work was visually inspected and no damage was observed.

Preventative Maintenance on CT-5/I100 kV line

1) Thermographic scans of CT-S are performed every 2 years. Last performed on November 4, 201S.

2) Minor PM on CT-5, completed every 18 months, last performed January 28, 201S.

This PM includes a fan blade inspection, inspect Isolated Phase Bus gaskets on the Low Voltage flanges, Inspect and check the torque on bolted connections on the Low Voltage bushings, inspect and clean as required the radiators and coolers, inspect the control cabinets, check doors and gaskets for weather tightness, check for insect nest, dirt and signs of moisture, check for signs of overheating, check and replace if required indicator lamps, check and repair if required heaters and thermostats, cycle each molded case breaker at least S times and inspect desiccant in breathers and replace if required.

3) Major PM on CT-5, performed every 3 years, last performed January 26, 2015.

This PM includes everything in the Minor PM plus inspects, cleans and Doble tests bushings, insulators and lightening arrestors and performs visual inspection of all tubing and fittings.

4) A PM is performed on CT-S relays every 4 years to inspect, clean and calibrate the relays. It was last performed August 21, 2013.

5) The breaker failure relay PM's at LCT Site (CB-1, -2, -11, -12) were performed in April 2012.

6) OCB101 PM - completed January 16, 2014 This PM includes verifying proper oil level in bushings, cleaning bushings, inspecting for external leaks on the breaker tank, bushing, sight gauges and drain valves, dielectric breakdown test, check shock absorber clearances, check breaker stroke, inspect pole tanks for foreign material, clean motor and aux contacts and breaker timing.

Enclosure I - Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 17 LCT Station Commercial Generation Capability The following is consistent with the response to RAI 8 in the December 14, 2012, RAI response that supported the LAR for the generator pole rewind work. There are minor differences in the Figure in that OCB 35 was replaced with OCB 36 and Unit 3 of the Lee Steam Station is the only unit remaining in service.

The LCT Station has commercial generation capability. During the KHU outage periods, commercial generation will only be allowed when preventative maintenance or surveillance testing is being performed for the LCT not energizing the standby bus.

When a LCT is aligned to Oconee, a dedicated power path is established using an isolated 100kV transmission line that is not connected to any other power sources or the system grid. If LCT 7C is aligned to Oconee, the following alignment is established per procedure to obtain the isolated power path: I) CBI and CS-90 closed 2) CB2, CB1 1, OCB-1 3, OCB-36, OCB-41 and CS-I1I open 3) OCB-1 01 always closed. Therefore, all connections to the system grid or any other power generation are isolated.

When LCT's are not aligned to Oconee, the 100kV Lee Switchyard and the 100kV Central Switchyard are typically tied together and the only nearby power source, besides the LCT's is the Lee Steam Station Unit 3.

A single line diagram of the 100 kV Lee and Central Switchyards is provided below:

-Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 18 Communication Protocol with the Lee Station for Reenercqizinpq the Standby Buses When one of the LCTs at Lee Station serves as an alternate emergency power source during a dual KHU unit outage, the second LCT will be available, not running, for the duration of the dual KHU outage. Communication is provided from Oconee Control Room to the Lee Steam Station Control Room. The Lee Steam Station (LSS) Control Room participates in the Oconee Operations conference call at the beginning of each shift. By procedure, upon completion of the shift rounds at the LCT site, the operator reports status of both LCT to Oconee Operations. The Lee Steam Station control room and the LCT site are staffed with continuous coverage while providing power to Oconee. Three independent lines of communication exist between LSS and Oconee. These consist of a microwave "ring down" line, local phone carrier line, and radios. If the LCT energizing the standby buses at ONS is lost, alarms will be generated at ONS and LCT Site Control Room. The operating procedure at LCT site contains specific steps to align the second LCT to the Lee/Central Power Path to provide power to transformer CT5 and the SL breakers.

4.0 Risk Insights The justification for the TS Completion Time 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. No credit was taken for the PSW System. The findings of the risk assessment confirm that the risk impact with adding a 55-day Completion Time to restore an inoperable KHU due to generator stator replacement work is insignificant. The relevant criteria are Incremental Core Damage Probability (ICDP) and Incremental Large Early Release Probability (ILERP). The increase in either of these metrics resulting from the addition of a new 55-day Completion Time to restore an inoperable KHU due to major maintenance is estimated to be insignificant.

The quantitative analysis included the following specific conditions:

No discretionary maintenance or testing will be performed on the Standby Shutdown Facility (SSF).

No discretionary maintenance or testing will be performed on the Emergency Feedwater (EFW) System.

No discretionary maintenance or testing will be performed on the Alternating Current (AC)

Power System.

Duke Energy reviewed the Probabilistic Risk Assessment (PRA) to gain additional insights concerning the configuration of ONS with one KHU. The results of the risk analysis show a risk improvement if no maintenance is performed on the SSF, EFW System and AC Power System.

The results of the risk analysis show a small risk increase using the average nominal maintenance unavailability values for the SSF, EFW System and AC Power System. By limiting maintenance, the risk results are expected to be between these two extremes (i.e., small risk impact).

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 19 Based on the PRA review, the following compensatory measures will be implemented during the period of non-compliance with the TS LCO when one KHU is inoperable. They include:

• During the total maintenance period, no discretionary maintenance or testing on the offsite power system (230 kV switchyard) will be performed. Furthermore, operability of required offsite circuits should be maintained at all times. Limiting the performance of maintenance or testing on the offsite power system and maintaining offsite circuits operable reduces the likelihood of losing offsite power and represents a reduction in risk.

Remaining at power to avert the risk associated with entry into and operation of shutdown cooling as it involves significant plant manipulations and evolutions on both the primary and secondary side by Operations personnel.

Remaining at power because the impact of a station blackout is deemed to be as severe at shutdown conditions as it is for at power conditions. The risk is neutral for remaining at power.

The insights from this risk analysis support the deterministic analysis showing that there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner of this license amendment request.

4.1 Risk Reduction Measures ONS assesses and manages the increase in risk that may result from proposed maintenance activities in accordance with 10 CFR 50.65, Requirements for Monitoring Effectiveness of Maintenance at Nuclear Power Plants. Duke Energy's Risk Management Process requires a Critical Activity Plan (CAP) be written for the generator stator replacement outages. The CAP will include multiple risk mitigation strategies.

The PRA analysis assumes that no discretionary maintenance or testing is allowed on SSF, EFW and essential AC Power Systems. The review also concluded that no discretionary maintenance or testing on the offsite power system (230 kV Switchyard) will be performed and that the operability of required offsite circuits should be maintained at all times. These two compensatory measures are included in a list of regulatory commitments (Enclosure 2 of this submittal).

Based on past Duke Energy/NRC correspondence related to the Keowee pole rewind LAR, including a November 13, 2013, Duke Energy/NRC meeting (Reference 18), Duke Energy commits to include the following risk reduction measures in the CAP:

ONS will not start the extended single KHU outage or a dual KHU outage if severe weather conditions are forecast within 2 days.

ONS will contact the system load dispatcher once per day to ensure no significant grid perturbations (high grid loading not able to withstand a single contingency of line or generation outage) are expected during extended TS completion time.

ONS will control the steam-driven emergency feedwater pump on each ONS unit as "protected" equipment during the extended TS completion time.

ONS will continuously staff the SSF during the dual KHU outages when the penstock is dewate red.

LCT and Central Switchyard will be protected.

2 nd LCT protected and available within one hour.

Prior to the start of the outage, verify a Jocassee Hydro Unit is available to be aligned to the

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 20 Oconee 230kV Yellow Bus in approximately one hour.

Temporary DG located at Keowee Hydro Station with capability to restore available KHU unit to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from dual KHU outage.

Reduced RCS Inventory not permitted during dual KHU outage.

FLEX equipment is available.

PSW System operable (capable of aligning the Fant 100 kV line or a KHU to the SSF).

Tier 2 and Tier 3 Acceptance Guidelines for TS chanqes The following provides a discussion of how ONS addresses the Tier 2 and Tier 3 acceptance guidelines for TS changes provided in Section 2.4 of Regulatory Guide 1.177, Revision 1 (Reference 8). The compensatory measures required to reduce risk impact during the 55-day Completion Time are described in Section 4.1 above and are included in the list of regulatory commitments provided in Enclosure 2 of this submittal. This information is consistent with the RAI 10 response provided by letter dated December 14, 2012, related to the LAR that supported the generator pole rewind work. During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the RAIs from the previous LAR for the generator pole rewind work.

Tier 2 - Avoidance of Risk-Significant Configurations Risk significant plant equipment outage configurations were identified using PRA insights gained from review of the cut sets.

The insights gained from the cut sets review show that LOOP events are the dominant risk contributor. The following SSCs show up in the LOOP cut sets as being risk significant and therefore are recommended to be protected as a compensatory measure during the Keowee Hydro generator stator replacement activities.

Protected SSCs Standby Shutdown Facility (SSF)

Main Feeder Bus 1 Main Feeder Bus 2 4160 V ac Switchgear 1TC 4160 V ac Switchgear 1 TD 4160 V ac Switchgear 3TC 4160 V ac Switchgear 3TD 4160 V ac Switchgear 3TE Standby Bus 1 Standby Bus 2 Transformer CT3 Transformer CT4 Transformer CT5 230/4 kV Transformer 4T 4 kV Switchgear Center B3T

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 21 Turbine Driven Emergency Feedwater Pump Emergency Feedwater System Header Tier 3 - Risk-Informed Configuration Risk Management 10 CFR 50.65(a)(4), RG 1.160 (Reference 9), RG 1.182 (Reference 10), and NUMARC 93-01 (Reference 11) require that prior to performing maintenance activities, risk assessments shall be performed to assess and manage the increase in risk that may result from proposed maintenance activities. These requirements are applicable for all plant modes. NUMARC 91-06 (Reference

12) requires utilities to assess and manage the risks that occur during the performance of outages.

The proposed LAR will not result in any significant changes to the current configuration risk management program. The existing program uses a blended approach of quantitative and qualitative evaluation of each configuration assessed. The Oconee on-line computerized risk software (Electronic Risk Assessment Tool or ERAT) considers both internal and external initiating events with the exception of seismic events. Thus, the overall change in plant risk during maintenance activities is expected to be addressed adequately considering the proposed amendment.

Oconee has several Nuclear System Directives (NSD), Administrative (AD) procedures, and Work Process Manual (WPM) procedures in place to ensure that risk significant plant configurations are avoided. These documents are used to address the Maintenance Rule requirements, including the on-line (and off-line) Maintenance Policy requirement to control the safety impact of combinations of equipment removed from service. The key documents are as follows:

AD-WC-ALL-0410, 'Work Activity Integrated Risk Management" (Reference 13),

• NSD 403, "Shutdown Risk Assessment (Modes 4, 5, 6, and No-Mode) per 10 CFR 50.65 (a)(4)" (Reference 14),

• NSD 415, "Operational Risk Management (Modes 1-3) per 10 CFR 50.65(a)(4)"

(Reference 15),

• WPM-609, "lnnage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

(Reference 16), and

• WPM-608, "Outage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

(Reference 17).

More specifically, the NSDs referenced above address the process, define the program and state individual group responsibilities to ensure compliance with the Maintenance Rule. The Work Process Manual procedures provide a consistent process for utilizing the computerized software assessment tool, ERAT, which manages the risk associated with equipment inoperability.

The Electronic Risk Assessment Tool (ERAT) is a Windows-based computer program used to facilitate risk informed decision making associated with station work activities. Its guidelines are

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 22 independent of the requirements of the Technical Specifications and Selected Licensee Commitments and are based on probabilistic risk assessment studies and deterministic approaches.

Additionally, prior to the release of work for execution, Operations personnel must consider the effects of severe weather and grid instabilities on plant operations. This qualitative evaluation is inherent of the duties of the Work Control Center Senior Reactor Operator (WCC SRO).

Responses to actual plant risk due to severe weather or grid instabilities are programmatically incorporated into applicable plant emergency or response procedures.

The key safety significant systems impacted by this proposed LAR are currently included in the Maintenance Rule program, and as such, availability and reliability performance criteria have been established to assure that they perform adequately.

5.0 REGULATORY EVALUATION

5.1 Applicable Regulatory Requirements/Criteria The following regulatory requirements in Title 10 of the Code of Federal Regulations (10 CFR) apply to this license amendment request:

10 CFR 50.36, "Technical Specifications," which requires, in part, that a licensee establish TSs with limiting conditions for operation (LCOs) and surveillance requirements (SRs) for equipment that is required for safe operation of the facility.

Specifically, Section 50.36(c) stipulates the items to be included in the TSs, including Section 50.36(c)(2), which stipulates the LCOs, and Section 50.36(c)(3),

which stipulates the SRs.

10 CER 50.63, "Loss of all alternating current power," which requires, in part, that all nuclear power plants have the capability to withstand a loss of all alternating current (AC) power (station blackout) for an established period of time, and to recover therefrom. ONS compliance with 10 CER 50.63 is described in Updated Final Safety Analysis Report (UFSAR) Section 8.3.2.2.4, "Station Blackout Analysis."

10 CFR 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear power plants," which includes the requirement to monitor the performance or condition of specified structures, systems, and components (SSCs) to provide reasonable assurance that the SSCs are capable of fulfilling their intended functions, and to balance preventive maintenance activities against the objective of minimizing the unavailability of the SSCs due to monitoring or preventive maintenance.

The principal design criteria (PDC) for ONS were developed in consideration of the seventy General Design Criteria for Nuclear Power Plant Construction Permits proposed by the Atomic Energy Commission (AEC) in a proposed rule-making published for 10CFR Part 50 in the Federal Register on July 11, 1967. The ONS, Units 1, 2, and 3, construction permits were issued on November 6, 1967, preceding the issuance of the GDC specified

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 23 in 10 CFR 50 Appendix A. The following criteria are applicable to the proposed amendment:

ONS UFSAR, Chapter 3, Criterion 24, "Emergency Power for Protection Systems,"

which states that in the event of loss of all offsite power, sufficient alternate sources of power shall be provided to permit the required functioning of the Protective Systems. In the event of loss of all off-site power to all units at Oconee or to any unit alone, sufficient power for operation of the Protective Systems of any unit will be available from either of two on-site independent hydroelectric generators.

ONS UFSAR, Chapter 3, Criterion 39, "Emergency Power for Engineered Safety Features (ESE)," which states that alternate power systems shall be provided and designed with adequate independency, redundancy, capacity, and testability to permit the functioning required of the ESE. As a minimum, the on-site power system and the off-site power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

5.2 Precedent Previously, the NRC approved a temporary change to TS 3.8.1 to allow performance of major maintenance on each KHU in 2014. This request is similar to previous LAR in that the time required to perform the maintenance is expected to exceed the Completion Time of TS 3.8.1 Required Action C.2.2.5. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The rewinds of the generator field poles were completed in February 2014 and August 2014 for KHU-2 and KHU-1, respectively.

Duke Energy currently plans to replace the generator stator starting January 2019. The temporary Completion Time requested for the stator replacement is similar to that requested and approved for the generator field pole rewinds. Duke Energy discussed the need to replace or refurbish the stator during the November 13, 2013, Duke Energy/NRC meeting associated with the temporary TS change for the pole rewinds. Duke Energy/NRC Correspondence related to this LAR is listed below.

June 27, 2012 License Amendment Request for Temporary Technical (Duke Energy letter) Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12181A312)

December 14, 2012 Additional Information Regarding License Amendment Request for (Duke Energy letter) Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 201 2-01 Supplement 1 (ADAMS Accession No. ML12359A039)

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 24 May 28, 2013 (Duke Energy Letter)

July 26, 2013 (Duke Energy letter)

November 26, 2013 (Duke Energy letter)

December 6, 2013 (Duke Energy letter)

January 8, 2014 (NRC letter)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 Supplement 2 (ADAMS Accession No. ML 13151AO23)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 Supplement 3 (ADAMS Accession No. ML13214A384)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01, Supplement 4 (ADAMS Accession No. ML13337A170)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 201 2-01 Supplement 5 (ADAMS Accession No. ML13349A002)

Oconee Nuclear Station, Units 1, 2, and 3. Issuance of Amendments Regarding Temporary Technical Specification Change Request to Extend the Completion Time for an Inoperable Keowee Hydro Unit (TAC Nos. ME9021, ME9022, and ME9023)

(ADAMS Accession No. ML13357A674) 5.3 No Significant Hazards Consideration Determination Duke Energy Carolinas, LLC, has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

1) Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

No. This change involves the temporary addition of a 55-day Completion Time for Technical Specification (TS) 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS Limiting Condition for Operation (LCO) 3.8.1.C. During the time that one Keowee Hydroelectric Unit (KHU) is inoperable for > 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, a Lee Combustion Turbine (LCT) will be energizing both standby buses, two offsite power sources will be maintained available, and maintenance on electrical distribution systems will not be performed unless necessary. In addition, risk significant systems (Emergency Feedwater System, Protected Service Water System, and Standby Shutdown Facility) will be verified operable (meeting LCO requirements) within 72

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> of entering TS 3.8.1 Condition C (i.e., prior to use of the 55-day Completion Time of Required Action C.2.2.5). The temporary 55-day Completion Time will decrease the likelihood of an unplanned forced shutdown of all three Oconee Units and the potential safety consequences and operational risks associated with that action. Avoiding this risk offsets the risks associated with having a design basis event during the temporary 55-day completion time for having one KHU inoperable.

