ML15261A120
| ML15261A120 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/01/1996 |
| From: | Crlenjak R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Hampton J DUKE POWER CO. |
| References | |
| NUDOCS 9604090210 | |
| Download: ML15261A120 (44) | |
Text
April 1, 1996 Duke Power Company ATTN:
Mr. J. W. Hampton Vice President Oconee Site P. 0. Box 1439 Seneca, SC 29679
SUBJECT:
MEETING
SUMMARY
-'OCONEE NUCLEAR STATION
Dear Mr. Hampton:
This refers to the open Management meeting that was conducted at our request at the Oconee Nuclear Station on March 22, 1996, to discuss the Oconee Unit 3 reactor trip event of March 16, 1996. A list of attendees and a copy of your presentation handout are enclosed.
It is our opinion that this meeting was beneficial in that it provided the NRC staff with a good overview of the results from your investigation of the reactor trip event. In addition, the meeting also provided an open forum to discuss the restart of Unit 3 as it related to the March 18, 1996, Confirmation of Action Letter.
In accordance with Section 2.790(a) of the NRC's "Rules of Practice," Part 2, Title 10, Code of Federal Regulations, a copy of this letter and its enclosures will be placed in the NRC Public Document Room.
Should you have any questions concerning this matter, please contact us.
Sincerely, Original signed by R. V. Crlenjak R. V. Crlenjak, Chief Reactor Projects Branch 1 Division of Reactor Projects Docket Nos. 50-269, 50-270, 50-287 License Nos. DPR-38, DPR-47, DPR-55
Enclosures:
- 1. List of Attendees
- 2. Licensee Presentation Handouts cc w/encls:
Mr. J. E. Burchfield Compliance Duke Power Company 090 P. 0. Box 1439 Seneca, SC 29679 cc w/encls cont'd:
(See page 2) 9604090210 960401 PDR ADOCK 05000269 P
DPC 2
cc w/encls cont'd:
Mr. Paul R. Newton Mr. G. A. Copp Legal Department (PB05E)
Licensing -
ECO50 Duke Power Company Duke Power Company 422 South Church Street P. 0. Box 1006 Charlotte, NC 28242-0001 Charlotte, NC 28201-1006 Mr. Robert P. Gruber Ms. Karen E* Long Executive Director Assistant Attorney General Public Staff - NCUC N. C. Department of Justice P. 0. Box 29520 P. 0. Box 629 Raleigh, NC 27626-0520 Raleigh, NC 27602 Mr. Robert B. Borsum Distribution w/encl:
Babcock and Wilcox Company L. A.,Wiens, NRR Nuclear Power Generation Division R. E. Carroll, Ru 1700 Rockville Pike, Suite 525 R. V. Crlenjak, Ru Rockville, MD 20852 G. A. Hallstrom, Ru PUBLIC Mr. J. Michael McGarry, III, Esq.
Winston and Strawn NRC Resident Inspector 1400 L Street, NW U. S. Nuclear Regulatory Comm.
Washington, D. C. 20005 78128 Rochester Highway Seneca, SC 29672 Office of Intergovernmental Relations 116 West Jones Street Raleigh, NC 27603 Mr. Max Batavia, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, SC 29201 County Supervisor of Oconee County Walhalla, SC 29621 Manager, LIS NUS Corporation 2650 McCormick Drive Clearwater, FL 34619-1035 SENDN.
