ML022460095
| ML022460095 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 08/30/2002 |
| From: | Byrne S, Halnon G, Herwig B, Stuart W, Andrea Torres South Carolina Electric & Gas Co |
| To: | NRC/RGN-II |
| References | |
| Download: ML022460095 (47) | |
Text
Agenda
- Opening Remarks (Steve Byrne)
- Outage Results (Alan Torres)
- RCS Hot Legs (Wayne Stuart)
- Spent Fuel Pool Re-rack (Bill Herwig)
- Plant Operation and Corrective Action (Greg Halnon)
- Closing Remarks (Steve Byrne)
RF-13 Outage Update Alan Torres
Refuel 13
- Outage Overview
- Goal Performance
- Nuclear Safety
- Industrial Safety
- Outage Duration
- Human Performance
- Radiation Exposure
- Capacity Factor for 90-day run
Refuel 13
- Major projects
- Completed MSIP on hot legs
- Implemented digital feed pump speed controls
- Repaired the A CCW heat exchanger
- Repaired Amertap
- Installed new excitation system
- Completed five year PMs on diesels
Refuel 13
- Outage Issues
- Service Water piping
- Scope of repair on CCW heat exchangers
- Coordination of changing schedules
- Outage Successes
- Total exposure
- Fuel handling
- Reactor coolant hot legs
CCW Heat Exchanger CCW Heat Exchanger CCW Heat Exchanger CCW Heat Exchanger V C Summer Hot Leg Repair Update Wayne Stuart
Root Cause Conclusions The Through Wall Crack in the Alpha Hot Leg Occurred Due To:
- Primary Water Stress Corrosion Cracking
-Temperature
-Environment
-Tensile Stress
- High Residual Stresses From Original Welding / Fabrication
RF 12 Actions
- Replaced weld in A hot leg and used Inconel 690 material not known to be susceptible to PWSCC
- Inspected and evaluated B and C hot leg nozzles
- Planned inspections of B and C hot leg nozzles in RF-13
In d ic a tio n s in V . C . S u m m e r R V N o z z le to P ip e W e ld R e g io n (R F -1 2 / R F -1 3 )
R F -1 3 Hot In d ic a tio n R F -1 2 P re M S IP Leg L o c a tio n /
Loop O rie n ta tio n UT UT ET ET L /D L /D B
3 5 /c irc 0 .5 N /A 0 .5 NA (N 2 6 5 )
.6 2 5 /
2 0 0 .8 /a x ia l 0 .2 5 N /A 0 .5
.3 1 7 3 4 8 /a x ia l 0 .2 5 N /A 0 .2 5 N /A C
3 0 9 /c ir 0 .5 NA 0 .5 .3 7 5 /
(N 1 4 5 )
.1 1
MSIP MSIP MSIP Indications in V. C. Summer RV Nozzle to Pipe Weld Region (RF-12 / RF-13)
RF-13 RF-13 Hot Indication RF-12 Pre MSIP Post-MSIP Leg Location/
Loop Orientation UT UT UT ET ET ET L/D L/D L/D B
35/circ 0.5 N/A 0.5 NA 0.5 N/A (N265)
.625/
200.8/axial 0.25 N/A 0.5 0.5 N/A
.317 348/axial 0.25 N/A 0.25 N/A 0.25 N/A C 0.375/
309/cir 0.5 NA 0.5 .375/ 0.5 (N145) 0.11
.11
VC Summer RF 13
- Verbal NRC approval for cycle 14 restart
- 10 Year ISI inspection planned in RF 14
- ASME Section XI, Supplement 10 Inspection
VC Summer RF 14
- Section XI inspection of B & C hot legs in RF 16, 18, &20
- Evaluating implementation of MSIP on A, B,
& C cold legs and on the pressurizer surge line
VC Summer RF 14
- CRDM Head Penetration 2002-01 & 02 Response Direction:
- VCS is very Low Susceptibility : 2.3 EDY
- Performed a Supplemental Visual Inspection in RF 13
- Evaluating potential BMV in RF 14
- Closely Monitoring the Industry for Future Developments
SPENT FUEL POOL RE-RACK PROJECT Bill Herwig
Project Goals
- Cost effectively increase pool storage capacity
- Eliminate Boraflex poison
- Accommodate a range of fuel designs, initial enrichment, and burnup
- Reduce the required minimum in-core hold time
Rerack Schedule 8/30/02 9/03 Fuel 7/24/01 Requested Receipt for LAR NRC Approval Submitted Refuel 14 of LAR 13 Months 2001 2002 2003 2004 4/02 10/03 8 Months Refuel 13 Refuel 14 9/30/02 6/03 Rack Start Rerack Installation Mod Complete
PLAN - CURRENT SFP RACKS Existing Empty Space 1
1 Cask Load Pit 2 Fuel Transfer Canal
- 11 Racks, 1276 Cells, 825 Assemblies Inventory
- Capacity to RF 17 in Spring 2008
PLAN-FUTURE SFP RACKS Region 2 1512 Cells Region 1 200 Cells
- 1712 Cells (436 Additional)
- Capacity: Up to RF 24 in Fall 2018
Fuel Handling
- Fuel, component, and basket handling to be performed by Master-Lee
- Material transfer will be in accordance with Reactor Engineering procedures
- Fuel will be moved 24/7 to support schedule
- Dummy fuel assembly will be used to perform 100% drag testing after rack installation
Scope
- Current pool inventory is 825 fuel assemblies
- Special considerations
- Top nozzle screw failure
- Early fuel design (A-E batches) susceptible to nozzle separation
- New SFHT procured as contingency
Scope
- Three debris baskets, 1 failed rod storage basket
- Handle with SFHT
- Three top nozzle baskets
- Handle with T-bar tool
- One RV specimen basket
- Handle with special purpose tool
- Two boraflex sample trees
- Handle with J-hook
Criticality Control
- There are just under 100 assemblies that cannot go in the existing region III racks.
