ML15286A076

Duke Energy Presentation in Support of October 13, 2015, Public Meeting with NRC Staff Pre-Application Meeting for LAR to Support Khu Stator Replacement. (Revised)

ML15286A076
Person / Time
Site:	Oconee
Issue date:	10/13/2015
From:	Duke Energy Carolinas
To:	Division of Operating Reactor Licensing
Whited J
References
Download: ML15286A076 (26)

Text

Oconee Nuclear Station Pre-Application Meeting - October 13, 2015 LAR to Support Keowee Stator Replacement

Duke Participants Doug Phelps, Critical Systems Engineering Director, Oconee Nuclear Station Chris Wasik, Regulatory Affairs Manager, Oconee Nuclear Station Darla King, Keowee Electrical System Lead Engineer, Oconee Nuclear Station Boyd Shingleton, Licensing Lead Engineer for Stator LAR, Oconee Nuclear Station For Information Only 2

Agenda Introduction/Background Chris Wasik Proposed Technical Specification Change Chris Wasik Keowee Outage Timeline Doug Phelps Diverse Backup Power for Emergency Power System Doug Phelps Risk Reduction Measures Doug Phelps For Information Only 3

Introduction Chris Wasik Regulatory Affairs Manager, Oconee Nuclear Station For Information Only 4

Keowee Generator Stator Project Keowee Hydro Station commissioned in 1971 2008 - 2009 preventative maintenance inspections identified aging mechanisms in rotor pole assemblies 2009 Duke Energy started planning efforts to refurbish/overhaul both Keowee generators First phase refurbished/replaced all 56 generator field poles on each KHU

• KHU-2 performed January 2014

• KHU-1 performed July 2014 Second phase is to replace stator for each KHU

• KHU-1 scheduled January 2018

• KHU-2 scheduled January 2019 5

For Information Only

Keowee Generator Stator Project 6

For Information Only

Keowee Generator Stator Project Licensing Background NRC approved LAR for one-time extended TS Completion Time to allow KHU rotor pole rewind work on January 8, 2014 ONS plans to request a one-time extended TS Completion Time to allow stator on each KHU to be replaced Similar justification will be provided for stator LAR 7

For Information Only

Proposed Technical Specification Change Current TS 3.8.1 C - KHU aligned to the overhead path inoperable Cumulative 45 day Completion Time to restore inoperable KHU over a 3 year period The License Amendment Request (LAR) will request a one-time 55 day Completion Time for each KHU to allow stator replacement 8

For Information Only

Keowee Generator Stator Project Doug Phelps Critical Systems Engineering Director Oconee Nuclear Station 9

For Information Only

Keowee Generator Stator Project 10 For Information Only Implementation Strategy Original strategy was a standard rewind, estimated to require a 100-120 day Technical Specification (TS) Allowed Outage Time (AOT)

Alternate strategy was developed based on benchmark trip Benchmark plant strategy was to pre-build stator remote to unit Feasibility study was conducted to determine if a pre-build strategy was viable for Keowee Study concluded pre-build stator strategy was feasible and reduces the required TS AOT by ~50%

ONS selected option to pre-build the stator in an assembly building to minimize required TS AOT As a result, the scope of the project expanded to include:

New Frames Stator Assembly Building Powerhouse Modifications Heavy hauling from the assembly facility to the powerhouse and haul path evaluation

Keowee Generator Stator Outage Timeline 11 For Information Only Start Finish 55 Days - Total Work Window 2 days - Dewater Dual KHU Outage 24 days physical work, generator restoration & testing with contingency 25 days physical work with contingency 2 days - Dewater Dual KHU Outage 2 days - Generator Isolation & Prep for Rotor/Stator Lifts