PUBLIC Depart men ofS Justic OFFICER VCrejkR SIGNATURE NAME a
'a~rim DATE A1/6 03/
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NO YES NO YES NO YES NO YES NO YES N
OFFICIAL REN CP DOCUMENT NAME:
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LIST OF ATTENDEES NUCLEAR REGULATORY COMMISSION:
S. Ebneter, Regional Administrator, Region II (RH)
H. Berkow, Director, Project Directorate 11-2, Office of Nuclear Reactor Regulation (NRR)
R. Crlenjak, Chief, Branch 1, Division of Reactor Projects (DRP), RII J. Rosenthal, Chief, Reactor Analysis Branch (RAB), Safety Programs Division (SPD), Office for Analysis and Evaluation of Operational Data (AEOD)
P. Harmon, Senior Resident Inspector - Oconee, DRP, RII W. Raughley, RAB, SPD, AEOD J. Lazevnick, Electrical Engineering Branch, Division of Engineering, NRR L. Wiens, Project Manager, Project Directorate 11-2, NRR G. Humphrey, Resident Inspector - Oconee, DRP, RH W. Burton, Region II Coordinator, Office of the Executive Director for Operations DUKE POWER COMPANY:
M. Tuckman, Senior Vice President, Duke Power Company J. Hampton, Vice President, Oconee Nuclear Station (ONS)
T. McMeekin, Vice President, McGuire Nuclear Station B. Peele, Station Manager, ONS W. Foster, Safety Assurance Manager, ONS J. Davis, Engineering Manager, ONS G. Rothenberger, Operations Superintendent, ONS D. Murdock, Manager, Major Projects, Electrical Support Services T. Saville, Reactor Engineering Manager, ONS L. Azzarello, Mechanical Systems Engineer, ONS C. Little, Manager, Electrical Engineering, ONS E. Birchfield, Manager, Regulatory Compliance, ONS D. Coyle, Systems Engineering Manager, ONS S. Capps, Keowee Upgrade Project Manager, ONS G. Hamrick, Chemistry Manager, ONS D. Hubbard, Maintenance Superintendent, ONS B. Earnherdt, Work Control Supervisor, ONS D. Bryson, Mechanical Systems Engineer, ONS B. Loftis, Electrical Systems Engineer, ONS B. Norris, Chemistry, ONS R. Todd, Safety-Review Group, ONS T. Grant, Electrical Engineer, ONS T. Pettit, Community Relations, ONS K. Growe, Vice President Staff, ONS D. Groux, Vice President Staff, ONS ENCLOSURE 1
OCONEE NUCLEAR SITE AGENDA
- Opening Remarks
- Plant Status
- Unit 3 Trip and Transient
- Electrical Test and Corrective Actions
- SEIT
- Closing Remarks ENCLOSURE 2
OCONEE.
NUCLEAR SITE HYLES
OCONEE NUCLEAR SITE Unit 3 Operating Sequence
- Initial Steady State Condition Cycle 16, 212 Day Run, 235 EFPD Full Power, 901 MWe Output
- Special Alignment for the Test
- Normal-to-Startup Source Transfer in Manual
- Shared Standby Bus Energized from Lee C-T
- Spurious Partial Load Shed Signal at 13:17:47 3 TE Switchgear Affected Hotwell, Condensate Booster, Heater Drain Pumps
- No Seal-in of Signal
OCONEE NUCLEAR SITE Unit 3 Operating Sequence (cont)
- Condensate System Flow Transient Standby Condensate Booster Pump Starts Automatically
- Remaining CBP Started Manually
- High Flow in Condensate System
- Low CBP Suction Pressure Detected and Times Out
- Anticipatory Reactor Trip (Loss of Main Feed Pumps) at 13:18:44
OCONEE NUCLEAR SITE Unit 3 Post Trip Response
- Secondary Side
- Emergency Feedwater Starts and Runs as Designed Condensate System Pressure Transient Causes Leaks in H2 Cooler and Stator Cooler Gaskets on Main Generator
- Apparent Stuck Open Hotwell Pump Discharge Valve
- Condensate Backflow Pulls Powdex Upstream of Polisher Bypass Branch SRestart of Condensate System Pumps Distributes Powdex
OCONEE NUCLEAR SITE Keowee Hydro Post Test Response
- KH-1 Load Rejected Energized the Underground Power Path to ONS
- KH-2 Load Rejected Realigned to Overhead Path
- Supplied Unit 3 Auxiliary Loads for Approx 3.5 Hours
OCONEE NUCLEAR SITE Unit 3 Trip Recovery
- Confirm Stability of Unit per EOP
- Reconnect 4160v Auxiliary Loads to Grid
- Re-establish RCS Forced Circulation
OCONEE NUCLEAR SITE Reconnect 4160v Auxiliary Loads to Grid
- Considered Possible Effects of Keowee Control Transfer
- Considered Paralleling Live Buses vs Dead Bus Transfer
- Considered Experience from October 1992 Load Rejection Test
- Considered Readiness of Operators for Particular Task
- Accomplished at 16:48
OCONEE NUCLEAR SITE Re-Establish RCS Forced Circulation
- Considered Effects on Keowee 2
- Considered Possibility of Losing RCPs During Paralleling
- Considered Effects of Additional Primary Heat Load on Secondary Flow Requirements and Inventories
- Recalled Lessons Learned from August 1994 OTSG Dryout Event Regarding Proceeding through EOP in Timely Manner
- Accomplished at 21:12 and 21:36
