ML17158A819
| ML17158A819 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 10/14/1994 |
| From: | Posulusny C NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9508150108 | |
| Download: ML17158A819 (28) | |
Text
LICENSEE:
October 14,
~4 Pennsylv "ower and Light Company FACILITY:
Susquehanna Steam Electric Station, Units 1 and 2
SUBJECT:
SUMMARY
OF OCTOBER 6, 1994 MEETING On October 6,
- 1994, a meeting was held in Rockville, Maryland, between NRR and Pennsylvania Power
& Light Company (PP&L) staff to discuss the June event which occurred at Susquehanna Steam Electric Station (SSES),
Unit 2, related to an increase in reactor recirculation pump speed and system flow which produced a high frequency, low energy vibration and associated noise in the plant containment structure.
Enclosure'1 is a list of those who attended the meeting and Enclosure 2 is the set of slides which were presented by the licensee staff.'P&L provided an overview discussion of the event which was reportedly caused by reactor recirculation pump vane passing phenomenon when a particular elevated pump speed was reached.
Part of the Unit 2 power uprate testing program included an increase of the reactor recirculation system flow to 108%
above the previous normal flow and the noise and vibration were noticed several hours after the higher flow had been reached.
PP&L indicated that it had conducted further evaluation of a large amount of data with GE Nuclear Energy staff and had not been able to pinpoint the exact trigger mechanism for the event.
In addition, PP&L plans to complete additional analysis, continue to monitor normal plant operations and is developing a plan for additional tests at higher flow rates.
The staff indicated that it would like to review the Unit 2 test plan after it is completed and PP&L agreed to provide it.
Also, the staff indicated that key information about the event would be included in the staff's safety evaluation for the Unit 1 power uprate and increased reactor recirculation flow amendment along with a discussion of any new PP&L operational commitments applicable to Unit 1 which may be precipitated by the flow test being conducted on Unit 2.
It was agreed that a subsequent status meeting may be needed to continue the exchange of information on this event.
/s/
Chester
- Poslusny, Project Manager Project Directorate I-2 Division of Reactor Projects I/II Office of Nuclear Reactor Regulation Docket Nos.
50-387/388
Enclosures:
As stated (2) cc w/encls:
See next page DISTRIBUTION w/Encl osure 1
WRussell/FMiraglia EJordan RZimmerman ACRS(10)
SVarga PChen JZwolinski RFrahm JStolz DKirkpatrick HO'Brien HAshar OGC
- GBarber, RGN-I MBannerjee, R-I
- WDean, EDO/R-I BSheron GHolahan RSpessard DISTRIBUTION w/Encl osures 1/2 (Docket File'I NRC
& Local PDRs PUBLIC EWenzinger, RGN-I
- JWhite, RGN-I CPoslusny OFFICE NAME PD,/
PDI-2 PH CPoslusny:rb
-2 D
JSt lz DATE 0/
94 0/
/94
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OFFICIAL REC RD COPY 9508f50%08 94l014 I'I
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 14, 1994 LICENSEE:
Pennsylvania Power'nd Light Company FACILITY:
SUBJECT:
Susquehanna Steam Electric Station, Units 1 and 2
SUMMARY
OF OCTOBER 6, 1994 MEETING On October 6,
- 1994, a meeting was held in Rockville, Maryland, between NRR and Pennsylvania Power
& Light Company (PPBL) staff to discuss the June event which occurred at Susquehanna Steam Electric Station (SSES),
Unit 2, related to an increase in reactor recirculation pump speed and system flow which produced a high frequency, low energy vibration and associated noise in the plant containment structure.
Enclosure 1 is a list of those who attended the meeting and Enclosure 2 is the set of slides which were presented by the licensee staff.
PP&L provided an overview discussion of the event which was reportedly caused by reactor recirculation pump vane passing phenomenon when a particular elevated pump speed was reached.
Part of the Unit 2 power uprate testing program included an increase of the reactor recirculation system flow to 108X above the previous normal flow and the noise and vibration were noticed several hours after the higher flow had been reached.
PP&L indicated that it had conducted further evaluation of a large amount of data with GE Nuclear Energy staff and had not been able to pinpoint the exact trigger mechanism for the event.
In addition, PP&L plans to complete additional analysis, continue to monitor normal plant operations and is developing a plan for additional tests at higher flow rates.
The staff indicated that it would like to review the Unit 2 test plan after it is completed and PP&L agreed to provide it.