ONS Electrical Distribution System 12 For Information Only 2

1 4

3 4

7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 26 27 28 31 33 54 55 56 57 58 59 60 61 4T KEOWEE HYDRO Gen 2 Gen 1 40 AUXILIARY POWER SYSTEM to B4T 1T CT1 6900 Main Generator Unit #1 6900 4160 NORMAL SOURCE STARTUP SOURCE 2TA 2TB 2T CT2 6900 4160 Main Generator Unit #2 6900 4160 NORMAL SOURCE STARTUP SOURCE 3TA 3TB 3TC 3TD 3TE 3T CT3 6900 Main Generator Unit #3 6900 4160 NORMAL SOURCE STARTUP SOURCE N1 N2 E1 E2 S1 S2 AUXILIARY POWER SYSTEM to B3T MFB #1 MFB #2 MFB #1 MFB #2 CT4 4160 CS 90 CT5 4160

22. 6 Miles Central White SK1 SK2 AUTO TRANSFORMER 5T STANDBY BUS #1 STANDBY BUS #2 KEOWEE OVERHEAD KATOMA ASBURY NEWPORT SOUTH HALL 525 KV RED BUS YELLOW BUS RED BUS YELLOW BUS 230 KV (NORTH GREENVILLE)

DACUS (CENTRAL)

OCONEE (CENTRAL)

CALHOUN JOCASSEE

13. 8 KV UNDERGROUND FEEDER 4160 EMERGENCY STARTUP BUS 6900 STARTUP BUS ELECTRICAL DISTRIBUTION B

W W

B W

B W

B Aux Transformer Aux Transformer Aux Transformer Main Transformer Main Transformer Main Transformer Startup Transformer Startup Transformer Startup Transformer 1TC 1TD 1TE N1 N2 E1 E2 S1 S2 2TC 2TD 2TE N1 N2 E1 E2 S1 S2 MFB #1 MFB #2 A

HPSWP B

PSWP SSF OTS1 30 1TA 1TB 1A1 RCP 1B1 RCP 1A2 RCP 1B2 RCP 2A1 RCP 2B1 RCP 2A2 RCP 2B2 RCP 3A1 RCP 3B2 RCP 3A2 RCP 3B1 RCP OCB 41 OCB 101 Central Switchyard 100 KV 1

11 7C CT 8C CT 2

12 34 13 Lee Switchyard 100KV

8. 5 Miles Fant Black OCB 35 SL1 SL2 A

B D

C 9

10 11 12 B6T/B7T PSW

ONS Transmission Lines 13 For Information Only Oconee Nuclear Station Oconee Nuclear Station

Backup Power for Emergency Power System Proposed LAR will credit the following backup power sources:

Underground Keowee Hydro Unit Dedicated Lee Combustion Turbine energizing both Standby Buses during extended completion time Remaining LCT available and capable of energizing the Standby Buses within one hour Required offsite power sources available SSF capable of mitigating SBO for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Two dedicated Jocassee Hydro Units available either of which has capacity of powering ONS shutdown loads in approximately one hour Temporary diesel generator at Keowee capable of restoring unwatered Underground KHU within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> PSW power system capable of powering SSF 14 For Information Only

Alternate Methods of Maintaining Safe Shutdown The following systems/equipment can be used to maintain all three Oconee units in a safe shutdown condition:

• SSF operable and capable of providing alternate shutdown capability

• PSW System operable and capable of providing alternate shutdown capability

• Turbine Driven Emergency Feedwater Pump capable of feeding steam generators

• FLEX equipment available One or more of the following power sources can be used to place all three Oconee units in cold shutdown:

• One LCT energizing ONS standby buses prior to outage start

• Underground KHU

• A second LCT can be started and aligned to the standby buses within one hour

• Two Jocassee Hydro Units available, either of which can be aligned to the Oconee 230kV Yellow Bus in approximately one hour

• Any of multiple offsite power sources 15 For Information Only

Lee Combustion Turbines Two LCTs (7C, 8C) available to power Oconee standby buses Dedicated line electrically separated from the system grid and offsite loads Capacity to supply ONS shutdown loads Routinely operated/tested, demonstrating reliability Black start capable, tested annually Included in the ONS Normal and Emergency Operating Procedures Verified available each shift Staffed continuously 16 For Information Only