The temporary addition of the 55-day Completion Time does not involve: 1) a physical alteration to the Oconee Units; 2) the installation of new or different equipment; 3) operating any installed equipment in a new or different manner; or 4) a change to any set points for parameters which initiate protective or mitigation action.

There is no adverse impact on containment integrity, radiological release pathways, fuel design, filtration systems, main steam relief valve set points, or radwaste systems. No new radiological release pathways are created.

The consequences of an event occurring during the temporary 55-day Completion Time are the same as those that would occur during the existing Completion Time.

Duke Energy reviewed the Probabilistic Risk Assessment (PRA) to gain additional insights concerning the configuration of ONS with one KHU. The results of the risk analysis show a risk improvement if no maintenance is performed on the SSF, EFW System and AC Power System. The results of the risk analysis show a small risk increase using the average nominal maintenance unavailability values for the SSF, EFW System and AC Power System. By limiting maintenance, the risk results are expected to be between these two extremes (i.e., small risk impact).

Therefore, the probability or consequences of an accident previously evaluated is not significantly increased.

2)

Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

No. This change involves the temporary addition of a 55-day Completion Time for TS 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS LCO 3.8.1. During the time period that one KHU is inoperable, the redundancy requirement for the emergency power source will be fulfilled by an LCT.

Compensatory measures previously specified will be in place to minimize electrical power sYstem vulnerabilities.

The temporary 55-day Completion Time does not involve a physical effect on the Oconee Units, nor is there any increased risk of an Oconee Unit trip or reactivity excursion. No new failure modes or credible accident scenarios are postulated from this activity.

Therefore, the possibility of a new or different kind of accident from any kind of accident previously evaluated is not created.

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 26

3)

Does the proposed amendment involve a significant reduction in a margin of safety?

No. This change involves the temporary addition of a 55-day Completion Time for TS 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS LCO 3.8.1. During the time period that one KHU is inoperable, the redundancy requirement for the emergency power source will be fulfilled by an LCT.

Compensatory measures previously specified will be in place to minimize electrical power system vulnerabilities.

The proposed TS change does not involve: 1) a physical alteration of the Oconee Units; 2) the installation of new or different equipment; 3) operating any installed equipment in a new or different manner; 4) a change to any set points for parameters which initiate protective or mitigation action; or 5) any impact on the fission product barriers or safety limits.

Therefore, this request does not involve a significant reduction in a margin of safety.

Based on the above, Duke Energy concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

5.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

6.0 ENVIRONMENTAL CONSIDERATION

Duke Energy Carolinas, LLC, has evaluated this license amendment request against the criteria for identification of licensing and regulatory actions requiring environmental assessment in accordance with 10 CFR 51.21. Duke Energy Carolinas, LLC has determined that this license amendment request meets the criteria for a categorical exclusion set forth in 10 CFR 51.22(c)(9). This determination is based on the fact that this change is being proposed as an amendment to a license issued pursuant to 10 CFR 50 that changes a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or that changes an inspection or a surveillance requirement, and the amendment meets the following specific criteria:

(i)

The amendment involves no significant hazards consideration.

As demonstrated in Section 5.3, adding a 3rd Completion Time to TS 3.8.1 Required Action C.2.2.5 does not involve significant hazards consideration.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 27 (ii)

There is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite.

This LAR will not change the types or amounts of any effluents that may be released offsite.

(iii)

There is no significant increase in individual or cumulative occupational radiation exposure.

This LAR will not increase the individual or cumulative occupational radiation exposure.

7.0 REFERENCES

1.

Nuclear Energy Institute (NEI) 99-02, Revision 6, Regulatory Assessment Performance Indicator Guideline, October 2009

2.

Duke Energy letter to NRC dated November 26, 2013

3.

System Operations Management Procedure 02-02, Operations Roles in the Risk Management Process

4.

General Electric Service Bulletin LM6000-1ND-0220, Revision 2, dated September 7, 2007

5.

General Electric Service Bulletin LM6000-1ND-0225, April 18, 2006

6.

General Electric Service Bulletin LM6000-1ND-0226, Revision 2, dated February 21, 2012

7.

GE Product Bulletin

8.

Regulatory Guide 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking:

Technical Specifications," Rev. 1, dated May 2011

9.

Regulatory Guide 1.160, "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," Rev. 3, dated May 2012 10 Regulatory Guide 1.182, Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants," dated May 2000 (withdrawn 11-27-12 by FRN 70847)

11.

NUMARC 93-01, "Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," Revision 4A, dated April 2011 12 NUMARC 91-06, "Guidelines for Industry Actions to Assess Shutdown Management, dated December 1991

13.

AD-WC-ALL-041 0, "Work Activity Integrated Risk Management"

14.

NSD 403, "Shutdown Risk Assessment (Modes 4, 5, 6, and No-Mode) per 10 CFR 50.65 (a)(4)"

15.

NSD 415, "Operational Risk Management (Modes 1-3) per 10 CFR 50.65 (a)(4)"

16.

WPM-609, "lnnage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

17.

WPM-608, "Outage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)

18.

NRC Summary of Meeting with Duke Energy Carolinas, LLC, to Discuss the Proposed One-Time TS Completion Time Change to perform KHU Generator Field Pole Rewind Maintenance - Oconee Nuclear Station Units 1, 2, and 3, dated December 4, 2013"

License Amendment Request No. 2015-08 February 26, 2015 Page 1 ENCLOSURE 2 - REGULATORY COMMITMENTS The following commitment table identifies those actions committed to by Duke Energy Carolinas, LLC (Duke Energy) in this submittal. Other actions discussed in the submittal represent intended or planned actions by Duke Energy. They are described to the Nuclear Regulatory Commission (NRC) for the NRC's information and are not regulatory commitments.

Commitment Completion Date 1 No discretionary maintenance or testing is allowed on SSF, foriTS 3.8da1 RA PSW, EFW, and essential AC Power Systems.

C.2.2.5 2

No discretionary maintenance or testing on the offsite power During 55-day CT system (230 kV Switchyard) will be performed and that the for TS 3.8.1 RA operability of required offsite circuits should be maintained at allC225 times.

Duke Energy commits to include the following risk reduction During KHU measures in the Critical Activity Plan:

generator stator ONS will not start the extended single KHU outage or a dual replacement KHU outage if severe weather conditions are forecast within outages 2 days.

ONS will contact the system load dispatcher once per day to ensure no significant grid perturbations (high grid loading not able to withstand a single contingency of line or generation outage) are expected during extended TS completion time.

ONS will control the steam-driven emergency feedwater pump on each ONS unit as "protected" equipment during the extended TS completion time.

ONS will continuously staff the SSF during the dual KHU outages when the penstock is dewatered.

LCT and Central Switchyard will be protected 2 nd LCT protected and available within one hour Prior to the start of the outage, verify a Jocassee Hydro Unit is available to be aligned to the Oconee 230kV Yellow Bus in approximately one hour Temporary DG located at Keowee Hydro Station with capability to restore available KHU unit to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from dual KHU outage Reduced RCS Inventory not permitted during dual KHU outage FLEX equipment available PSW System available and with power system capable of aligning the Fant 100 kV line or a KHU to the SSF 4

Duke Energy will not use the 2nd Completion Time for Required generaorn sntatorH Action C.2.2.5 for planned Keowee work prior to the Keowee otgeseromplete.o

___generator stator outage for each KHU.ouaecmpt.

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 1 MARKED UP TECHNICAL SPECIFICATION PAGES

AC Sources - Operating 3.8.1 ACTIONS CONDITION REEQUIRED ACTION COMPLETION TIME C.

(continued)

C.2.2.3--------NOTE------

Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform work.

Sstator replacement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE and the requirements of LCO 3.8.3, "DC Sources-Operating," LCO 3.8.6, "Vital Inverters-Operating," LCO 3.8.8, "Distribution Systems-Operating," LCO 3.3.17, "EPSL Automatic Transfer Function," LCO 3.3.18, "EPSL Voltage Sensing Circuits," LCO 3.3.19, "EPSL 230 kV Switchyard DGVP,"

and LCO 3.3.21, "EPSL Keowee Emergency Start Function" are met.

AND.

(cntnud OCONEE UNITS 1, 2, & 3 3.8.1-4 OCOEE NIT 1,2, 3.8.-4Amendment Nos. 38,35 8

I

AC Sources - Operating 3.8.1 ACTIONS CONDITION J

REQUIRED ACTION fCOMPLETION TIME C. (continued)

C.2.2.4 Verify alternate power source capability by performing SR 3.8.1.16.

AND C.2.2.5 Restore KHU and its required overhead emergency power path to OPERABLE status.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AND Every 31 days thereafter 28 days when Condition due to an inoperable Keowee main step-up transformer AND NOTE---.......

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not aplcbedrn enrtor feW4work.

3 o

plicable until 1 year after the KHU is declared OPERABLE work.

45 days from discovery of initial inoperability when Condition due to an inoperable KHU

/

(continued)

OCONEE UNITS 1,2, & 3 3.8.1-5 OCONE UITS1,2 &33.81-5Amendment Nos. 38,35 & 8

AC Sources - Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME C. (continued)

PSW,]

AND NOTE---.......

1. No discretionary maintenance or testing allowed on SSEFW and essential AC Power Systems.

2. Only applicable one time for each KHU I J f=-rew work and 1.

stator replacement

3. Only applicable if the SSF and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

t Jdays from initial inoperability when Condition due to an inoperable KHU to pef r eeao[

~work D.

KHU or its required underground power path inoperable.

D.1 Perform SR 3.8.1.4 for OPERABLE KHU.

AND D.2 Energize either standby bus from LCT via isolated power path.

1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> if not performed in previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 24 hours AND 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from subsequent discovery of deenergized required standby bus (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-6 OCONE UNIT 1,2,& 3 38.1-6Amendment Nos. 38,385, &8381

License Amendment Request No. 2015-08 February 26, 2016 ATTACHMENT 2 RETYPED TECHNICAL SPECIFICATION PAGES

AC Sources - Operating 3.8.1 ACTIONS CONDITION JREQUIRED ACTION

[COMPLETION TIME C.

(continued)

C.2.2.3-----NOTE-Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work.

Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE and the requirements of LCO 3.8.3, "DC Sources-Operating," LCO 3.8.6, "Vital Inverters-Operating," LCO 3.8.8, "Distribution Systems-Operating," LCO 3.3.17, "EPSL Automatic Transfer Function," LCO 3.3.18, "EPSL Voltage Sensing Circuits," LCO 3.3.19, "EPSL 230 kV Switchyard DGVP,"

and LCO 3.3.21, "EPSL Keowee Emergency Start Function" are met.

AND 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-4 OCONE UITS1,2,& 33.81-4Amendment Nos. xxx, xxx, & xxx

AC Sources - Operating 3.8.1 ACTIONS CONDITION IREQUIRED ACTION COMPLETION TIME C. (continued)

C.2.2.4 Verify alternate power source capability by performing SR 3.8.1.16.

AND C.2.2.5 Restore KHU and its required overhead emergency power path to OPERABLE status.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AND Every 31 days thereafter 28 days when Condition due to an inoperable Keowee main step-up transformer AND NOTE----

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not applicable during generator stator replacement work.

3.

Not applicable until 1 year after the KHU is declared OPERABLE following generator stator replacement work for planned work.

45 days from discovery of initial inoperability when Condition due to an inoperable KHU

.(continued)

OCONEE UNITS 1, 2, & 3 3.8.1-5 OCONE UITS, 2 & 33.81-5Amendment Nos. xxx, xxx, & xxx

AC Sources - Operating 3.8.1 ACTIONS CONDITION JREQUIRED ACTION jCOMPLETION TIME C. (continued)

AND NOTE---.......

1. No discretionary maintenance or testing allowed on SSF, PSW, EFW and essential AC Power Systems.

2. Only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021.

3. Only applicable if the SSF and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

55 days from initial inoperability when Condition due to an inoperable KHU to perform generator stator replacement work

03.

KHU or its required D.1 Perform SR 3.8.1.4 for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> if not performed underground power OPERABLE KHU.

in previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> path inoperable.

AND D.2 Energize either 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> standby bus from LCT via isolated power AND path.

1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from subsequent discovery of deenergized required standby bus (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-6 OCONE UNTS 12, & 3.81-6Amendment Nos. xxx, xxx, & xxx

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 3 MARKED UP TECHNICAL SPECIFICATION BASES PAGES

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1. C.2.2.2, C.2.2.3. C.2.2.4. and C.2.2.5 (continued)

Verifying by administrative means allows a check of logs or other information to determine the OPERABILITY status of required equipment in place of requiring unique performance of Surveillance Requirements.

If the AC Source is subsequently determined inoperable, or an LCO stated in Required Action C.2.2.3 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L. Required Action C.2.2.3 is modified by a note indicating that it is not applicable to the remaining KHU and its required underground steaergen power path or LCO 3.3.21 when in Condition H to perform replacement generatorf*..

work. This note is needed to allow entry into the 60 hour6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> dual unit outage to reassemble the refurbished KHU and return it to functional condition, as well as perform balance runs and shots, post modification testing, and a commissioning run prior to declaring the refurbished KHU operable. Without this note, entry into Condition L would be required allowing only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> to restore the KHU and its required underground path and only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21.

Required Action C.2.2.4 requires verifying alternate power source capability by performing SIR 3.8.1.16. This confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable. If SIR 3.8.1.16 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

D.1, D.2 and D.3 With the KHU or its required underground emergency power path inoperable, sufficient AC power sources remain available to ensure safe shutdown of the unit in the event of a transient or accident. Operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the remaining KHU and its required overhead emergency power path are tested using SR 3.8.1.4 within one hour if not performed in the previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. SR 3.8.1.4 is only required to be performed when the KHU associated with the overhead emergency power path is OPERABLE. This Required Action provides assurance that no undetected failures have occurred in the overhead emergency power path. Since Required Action D.1 only specifies "perform," a failure of SR 3.8.1.4 acceptance criteria does not result in a Required Action not met. However, if the KHU and its required overhead emergency path fails SIR 3.8.1.4, both KHUs and their required emergency power paths are inoperable, and Condition I for both KHUs and their emergency power paths inoperable for reasons other than Condition G or H is entered concurrent with Condition 0. This OCONEE UNITS 1, 2, & 3 B 3.8.1-12 OCOEEUNIS

,, &3 3..112 BASES REVISION DATED 052/1--5 I

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1, C.2.2.2. C.2.2.3. C.2.2.4. and C.2.2.5 (continued) repairs which are estimated to be necessary every six to eight years.

Also, generator thrust and guide bearing replacements are necessary.

Other items which manifest as failures are expected to be rare and may be performed during the permitted maintenance periods. The 45-day Completion Time of Required Action C.2.2.5 is allowed to be applied cumulatively over a rolling three year period for each KHU. This Completion Time is 45 days from discovery of initial inoperability of the KHU. This effectively limits the time the KHU can be inoperable to 45 days from discovery of initial inoperability rather than 45 days from entry into Condition C and precludes any additional time that may be gained as a result of switching an inoperable KHU from the underground to the overhead emergency power path. The Completion Time is modified by three notes. Note 1 indicates that the Completion Time is cumulative per a rolling 3-year time period for each KHU. For example, if KHU-1 is inoperable for 15 days, the 45-day Completion Time for KHU-1 is reduced to 30 days for the rolling 3-year time period containing the 15 day inoperability. This requires a review of entries for the previous 3 years to determine the remaining time allowed in the 45-day Completion Time. If the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time of C.2.1 is not exceeded, the 45-day Coinpletion is not applicable and is not reduced. Notes 2 and 3 indicate for planned work the Completion Time is not applicable during generator id

'.....,,]

,,work or until one year after the KHU is declared OPERABLE following generatot i,.*~

c"!~

work. Note 2 is added to avoid using up the stato F

4-day Completion Time concurrent with the II-a.y Completion Time replacement

/

and preserves some time to perform emergent main nc work should allowed.

