05000446/LER-2002-001, Reactor Trip Due to Primary Water Pump Vibration High Signal on June 6, 2002
| ML022260887 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/05/2002 |
| From: | Walker R TXU Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10200, CPSES-200202602, TXX-02114 LER-02-001-00 | |
| Download: ML022260887 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4462002001R00 - NRC Website | |
text
TXU TXU Energy Comanche Peak Steam Electric Station P.O. Box 1002 (E01)
Glen Rose,TX 76043 Tel: 254 897 8920 Fax: 254 897 6652 lance.terry@txu.com C. Lance Terry Senior Vice President &
Principal Nuclear Officer Ref: IOCFR50.73(a)(2)(iv)(A)
CPSES-200202602 Log # TXX-02114 File # 10200 August 5, 2002 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 SUBJECT: COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NO. 50-446 ACTUATION OF REACTOR PROTECTION SYSTEM LICENSEE EVENT REPORT 446/02-001-00 Enclosed is Licensee Event Report (LER) 02-001-00 for Comanche Peak Steam Electric Station Unit 2, "Reactor Trip due to Primary Water Pump Vibration High Signal."
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway Comanche Peak Diablo Canyon Palo Verde South Texas Project Wolf Creek
TXU TXX-021 14 Page 2 of 2 This communication contains the following new commitment which will be completed as noted:
Commitment Number
Commitment
27270 Engineering will evaluate other turbine/generator protection cabinets to determine if similar circuit designs exist.
The Commitment number is used by TXU Generation Company LP for the internal tracking of CPSES commitments.
Sincerely, TXU Generation Company LP By:
TXU Generation Management Company LLC, Its General Partner C. L. Terry Senior Vice President and Principal Nuclear Officer By:
'Wker Roger D.
Wker Regulatory Affairs Manager GLM/gm Enclosures c -
E. W. Merschoff, Region IV W. D. Johnson, Region IV D. H. Jaffe, NRR Resident Inspectors, CPSES
Enclosure to TXX-02114 NBC FORM 346 US. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31540104 (7-2001)
EXPIRES 0713112004 Estimated burden per response to conply with this mandatory information collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are iscorporated into the licensing process and fed beck to industry. Seed comanents regarding burden estimate to the Records MLNEemE Nt Branch (TT E()R U.S. Nuclear Regulatory Conmission. Washngton, DC LICENSEE EVENT REPORT (LER) 20555-001,orbyintrnte-mailto bjsl~nrc.gov,stndtotbeDeskObsicerOfficeof Infirm tion and Regulstory Affairs, NEOB-10202(3150-0104), Office of Management and Budget, Washintoon. DC 20503.
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Facility Name (I)
Docket Nunter (2)
Page (3)
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 1 OF 5 Title (4)
REACTOR TRIP DUE TO PRIMARY WATER PUMP VIBRATION HIGH SIGNAL Event Date (5 LER Nunter (6)
Rport Dat (7)
Other Fwdmlies Involved (8)
Month Day Year Year Sequentiasl Revision Month [ Day Year Fadlity Name Docket Numrers Number Nunber I
05000 06 06 02 02 001 H 00 1 08 05 02 05000 Operating I hsrp ssbite usatt h
of 10 CFR :(Check all that apply) (Ill)-
Mode (9) 1 20.2201 (b)_
20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
Power 20.2201 (d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) ei 100 20.2203(a)(1) 20.2203(a)(4) 50.73(a){2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(2)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)
X 50.73(a)(2)(iv)(A) 50.72(a)(2)(x) 20.2203(a)(2)(iii)
I 50.36(c)(2)
=
50.73(a)(2)(v)(A)
I 73.71(a)(4) 20.2203(a)(2)fiv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or
=
in =
(If more space is re d use additionilcopiesof SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On June 6, 2002, CPSES Unit 2 was in Mode 1, Power Operation, operating at 100 percent power. At 1858 hours0.0215 days <br />0.516 hours <br />0.00307 weeks <br />7.06969e-4 months <br />, Operators (utility, licensed) in the Unit 2 Control Room received a "Generator Electronic Protection Failure Alarm." Maintenance personnel (utility, non-licensed) investigated and found faults indicated in Electronic Generator Protection cabinet 2-JC52 (EIIS: (CAB)), which contains the Channel 1 Primary Water Pump (EIIS:(P)) 2-01 Shaft Vibration Detector (EIIS:(DET)). The Primary Water Pump Shaft Vibration trip uses a 2 out of 2 channel logic with a trip setpoint of 6.3 volts. Voltage readings were taken on both vibration detector channels (EIIS:(CHA)), and the voltages measured on both channels were normal (3.6 volts and 3.5 volts), indicating that there was not an actual problem with pump vibration.