Lee Combustion Turbines 17 For Information Only

Jocassee Hydro Station Two of the four Jocassee Hydro Units can be separated from the grid and dedicated to ONS in approximately one hour Each Jocassee Hydro Station unit is rated at 195 MVA Two transmission lines, north of ONS, directly connect the Jocassee 230 kV switchyard to the Oconee 230 kV switchyard Capacity to supply ONS shutdown loads Routinely operated/tested, demonstrating reliability Black start capable, tested annually Included in the ONS Emergency Operating Procedures Verified available each shift Staffed continuously 18 For Information Only

Jocassee Hydro Station 19 For Information Only

Temporary DG located at Keowee for restoring U/G KHU Onsite DG supplies backup power to KHS during dual KHU outage when unwatered Adequate capacity to restore the underground KHU Allows for rapid restoration of the underground KHU during loss of all power ( 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />)

Black start capable Use approved Keowee operating procedures Operated and tested prior to outage Verified available each shift Keowee Hydro Station continuously staffed 20 For Information Only

Standby Shutdown Facility and Protected Service Water System Standby Shutdown Facility

Provides an alternate means to achieve and maintain the ONS units in safe shutdown conditions

Provides additional defense in depth protection by serving as a backup to existing safety systems

Includes a dedicated power system including a diesel generator

Credited to mitigate Station Blackout, and other non design basis events

Mission time is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />

Staffed continuously during dual KHU outages when unwatered Protected Service Water

Provides an alternate means to achieve and maintain the ONS units in safe shutdown conditions

Provides additional defense in depth protection by serving as a backup to existing safety systems

Alternate power path to connect the SSF switchgear, with sufficient capacity to operate SSF equipment in the event of a failure of the SSF diesel generator 21 For Information Only

Defense-in-Depth - Multiple Diverse Backup Power Sources 22 For Information Only Start Finish Keowee Outage Timeline 55 Days - Total Work Window 2 days - Dewater Dual KHU Outage FLEX equipment available SSF Operable (including SSF DG) 1 Lee CT running and energizing Standby Buses 2nd Lee CT in Standby available within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 9 offsite power sources available Two Jocassee Hydro Units available within ~ 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 25 days physical work 2 days - Dewater Dual KHU Outage Underground (U/G) KHU existing additional 2 days - Generator Isolation & Prep for Rotor/Stator Lifts 24 days physical work, generator restoration & testing Temporary Diesel Generator at Keowee for restoring KHU associated U/G Path PSW Power System available* and capable of providing power to the SSF

• commercial power feed during dual KHU outage, Keowee or commercial power feed during single KHU outage

Risk Reduction Measures - Regulatory Commitments Duke Energy will commit to the following:

ONS will not start the extended single KHU outage or a dual KHU outage if severe weather conditions are forecast within the next two 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 avoid component testing or maintenance of safety systems and important non safety equipment in the offsite power systems that can increase the likelihood of a plant transient (unit trip) or LOOP. In addition, no discretionary switchyard maintenance will be performed.

ONS will verify that TS required systems, subsystems, trains, components, and devices that depend on the remaining power sources are operable and preclude subsequent nondiscretionary testing or maintenance activities on these systems, subsystems, trains, components, and devices during the extended TS completion time.

ONS will control the steam-driven emergency feedwater pump(s) as protected equipment during the extended TS completion time.

ONS will continuously staff the SSF during the dual KHU outages in which the intake is de-watered.

23 For Information Only

Other Risk Reduction Measures Critical Activity Plan, approved by the Plant Operations Review Committee prior to implementation, used for risk management. Plan will include the following risk reduction measures:

LCT and Central Switchyard protected 2nd LCT protected and available within one hour Two Jocassee Hydro Units available either of which can 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 PSW available to backup SSF FLEX equipment available 24 For Information Only

Summary Stator replacement is needed and will improve equipment reliability for emergency power system

• Stator replacement outages scheduled for January 2018 and January 2019 Additional diverse backup power sources result in electrical system defense-in-depth that provides level of protection equivalent with Branch Technical Position guidelines Additional risk reduction measures will be implemented and managed by critical activity plan Staff approval of LAR is essential to allow Duke Energy to implement KHU reliability improvements 25 For Information Only

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