KH*U to perform generatorL~~ c. s;!"*ok h/

• ay Completion Time is modified by three notes that provide Protected Service conditions for using the extended outage. Note 1 indicates that n/o Water (PSW),

discretionary maintenance or testing is allowed on the Standby/Shutdown Facility (SSF), !'mergency Feedwater (EFW), and essential t~ernating current (AC) Power Systems. Note 2 indicates that the *Jday Completion Time is only applicable one time for each tKHU due to generato 'vork and expires on *.....,

Note 3 indicates that it is only applicable if the SSF~and EFW are admini tratively PSW

]

verified OPERABLE prior to entering the extended Com~p~e~tio nin._T-his-

• in-r-a~tes-pi6 b*bilIit-y, evyen in the unIkelyeven-t-of a n ad diti onal\\

J failure, that the risk significant systems will function as required to su port their safety function.

September 30, 2021 i

Required Actions C.2.2.1, C.2.2.2, C.2.2.3, and C.2.2.4 must be met in order to allow the longer restoration times of Required Action C.2.2.5.

OCONEE UNITS 1, 2, & 3 B 3.8.1-10 OCOEEUNIS

,, &3 3..110 BASES REVISION DATED 05/2141!5 I

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1. C.2.2.2. C.2.2.3. C.2.2.4. and C.2.2.5 (continued)

If the inoperable KHU or its required overhead emergency power path are not restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by Required Action C.2.1, a controlled shutdown must be initiated as required by the Required Actions for Condition M unless the extended Completion Times of Required Action C.2.2.5 are applicable. The second Completion Time for Required Action C.2.1 establishes a limit on the maximum time allowed for a KHU to be inoperable during any single contiguous occurrence of having a KHU inoperable. If Condition C is entered as a result of switching an inoperable KHU from the underground to the overhead emergency power path, it may have been inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This could lead to a total of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> since the initial failure of the KHU. The second Completion Time allows for an exception to the normal "time zero" for beginning the allowed time "clock." This will result in establishing the "time zero" at the time the KHU become inoperable, instead of at the time Condition C was entered.

The extended Completion Times of Required Action C.2.2.5 apply when the KHU or its required overhead emergency power path is inoperable due to an inoperable Keowee main step-up transformer, an inoperable stator KHU (if not used for that KHU in the previous 3 years), or a KHU made replacement inoperable to perform generator[c. p.'rc!_work. In order to use the extended Completion Times, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering Condition C both standby buses must be energized from an LCT (Required Action C.2.2.1), KHU generation to the grid except for testing must be suspended (Required Action C.2.2.2), the remaining KHU and its required underground emergency power path and both required offsite sources must be verified OPERABLE, the LCOs indicated in Required Action C.2.2.3 must be verified to be met, and alternate power source capability must be verified by performing SR 3.8.1.16.

Required Action C.2.2.5 permits maintenance and repair of a Keowee main step-up transformer which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Transformer replacement is rare but is time extensive. A 28 day Completion Time is permitted by Required Action C.2.2.5 to restore the KHU and its overhead power path to OPERABLE status when inoperable due to an inoperable Keowee main step-up transformer. This allows a reasonable period of time for transformer replacement.

Required Action C.2.2.5 also permits maintenance and repair of a KHU which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The primary long term maintenance items are expected to be hydro turbine runner and discharge ring welding OCONEE UNITS 1, 2, & 3 B 3.8.1-9 OCOEEUNTS

,, 3 38.-9 BASES REVISION DATED 05/2-1/5 I

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 4 RETYPED TECHNICAL SPECIFICATION BASES PAGES

AC Sources - Operating B] 3.8.1 BASES ACTIONS 0.1. C.2.1, 0.2.2.1, C.2.2.2, 0.2.2.3, C.2.2.4, and 0.2.2.5 (continued)

If the inoperable KHU or its required overhead emergency power path are not restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by Required Action 0.2.1, a controlled shutdown must be initiated as required by the Required Actions for Condition M unless the extended Completion Times of Required Action C.2.2.5 are applicable. The second Completion Time for Required Action 0.2.1 establishes a limit on the maximum time allowed for a KHU to be inoperable during any single contiguous occurrence of having a KHU inoperable. If Condition C is entered as a result of switching an inoperable KHU from the underground to the overhead emergency power path, it may have been inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This could lead to a total of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> since the initial failure of the KHU. The second Completion Time allows for an exception to the normal "time zero" for beginning the allowed time "clock." This will result in establishing the "time zero" at the time the KHU become inoperable, instead of at the time Condition C was entered.

The extended Completion Times of Required Action C.2.2.5 apply when the KHU or its required overhead emergency power path is inoperable due to an inoperable Keowee main step-up transformer, an inoperable KHU (if not used for that KHU in the previous 3 years), or a KHU made inoperable to perform generator stator replacement work. In order to use the extended Completion Times, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering Condition C both standby buses must be energized from an LOT (Required Action C.2.2.1), KHU generation to the grid except for testing must be suspended (Required Action 0.2.2.2), the remaining KHU and its required underground emergency power path and both required offsite sources must be verified OPERABLE, the LCOs indicated in Required Action C.2.2.3 must be verified to be met, and alternate power source capability must be verified by performing SR 3.8.1.16.

Required Action C.2.2.5 permits maintenance and repair of a Keowee main step-up transformer which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Transformer replacement is rare but is time extensive. A 28 day Completion Time is permitted by Required Action 0.2.2.5 to restore the KHU and its overhead power path to OPERABLE status when inoperable due to an inoperable Keowee main step-up transformer. This allows a reasonable period of time for transformer replacement.

Required Action C.2.2.5 also permits maintenance and repair of a KHU which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The primary long term maintenance items are expected to be hydro turbine runner and discharge ring welding OCONEE UNITS 1, 2, & 3 B 3.8.1-9 OCONE UNTS 1 2,& 3 3.81-9 BASES REVISION DATED

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1, C.2.1, C.2.2.1, C.2.2.2, C.2.2.3, C.2.2.4, and C.2.2.5 (continued) repairs which are estimated to be necessary every six to eight years.

Also, generator thrust and guide bearing replacements are necessary.

Other items which manifest as failures are expected to be rare and may be performed during the permitted maintenance periods. The 45-day Completion Time of Required Action C.2.2.5 is allowed to be applied cumulatively over a rolling three year period for each KHU. This Completion Time is 45 days from discovery of initial inoperability of the KHU. This effectively limits the time the KHU can be inoperable to 45 days from discovery of initial inoperability rather than 45 days from entry into Condition C and precludes any additional time that may be gained as a result of switching an inoperable KHU from the underground to the overhead emergency power path. The Completion Time is modified by three notes. Note 1 indicates that the Completion Time is cumulative per a rolling 3-year time period for each KHU. For example, if KHU-1 is inoperable for 15 days, the 45-day Completion Time for KHU-1 is reduced to 30 days for the rolling 3-year time period containing the 15 day inoperability. This requires a review of entries for the previous 3 years to determine the remaining time allowed in the 45-day Completion Time. If the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time of C.2.1 is not exceeded, the 45-day Completion is not applicable and is not reduced. Notes 2 and 3 indicate the Completion Time is not applicable during generator stator replacement work or until one year after the KHU is declared OPERABLE following generator stator replacement work. Note 2 is added to avoid using up the 45-day Completion Time concurrent with the 55-day Completion Time and preserves some time to perform emergent maintenance work should the need arise. Note 3 is added to require a one year waiting period prior to use for planned work.

The temporary 55-day Completion Time of Required Action C.2.2.5 is allowed for each KHU to perform generator stator replacement work. The 55-day Completion Time is modified by three notes that provide conditions for using the extended outage. Note 1 indicates that no discretionary maintenance or testing is allowed on the Standby Shutdown Facility (SSF), Protected Service Water (PSW), Emergency Feedwater (EFW), and essential alternating current (AC) Power Systems. Note 2 indicates that the 55-day Completion Time is only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021. Note 3 indicates that it is only applicable if the SSF, PSW and EFW are administratively verified OPERABLE prior to entering the extended Completion Time. This increases the probability, even in the unlikely event of an additional failure, that the risk significant systems will function as required to support their safety function.

Required Actions C.2.2.1, C.2.2.2, C.2.2.3, and C.2.2.4 must be met in order to allow the longer restoration times of Required Action C.2.2.5.

OCONEE UNITS 1,2, & 3 B 3.8.1-10 OCONE

UITS1,

, & B.8.-10 BASES REVISION DATED

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1, C.2.1, C.2.2.1, C.2.2.2, C.2.2.3, C.2.2.4, and C.2.2.5 (continued)

Verifying by administrative means allows a check of logs or other information to determine the OPERABILITY status of required equipment in place of requiring unique performance of Surveillance Requirements. If the AC Source is subsequently determined inoperable, or an LCO stated in Required Action C.2.2.3 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

Required Action C.2.2.3 is modified by a note indicating that it is not applicable to the remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work. This note is needed to allow entry into the 60 hour6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> dual unit outage to reassemble the refurbished KHU and return it to functional condition, as well as perform balance runs and shots, post modification testing, and a commissioning run prior to declaring the refurbished KHU operable. Without this note, entry into Condition L would be required allowing only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> to restore the KHU and its required underground path and only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21.

Required Action C.2.2.4 requires verifying alternate power source capability by performing SR 3.8.1.16. This confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable. If SR 3.8.1.16 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

0.1. D.2 and D.3 With the KHU or its required underground emergency power path inoperable, sufficient AC power sources remain available to ensure safe shutdown of the unit in the event of a transient or accident. Operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the remaining KHU and its required overhead emergency power path are tested using SR 3.8.1.4 within one hour if not performed in the previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. SR 3.8.1.4 is only required to be performed when the KHU associated with the overhead emergency power path is OPERABLE. This Required Action provides assurance that no undetected failures have occurred in the overhead emergency power path. Since Required Action D.1 only specifies "perform," a failure of SR 3.8.1.4 acceptance criteria does not result in a Required Action not met. However, if the KHU and its required overhead emergency path fails SR 3.8.1.4, both KHUs and their required emergency power paths are inoperable, and Condition I for both KHUs and their emergency power paths inoperable for reasons other than Condition G or H is entered concurrent with Condition D. This OCONEE UNITS 1, 2, & 3 B 3.8.1-12 OCONE

UITS1,

, & B.8.-12 BASES REVISION DATED

DUKE scott L.

Batson FkIFD(~YVice President ENERGY°Oconee Nuclear Station Duke Energy ONOIVP I7800 Rochester Hwy Seneca, SC 29672 o: 864.873.3274 f~864.873. 4208 Scott.Batson@duke-energy.corm ON-201 6-021 10 CFR 50.90 February 26, 2016 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 License Amendment Request for a Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replacement License Amendment Request (LAR) No. 2015-08 In accordance with 10 CF..R 50.90, Duke Energy Carolinas, LLC (Duke Energy) proposes to amend Renewed Facility Operating License Nos. DPR-38, DPR-47, and DPR-55 for ONS Units 1, 2, and 3, respectively. This LAR proposes to add a temporary Completion Time to Technical Specification (TS) 3.8.1 Required Action (RA) C.2.2.5 to allow sufficient time to replace the stator on each Keowee Hydro Unit (KHU).

The Keowee hydroelectric station has been in service since 1971. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The generator pole rewinds were completed in February 2014 and August 2014 for each KHU.

Duke Energy currently plans to replace the generator stator on each KHU starting in January 2019.

The current TS 3.8.1 RA C.2.2.5 maintenance provision requires the KHU and its required overhead emergency power path to be restored to operable status within 45 days of discovery of an initial inoperability when Condition C is entered due to an inoperable KHU if not used for that KHU in the previous 3 years. This 45-day time period is not sufficient to allow the KHU generator stator replacement work to be performed. As such, Duke Energy proposes to add a temporary Completion Time to RA C.2.2.5 that would allow 55 days to restore an inoperable KHU due to stator replacement to be used once for each KHU. The proposed changes are similar to those previously reviewed and approved to support the KHU generator pole rewinds.

The NRC approved a 62-day Completion Time for the generator pole rewind work by NRC letter dated January 8, 2014. During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the Request for Additional Information (RAI) questions from the previous LAR for the generator pole rewind work to facilitate NRC review.

As such, Enclosure 1 of this LAR addresses the RAI questions from the previous LAR RAI responses where appropriate.

I ^/)

Nuclear Regulatory Commission License Amendment Request No. 2015-08 February 26, 2016 Page 2 An evaluation of the proposed temporary change is provided in Enclosure 1. A No Significant Hazards Consideration Evaluation and the Environmental Impact Analysis are also included in. Enclosure 2 provides a list of the regulatory commitments made in this submittal.

The marked up and revised Technical Specification pages are provided in Attachment 1 and 2, respectively. The marked up and revised TS Bases pages are provided in Attachments 3 and 4, respectively. The TS Bases pages are provided for information only.

In accordance with Duke Energy administrative procedures and the Quality Assurance Program Topical Report, the proposed TS changes have been reviewed and approved by the Plant Operations Review Committee. Additionally, a copy of this LAR is being sent to the State of South Carolina in accordance with 10 CFR 50.91 requirements.

Duke Energy requests approval of the proposed LAR by October 31, 2017. Implementation of these changes will not result in an undue risk to the health and safety of the public. The Oconee Updated Final Safety Analysis Report has been reviewed and no changes are necessary to support this LAR.

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

I declare under penalty of perjury that the foregoing is true and correct. Executed on February 26, 2016.

Sincerely, Scott L. Batson Vice President Oconee Nuclear Station

Enclosures:

1. Evaluation of Proposed Change

2. Regulatory Commitments Attachments:

1. Marked up Technical Specification Pages

2. Revised Technical Specification Pages

3. Marked up Technical Specification Base Pages

4. Revised Technical Specification Bases Pages

Nuclear Regulatory Commission License Amendment Request No. 2015-08 February 26, 2016 Page 3 cc w/Enclosures and Attachments:

Ms. Catherine Haney U. S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. James R. Hall, Senior Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852 Mr. Jeffery A. Whited, Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 B1A Rockville, MD 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Site Ms. Susan 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 1 EVALUATION OF PROPOSED CHANGE

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016

Subject:

License Amendment Request for a Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Keowee Stator Replacement

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION

3. TECHNICAL EVALUATION

4. RISK INSIGHTS

5. REGULATORY EVALUATION

6. ENVIRONMENTAL CONSIDERATION

7. REFERENCES

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 1 1.0

SUMMARY

DESCRIPTION This License Amendment Request (LAR) proposes to add a temporary Completion Time to Technical Specification (TS) 3.8.1 Required Action (RA) C.2.2.5 to allow sufficient time to replace the generator stator on each Keowee Hydro Unit (KHU).

The Keowee hydroelectric station has been in service since 1971'. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The generator pole rewinds were completed in February 2014 and August 2014 for each KHU.

Duke Energy currently plans to replace the generator stator on each KHU starting in January 2019.

Currently, TS 3.8.1 IRA C.2.2.5 requires the KHU and its required overhead emergency power path to be restored to operable status within 45 days of discovery of an initial inoperability when Condition C is entered due to an inoperable KHU if not used for that KHU in the previous 3 years.

This 45-day time period is not sufficient to allow the KHU generator stator replacement work to be performed. As such, Duke Energy proposes to add a temporary Completion Time to RA C.2.2.5 that would allow 55 days to restore an inoperable KHU due to stator replacement to be used once for each KHU.

The proposed changes and commitments are similar to those previously reviewed and approved to support the KHU generator pole rewinds. The differences are as follows:

55-day Completion Time for stator outage versus 62-day for pole rewind outages;

• The TS will require the Protected Service Water (PSW) system to be verified operable prior to entering the extended completion time and that no discretionary maintenance or testing will be allowed on the PSW system. Note that we only credited the ability to align PSW power to the Standby Shutdown Facility (SSF) for the pole rewind LAR as the PSW modification was in progress at the time.