OCONEE NUCLEAR SITE Cool Down to DHR (LPI) System Conditions
- Considered Probable Link of Unit 3 Trip to Electrical Test
- Temperature Limit on Upper Surge Tank Supply
- Backleakage of LPI System Isolation Valve
- Condensate System Cleanup in Progress Throughout
- Accomplished at 10:19 on 3/18/96
OCONEE NUCLEAR SITE Equipment Failure Investigation
- Failure Investigation Process (FIP) Used on Resin and Water Hammer
- Walked Down Condensate System
- Repaired Gaskets
OCONEE NUCL EA SITE Secondary Side Chemistry Control
- OTSG Blowdown, Hot Soak
- Piping and Instrument Line Flushes
- Sampling and Inspections
- Planning Carefully for Unit Startup Sequence
OCONEE NUCLEAR SITE Other Issues
- 4 Hour NRC Notification Late
- Emergency Classification (None vs Unusual Event)
- Minor Equipment Problems Not Untypical of Unit Trips
OCONEE NUCLEAR SITE Walkdown of Keowee Systems
- Restoration Steps in Electrical Test Procedure
- AC Power System Alignment
- Operators' Duty Station Responsibilities
OCONEE NUCLEA SITE NRC Notification Before Using Keowee in Manner to Decrease Emergency Power Reliability
- Voluntary LCO's on Keowee or ONS Emergency Power
- Significant Testing, Troubleshooting, Maintenance on Keowee or ONS Emergency Power
- NRC Resident is the Contact
OCONEE NUCLEAR SITE Lee Combustion Turbine Availability
- Daily Contact Between Lee and Oconee
- NRC Resident is the Contact
- Expressed Our Preference to Have the Black Start Capable C-T
OCONEE NUCL EAR SITE Summary
- Auto Scram on Unit 3 During Test Unexpected and Unacceptable Result
- Pre-and Post-Trip Response is Understood
- Applied Conservative Decision Making During Recovery
OCONEE NUCLEAR SITE Electrical Test and Failure Investigation
- Purpose of the test
- Precautions taken in test preparation
- Test revealed an equipment failure outside the tested systems
- Root cause of the equipment failure and corrective action
- Test results
- Future testing plans
OCONEE NUCLEAR SITE Purpose of Test - Verify
- Degraded Grid Protection Logic
- Proper Switchyard Isolation
- Keowee Over Frequency Protection Modification
- Keowee Protective Relaying Zone Overlap
OCONEE NUCLEAR SITE Precautions Taken in Test Preparation
- Field walk down of procedure
- Designated as infrequently performed test
- Pre-prejob briefings held on Thursday
- Prejob briefing held on Saturday morning
- Lee Combustion Turbine energized standby bus via dedicated line
- Disconnect joints scanned with thermography
- Incorporated "Compensatory Actions" plans
OCONEE NUCLEAR SITE Test Revealed an Equipment Failure Outside the Boundary of Tested Systems
- Initiation of switchyard isolation
- Momentary Loadshed signal to one relay (channel) of Unit 3 TE switchgear
- Loss of Unit 3 TE non-essential loads - manual reclosure not blocked
- Instability of condensate system due to loss of loads resulted in Unit 3 trip 58 seconds later
- Immediately began implementation of "Compensatory Actions" by procedure
OCONEE NUCLEA SITE Failure Investigation Process
- Initiated Failure Investigation Process (FIP)
- Established two Engineering Teams for 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> effort
- Followed FIP to investigate and document each potential cause determined to be plausible
OCONEE NUCLEAR SITE Root Cause Investigation
- Identified suspect 3RLS1X relay by study of circuits and troubleshooting
- Developed procedure to test relay and contact in place
- Bench tested and conducted detailed failure analysis with supplier
OCONEE NUCLEAR SITE Corrective Action Taken
- Replaced relay
- Conducted in place test of new relay
- Reviewed operating experience and found no failures of this type
- Very low failure rate of relays
OCONEE NUCLEAR SITE Preliminary Planned Corrective Action
- Formally document our failure analysis of the relay
- Work with relay supplier and manufacturer to determine a reliable visual examination of installed Cutler-Hammer D23/26 Relays
- Perform visual examination of a sample population of installed relays to help determine the extent of the problem
- Take appropriate corrective action based upon examination
- Share the results of our failure analysis with the industry
OCONEE NUCLEAR SITE Test Results
- Degraded Grid Logic Section Successfully Completed
- Switchyard Isolation Section Completed
- Keowee Units Separated from the Grid Properly
- Over-frequency Protection Operated Properly
OCONEE NUCLEAR SITE Future Testing
- Plan to Complete Test During April 1996