At 1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />, the Maintenance personnel returned to cabinet 2-JC52 and found that the conditions had changed. Channel 1 at that time was showing additional alarms and the voltage measured was zero. Maintenance and Operations personnel were evaluating the next course of action when, at 1924 hours0.0223 days <br />0.534 hours <br />0.00318 weeks <br />7.32082e-4 months <br />, a "Turbine Generator Channel 1 Primary Water Pump Vibration High" signal was received. This resulted in a Unit 2 Turbine Generator (EIIS:(TG)) trip which caused a trip of the Unit 2 Main Turbine (EIIS:(TRB)). The Unit 2 reactor (EIIS:(RCT))
automatically tripped on a "Turbine Trip >50% Power" signal. All control rods (EIIS: (AA))
fully inserted, and all Auxiliary Feedwater (EIIS:(BA)) pumps started automatically on Steam Generator (EIIS:(SG)) Lo-Lo level.
(If imoe space is requdreds use adduional copies of (If more space is requited, use additionl copies of NRC Form 36WA) (17)
III.
ANALYSIS OF THE EVENT
A.
SAFETY SYSTEM RESPONSES THAT OCCURRED The Reactor Protection System and The Auxiliary Feedwater System actuated during the event.
The Unit 2 reactor automatically tripped on a "Turbine Trip >50% Power" signal, and all three Auxiliary Feedwater pumps automatically started on "Steam Generator Lo-Lo water level" signals.
B.
DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY Not applicable - no safety system train was deemed inoperable.
C.
SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT This event is specifically bounded by the Final Safety Analysis Report (FSAR) accident analysis of the turbine trip presented in Section 15.2.3 of the CPSES FSAR. The analysis uses conservative assumptions to demonstrate the capability of pressure relieving devices and to demonstrate core protection margins. The event of June 6, 2002, occurred at 100 percent reactor power, and all systems and components functioned as designed. There were no safety system functional failures associated with this event.
Based on the above, it is concluded that the event of June 6, 2002, did not adversely affect the safe operation of CPSES Unit 2 or the health and safety of the public.
IV.
CAUSE OF THE EVENT
TXU Energy believes that a circuit breaker (EIIS:(BKR)) in Vibration Expansion Measuring cabinet 2-JM03 (EIIS: (CAB)) failed open which caused a spurious "Turbine Generator Channel 1 Primary Water Pump Vibration High" signal. Post trip troubleshooting using a replacement breaker revealed that when the channel 1 vibration detector circuit breaker is opened a voltage spike enters the channel 2 circuit, and this voltage spike on Channel 2 satisfies the "2 of 2" logic trip on the Primary Water Vibration Detector circuit.
(If more space i required. use additional copies of NRC Fonn 366A) (17)
V.
CORRECTIVE ACTIONS
The failed breaker has been replaced. The cause of the breaker failure is being determined through failure analysis techniques at a testing laboratory. Maintenance personnel received instruction related to blocking the Primary Water Pump vibration detector trip prior to working on the circuit, and Operations personnel were provided information on the trip via a lessons learned.
Engineering will evaluate other turbine/generator protection cabinets to determine if similar circuit designs exist. Digital upgrades planned for this equipment eliminate this circuitry thereby minimizing the probability of a single component failure generating a Turbine Generator trip signal. The Turbine Generator vendor (Siemens) has provided potential equipment modifications which could be implemented prior to the digital upgrade.
VI.
PREVIOUS SIMILAR EVENTS
There have been other previous events which resulted in a turbine trip followed by an automatic reactor trip. However, the causes of those events were sufficiently different such that the corrective actions taken for the previous events would not have prevented this event.