Note 3 to the 45-day Completion Time is modified to only require a one year waiting period after stator replacement for planned work versus all work.

• The SSF will be continuously staffed during dual KHU outages when the penstock is dewatered versus during any dual KHU outage.

During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the Request for Additional Information (RAl) questions from the previous LAR for the generator pole rewind work to facilitate NRC review. As such, Enclosure I of this LAR addresses the RAl questions from the previous LAR RAl responses, where appropriate.

This work will be controlled by a Critical Activity Plan (CAP), which will require Plant Operations Review Committee approval. The work will be categorized as a planned overhaul activity relative to reporting unavailable Performance Indicator hours in accordance with Nuclear Energy Institute (NEI) 99-02, Revision 6 (Reference 1).

An evaluation of the safety impact of the proposed temporary change is provided in the Section 3.0, Technical Evaluation, below. A No Significant Hazards Consideration Evaluation and the Environmental Impact Analysis are also included in Section 5.0 and 6.0, respectively. The marked up and revised Technical Specification pages are provided in Attachment 1 and 2, respectively. The marked up and revised TS Bases pages are provided in Attachments 3 and 4, respectively. The TS Bases pages are provided for information only.

Duke Energy requests approval of the proposed LAR by October 31, 2017.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 P~age 2 2.0 DETAILED DESCRIPTION 2.1 Technical Specification Change Description Duke Energy proposes to replace the existing expired 62-day Completion Time for an inoperable KHU that was used for the Keowee field pole rewind work with a one-time 55-day Completion Time for TS 3.8.1 RA C.2.2.5 applicable only to generator stator replacement. The associated Notes are revised accordingly. A new expiration date of September 30, 2021, has been added in place of the expired date. Additional requirements are added to require verification that the Protected Service Water (PSW) System is operable prior to entering the extended Completion Time and to preclude discretionary maintenance or testing on the PSW System. Note that work on the PSW System had not been completed when the LAP, to support the Keowee field pole rewind work was approved. The revised Completion Time and associated notes are as follows:

AND

-~NOTE-

1. No discretionary maintenance or testing allowed on SSF, PSW, EFW and essential AC Power Systems.

2. Only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021.

3. Only applicable if the SSF, PSW, and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

55 days from initial inoperability when Condition due to an inoperable KHU if entered to perform generator stator replacement work.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 3 Required Action 0.2.2.3 Note will be revised to change "field pole rewind" work to "stator replacement" work as follows:

-~NOTE----

Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work.

This note is needed to allow use of the 60-hour dual KHU outage to disassemble and reassemble the KHU and return it to a functional condition. Without this note, entry into Condition L would be required and only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> (The note to Required Action L allows a 12 delay prior to starting the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Completion Time clock when entered for the purposes of restoring the KHU undergoing maintenance) would be allowed to restore the KHU and its required underground path or only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21, EPSL Keowee Emergency Start Function.

Revise Note 2 and 3 that modifies the 45-day Completion Time of TS 3.8.1 Required Action C.2.2.5 to replace "field pole rewind" with "stator replacement" as follows:

-NOTE-.........

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not applicable during generator stator replacement work.

3.

Not applicable until 1 year after the KHU is declared OPERABLE following generator stator replacement work for planned work.

Note 2 is retained to avoid using up the 45 day Completion Time concurrent with the new 55-day Completion Time and will provide some time to allow Duke Energy to perform emergent maintenance work should the need arise. Note 3 imposes a one year waiting period for planned work.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 4 2.2 Reason for the Proposed TS Change The Keowee hydroelectric station has been in service since 1971. A history of Keowee hydro station major maintenance was provided in a Duke Energy letter to the NRC dated November 26, 2013 (Reference 2). This letter provided a supplement to the LAR submitted to support the generator pole rewinds performed on each KHU in 2014. The need for major refurbishment work within the generator, including generator field pole rewinds and generator stator replacement, was identified during a March 2009 generator inspection. The generator pole rewinds were completed in February 2014 and August 2014, for KHU-2 and KHU-1, respectively.

Duke Energy requested and received a license amendment that provided a one-time 62-day Completion Time to allow this work activity to be performed with the ONS units at power. Duke Energy plans to replace the generator stator on each KHU starting in January 2019. Duke Energy factored in the lessons learned from the generator pole rewind work during development of the generator stator replacement schedule. Duke Energy also evaluated options available to shorten the TS out of service time for a KHU undergoing stator replacement and selected the option that provides the shortest out of service time to minimize the period of inoperability.

However, this option still results in required TS out of service time that exceeds the current 45-day Completion Time of TS 3.8.1 Required Action C.2.2.5 by 10 days thus requiring a TS change to allow the work to proceed. A detailed schedule for the stator replacement is provided in Section 2.4 below. This schedule provides the basis for the proposed one-time 55-day Completion Time.

2.3 Description of Keowee Stator Replacement Original construction of the Keowee generators was performed by assembling both the stator and rotor components in the powerhouse, thus avoiding transfer through the shipping bay of preassembled components. This method of assembly was common at the time of construction (circa 1970). The generators are identical and provide on-site emergency power for Duke Energy's Oconee Nuclear Station (ONS).

Recent generator evaluations have concluded that the Keowee generator stator core and coils are reaching their end of life and require replacement. Initial planning studies indicated that traditional "in-place" disassembly and installation of replacement core and coils would require a lengthy outage for each unit (approximately 120 days). Duke Energy plans to use modern advancements in hydroelectric generator stator replacement practices based on successful pre-assembly of stators outside the confines of the powerhouse to facilitate a much shorter KHU outage, as described below.

The stator replacement will utilize a location remote to the powerhouse to perform the generator stator pre-builds. Prior to transport of the new stator to the powerhouse, the existing stator will be removed in one piece from the generator pit and transported out of the powerhouse. The existing stator will be wrapped and sealed due to probable presence of lead paint and asbestos then transported to the remote location. The new stator complete with core and windings will be transported to the shipping bay, lifted by the powerhouse overhead crane, and installed into the generator pit.

Precise operation of the powerhouse crane is required for rotor or stator lifts immediately adjacent to its companion component under limited clearances. The powerhouse crane is critical to outage activities. The crane was overhauled prior to the 2014 Keowee rotor pole replacement

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 5 rewind outages. This recent overhaul will continue to ensure reliable operation during the generator stator outages. The existing powerhouse roll-up door is 20 feet (ft) wide and will not accommodate transport of the 37.5-ft-diameter stator. As such, the building entrance will be widened to approximately 40 ft.

The stator pre-build location will be remote from the powerhouse yet reasonably close and at nearly the same elevation as the powerhouse due to transport considerations. The stator pre-build structure will be climate-controlled and supported on a reinforced concrete slab approximately 60 ft wide by 75 ft long, providing sufficient working space to maximize efficiency.

2.4 Keowee Stator Replacement Schedule The schedule for the 55-day generator stator replacement outage is derived as follows:

2 days - generator isolation and preparation for rotor and stator lifts 2 days - dual KHU outage; key inhibit operable KHU generator, lower intake gate to dewater KHUs, perform rotor sweep, remove generator rotor, install shaft locking device on KHU under repair, raise head gate and restore remaining KHU to OPERABLE status.

25 days - remove outer cooler covers and piping, install lifting devices for old stator, lift old stator onto heavy hauler and transport to temporary storage location, clean and inspect sole plates (7 day contingency to repair concrete if necessary), transport new stator from Stator Assembly Building, lift new stator into the generator, set stator to permanent location, perform electrical testing (3 days contingency to jumper coils due to coil failure) 2 days - dual KHU outage; key inhibit operable KHU generator, lower intake gate, remove shaft locking device, install generator rotor, perform rotor sweep, weld sole plates to sole plate adapters, raise head gate and restore remaining KHU to OPERABLE status 24 days - stator cleanup, install stator ancillary equipment (e.g., coolers, cooler piping),

install generator upper bracket, assembly closeout, generator restoration, balance runs (contingency, only if necessary), KHU operability checks.

Schedule Contingency 1 day contingency has been included prior to the start of each dual KHU outage to account for schedule delays caused by delayed entry into each dual KHU outage for severe weather. Duke Energy has committed to not enter a dual KHU outage if severe weather is forecast to occur during the dual KHU outage.

3 days of contingency has been added to account for schedule delays caused by severe weather (icing, high humidity, rain) that would preclude transport of the old stator from the Keowee Hydro-station or transport of the new stator from the temporary structure to the Keowee Hydro Station.

7 days of contingency has been added to the schedule to allow time to repair concrete should cracking or other damage be discovered after old stator has been removed from the generator. In order to mitigate this, risk limited inspection of the stator foundation will be performed prior to stator replacement.

3 days of contingency has been added to allow time to repair any coils that are damaged during transport and installation of the new stator in the Keowee Hydro Station.

2 days contingency has been added to account for time lost due to replacement of broken drills/taps that may occur during the drilling and tapping of the stator upper bracket.

1 day has been added for balance shots, if required, on the rotor after installation.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 6 This work will be controlled by a Critical Activity Plan, which will require Plant Operations Review Committee approval. The work will be categorized as a planned overhaul activity relative to reporting unavailable Performance Indicator hours in accordance with NEI 99-02, Revision 6.

3.0 TECHNICAL EVALUATION

3.1 System Descriptions 3.1.1 AC Power System The Oconee Nuclear Station (ONS) AC Power System consists of the offsite power sources (preferred power) and the onsite standby power sources, Keowee Hydro Units (KHUs). This system is designed to supply the required Engineered Safeguards (ES) loads of one unit and safe shutdown loads of the other two units and is so arranged that no single failure can disable enough loads to jeopardize plant safety. The design of the AC Power System provides independence and redundancy to ensure an available source of power to the ES systems.

The Keowee Hydro Station contains two units rated 87,500 kVA each, which generate at 13.8 kV.

The KHU turbine generators are powered through a common intake by water taken from Lake Keowee. Upon loss of power from the Oconee generating unit and 230 kV switchyard, power is supplied from both KHUs through two separate and independent routes. The underground emergency power path is from one KHU through the underground feeder circuit, transformer CT-4, the CT-4 output breakers (SK breakers), standby bus and the standby breakers (S breakers). The overhead emergency power path is from the other KHU through the startup transformer and the startup breakers (E breakers).

The standby buses can also receive power from either one of two combustion turbine generators at the Lee Steam Station through a dedicated 100 kV transmission line, transformer CT-5, and both CT-5 output breakers (SL breakers). The 100 kV transmission line can be supplied from a Lee combustion turbine (LCT) and electrically separated from the system grid and offsite loads.

The limiting capacity available from any of the multiple sources of AC power is 22.4 MVA (limited by either CT-4 or CT-5 transformer capacities).

3.1.2 Emergency Feedwater: (EFW) System The EFW system automatically supplies feedwater to the steam generators to remove decay heat from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply. The EFW pumps take suction through suction lines from the upper surge tank (UST) and condenser hotwell and pump to the steam generator secondary side through the EFW nozzles. The steam generators function as a heat sink for core decay heat. The heat load is dissipated by releasing steam to the atmosphere from the steam generators via the main steam relief valves (MSRVs) or atmospheric dump valves (ADVs). If the main condenser is available, steam may be released via the Turbine Bypass System and recirculated to the condenser hotwell.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 7 3.1.3 Standby Shutdown Facility (SSF)

The SSF is designed as a standby system for use under certain emergency conditions. The SSF includes a dedicated power system. The SSF provides additional defense-in-depth protection for the health and safety of the public by serving as a backup to existing safety systems. The SSF is provided as an alternate means to achieve and maintain the unit in MODE 3 with average RCS temperature >_ 5250F (unless the initiating event causes the unit to be driven to a lower temperature) following fire, turbine building flood, and station blackout (SBO) events. The SSF is designed in accordance with criteria associated with these events. The SSF Auxiliary Service Water System is credited as a backup to Emergency Feedwater due to lack of tornado missile protection for the EFW System. In addition, the SSF may be activated as necessary in response to events associated with plant security. The SSF requires manual activation and can be activated if emergency systems are not available.

3.1.4 Protected Service Water (PSW) System The PSW system provides a diverse means to achieve and maintain safe shutdown by providing secondary side decay heat removal, reactor coolant pump seal cooling, primary system inventory control, and RCS boration for reactivity management during certain plant scenarios that disable the 4160 V essential electrical power distribution system.

The PSW system is not an Engineered Safety Feature Actuation System (ESFAS) and is not credited to mitigate design basis events as contained in UFSAR Chapters 6 and 15. No credit is taken in the safety analyses for PSW system operation following design basis events. The Protected Service Water (PSW) system is designed as a standby system for use under emergency conditions. The PSW system provides added "defense in-depth" protection by serving as a backup to existing safety systems. The PSW system is provided as an alternate means to achieve and maintain safe shutdown conditions for one, two or three units following postulated scenarios that damage essential systems and components normally used for safe shutdown.

3.2 Diversity and Defense-In-Depth of ONS Electrical System ONS can receive offsite power from multiple offsite sources that approach from the north, southwest, southeast, and east. Either of two LCTs can provide power to the safety related electrical buses at ONS. During the single KHU outage, the remaining KHU will be available to provide power via the underground emergency power path with capability to align to the overhead emergency power path. The LCTs are located to the southeast of ONS and can provide power via an isolated power path (electrically isolated from the grid) to the ONS standby buses via Transformer CT5. This transformer is located on the opposite side of the station from the 230 kV switchyard. Either of two Jocassee Hydro Units can be electrically separated from the grid and aligned directly to provide power to the 230 kV switchyard Yellow Bus to power safe shutdown loads. The Jocassee Hydro Units are located north of ONS while the LCTs are located in the opposite direction, southeast of ONS.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 8 3.3 Current Technical Specification Requirements The following is required by existing TS 3.8.1 Action C prior to exceeding the 72-hour Completion Time of Required Action C.2.1:

1) Energize both standby buses using a Lee Combustion Turbine.

2) Suspend KHU generation to the grid except for testing.

3) Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE.

4) Verify by administrative means that other electrical TS Limiting Conditions for Operation (LCOs) (3.8.3, 3.8.6, 3.8.8) and instrumentation TS LCOs (3.3.17, 3.3.18, 3.3.19, and 3.3.21 ) are fully met.

5) Verify alternate power source capability by performing SR 3.8.1.16.

With both standby buses energized from an LCT via an isolated power path, a high degree of reliability for the emergency power system is provided. In this configuration, the LCT is serving as an emergency power source. Suspending KHU generation reduces the number of possible failures which could cause loss of the underground emergency power path. Verifying that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE provides additional assurance that offsite power will be available and that the KHU and its required underground emergency power path are available. Verifying the other electrical power system LCOs and emergency power switching logic (EPSL) LCOs are met increases the probability, even in the unlikely event of an additional failures, that the DC power system and the 120 VAC Vital Instrumentation power panelboards will function as required to support EPSL, power will not be lost to ES equipment, and the EPSL will function as required.

Verifying alternate power source capability by performing SR 3.8.1.16 confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable.

3.4 Additional Requirements Imposed by Proposed TS Change The proposed TS change will also require that TS LCOs 3.7.5, "Emergency Feedwater (EFW)

System," 3.7.10, "Protected Service Water (PSW) System," and 3.10.1, "Standby Shutdown Facility (SSF)," be administratively verified as met prior to exceeding the 72-hour Completion Time of Required Action C.2.1. This increases the probability, even in the unlikely event of an additional failure that these risk significant systems will function as required to support their safety function. The proposed 55-day Completion Time is modified by three notes. The first note states no discretionary maintenance or testing is permitted on SSF, PSW, EFW and essential AC power systems. The second note states that the 55-day Completion Time is only applicable one time for each KHU due to generator stator work and provides an expiration date of September 30, 2021.

The third note states that the Completion Time is only applicable if the SSF, PSW, and EFW Systems are administratively verified OPERABLE prior to entering the extended Completion Time. By limiting the performance of discretionary maintenance or testing there is improved defense-in-depth. Discretionary maintenance is optional, therefore, only required preventative maintenance to ensure equipment reliability and required TS or Selected Licensee Commitment (SLC) surveillance testing will be planned on SSF, PSW, EFW, and essential AC Power Systems during the extended Completion Time. In addition, no discretionary maintenance or testing will be planned on 230 kV switchyard equipment where human error could contribute to the likelihood of a Loss of Offsite Power (LOOP). Any emergent maintenance or testing identified as required for

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 9 these systems during the extended Completion Time will be appropriately reviewed to ensure that their performance will not add undue risk. In accordance with System Operations Management Procedure 02-02, "Operations Roles in the Risk Management Process," (Reference 4) selected plant equipment will be posted as "protected" to ensure that no persons inadvertently enter the area of the equipment. This equipment includes, but is not limited to, the 230 kV switchyard and main transformer yards, the essential switchgear rooms, and the SSF, PSW, EFW, and essential AC Power Systems. Station personnel will verify once per shift that the above compensatory measures remain in place.