- Test will include repeating the switchyard isolation section
OCONEE NUCLEAR SITE Significant Event Investigation Team (SEIT)
Jim Hampton
OCONEE NUCLEAR SITE SEIT Charter
- Develop and validate sequence of events
- Evaluate safety significance of event
- Determine root cause and contributing factors for event
- Evaluate station response during and after event
- Evaluate equipment performance during event
OCONEE NUCLEAR SITE SEIT Members
- Gary Gilbert - NSRB Staff, Assistant Team Leader
- Dennis Murdock - Manager Major Projects, ESS
- John Thrasher - MNS Modification Engineering Manager
- Tommy Loflin - ONS Operations Training
- Vijay Daji - GO Safety Analysis Section
- Tom Crawford - CNS Systems and Component Engineering Manager
OCONEE NUCLEAR SITE Restart Recommendations
- EFW hotwell suction piping should be flushed
- Additional Chemistry resources during heatup and startup
- Walkdown condensate and feedwater systems
- Block reclosure of PCB-12 and PCB-15
- Replace relay 3RLS1X and test new relay
- Confirm failure mechanism for relay 3RLS 1 X
OCONEE NUCLEAR SITE Restart Recommendations
- Enhance Loss of Power AP regarding response of E breakers
- Complete troubleshooting of RCP vibration probe
- Clarify position on exiting EOP while in natural circulation
OCONEE N""EEAR Longer-Term Secondary System Recommendations
- Inspect/repair hotwell pump check valves 0
- Monitor resin levels once TBVs are used
>> If elevated resin levels are detected, limit power escalation until stabilized
- Monitor and trend clean up of resins in hotwell/condensate system
- Evaluate procedure changes for restarting condensate system following an abnormal shutdown
OCONEE NUCLEAR Longer-Term Keowee/EPSL SITE Recommendations
- Evaluate reclosure modification for PCB-12 and PCB-15
- Evaluate modification to close both E breakers during a loss of power to both MFBs
- Consider development of emergency power logic simulator
OCONEE NUCLEAR SIT Longer-Term Team Response Recommendations
- Upgrade Operations procedure for 10CFR50.72 reports
- Review existing guidance for Unusual Event classification due to loss of offsite power
- Assess guidance for optional ERO activation/staffing
- Reinforce expectations regarding operation of control room equipment
OCONEE NUCLEAR SITE Longer-Term Procedure Quality Recommendations
- Requal training should reinforce expectations on exiting EOP while in natural circulation
- Consider logging time EOP is exited
- Enhance procedural guidance regarding restarting RCPs
- Reinforce revised loss of power AP guidance in simulator training
- Enhance degraded grid/switchyard isolation periodic test to:
>> Add caution about potential loss of power if PCB-9 is opened
>> Perform live bus transfer to grid per loss of power AP if any unit is tied to yellow bus
>> Revise, as necessary, guidance related to written evaluation of statalarms a Enhance procedures regarding supplying EFW from another unit
OCONEE NUCLEAR SITE Longer-Term Simulator Fidelity Recommendations
- Improve modeling of E breakers during load shed conditions
- Improve modeling of manual synchronization of Keowee units to the grid
OCONEE NUCLEAR E Longer-Term Material Condition Recommendations
- Resolve temperature problems related to 230 KV and 500 KV switchyard relay houses
- Give high priority to modifications related to RCP vibration monitoring
- Implement changes to minimize potential for seat leakage for LPI valves
- Resolve problems with data gaps in transient monitor
- Assign high priority to completing modifications to CS-64
- Implement improvements related to STAR module
OCONEE NUCLEAR SITE Strengths
- Pre-planned contingency actions for test
- Excellent management oversight before, during, and after test
- Well-planned staff augmentation
- Good pre-job briefings and crew tailgates
- Prompt initiation of SEIT
- Systematic implementation of formal Failure Investigation Process
- Conservative decision making throughout event
- Simulator natural circulation model agrees well with plant response
OCONEE NUCLEAR SITE Closing Remarks
- Clearly recognized safety significance of this test
- Planning and execution was deliberate and conservative
- Keowee and Emergency Power System operated as designed
OCONEE NUCLEAR SITE Closing Remarks
- Equipment failure was unrelated to Keowee Modification.
- Conducted comprehensive investigation to evaluate equipment & personnel response to event.
- When restart items for SEIT and post-trip review are complete, we believe we can safely restart Unit 3.