Also, the staff indicated that key information about the event would be included in the staff's safety evaluation for the Unit 1 power uprate and increased reactor recirculation flow amendment along with a discussion of any new PP&L operational commitments applicable to Unit 1 which may be precipitated by the flow test being conducted on Unit 2.
It was agreed that a subsequent status meeting may be needed to continue the exchange of information on this event.
Docket Nos.
50-387/388
Enclosures:
As stated (2) cc w/encls:
See next page Chester
- Poslusny, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Pennsylvania Power
& Light Company Susquehanna Steam Electric Station, Units 1
& 2 CC:
Jay Silberg, Esq.
- Shaw, Pittman, Potts
& Trowbridge 2300 N Street N.W.
Washington, D.C.
20037 Bryan A. Snapp, Esq.
Assistant Corporate Counsel Pennsylvania Power
& Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Nr. J.
M. Kenny Licensing Group Supervisor Pennsylvania Power
& Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Hr. Scott Barber Senior Resident Inspector U. S. Nuclear Regulatory Commission P.O.
Box 35 Berwick, Pennsylvania 18603-0035 Hr. William P. Dornsife, Director Bureau of Radiation Protection Pennsylvania Department of Environmental Resources P. 0.
Box 8469 Harrisburg, Pennsylvania 17105-8469 Hr. Jesse C. Tilton, III Allegheny Elec. Cooperative, Inc.
212 Locust Street P.O.
Box 1266 Harr isburg, Pennsylvania 17108-1266 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 Nr. Harold G. Stanley Superintendent of Plant Susquehanna Steam Electric Station Pennsylvania Power and Light Company Box 467 Berwick, Pennsylvania 18603 Hr. Herbert D. Woodeshick
- Special Office of the President Pennsylvania Power and Light Company Rural Route 1,
Box 1797 Berwick, Pennsylvania 18603 George T. Jones Manager-Engineering Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Nr. Robert G. Byram Senior Vice President-Nuclear Pennsylvania Power
& Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Dr. Judith Johnsrud National Energy Committee Sierra Club 433 Orlando Avenue State College, PA 16803
LIST OF ATTENDEES MEETING BETWEEN NRC AND PP&L OCTOBER 6 1994 NAME C. Poslusny P.
Chen R.
Frahm D. Kirkpatrick H. Asher G. Barber M. Banerjee C. Dvorscak J. Vernarr J.
Refling J. Bartos M. Detamore G. Miller J.
Kenny R. Sgarro D. Panluatz V. Kumar M. Torres D. Glassie T.
Ryan ORGANIZ T ION NRC/NRR NRC/NRR NRC/NRR NRC/NRR NRC/NRR NRC/RGN-I NRC/RGN-I (Susquehanna)
PP&L PP&L PP&L PP&L PP&L PP&L PP&L PP&L GE GE GE PECO Energy PECO Energy ENCLOSURE 1
us ue anna nit ontainment oise nvesti ation enns vania ower 1
John A. Bartos October 6,1994 ENCLOSURE 2
resentation ut inc
+Background
+Review Event Observations
+Investigation Action Plan
+Investigation Status
+ Schedule
us ue anna nit
+GE BWR4
+Mark IIContainment
+Reactor Power - 3441 MW
+ Generator Power - 1100 MW, riet,,
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+ Original Licensed Core Flow - 100 Mlb/Hr
+Extended Core Flow - 108 Mlb/Hr
ower rate est ro ram
+Four Test Plateaus
- A/B 900/0 Power
- C 960/o Power
- D 98%0 Power E
100 10 Power 108 Mlb/HrCore Flow
Dai y Power Leve, 100%
90%
80%
L 70%
0 CL 60%
50%
D 40%
30%
Q.
20%
10%
0%
June-11 June-13 June-15 June-17 June-19 June-21 June-23 June-25 June-27 June-29 July-1
Increase ore F ow Tests
+Reset MG Set High Speed Stops
+Recirculation Control System Stability
+Feedwater System Stability
+EHC System Stability
ontainment oise
+ Loud audible sound in reactor building.
+ Noise appears to originate in containment.
+ Noise Characteristics
. Steady rhythmic noise.
131 Hz base frequency.
1 Hz beat frequency.
+ Coincident with recirc. pump vane passing frequency.
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T-A
oise Event ant on itions During ontainment
+Reactor at 92% ofuprated power.