The essential AC Power System encompasses equipment and risk significant systems associated with normal AC power availability as well as offsite power. Oconee has multiple available sources of electrical power to an ONS unit. These include the following:

1. The Oconee Unit Generator to Auxiliary Transformer (IT, 2T, 3T),

2. 230kV Switchyard to Startup Transformer (CT1, CT2, CT3),

3. Keowee Overhead Power Path through PCB-9,

4. Keowee Underground Power Path through CT-4, and

5. Lee Steam Station through CT-5.

The EFW System automatically supplies feedwater to the steam generators to remove decay heat from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply. ONS also takes credit for recovery actions of EFW (cross connect from another unit) to avoid using the SSF. The SSF Auxiliary Service Water System is designed to provide a backup supply of water to the steam generators in the event of a total loss of all main and emergency feedwater. The SSF emergency procedure has entry conditions for the SSF on unavailability of EFW. The PSW system provides a diverse means to achieve and maintain safe shutdown by providing secondary side decay heat removal, reactor coolant pump seal cooling, RCS primary inventory control, and RCS boration for reactivity management following scenarios that disable the 4160 V essential electrical power distribution system.

During the KHU outages, the protocol for work coordination and communication will be consistent with that established in the Nuclear Switchyard Interface agreement and the Nuclear Switchyard Operating Guidelines currently in place. Oconee will minimize risk through proper coordination between the plant and the Transmission Control Center (TCC). Transmission Coordinators at the TCC routinely communicate transmission matters such as system configurations, work at other sites, line switching and work being performed by site personnel that may have an effect on the nuclear plant. Transmission communicates to the Oconee Switchyard Coordinator or designee any planned operations of site equipment that could have an impact at ONS. Notification of planned activities requires a fourteen week lead-time. This lead-time is necessary for risk analysis on activities that may impact reliability of offsite power to ONS. Similarly, the Oconee Switchyard Coordinator or Work Control personnel notify the TCC of plant risk changes that increase the plant's sensitivity to offsite power status. This notification will be a prerequisite in the Critical Activity Plan for the planned maintenance activity. As part of the Critical Activity Plan for this work activity, the Work Control Center is to notify the TCC and the System Operating Center to take action to ensure grid reliability and minimize risks (e.g., minimize non-critical maintenance work affecting ONS ties in surrounding power paths and substations).

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 10 3.5 Backup Power for Emergency Power System a)

Currently Required by Technical Specifications The proposed TS change for the generator stator replacement work credits a LCT as a backup power source to the inoperabie KHU to support the one-time 55-day Completion Time to maintain the defense-in-depth design philosophy of the electrical system to meet its intended design function. ONS TS 3.8.1 Required Action C.2.2.1 requires a LCT to be energizing both standby buses via an isolated power path within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time of Required Action C.2.2.5. ONS TS Condition H requires a LCT to be energizing both standby buses via an isolated power path prior to entry into a dual KHU outage. During the planned extended outages, the remaining KHU is required by TS 3.8.1 to be operable and aligned to the underground emergency power path with capability to be manually aligned to the overhead emergency power path. Both required offsite power sources are required to be verified operable by TS 3.8.1 Required Action C.2.2.3 within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time of Required Action C.2.2.5. The proposed TS change requires that the SSF, PSW, and Emergency Feedwater (EFW) Systems be administratively verified operable with 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow use of the 55-day Completion Time and does not permit discretionary maintenance or testing on the SSF, PSW, EFW and essential AC power systems. Consistent with the LAR for generator field pole rewind work, Duke Energy commits to prohibit discretionary maintenance on the offsite power system (230 kV Switchyard) during the extended Completion Time for generator stator replacement work and to maintain operability of required offsite circuits at all times (note that this is also a TS requirement). Duke Energy will use a Critical Activity Plan (CAP) for the generator stator replacement outages and include similar risk mitigation strategies to those that are currently used in CAPs for scheduled dual KHU outages. The CAP will also include requirements to notify the Transmission Control Center and System Operating Center to take action to ensure grid reliability and minimize risks.

b)

Additional Backup Power Sources Duke Energy will provide an additional backup power source and implement risk reduction measures to ensure safe shutdown should a loss of all station power occur during the generator stator replacement work. Duke Energy will use a nearby hydro unit (Duke Energy's Jocassee Hydroelectric Station) as an additional backup power source to provide additional defense-in-depth for the electrical power system at ONS. A Jocassee Hydro Unit can be black-started, aligned and dedicated to ONS via a power path isolated from the grid in accordance with approved procedures in approximately one hour.

The Jocassee Hydro Station contains four units rated 195 MW each. All four units generate at 14.4 kV, which is then stepped up to 230 kV. The Jocassee Hydro Station has a similar switchyard layout to ONS. It has a 230 kV and 525 kV switchyard, both in a breaker-and-a-half configuration connected via an auto-transformer. In the unlikely event that all other power sources (Offsite Grid, KHU Overhead, KHU Underground, and CT5) are unavailable, and ONS is experiencing a Station Blackout, the Emergency Operating Procedure will be entered. When all power sources are confirmed to be unavailable, the following steps will be taken at ONS to dedicate a Jocassee Unit via the Jocassee Black Line:

1) Transmission Control Center (TCC) is informed of the following "Jocassee Hydro is needed to power ONS and 230 kV Yellow Bus has been separated from the Grid."

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 11

2) Jocassee Black Line is isolated.

3) When notified by the TCC that Jocassee Black Line is energized, PCB 15 (Jocassee Black Line Yellow Bus Tie) is closed. (This energizes the Yellow Bus and each ONS unit's startup transformer.)

To address the additional risk incurred to ONS during a dual KHU outage, Duke Energy will provide a temporary diesel generator at the Keowee Hydro Station to allow recovering the remaining operable but dewatered KHU within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. This recovery time is consistent with the required 4-hour station blackout coping duration for ONS. The temporary diesel generator allows recovery of the KHU by providing power to operate Keowee Hydro Station electrical auxiliaries, the intake gate hoist to provide water to the remaining available KHU, and the powerhouse crane to set the locking beam in place should the rotor be in transit. Note the rotor is removed/replaced during the dual KHU outages; the stator is removed/replaced after the dual KHU outages.

Additionally, the Fant 100 kV line or a KHU can be aligned to the SSF via the Protected Service Water (PSW) system should the SSF diesel generator (DG) fail to start and run. This provides additional contingency for failures of transformer CT5 and Keowee power paths and allows realignment of these sources to PSW and the SSF. The SSF and PSW provide alternate means of maintaining safe shutdown for all three ONS units until power can be restored to ONS.

c)

Action that will be Taken if Backup Power Sources Become Unavailable TS 3.8.1 Required Action C.2.2.1 requires a LCT to be energizing both standby buses via an isolated power path within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and within one hour from subsequent discovery of a deenergized standby bus. If the transmission line fails or the LCTs cannot be started and aligned to energize the standby buses within one hour then entry into TS 3.8.1 Condition M is required and all three ONS units are required to be placed in MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 5 within 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />. Should the Jocassee Hydro source become unavailable during the Keowee generator stator replacement outages, the Critical Activity Plan will require immediate action to restore the Jocassee Hydro source to available status.

3.6 Alternate Methods of Maintaining Safe Shutdown The following systems/equipment can be used to maintain all three ONS units in a safe shutdown condition should a loss of all station power occur until power can be restored:

Turbine Driven Emergency Feedwater Pump capable of feeding steam generators, SSF operable and capable of providing alternate shutdown capability, PSW System operable and capable of providing alternate shutdown capability, and Onsite diesel-driven feedwater pump capable of feeding steam generators.

A station blackout would result from the loss of all offsite power, the loss of the LCT energizing the standby buses, and the loss of the remaining KHU. Should this occur, emergency power will be restored within one hour by starting the second LCT and aligning to the standby buses, or starting one of the Jocassee Hydro Units and aligning to the Yellow Bus in the 230 kV switchyard.

Should the remaining KHU be inoperable due to being dewatered during one of the two dual KHU outages, a temporary DG located at the KHS will be used to restore the KHU within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 12 3.7 Standby Shutdown Facility (SSF) Ability to Mitigate Station Blackout The SSF houses stand-alone systems that are designed to maintain the plant in a safe and stable condition following postulated emergency events that are distinct from the design basis accidents for which the plant systems were originally designed. The system provides additional defense-in-depth protection for the health and safety of the public by serving as a backup to existing safety systems. As such, the SSF provides an alternate means to achieve and maintain MODE 3 with an average Reactor Coolant temperature _Ž 525°F (RCS cold leg temperature

_< 555°F and RCS pressure - 2155 psig) following postulated fire, turbine building flooding, and station blackout (SBO) events, and is designed in accordance with criteria associated with these events.

Loss of all other station power does not impact the SSF's capability to mitigate each event. The SSF is also credited as the alternate AC (AAC) power source and the source of decay heat removal required to demonstrate safe shutdown during the required four hour station blackout coping duration. The SSF is capable of maintaining all three ONS units in a safe shutdown condition for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following a fire, turbine building flood, or station blackout event.

3.8 Keowee Reliability The KHUs have been > 99% reliable. Below is a calculation of recent reliability of the KHUs based on number of starts versus the number of failures.

KEOWEE RELIABILITY (3+YRS) - 6/2012-11/2015 The calculation of the Keowee Units' Reliability is depicted below:

Baseline Data (06/01/12 - 11/30/15)

Total KHU Start/Load Run Demands for KHU-1 667 Total KHU Start/Load Run Demands for KHU-2 629 KHU-1 Failures (06/01/12 - Present)

1. 10/2013 - Guide Bearing Oil low level actuated and locked in causing a Normal Lockout on KI and prevented an Emergency Start

2. 5/2015 - Proportional valve failure in the KHU-1 governor caused an Emergency Lockout of KHU-I.

3. 6/2015 - KHU-1 Emergency lockout due to human performance error during Troubleshooting in GCS cabinet.

KHU-2 Failures (06/01/12 - Present)

1. 8/2013 - KHU-2 86E2 Lockout due to 86E2X relay chatter

2. 9/2013 - KHU-2 86E2 Lockout due to 86E2X relay chatter

3. 6/2014 - Keowee Main Transformer Lockout 86T tripped rendering the Keowee Overhead Power Path inoperable. Failure was determined to be an adverse interaction during maintenance in the ACB-2 cabinet.

4. 1/2015 - Keowee Main Transformer Lockout 86T and Emergency Lockout 86E2 were received after a failure of the Y-relay in the ACB-2 circuit.

5. 3/2015 - Gen#2 Bearing Oil Level Hi and Unit#2 Normal Lockout were received on KHU-2.

With the Bearing Oil Level Hi locked in, KHU-2 was unavailable for Emergency Start.

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 13 RELIABILITY CALCULATION:

Reliability = 1 - (Total Failures / Total Start(Load Run) Demands)

Total Start/Load Run Demands Total Failures Reliability KHU-1 667 3

0.9955 KHU-2 629 5

0.9921 3.9 Lee Combustion Turbine Reliability Duke Energy replaced the original three Lee Combustion Turbines with two new LCTs in January 2007 to improve LCT reliability. The new LCTs have been > 98% reliable. Below is a calculation of the reliability of the LCTs based on number of starts versus the number of failures.

LCT RELIABILITY ('-9 YRS)

The calculation of the LCT Reliability is depicted below:

1/2007 - 11/30/2015 Total LCT Start/Load Run Demands for 7C 627 Total LCT Start/Load Run Demands for 8C 635 RELIABILITY CALCULATION:

Reliability = 1 - (Total Failures I Total Start (Load Run) Demands)

Total Start/Load Run Demands Total Failures Reliability LCT starts failures reliability 7C 627 6

0.9904 (99.0%)

8C 635 8

0.9874 (98.7%)

By letter dated December 14, 2012, in response to an NRC RAI question (RAI 6) related to the LAR submitted to support the Keowee pole rewinds performed in 2014, Duke Energy provided; a description of activities being performed to prepare the LCTs for the pole rewind outages, the latest LCT testing and summary of test results performed to comply with TS 5.5.19 (LCT Testing Program), available test results and associated maintenance records for at least five years, and identified any failures that resulted in the loss of a LCT. The following information updates the response to that question.

The LCT's and Lee/Central Power path are maintained to nuclear standards and have a robust preventive maintenance (PM) program. Gas turbine inspections were completed in 2015 while the engines were at General Electric (GE). During the turbine refurbishment, GE found some parts on the turbine outside of tolerances and they were replaced. Electrical generator inspections were performed on both generators in 2013. No issues were found during the generator inspection.

Internal water wash of the turbines is performed in the Spring and Fall of each year. This ensures the engine efficiency is maintained at its highest level. Annual boroscope inspections are performed on both LCT's to provide early detection of any internal degradation. Boroscope inspections have been performed annually since installation of the LCT's and no internal issues exist. Gas turbine inspections consist of all maintenance items outlined by the original equipment manufacturer (OEM) which are listed in LM6000 Service Letter 6000-05-03, "Preventative Maintenance and Servicing Checks." Electrical generator inspections are per Oconee Nuclear

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 14 Station prescribed maintenance strategy and include normal electrical tests and inspections such as winding insulation test, shaft ground inspections, excitation tests and inspections.

In the latter half of 2015 both LCTs were serviced by General Electric (GE) to fix items identified in GE service bulletins. Service Bulletins 220 (Reference 4) and 225 (Reference 5) identified a lack of oil flow through the Inlet Gearbox (IGB) which can increase spline wear and lead to disengagement of the IGB from the high pressure compressor (HPC) rotor shaft, resulting in high core speed on startup, fluctuating core speed at power, and the inability to restart the gas turbine following a shutdown. Service Bulletin 236 (Reference 6) identified a potential problem with Compressor Rear Frame (CRF) tubing wear. Thermal stresses and vibration may cause the clamp to move off the wear sleeve and against the single wall section of the ORE tube. Vibration then causes the clamp to wear into the tube causing it to leak.

The Mark 6e control system has been updated with S6 software and trips have been changed from 1/2 logic to 2/2 logic to prevent unnecessary trips due to due to false indications from the sensors and to increase reliability.

A Lee CT load bank test was successfully completed in December 2014. This testing proved the Lee CTs can meet all Oconee loads without the gas compressors operating.

TS Section 5.5.19a verifies an LCT can energize both standby buses using the 100KV line electrically separated from system grid and offsite loads every 12 months. This testing was last performed on November 2, 2015, with all acceptance criteria met. Additionally, the requirements of this action are met each time a LCT is aligned to ONS which typically occurs a few times each year.

TS Section 5.5.19b verifies an LCT can supply equivalent of one Unit's LOCA loads plus two Unit's LOOP loads when connected to system every 12 months. This testing was last performed on January 19, 2015, with all acceptance criteria met. The LCT's have a monthly PM (non-TS related) to align each unit to the system grid and load to full power which is well in excess of LOCA/LOOP load requirements.

TS Section 5.5.19c verifies an LCT can provide the equivalent of one Unit's LOCA loads within one hour through 100KV line electrically separated from system grid and offsite loads every 24 months. This last performed on October 31, 2015, with all acceptance criteria met.

The following additional failures have occurred that resulted in a Maintenance Rule Functional Failure (MRFF) of an individual LCT since the December 14, 2012, RAI 7 response. (The redundant LCT and the power path were available during the below MRFFs.)

April 12, 2013 - LOT 8C tripped during system generation from a false "Air Inlet Screen D/P Sensor A Hi" signal. The signal was generated by a short on the circuit board containing the Air Inlet Screen High D/P signal. The short was directly caused by foreign material (stranded wire clippings), that migrated across channels 7, 8, and 9 on the circuit board. All circuit boards in all cabinets on both units were inspected and all wire clippings have been removed.