- All fuel assemblies currently in the spent fuel pool can go in the new region II racks.
- 1000 gallons of fresh water may be added to the pool between boron measurements.
Plant Operations and Corrective Action Program Greg Halnon
C FWP TRIP/ POWER HISTORY RX TRIP Cycle 14 6/01/02 - 8/20/02 TURB OVR 120 SPD TEST 100 80 Power (%)
C FWP 60 A FWP Lock Out TRIP Reset 40 20 0
5/24/02 6/3/02 6/13/02 6/23/02 7/3/02 7/13/02 7/23/02 8/2/02 8/12/02 8/22/02 9/1/02 Date IR RX TRIP
N-36 Trip
- June 1, 2002; 1839 hours0.0213 days <br />0.511 hours <br />0.00304 weeks <br />6.997395e-4 months <br />
- Initial Power Level: 2%
- Trip Setpoint Exceeded: 1 of 2 IR High Flux 18%
- Plant Response: Both Trains SSPS Actuated
- Operator Response: Good, no anomalies
- Root Cause: N-36 IR spurious noise caused signal to exceed setpoint
- Plant Recovery: Uneventful
Parameters
- Pressure: 2238 psig to 2210 psig
- Pressurizer: 31% to 22% level
- Tave: 561ºF to 553ºF
- No lifting of relief valves
- No significant change in SG levels and pressure
Root Cause
- Potential noise on high voltage power supply
- Has not recurred nor been able to recreate
- Card in the pre-amp circuit
- Found blistered capacitors
- Potential cause of spikes, but a high or low failure would be more probable
- Same cards inspected on N-35, found visually sat
- Other circuit checks recommended by Gammametrics vendor on both N-36 and N-35 were sat.
- Replaced cards now at vendor for root cause assessment
C Feedwater Pump Trip Event
- June 17, 2002; 1902 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.23711e-4 months <br />
- Initial Power Level: 99%
- Trip Setpoint Exceeded: Lo Lo Lvl A-SG
- Plant Response: Normal Post Trip Response
- Operator Response: Satisfactory Response
- Root Cause: Trip of C FWP with complications
- Plant Recovery: Uneventful on June 18th
Cause of Trip
- Six minutes later the reactor tripped due to LOLO level (30%) in the A SG.
- Based on the crew response, the trip should have been avoidable.
Cause of Trip
- The recirculation valves on the A and B FW pumps failed open 4 minutes after the trip.
- The DCS logic detected bad quality for the flow channels for A and B and failed the valves open as designed.
- Bad quality was detected because the A and B flow channels were pegged high to makeup for the loss of the C pump.
- The DCS logic fails the recirc valve open in this case to protect the pump from dead head or low flow.
Cause of Trip
- The recirculation valves on the A and B FW pumps failed open after the trip.
- The new digital logic fails the recirc valve open in this case to protect the pump from dead head or low flow.
- Lower flow to the Steam Generators caused levels to decrease
SG Level Response B&C FWP Recircs 70.00 begin failing open 60.00 Reactor trip at 50.00 30% SG level SG Level (%)
40.00 C FWP TRIP 30.00 20.00 A & B FWPs begin to increase 10.00 flow and SG levels start to recover 0.00 18:51:50 18:53:17 18:54:43 18:56:10 18:57:36 18:59:02 19:00:29 19:01:55 19:03:22 19:04:48 Tim e
Corrective Actions
- Actions taken prior to re-start
- Initial failure analysis for fuse failure directed replacing all fuses with different style deemed more reliable, inspecting and re-lugging relay connections.
- Recorders were installed to monitor circuit current for all three pumps
- DCS logic modified to alarm bad quality without causing automatic action
Root Cause Efforts
- Blown fuse support and refute focused on two primary possibilities:
- Defective fuse
- Over-current
- No cause for over-current discovered
- Vendor investigation of actual fuse indicated no defect, possible over-current.
- Fuses for all three pumps replaced with a different style, inspected and re-terminated some relay connections.
- Circuit current was monitored for several weeks after start-up with no anomalies noted.
Root Cause Efforts
- Recirc Valves Root cause in progress with an overall FW assessment.
- Questions include
- Adequacy of design and testing of digital mods
- Other areas of single point vulnerability in the FW system
- How to prevent similar events with mods in the future.
Corrective Action Program
- March 2001-NRC PI&R inspection
- May 2001-INPO plant pvaluation
- August 2001-Internal self-assessment
- Fall 2001-Manager teams to address weakness
- March 2002-NRC PI&R inspection
Corrective Action Program Statistics 1998 1999 2000 2001 2002 TOTAL CERs 516 1527 1907 2431 2791 9172 Initiated Average Per Day 3.0 4.2 5.2 6.7 11.8 6.1 CERs Open 10 62 99 422 1253 1846 Percent (%)
Open 1.9% 4.1% 5.2% 17.4% 44.9% 20.1%
- Open CERs have a status of Screened, Unscreened or Ready For Approval
Corrective Action Program
- Weekly Management Oversight
- Total open by year
- Cumulative opened vs. closed (year-to-date &
weekly statistics)
- Top 10 oldest
- Backlogs for evaluation and action
- Open high significant evaluations
- Open low significant evaluations
Corrective Action Program
- Seeking Continuous Improvement
- Additional program changes
- Planned CAP self-assessment
- Planned trending self-assessment
- On-going effectiveness review