+Recirc pump A at 1571 rpm.
+Recirc pump B at 1582 rpm.
+Core flow at 108 Mlb/Hr.
+Increased core flow:tests complete.
ant servations urin t e ontainment oise vent
+Allinstalled plant instrumentation indicated normal readings.
+Recirc pump vibration readings showed no unusual increases.
+ Hatch cover to the wetwell air space was observed to be vibrating.
+ Reports of some small pipes vibrating more than normal.
ctions to iminate oise
+ B.ecirc pump speeds individually reduced t
.1515 rpm.
+ Pump A reduced first.
Magnitude ofnoise reduced.
Beat frequency increased to 6 Hz.
+ Pump 8 speed reduction eliminated noise.
+ Core flowat 103 Mlb/Hr.
Im act n
ontinue eration
+ "Hold"placed on the test program.
Performed an industry event search.
Contacted GE and other utilities.
Performed a safety assessment.
+ Safety assessment reviewed by POR'.C.
+ Temporary restriction pump operation established.
(Speed < 1515 rpm.)
+ Test program "Hold"lifted.
+ Test program successfully completed.
ost vent eview
+ Event data reviewed by GE/PP8'cL team.
Review held on July 27 - 28 in San Jose.
Formal Kepner Tregoe analysis..
+Define Problem - Should Vs. Actual.
+ Speci facts What is. Vs. What is not.
+Develop probable causes.
+ Test causes against problem definition and event facts.
+Veri results against log'ic and reality.
Event Review Resu ts
+ One root cause is the recirculation pump vane passing pressure pulses.
+ The noise is an amplification ofthe pressure pulses.
+ Insufficient data exists to explain the amplification mechanism.
+ A number ofpossible amplification mechanisms exist.
+ Need to obtain more data &om:
Additional analysis.
Normal plant operations.
A special test.
~,
oti ication
+Notice on Nuc ear Networ
+Presentation to B Group.
Owners
ontainment oise ction P an
+ Collect additional plant data.
+ Perforin additional mechanical and hydraulic analysis.
+ Perforin test to recreate the. noise and take additional data.
'I
+ Analyze data and issue findings.
+ Revise or eliminate plant operating restrictions.
+ Keep NRC informed ofprogress.
itiona P ant Data ctivities at ering
+ Develop a noise and vibration data collection plan.
Status:
Plan in draft.
+ Benchmark Unit 2 noise and vibration levels.
Status:
Data collection in progress.
+ Hammer test Unit 1 and 2 wetwell air space hatches.
Status:
Complete
+ Review GETARS data for event.
Status:
Complete.
itiona ant ata at erin ctivities I
+Analyze pump vibration data for low frequency data.
Status:
Work in progress.
+ Develop an in containment inspection plan.
Status:
Complete.
- 1110113, 113, S1S P
+Develop an acoustic/ hydraulic model ofth recirc. system.
Status: Work in progress.
+ Review piping models for natural frequencies and mode shapes.
Status:
Complete.
+ Review sensitivity ofsmall attached piping.
Status: Work in progress.
actions a ysis
+ Review containment vibration modes.
Status:
Complete.
f
+ Review the snubber reduction program Status:
Complete.
+Model suppression pool covers to determine input motion required to excite them.
Status:
Complete.
'V itiona a ysis
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+ Review vibration transmission mechanisms.
~,
Status:
Complete.
+ Calculate noise generated by vibrating hatches.
Status: Work in progress.
+ Review steam dryer test report.
Status:
Complete.
I ~<<'ts >lj<<
T
est
'ectives
'Pl],,'gP':
C
+Recreyte containment noise.
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+Defirie plant conditions that result in observed noise.
+Collect vibration and noise data related to phenomena.
+Determine ifthe noise can be avoided.
A ction
~ Q
~ 'i
'~ 5'i<<
jlj an ar et ates Date gl
+ NRC Status Meeting
+ Complete Analysis
+ Perform Test
+ Complete Analysis of ofTest Results
+ Inform NRC Analysis Results 10/06/94 11/01/94 11/03/94 11/30/94 12/09/94
onC uSions
"'I -"
+ Vane. passing pulses are one. ofthe root causes.
I
+Administrative controls are in place to prevent the uncontrolled reoccurrence ofthe noise.
+A comprehensive plan to determine other root causes is in place.
+ Plan activities are on. schedule.
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