July 15, 2013 - While generating to the grid LCT 70 shutdown on a false Generator Lube Oil (GLO) Supply Temperature Sensor Al HIHI. The temperature trend showed a momentary

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 15 spike from 144 to 176 degrees F. The software has been updated to require 2 out of 2 for the shutdown to occur during grid operation and Oconee Mode.

September 18, 2013 - LOT 70 tripped while attempting to align to the ONS dedicated line in preparation for KHU outage. Subsequent investigation revealed that a relay (K85A) had been partially dislodged from its socket, most likely during maintenance performed on 9/17/13 in the cabinet in which K85A is located. The relay did not operate when required and triggered a unit lockout and trip. LOT 70 had been successfully started and run prior to the maintenance that was performed in the cabinet. Testing confirmed that the partially dislodged condition of the relay would cause the unit lockout.

November 19, 2013 - An internal fault occurred in the LOT 70 13.8/5kv auxiliary transformer which caused a voltage drop on the 70 480V bus. The control system for LOT 70 detected the voltage drop, interpreted it as a loss of 480V MOO power and initiated a trip of the unit.

The fault was successfully cleared by the 13.8kV feeder breaker that supplies the transformer.

March 4, 2014 - LOT 70 was being started to support grid operation. The start sequence would not complete because SOV-2090 would not operate. This valve is in the fuel system and is used to purge and bleed the system during startup and shutdown. The cause of the failure to operate was mechanical binding. The valve and all similar valves have been replaced and PMs have been established to replace the valves on a 6 year frequency.

February 25, 2015 - While generating to the grid, LOT 80 tripped off due to low lube oil pressure. An algae like material was found in the lube oil pump inlet strainer. The lube oil tanks on LOT 70 and 80 were cleaned. Actions are in place to add biological testing to semi-annual oil analysis and to establish PMs to clean the tanks on a 2 year frequency.

Failures in the LOTs are reviewed to consider the potential extent of condition. Programmatic controls for the LOTs are warranted to ensure availability and reliability are maintained. As such, the LOTs are included in the Selected Licensee Commitments (SLC) Manual and are subject to formal functionality assessments. Duke Energy Administrative Procedure AD-OP-ALL-01 05, Operability Determinations and Functionality Assessments, provides guidance on functionality assessments. Per AD-OP-ALL-Ol105, the formal functionality assessment content includes a required extent of condition section which considers other components, trains, systems, or units affected by the failure. In the December 14, 2012, RAI response, two specific failures were reviewed for common cause/extent of condition if the same components were used in both LOTs.

No additional failures have occurred since then that would require a common cause/extent of condition review.

There have not been any repetitive MRFFs on the LOT system. The LOTs are included in the ONS Maintenance Rule program. This program tracks unavailability and reliability of the LOTs.

Preventive maintenance and performance monitoring are performed on the LOTs to ensure continued equipment reliability. Some of the PMs/Monitoring include:

• An annual major turbine outage, A major 5 year generator outage, although other smaller electrical and generator maintenance PMs are performed on more frequent basis,

• Annual Black Start test, Daily Operator rounds,

Enclosure I - Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 16 Daily phone call with Oconee Operations Control Room for updates on status, equipment concerns, and Selected License Commitment (SLC) 16.8.6, Lee/Central Alternate Power System, is used to log and track the time the LCTs are not available to energize the Oconee Standby Buses.

The SLC Commitment requires two LCTs be available for supplying power to the Oconee Standby Buses through a separated 100 kV power path within one hour of a loss of both On-Site Emergency Power Paths. Requirements for energizing the Oconee Standby Buses are found in TS.

Duke Energy provided a summary of recent (during the past year) failure/outage and any preventative maintenance performed on the 100 kV line, and associated Transformer CT-5 at the Oconee plant in the response to RAI 7 provided by letter dated December 14, 2012, to support approval of the LAR that supported the Keowee generator pole rewind work. One additional failure has occurred since the December 14, 2012, RAl response that resulted in a MRFF of the Lee/Central Power (LCP) System path.

July 17, 2013 - While aligned to ONS, the LCT Switchyard was struck by lightning.

Protective relaying actuated as designed and opened the expected breakers. Power Delivery functional tested CB1 breaker and the breaker operated as expected. The bus work was visually inspected and no damage was observed.

Preventative Maintenance on CT-5/I100 kV line

1) Thermographic scans of CT-S are performed every 2 years. Last performed on November 4, 201S.

2) Minor PM on CT-5, completed every 18 months, last performed January 28, 201S.

This PM includes a fan blade inspection, inspect Isolated Phase Bus gaskets on the Low Voltage flanges, Inspect and check the torque on bolted connections on the Low Voltage bushings, inspect and clean as required the radiators and coolers, inspect the control cabinets, check doors and gaskets for weather tightness, check for insect nest, dirt and signs of moisture, check for signs of overheating, check and replace if required indicator lamps, check and repair if required heaters and thermostats, cycle each molded case breaker at least S times and inspect desiccant in breathers and replace if required.

3) Major PM on CT-5, performed every 3 years, last performed January 26, 2015.

This PM includes everything in the Minor PM plus inspects, cleans and Doble tests bushings, insulators and lightening arrestors and performs visual inspection of all tubing and fittings.

4) A PM is performed on CT-S relays every 4 years to inspect, clean and calibrate the relays. It was last performed August 21, 2013.

5) The breaker failure relay PM's at LCT Site (CB-1, -2, -11, -12) were performed in April 2012.

6) OCB101 PM - completed January 16, 2014 This PM includes verifying proper oil level in bushings, cleaning bushings, inspecting for external leaks on the breaker tank, bushing, sight gauges and drain valves, dielectric breakdown test, check shock absorber clearances, check breaker stroke, inspect pole tanks for foreign material, clean motor and aux contacts and breaker timing.

Enclosure I - Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 17 LCT Station Commercial Generation Capability The following is consistent with the response to RAI 8 in the December 14, 2012, RAI response that supported the LAR for the generator pole rewind work. There are minor differences in the Figure in that OCB 35 was replaced with OCB 36 and Unit 3 of the Lee Steam Station is the only unit remaining in service.

The LCT Station has commercial generation capability. During the KHU outage periods, commercial generation will only be allowed when preventative maintenance or surveillance testing is being performed for the LCT not energizing the standby bus.

When a LCT is aligned to Oconee, a dedicated power path is established using an isolated 100kV transmission line that is not connected to any other power sources or the system grid. If LCT 7C is aligned to Oconee, the following alignment is established per procedure to obtain the isolated power path: I) CBI and CS-90 closed 2) CB2, CB1 1, OCB-1 3, OCB-36, OCB-41 and CS-I1I open 3) OCB-1 01 always closed. Therefore, all connections to the system grid or any other power generation are isolated.

When LCT's are not aligned to Oconee, the 100kV Lee Switchyard and the 100kV Central Switchyard are typically tied together and the only nearby power source, besides the LCT's is the Lee Steam Station Unit 3.

A single line diagram of the 100 kV Lee and Central Switchyards is provided below:

-Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 18 Communication Protocol with the Lee Station for Reenercqizinpq the Standby Buses When one of the LCTs at Lee Station serves as an alternate emergency power source during a dual KHU unit outage, the second LCT will be available, not running, for the duration of the dual KHU outage. Communication is provided from Oconee Control Room to the Lee Steam Station Control Room. The Lee Steam Station (LSS) Control Room participates in the Oconee Operations conference call at the beginning of each shift. By procedure, upon completion of the shift rounds at the LCT site, the operator reports status of both LCT to Oconee Operations. The Lee Steam Station control room and the LCT site are staffed with continuous coverage while providing power to Oconee. Three independent lines of communication exist between LSS and Oconee. These consist of a microwave "ring down" line, local phone carrier line, and radios. If the LCT energizing the standby buses at ONS is lost, alarms will be generated at ONS and LCT Site Control Room. The operating procedure at LCT site contains specific steps to align the second LCT to the Lee/Central Power Path to provide power to transformer CT5 and the SL breakers.

4.0 Risk Insights The justification for the TS Completion Time 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. No credit was taken for the PSW System. The findings of the risk assessment confirm that the risk impact with adding a 55-day Completion Time to restore an inoperable KHU due to generator stator replacement work is insignificant. The relevant criteria are Incremental Core Damage Probability (ICDP) and Incremental Large Early Release Probability (ILERP). The increase in either of these metrics resulting from the addition of a new 55-day Completion Time to restore an inoperable KHU due to major maintenance is estimated to be insignificant.

The quantitative analysis included the following specific conditions:

No discretionary maintenance or testing will be performed on the Standby Shutdown Facility (SSF).

No discretionary maintenance or testing will be performed on the Emergency Feedwater (EFW) System.

No discretionary maintenance or testing will be performed on the Alternating Current (AC)

Power System.

Duke Energy reviewed the Probabilistic Risk Assessment (PRA) to gain additional insights concerning the configuration of ONS with one KHU. The results of the risk analysis show a risk improvement if no maintenance is performed on the SSF, EFW System and AC Power System.

The results of the risk analysis show a small risk increase using the average nominal maintenance unavailability values for the SSF, EFW System and AC Power System. By limiting maintenance, the risk results are expected to be between these two extremes (i.e., small risk impact).

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 19 Based on the PRA review, the following compensatory measures will be implemented during the period of non-compliance with the TS LCO when one KHU is inoperable. They include:

• During the total maintenance period, no discretionary maintenance or testing on the offsite power system (230 kV switchyard) will be performed. Furthermore, operability of required offsite circuits should be maintained at all times. Limiting the performance of maintenance or testing on the offsite power system and maintaining offsite circuits operable reduces the likelihood of losing offsite power and represents a reduction in risk.

Remaining at power to avert the risk associated with entry into and operation of shutdown cooling as it involves significant plant manipulations and evolutions on both the primary and secondary side by Operations personnel.

Remaining at power because the impact of a station blackout is deemed to be as severe at shutdown conditions as it is for at power conditions. The risk is neutral for remaining at power.

The insights from this risk analysis support the deterministic analysis showing that there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner of this license amendment request.

4.1 Risk Reduction Measures ONS assesses and manages the increase in risk that may result from proposed maintenance activities in accordance with 10 CFR 50.65, Requirements for Monitoring Effectiveness of Maintenance at Nuclear Power Plants. Duke Energy's Risk Management Process requires a Critical Activity Plan (CAP) be written for the generator stator replacement outages. The CAP will include multiple risk mitigation strategies.

The PRA analysis assumes that no discretionary maintenance or testing is allowed on SSF, EFW and essential AC Power Systems. The review also concluded that no discretionary maintenance or testing on the offsite power system (230 kV Switchyard) will be performed and that the operability of required offsite circuits should be maintained at all times. These two compensatory measures are included in a list of regulatory commitments (Enclosure 2 of this submittal).

Based on past Duke Energy/NRC correspondence related to the Keowee pole rewind LAR, including a November 13, 2013, Duke Energy/NRC meeting (Reference 18), Duke Energy commits to include the following risk reduction measures in the CAP:

ONS will not start the extended single KHU outage or a dual KHU outage if severe weather conditions are forecast within 2 days.

ONS will contact the system load dispatcher once per day to ensure no significant grid perturbations (high grid loading not able to withstand a single contingency of line or generation outage) are expected during extended TS completion time.

ONS will control the steam-driven emergency feedwater pump on each ONS unit as "protected" equipment during the extended TS completion time.

ONS will continuously staff the SSF during the dual KHU outages when the penstock is dewate red.

LCT and Central Switchyard will be protected.

2 nd LCT protected and available within one hour.

Prior to the start of the outage, verify a Jocassee Hydro Unit is available to be aligned to the

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 20 Oconee 230kV Yellow Bus in approximately one hour.

Temporary DG located at Keowee Hydro Station with capability to restore available KHU unit to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from dual KHU outage.

Reduced RCS Inventory not permitted during dual KHU outage.

FLEX equipment is available.

PSW System operable (capable of aligning the Fant 100 kV line or a KHU to the SSF).

Tier 2 and Tier 3 Acceptance Guidelines for TS chanqes The following provides a discussion of how ONS addresses the Tier 2 and Tier 3 acceptance guidelines for TS changes provided in Section 2.4 of Regulatory Guide 1.177, Revision 1 (Reference 8). The compensatory measures required to reduce risk impact during the 55-day Completion Time are described in Section 4.1 above and are included in the list of regulatory commitments provided in Enclosure 2 of this submittal. This information is consistent with the RAI 10 response provided by letter dated December 14, 2012, related to the LAR that supported the generator pole rewind work. During the October 13, 2015, pre-application meeting for this LAR, NRC Staff recommended Duke Energy address the RAIs from the previous LAR for the generator pole rewind work.

Tier 2 - Avoidance of Risk-Significant Configurations Risk significant plant equipment outage configurations were identified using PRA insights gained from review of the cut sets.

The insights gained from the cut sets review show that LOOP events are the dominant risk contributor. The following SSCs show up in the LOOP cut sets as being risk significant and therefore are recommended to be protected as a compensatory measure during the Keowee Hydro generator stator replacement activities.

Protected SSCs Standby Shutdown Facility (SSF)

Main Feeder Bus 1 Main Feeder Bus 2 4160 V ac Switchgear 1TC 4160 V ac Switchgear 1 TD 4160 V ac Switchgear 3TC 4160 V ac Switchgear 3TD 4160 V ac Switchgear 3TE Standby Bus 1 Standby Bus 2 Transformer CT3 Transformer CT4 Transformer CT5 230/4 kV Transformer 4T 4 kV Switchgear Center B3T

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 21 Turbine Driven Emergency Feedwater Pump Emergency Feedwater System Header Tier 3 - Risk-Informed Configuration Risk Management 10 CFR 50.65(a)(4), RG 1.160 (Reference 9), RG 1.182 (Reference 10), and NUMARC 93-01 (Reference 11) require that prior to performing maintenance activities, risk assessments shall be performed to assess and manage the increase in risk that may result from proposed maintenance activities. These requirements are applicable for all plant modes. NUMARC 91-06 (Reference

12) requires utilities to assess and manage the risks that occur during the performance of outages.

The proposed LAR will not result in any significant changes to the current configuration risk management program. The existing program uses a blended approach of quantitative and qualitative evaluation of each configuration assessed. The Oconee on-line computerized risk software (Electronic Risk Assessment Tool or ERAT) considers both internal and external initiating events with the exception of seismic events. Thus, the overall change in plant risk during maintenance activities is expected to be addressed adequately considering the proposed amendment.

Oconee has several Nuclear System Directives (NSD), Administrative (AD) procedures, and Work Process Manual (WPM) procedures in place to ensure that risk significant plant configurations are avoided. These documents are used to address the Maintenance Rule requirements, including the on-line (and off-line) Maintenance Policy requirement to control the safety impact of combinations of equipment removed from service. The key documents are as follows:

AD-WC-ALL-0410, 'Work Activity Integrated Risk Management" (Reference 13),

• NSD 403, "Shutdown Risk Assessment (Modes 4, 5, 6, and No-Mode) per 10 CFR 50.65 (a)(4)" (Reference 14),

• NSD 415, "Operational Risk Management (Modes 1-3) per 10 CFR 50.65(a)(4)"

(Reference 15),

• WPM-609, "lnnage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

(Reference 16), and

• WPM-608, "Outage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

(Reference 17).

More specifically, the NSDs referenced above address the process, define the program and state individual group responsibilities to ensure compliance with the Maintenance Rule. The Work Process Manual procedures provide a consistent process for utilizing the computerized software assessment tool, ERAT, which manages the risk associated with equipment inoperability.

The Electronic Risk Assessment Tool (ERAT) is a Windows-based computer program used to facilitate risk informed decision making associated with station work activities. Its guidelines are

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 22 independent of the requirements of the Technical Specifications and Selected Licensee Commitments and are based on probabilistic risk assessment studies and deterministic approaches.

Additionally, prior to the release of work for execution, Operations personnel must consider the effects of severe weather and grid instabilities on plant operations. This qualitative evaluation is inherent of the duties of the Work Control Center Senior Reactor Operator (WCC SRO).

Responses to actual plant risk due to severe weather or grid instabilities are programmatically incorporated into applicable plant emergency or response procedures.

The key safety significant systems impacted by this proposed LAR are currently included in the Maintenance Rule program, and as such, availability and reliability performance criteria have been established to assure that they perform adequately.

5.0 REGULATORY EVALUATION

5.1 Applicable Regulatory Requirements/Criteria The following regulatory requirements in Title 10 of the Code of Federal Regulations (10 CFR) apply to this license amendment request:

10 CFR 50.36, "Technical Specifications," which requires, in part, that a licensee establish TSs with limiting conditions for operation (LCOs) and surveillance requirements (SRs) for equipment that is required for safe operation of the facility.

