ML15282A072
| ML15282A072 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/09/2015 |
| From: | Shingleton B Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation |
| Whited, Jeffrey, NRR/DORL/LPLII-1 | |
| References | |
| CAC MF6762, CAC MF6763, CAC MF6764 | |
| Download: ML15282A072 (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
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 A
HPSWP B
PSWP
ONS Transmission Lines 13 For Information Only Oconee Nuclear Station Oconee Nuclear Station
Defense-in-Depth - Multiple Diverse Backup Power Sources 14 For Information Only
- commercial power feed during dual KHU outage, Keowee or commercial power feed during single KHU outage
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 FLEX equipment available 15 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 16 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 17 For Information Only
Lee Combustion Turbines 18 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 19 For Information Only
Jocassee Hydro Station 20 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 21 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 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 22 For Information Only
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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