Specifically, Section 50.36(c) stipulates the items to be included in the TSs, including Section 50.36(c)(2), which stipulates the LCOs, and Section 50.36(c)(3),

which stipulates the SRs.

10 CER 50.63, "Loss of all alternating current power," which requires, in part, that all nuclear power plants have the capability to withstand a loss of all alternating current (AC) power (station blackout) for an established period of time, and to recover therefrom. ONS compliance with 10 CER 50.63 is described in Updated Final Safety Analysis Report (UFSAR) Section 8.3.2.2.4, "Station Blackout Analysis."

10 CFR 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear power plants," which includes the requirement to monitor the performance or condition of specified structures, systems, and components (SSCs) to provide reasonable assurance that the SSCs are capable of fulfilling their intended functions, and to balance preventive maintenance activities against the objective of minimizing the unavailability of the SSCs due to monitoring or preventive maintenance.

The principal design criteria (PDC) for ONS were developed in consideration of the seventy General Design Criteria for Nuclear Power Plant Construction Permits proposed by the Atomic Energy Commission (AEC) in a proposed rule-making published for 10CFR Part 50 in the Federal Register on July 11, 1967. The ONS, Units 1, 2, and 3, construction permits were issued on November 6, 1967, preceding the issuance of the GDC specified

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 23 in 10 CFR 50 Appendix A. The following criteria are applicable to the proposed amendment:

ONS UFSAR, Chapter 3, Criterion 24, "Emergency Power for Protection Systems,"

which states that in the event of loss of all offsite power, sufficient alternate sources of power shall be provided to permit the required functioning of the Protective Systems. In the event of loss of all off-site power to all units at Oconee or to any unit alone, sufficient power for operation of the Protective Systems of any unit will be available from either of two on-site independent hydroelectric generators.

ONS UFSAR, Chapter 3, Criterion 39, "Emergency Power for Engineered Safety Features (ESE)," which states that alternate power systems shall be provided and designed with adequate independency, redundancy, capacity, and testability to permit the functioning required of the ESE. As a minimum, the on-site power system and the off-site power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

5.2 Precedent Previously, the NRC approved a temporary change to TS 3.8.1 to allow performance of major maintenance on each KHU in 2014. This request is similar to previous LAR in that the time required to perform the maintenance is expected to exceed the Completion Time of TS 3.8.1 Required Action C.2.2.5. A March 2009 generator inspection identified the need for major refurbishment work within the generator, including generator field pole rewinds and a generator stator replacement. The rewinds of the generator field poles were completed in February 2014 and August 2014 for KHU-2 and KHU-1, respectively.

Duke Energy currently plans to replace the generator stator starting January 2019. The temporary Completion Time requested for the stator replacement is similar to that requested and approved for the generator field pole rewinds. Duke Energy discussed the need to replace or refurbish the stator during the November 13, 2013, Duke Energy/NRC meeting associated with the temporary TS change for the pole rewinds. Duke Energy/NRC Correspondence related to this LAR is listed below.

June 27, 2012 License Amendment Request for Temporary Technical (Duke Energy letter) Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12181A312)

December 14, 2012 Additional Information Regarding License Amendment Request for (Duke Energy letter) Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 201 2-01 Supplement 1 (ADAMS Accession No. ML12359A039)

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 24 May 28, 2013 (Duke Energy Letter)

July 26, 2013 (Duke Energy letter)

November 26, 2013 (Duke Energy letter)

December 6, 2013 (Duke Energy letter)

January 8, 2014 (NRC letter)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 Supplement 2 (ADAMS Accession No. ML 13151AO23)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01 Supplement 3 (ADAMS Accession No. ML13214A384)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 2012-01, Supplement 4 (ADAMS Accession No. ML13337A170)

Additional Information Regarding License Amendment Request for Temporary Technical Specification Change to Add a Required Action Completion Time for One Keowee Hydro Unit Inoperable for Generator Field Pole Rewinds - LAR 201 2-01 Supplement 5 (ADAMS Accession No. ML13349A002)

Oconee Nuclear Station, Units 1, 2, and 3. Issuance of Amendments Regarding Temporary Technical Specification Change Request to Extend the Completion Time for an Inoperable Keowee Hydro Unit (TAC Nos. ME9021, ME9022, and ME9023)

(ADAMS Accession No. ML13357A674) 5.3 No Significant Hazards Consideration Determination Duke Energy Carolinas, LLC, has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

1) Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

No. This change involves the temporary addition of a 55-day Completion Time for Technical Specification (TS) 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS Limiting Condition for Operation (LCO) 3.8.1.C. During the time that one Keowee Hydroelectric Unit (KHU) is inoperable for > 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, a Lee Combustion Turbine (LCT) will be energizing both standby buses, two offsite power sources will be maintained available, and maintenance on electrical distribution systems will not be performed unless necessary. In addition, risk significant systems (Emergency Feedwater System, Protected Service Water System, and Standby Shutdown Facility) will be verified operable (meeting LCO requirements) within 72

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> of entering TS 3.8.1 Condition C (i.e., prior to use of the 55-day Completion Time of Required Action C.2.2.5). The temporary 55-day Completion Time will decrease the likelihood of an unplanned forced shutdown of all three Oconee Units and the potential safety consequences and operational risks associated with that action. Avoiding this risk offsets the risks associated with having a design basis event during the temporary 55-day completion time for having one KHU inoperable.

The temporary addition of the 55-day Completion Time does not involve: 1) a physical alteration to the Oconee Units; 2) the installation of new or different equipment; 3) operating any installed equipment in a new or different manner; or 4) a change to any set points for parameters which initiate protective or mitigation action.

There is no adverse impact on containment integrity, radiological release pathways, fuel design, filtration systems, main steam relief valve set points, or radwaste systems. No new radiological release pathways are created.

The consequences of an event occurring during the temporary 55-day Completion Time are the same as those that would occur during the existing Completion Time.

Duke Energy reviewed the Probabilistic Risk Assessment (PRA) to gain additional insights concerning the configuration of ONS with one KHU. The results of the risk analysis show a risk improvement if no maintenance is performed on the SSF, EFW System and AC Power System. The results of the risk analysis show a small risk increase using the average nominal maintenance unavailability values for the SSF, EFW System and AC Power System. By limiting maintenance, the risk results are expected to be between these two extremes (i.e., small risk impact).

Therefore, the probability or consequences of an accident previously evaluated is not significantly increased.

2)

Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

No. This change involves the temporary addition of a 55-day Completion Time for TS 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS LCO 3.8.1. During the time period that one KHU is inoperable, the redundancy requirement for the emergency power source will be fulfilled by an LCT.

Compensatory measures previously specified will be in place to minimize electrical power sYstem vulnerabilities.

The temporary 55-day Completion Time does not involve a physical effect on the Oconee Units, nor is there any increased risk of an Oconee Unit trip or reactivity excursion. No new failure modes or credible accident scenarios are postulated from this activity.

Therefore, the possibility of a new or different kind of accident from any kind of accident previously evaluated is not created.

- Evaluation of Proposed Change License Amendment Request No. 201 5-08 February 26, 2016 Page 26

3)

Does the proposed amendment involve a significant reduction in a margin of safety?

No. This change involves the temporary addition of a 55-day Completion Time for TS 3.8.1 Required Action C.2.2.5 associated with restoring compliance with TS LCO 3.8.1. During the time period that one KHU is inoperable, the redundancy requirement for the emergency power source will be fulfilled by an LCT.

Compensatory measures previously specified will be in place to minimize electrical power system vulnerabilities.

The proposed TS change does not involve: 1) a physical alteration of the Oconee Units; 2) the installation of new or different equipment; 3) operating any installed equipment in a new or different manner; 4) a change to any set points for parameters which initiate protective or mitigation action; or 5) any impact on the fission product barriers or safety limits.

Therefore, this request does not involve a significant reduction in a margin of safety.

Based on the above, Duke Energy concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

5.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

6.0 ENVIRONMENTAL CONSIDERATION

Duke Energy Carolinas, LLC, has evaluated this license amendment request against the criteria for identification of licensing and regulatory actions requiring environmental assessment in accordance with 10 CFR 51.21. Duke Energy Carolinas, LLC has determined that this license amendment request meets the criteria for a categorical exclusion set forth in 10 CFR 51.22(c)(9). This determination is based on the fact that this change is being proposed as an amendment to a license issued pursuant to 10 CFR 50 that changes a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or that changes an inspection or a surveillance requirement, and the amendment meets the following specific criteria:

(i)

The amendment involves no significant hazards consideration.

As demonstrated in Section 5.3, adding a 3rd Completion Time to TS 3.8.1 Required Action C.2.2.5 does not involve significant hazards consideration.

- Evaluation of Proposed Change License Amendment Request No. 2015-08 February 26, 2016 Page 27 (ii)

There is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite.

This LAR will not change the types or amounts of any effluents that may be released offsite.

(iii)

There is no significant increase in individual or cumulative occupational radiation exposure.

This LAR will not increase the individual or cumulative occupational radiation exposure.

7.0 REFERENCES

1.

Nuclear Energy Institute (NEI) 99-02, Revision 6, Regulatory Assessment Performance Indicator Guideline, October 2009

2.

Duke Energy letter to NRC dated November 26, 2013

3.

System Operations Management Procedure 02-02, Operations Roles in the Risk Management Process

4.

General Electric Service Bulletin LM6000-1ND-0220, Revision 2, dated September 7, 2007

5.

General Electric Service Bulletin LM6000-1ND-0225, April 18, 2006

6.

General Electric Service Bulletin LM6000-1ND-0226, Revision 2, dated February 21, 2012

7.

GE Product Bulletin

8.

Regulatory Guide 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking:

Technical Specifications," Rev. 1, dated May 2011

9.

Regulatory Guide 1.160, "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," Rev. 3, dated May 2012 10 Regulatory Guide 1.182, Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants," dated May 2000 (withdrawn 11-27-12 by FRN 70847)

11.

NUMARC 93-01, "Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," Revision 4A, dated April 2011 12 NUMARC 91-06, "Guidelines for Industry Actions to Assess Shutdown Management, dated December 1991

13.

AD-WC-ALL-041 0, "Work Activity Integrated Risk Management"

14.

NSD 403, "Shutdown Risk Assessment (Modes 4, 5, 6, and No-Mode) per 10 CFR 50.65 (a)(4)"

15.

NSD 415, "Operational Risk Management (Modes 1-3) per 10 CFR 50.65 (a)(4)"

16.

WPM-609, "lnnage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)"

17.

WPM-608, "Outage Risk Assessment Utilizing Electronic Risk Assessment Tool (ERAT)

18.

NRC Summary of Meeting with Duke Energy Carolinas, LLC, to Discuss the Proposed One-Time TS Completion Time Change to perform KHU Generator Field Pole Rewind Maintenance - Oconee Nuclear Station Units 1, 2, and 3, dated December 4, 2013"

License Amendment Request No. 2015-08 February 26, 2015 Page 1 ENCLOSURE 2 - REGULATORY COMMITMENTS The following commitment table identifies those actions committed to by Duke Energy Carolinas, LLC (Duke Energy) in this submittal. Other actions discussed in the submittal represent intended or planned actions by Duke Energy. They are described to the Nuclear Regulatory Commission (NRC) for the NRC's information and are not regulatory commitments.

Commitment Completion Date 1 No discretionary maintenance or testing is allowed on SSF, foriTS 3.8da1 RA PSW, EFW, and essential AC Power Systems.

C.2.2.5 2

No discretionary maintenance or testing on the offsite power During 55-day CT system (230 kV Switchyard) will be performed and that the for TS 3.8.1 RA operability of required offsite circuits should be maintained at allC225 times.

Duke Energy commits to include the following risk reduction During KHU measures in the Critical Activity Plan:

generator stator ONS will not start the extended single KHU outage or a dual replacement KHU outage if severe weather conditions are forecast within outages 2 days.

ONS will contact the system load dispatcher once per day to ensure no significant grid perturbations (high grid loading not able to withstand a single contingency of line or generation outage) are expected during extended TS completion time.

ONS will control the steam-driven emergency feedwater pump on each ONS unit as "protected" equipment during the extended TS completion time.

ONS will continuously staff the SSF during the dual KHU outages when the penstock is dewatered.

LCT and Central Switchyard will be protected 2 nd LCT protected and available within one hour Prior to the start of the outage, verify a Jocassee Hydro Unit is available to be aligned to the Oconee 230kV Yellow Bus in approximately one hour Temporary DG located at Keowee Hydro Station with capability to restore available KHU unit to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> from dual KHU outage Reduced RCS Inventory not permitted during dual KHU outage FLEX equipment available PSW System available and with power system capable of aligning the Fant 100 kV line or a KHU to the SSF 4

Duke Energy will not use the 2nd Completion Time for Required generaorn sntatorH Action C.2.2.5 for planned Keowee work prior to the Keowee otgeseromplete.o

___generator stator outage for each KHU.ouaecmpt.

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 1 MARKED UP TECHNICAL SPECIFICATION PAGES

AC Sources - Operating 3.8.1 ACTIONS CONDITION REEQUIRED ACTION COMPLETION TIME C.

(continued)

C.2.2.3--------NOTE------

Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform work.

Sstator replacement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE and the requirements of LCO 3.8.3, "DC Sources-Operating," LCO 3.8.6, "Vital Inverters-Operating," LCO 3.8.8, "Distribution Systems-Operating," LCO 3.3.17, "EPSL Automatic Transfer Function," LCO 3.3.18, "EPSL Voltage Sensing Circuits," LCO 3.3.19, "EPSL 230 kV Switchyard DGVP,"

and LCO 3.3.21, "EPSL Keowee Emergency Start Function" are met.

AND.

(cntnud OCONEE UNITS 1, 2, & 3 3.8.1-4 OCOEE NIT 1,2, 3.8.-4Amendment Nos. 38,35 8

I

AC Sources - Operating 3.8.1 ACTIONS CONDITION J

REQUIRED ACTION fCOMPLETION TIME C. (continued)

C.2.2.4 Verify alternate power source capability by performing SR 3.8.1.16.

AND C.2.2.5 Restore KHU and its required overhead emergency power path to OPERABLE status.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AND Every 31 days thereafter 28 days when Condition due to an inoperable Keowee main step-up transformer AND NOTE---.......

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not aplcbedrn enrtor feW4work.

3 o

plicable until 1 year after the KHU is declared OPERABLE work.

45 days from discovery of initial inoperability when Condition due to an inoperable KHU

/

(continued)

OCONEE UNITS 1,2, & 3 3.8.1-5 OCONE UITS1,2 &33.81-5Amendment Nos. 38,35 & 8

AC Sources - Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME C. (continued)

PSW,]

AND NOTE---.......

1. No discretionary maintenance or testing allowed on SSEFW and essential AC Power Systems.

2. Only applicable one time for each KHU I J f=-rew work and 1.

stator replacement

3. Only applicable if the SSF and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

t Jdays from initial inoperability when Condition due to an inoperable KHU to pef r eeao[

~work D.

KHU or its required underground power path inoperable.

D.1 Perform SR 3.8.1.4 for OPERABLE KHU.

AND D.2 Energize either standby bus from LCT via isolated power path.

1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> if not performed in previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 24 hours AND 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from subsequent discovery of deenergized required standby bus (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-6 OCONE UNIT 1,2,& 3 38.1-6Amendment Nos. 38,385, &8381

License Amendment Request No. 2015-08 February 26, 2016 ATTACHMENT 2 RETYPED TECHNICAL SPECIFICATION PAGES

AC Sources - Operating 3.8.1 ACTIONS CONDITION JREQUIRED ACTION

[COMPLETION TIME C.

(continued)

C.2.2.3-----NOTE-Not applicable to remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work.

Verify by administrative means that the remaining KHU and its required underground emergency power path and both required offsite sources are OPERABLE and the requirements of LCO 3.8.3, "DC Sources-Operating," LCO 3.8.6, "Vital Inverters-Operating," LCO 3.8.8, "Distribution Systems-Operating," LCO 3.3.17, "EPSL Automatic Transfer Function," LCO 3.3.18, "EPSL Voltage Sensing Circuits," LCO 3.3.19, "EPSL 230 kV Switchyard DGVP,"

and LCO 3.3.21, "EPSL Keowee Emergency Start Function" are met.

AND 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-4 OCONE UITS1,2,& 33.81-4Amendment Nos. xxx, xxx, & xxx

AC Sources - Operating 3.8.1 ACTIONS CONDITION IREQUIRED ACTION COMPLETION TIME C. (continued)

C.2.2.4 Verify alternate power source capability by performing SR 3.8.1.16.

AND C.2.2.5 Restore KHU and its required overhead emergency power path to OPERABLE status.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AND Every 31 days thereafter 28 days when Condition due to an inoperable Keowee main step-up transformer AND NOTE----

1.

Not to exceed 45 days cumulative per rolling 3-year time period for each KHU.

2.

Not applicable during generator stator replacement work.

3.

Not applicable until 1 year after the KHU is declared OPERABLE following generator stator replacement work for planned work.

45 days from discovery of initial inoperability when Condition due to an inoperable KHU

.(continued)

OCONEE UNITS 1, 2, & 3 3.8.1-5 OCONE UITS, 2 & 33.81-5Amendment Nos. xxx, xxx, & xxx

AC Sources - Operating 3.8.1 ACTIONS CONDITION JREQUIRED ACTION jCOMPLETION TIME C. (continued)

AND NOTE---.......

1. No discretionary maintenance or testing allowed on SSF, PSW, EFW and essential AC Power Systems.

2. Only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021.

3. Only applicable if the SSF and EFW are administratively verified OPERABLE prior to entering the extended Completion Time.

55 days from initial inoperability when Condition due to an inoperable KHU to perform generator stator replacement work

03.

KHU or its required D.1 Perform SR 3.8.1.4 for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> if not performed underground power OPERABLE KHU.

in previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> path inoperable.

AND D.2 Energize either 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> standby bus from LCT via isolated power AND path.

1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from subsequent discovery of deenergized required standby bus (continued)

OCONEE UNITS 1, 2, & 3 3.8.1-6 OCONE UNTS 12, & 3.81-6Amendment Nos. xxx, xxx, & xxx

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 3 MARKED UP TECHNICAL SPECIFICATION BASES PAGES

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1. C.2.2.2, C.2.2.3. C.2.2.4. and C.2.2.5 (continued)

Verifying by administrative means allows a check of logs or other information to determine the OPERABILITY status of required equipment in place of requiring unique performance of Surveillance Requirements.

If the AC Source is subsequently determined inoperable, or an LCO stated in Required Action C.2.2.3 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L. Required Action C.2.2.3 is modified by a note indicating that it is not applicable to the remaining KHU and its required underground steaergen power path or LCO 3.3.21 when in Condition H to perform replacement generatorf*..

work. This note is needed to allow entry into the 60 hour6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> dual unit outage to reassemble the refurbished KHU and return it to functional condition, as well as perform balance runs and shots, post modification testing, and a commissioning run prior to declaring the refurbished KHU operable. Without this note, entry into Condition L would be required allowing only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> to restore the KHU and its required underground path and only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21.

Required Action C.2.2.4 requires verifying alternate power source capability by performing SIR 3.8.1.16. This confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable. If SIR 3.8.1.16 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

D.1, D.2 and D.3 With the KHU or its required underground emergency power path inoperable, sufficient AC power sources remain available to ensure safe shutdown of the unit in the event of a transient or accident. Operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the remaining KHU and its required overhead emergency power path are tested using SR 3.8.1.4 within one hour if not performed in the previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. SR 3.8.1.4 is only required to be performed when the KHU associated with the overhead emergency power path is OPERABLE. This Required Action provides assurance that no undetected failures have occurred in the overhead emergency power path. Since Required Action D.1 only specifies "perform," a failure of SR 3.8.1.4 acceptance criteria does not result in a Required Action not met. However, if the KHU and its required overhead emergency path fails SIR 3.8.1.4, both KHUs and their required emergency power paths are inoperable, and Condition I for both KHUs and their emergency power paths inoperable for reasons other than Condition G or H is entered concurrent with Condition 0. This OCONEE UNITS 1, 2, & 3 B 3.8.1-12 OCOEEUNIS

,, &3 3..112 BASES REVISION DATED 052/1--5 I

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1, C.2.2.2. C.2.2.3. C.2.2.4. and C.2.2.5 (continued) repairs which are estimated to be necessary every six to eight years.

Also, generator thrust and guide bearing replacements are necessary.

Other items which manifest as failures are expected to be rare and may be performed during the permitted maintenance periods. The 45-day Completion Time of Required Action C.2.2.5 is allowed to be applied cumulatively over a rolling three year period for each KHU. This Completion Time is 45 days from discovery of initial inoperability of the KHU. This effectively limits the time the KHU can be inoperable to 45 days from discovery of initial inoperability rather than 45 days from entry into Condition C and precludes any additional time that may be gained as a result of switching an inoperable KHU from the underground to the overhead emergency power path. The Completion Time is modified by three notes. Note 1 indicates that the Completion Time is cumulative per a rolling 3-year time period for each KHU. For example, if KHU-1 is inoperable for 15 days, the 45-day Completion Time for KHU-1 is reduced to 30 days for the rolling 3-year time period containing the 15 day inoperability. This requires a review of entries for the previous 3 years to determine the remaining time allowed in the 45-day Completion Time. If the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time of C.2.1 is not exceeded, the 45-day Coinpletion is not applicable and is not reduced. Notes 2 and 3 indicate for planned work the Completion Time is not applicable during generator id

'.....,,]

,,work or until one year after the KHU is declared OPERABLE following generatot i,.*~

c"!~

work. Note 2 is added to avoid using up the stato F

4-day Completion Time concurrent with the II-a.y Completion Time replacement

/

and preserves some time to perform emergent main nc work should allowed.

KH*U to perform generatorL~~ c. s;!"*ok h/

• ay Completion Time is modified by three notes that provide Protected Service conditions for using the extended outage. Note 1 indicates that n/o Water (PSW),

discretionary maintenance or testing is allowed on the Standby/Shutdown Facility (SSF), !'mergency Feedwater (EFW), and essential t~ernating current (AC) Power Systems. Note 2 indicates that the *Jday Completion Time is only applicable one time for each tKHU due to generato 'vork and expires on *.....,

Note 3 indicates that it is only applicable if the SSF~and EFW are admini tratively PSW

]

verified OPERABLE prior to entering the extended Com~p~e~tio nin._T-his-

• in-r-a~tes-pi6 b*bilIit-y, evyen in the unIkelyeven-t-of a n ad diti onal\\

J failure, that the risk significant systems will function as required to su port their safety function.

September 30, 2021 i

Required Actions C.2.2.1, C.2.2.2, C.2.2.3, and C.2.2.4 must be met in order to allow the longer restoration times of Required Action C.2.2.5.

OCONEE UNITS 1, 2, & 3 B 3.8.1-10 OCOEEUNIS

,, &3 3..110 BASES REVISION DATED 05/2141!5 I

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1. C.2.1. C.2.2.1. C.2.2.2. C.2.2.3. C.2.2.4. and C.2.2.5 (continued)

If the inoperable KHU or its required overhead emergency power path are not restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by Required Action C.2.1, a controlled shutdown must be initiated as required by the Required Actions for Condition M unless the extended Completion Times of Required Action C.2.2.5 are applicable. The second Completion Time for Required Action C.2.1 establishes a limit on the maximum time allowed for a KHU to be inoperable during any single contiguous occurrence of having a KHU inoperable. If Condition C is entered as a result of switching an inoperable KHU from the underground to the overhead emergency power path, it may have been inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This could lead to a total of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> since the initial failure of the KHU. The second Completion Time allows for an exception to the normal "time zero" for beginning the allowed time "clock." This will result in establishing the "time zero" at the time the KHU become inoperable, instead of at the time Condition C was entered.

The extended Completion Times of Required Action C.2.2.5 apply when the KHU or its required overhead emergency power path is inoperable due to an inoperable Keowee main step-up transformer, an inoperable stator KHU (if not used for that KHU in the previous 3 years), or a KHU made replacement inoperable to perform generator[c. p.'rc!_work. In order to use the extended Completion Times, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering Condition C both standby buses must be energized from an LCT (Required Action C.2.2.1), KHU generation to the grid except for testing must be suspended (Required Action C.2.2.2), the remaining KHU and its required underground emergency power path and both required offsite sources must be verified OPERABLE, the LCOs indicated in Required Action C.2.2.3 must be verified to be met, and alternate power source capability must be verified by performing SR 3.8.1.16.

Required Action C.2.2.5 permits maintenance and repair of a Keowee main step-up transformer which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Transformer replacement is rare but is time extensive. A 28 day Completion Time is permitted by Required Action C.2.2.5 to restore the KHU and its overhead power path to OPERABLE status when inoperable due to an inoperable Keowee main step-up transformer. This allows a reasonable period of time for transformer replacement.

Required Action C.2.2.5 also permits maintenance and repair of a KHU which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The primary long term maintenance items are expected to be hydro turbine runner and discharge ring welding OCONEE UNITS 1, 2, & 3 B 3.8.1-9 OCOEEUNTS

,, 3 38.-9 BASES REVISION DATED 05/2-1/5 I

License Amendment Request No. 201 5-08 February 26, 2016 ATTACHMENT 4 RETYPED TECHNICAL SPECIFICATION BASES PAGES

AC Sources - Operating B] 3.8.1 BASES ACTIONS 0.1. C.2.1, 0.2.2.1, C.2.2.2, 0.2.2.3, C.2.2.4, and 0.2.2.5 (continued)

If the inoperable KHU or its required overhead emergency power path are not restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by Required Action 0.2.1, a controlled shutdown must be initiated as required by the Required Actions for Condition M unless the extended Completion Times of Required Action C.2.2.5 are applicable. The second Completion Time for Required Action 0.2.1 establishes a limit on the maximum time allowed for a KHU to be inoperable during any single contiguous occurrence of having a KHU inoperable. If Condition C is entered as a result of switching an inoperable KHU from the underground to the overhead emergency power path, it may have been inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This could lead to a total of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> since the initial failure of the KHU. The second Completion Time allows for an exception to the normal "time zero" for beginning the allowed time "clock." This will result in establishing the "time zero" at the time the KHU become inoperable, instead of at the time Condition C was entered.

The extended Completion Times of Required Action C.2.2.5 apply when the KHU or its required overhead emergency power path is inoperable due to an inoperable Keowee main step-up transformer, an inoperable KHU (if not used for that KHU in the previous 3 years), or a KHU made inoperable to perform generator stator replacement work. In order to use the extended Completion Times, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering Condition C both standby buses must be energized from an LOT (Required Action C.2.2.1), KHU generation to the grid except for testing must be suspended (Required Action 0.2.2.2), the remaining KHU and its required underground emergency power path and both required offsite sources must be verified OPERABLE, the LCOs indicated in Required Action C.2.2.3 must be verified to be met, and alternate power source capability must be verified by performing SR 3.8.1.16.

Required Action C.2.2.5 permits maintenance and repair of a Keowee main step-up transformer which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Transformer replacement is rare but is time extensive. A 28 day Completion Time is permitted by Required Action 0.2.2.5 to restore the KHU and its overhead power path to OPERABLE status when inoperable due to an inoperable Keowee main step-up transformer. This allows a reasonable period of time for transformer replacement.

Required Action C.2.2.5 also permits maintenance and repair of a KHU which requires longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The primary long term maintenance items are expected to be hydro turbine runner and discharge ring welding OCONEE UNITS 1, 2, & 3 B 3.8.1-9 OCONE UNTS 1 2,& 3 3.81-9 BASES REVISION DATED

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1, C.2.1, C.2.2.1, C.2.2.2, C.2.2.3, C.2.2.4, and C.2.2.5 (continued) repairs which are estimated to be necessary every six to eight years.

Also, generator thrust and guide bearing replacements are necessary.

Other items which manifest as failures are expected to be rare and may be performed during the permitted maintenance periods. The 45-day Completion Time of Required Action C.2.2.5 is allowed to be applied cumulatively over a rolling three year period for each KHU. This Completion Time is 45 days from discovery of initial inoperability of the KHU. This effectively limits the time the KHU can be inoperable to 45 days from discovery of initial inoperability rather than 45 days from entry into Condition C and precludes any additional time that may be gained as a result of switching an inoperable KHU from the underground to the overhead emergency power path. The Completion Time is modified by three notes. Note 1 indicates that the Completion Time is cumulative per a rolling 3-year time period for each KHU. For example, if KHU-1 is inoperable for 15 days, the 45-day Completion Time for KHU-1 is reduced to 30 days for the rolling 3-year time period containing the 15 day inoperability. This requires a review of entries for the previous 3 years to determine the remaining time allowed in the 45-day Completion Time. If the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time of C.2.1 is not exceeded, the 45-day Completion is not applicable and is not reduced. Notes 2 and 3 indicate the Completion Time is not applicable during generator stator replacement work or until one year after the KHU is declared OPERABLE following generator stator replacement work. Note 2 is added to avoid using up the 45-day Completion Time concurrent with the 55-day Completion Time and preserves some time to perform emergent maintenance work should the need arise. Note 3 is added to require a one year waiting period prior to use for planned work.

The temporary 55-day Completion Time of Required Action C.2.2.5 is allowed for each KHU to perform generator stator replacement work. The 55-day Completion Time is modified by three notes that provide conditions for using the extended outage. Note 1 indicates that no discretionary maintenance or testing is allowed on the Standby Shutdown Facility (SSF), Protected Service Water (PSW), Emergency Feedwater (EFW), and essential alternating current (AC) Power Systems. Note 2 indicates that the 55-day Completion Time is only applicable one time for each KHU due to generator stator replacement work and expires on September 30, 2021. Note 3 indicates that it is only applicable if the SSF, PSW and EFW are administratively verified OPERABLE prior to entering the extended Completion Time. This increases the probability, even in the unlikely event of an additional failure, that the risk significant systems will function as required to support their safety function.

Required Actions C.2.2.1, C.2.2.2, C.2.2.3, and C.2.2.4 must be met in order to allow the longer restoration times of Required Action C.2.2.5.

OCONEE UNITS 1,2, & 3 B 3.8.1-10 OCONE

UITS1,

, & B.8.-10 BASES REVISION DATED

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1, C.2.1, C.2.2.1, C.2.2.2, C.2.2.3, C.2.2.4, and C.2.2.5 (continued)

Verifying by administrative means allows a check of logs or other information to determine the OPERABILITY status of required equipment in place of requiring unique performance of Surveillance Requirements. If the AC Source is subsequently determined inoperable, or an LCO stated in Required Action C.2.2.3 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

Required Action C.2.2.3 is modified by a note indicating that it is not applicable to the remaining KHU and its required underground emergency power path or LCO 3.3.21 when in Condition H to perform generator stator replacement work. This note is needed to allow entry into the 60 hour6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> dual unit outage to reassemble the refurbished KHU and return it to functional condition, as well as perform balance runs and shots, post modification testing, and a commissioning run prior to declaring the refurbished KHU operable. Without this note, entry into Condition L would be required allowing only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> to restore the KHU and its required underground path and only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore compliance with LCO 3.3.21.

Required Action C.2.2.4 requires verifying alternate power source capability by performing SR 3.8.1.16. This confirms that entry into Condition C is due only to an inoperable main step-up transformer or an inoperable KHU, as applicable. If SR 3.8.1.16 is subsequently determined not met, continued operation up to a maximum of four hours is allowed by ACTION L.

0.1. D.2 and D.3 With the KHU or its required underground emergency power path inoperable, sufficient AC power sources remain available to ensure safe shutdown of the unit in the event of a transient or accident. Operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the remaining KHU and its required overhead emergency power path are tested using SR 3.8.1.4 within one hour if not performed in the previous 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. SR 3.8.1.4 is only required to be performed when the KHU associated with the overhead emergency power path is OPERABLE. This Required Action provides assurance that no undetected failures have occurred in the overhead emergency power path. Since Required Action D.1 only specifies "perform," a failure of SR 3.8.1.4 acceptance criteria does not result in a Required Action not met. However, if the KHU and its required overhead emergency path fails SR 3.8.1.4, both KHUs and their required emergency power paths are inoperable, and Condition I for both KHUs and their emergency power paths inoperable for reasons other than Condition G or H is entered concurrent with Condition D. This OCONEE UNITS 1, 2, & 3 B 3.8.1-12 OCONE

UITS1,

, & B.8.-12 BASES REVISION DATED