05000445/LER-2010-001, Loss of XST1 Due to Breakers 7030 and 7040 Opening as a Result of a B-Phase to Ground Fault
| ML101680412 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 06/07/2010 |
| From: | Flores R Luminant Generation Co, Luminant Power |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CP-201000603, TXX-10063 LER 10-001-00 | |
| Download: ML101680412 (6) | |
| 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)(ii)(B), Unanalyzed Condition 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)(x) 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 |
| 4452010001R00 - NRC Website | |
text
Rafael Flores Senior Vice President
& Chief Nuclear Officer rafael.flores@Luminant.com Luminant Power P 0 Box 1002 6322 North FM 56 Glen Rose, TX 76043 Luminant 254 897 5550 C 817 559 0403 F 254 897 6652 CP-201000603 Log # TXX-10063 Ref. # 10CFR50.73(a)(2)(iv)(A)
June 7, 2010 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NOS. 50-445 and 50-446 LOSS OF XST1 DUE TO BREAKERS 7030 AND 7040 OPENING AS A RESULT OF A B-PHASE TO GROUND FAULT LICENSEE EVENT REPORT 446/10-001-00
Dear Sir or Madam:
Pursuant to 10CFR50.73(a)(2)(iv)(A), Luminant Generation Company LLC (Luminant Power) hereby submits enclosed Licensee Event Report (LER) 446/10-001-00, "Loss of XST1 Due to Breakers 7030 and 7040 Opening As a Result of a B-Phase to Ground Fault." This event did not result in a safety system functional failure. This event did not affect the health and safety of the public or plant personnel.
This communication contains no licensing basis comnmitments regarding Comanche Peak Units I and 2.
Should you have any questions, please contact Ms. Tamera J. Ervin-Walker at (254)897-6902.
Sincerely, Luminant Generation Company LLC Rafael Flores BY:Kd/72*L-*
By:F~rdW. Madden Director, Oversight & Regulatory Affairs TJEW Enclosure c -
E. E. Collins, Region IV Balwant Singal, NRR Resident Inspectors, Comanche Peak A member of the STARS (Strategic Teaning and Resource Sharing) Alliance Callaway ' Comanche Peak ' Diablo Canyon
- Palo Verde - Sai Onofre
- South Texas Project
- Wolf Creek
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION ffPIROYED BY OMB NO. 3150-0104 EXPIRES:
(9-2007)
OIl uLu
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Comanche Peak Nuclear Power Plant (CPNPP) Unit 2 05000 446 1 OF5
- 4. TITLE LOSS OF XST1 DUE TO BREAKERS 7030 AND 7040 OPENING AS A RESULT OF A B-PHASE TO GROUND FAULT
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SFACILITY NAME DOCUMENT NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR CINP M
Unit 1 5000 44 NUMBER NO.
CPNPP Unit 1 05000445 04 12 2010 2010
-- 001 --
0 06 07 2010 FACILITY NAME DOCUMENTNUMBER I
05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
LI 20.2203(a)(3)(i)
[1 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 [1] 20.2201(d)
LI 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A)
[]
50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4) 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[] 20.2203(a)(2)(i)
[] 50.36(c)(1)(i)(A)
[]
50.73(a)(2)(iii)
H 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL E]
20.2203(a)(2)(ii)
[] 50.36(c)(1)(ii)(A)
[]
50.73(a)(2)(iv)(A)
[]
50.73(a)(2)(x)
E] 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
E]
50.73(a)(2)(i)(A)
E]
50.73(a)(2)(v)(C)
El OTHER 100 El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(O)
VOLUNTARY LER
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Timothy A. Hope, Nuclear Licensing Manager 254-897-6370CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION L
YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
L NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 12, 2010 at approximately 0720, CPNPP experienced a phase-to-ground fault between Startup Transformer XST1 and the 138kV switchyard while Unit 2 was operating at 100% power and Unit 1 was off-line for refueling. Alarms were received in the Unit 2 control room indicating that Startup Transformer XST1 was de-energized, which caused a slow transfer of the Unit 2 Class 1 E buses to XST2. The Unit 2 blackout sequencers actuated, and the Unit 2 motor-driven feedwater pumps and turbine-driven auxiliary feedwater water pump automatically started. The reactor operator reduced turbine load by 50 mega-watts electric. Spent Fuel Pool (SFP) cooling pumps, common to both Units, were load shed by design due to Unit 2 blackout sequencer actuation, and subsequently restarted by procedure. Investigation determined a B-phase insulator on a 138kV transmission tower had black marks and foreign material hanging down. Eight hours later the insulator was replaced and XST1 was restored as the preferred offsite power source to the Unit 2 Class 1E buses.
All times in this report are approximate and are Central Daylight Time unless noted otherwise.
NRC FORM 366 (9-2007)
PRINTED ON RECYCLED PAPER (If more space is required, use additional copies of SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES:
On April 12, 2010, Comanche Peak Nuclear Power Plant (CPNPP) Unit 1 was de-fueled as part of the 1RF14 refueling outage and CPNPP Unit 2 was in Mode 1 operating at 100% power. At 0720, CPNPP experienced a loss of power to startup transformer XST1 [EIIS: (XFMR)] which is the preferred offsite power source to the Unit 2 Class 1 E buses and the alternate power source for Unit
- 1. The Control Room (CR) Operators (Utility, Licensed) entered Technical Specification (TS) 3.8.1 Limiting Condition for Operation (LCO), Condition A for one required source of offsite power inoperable.
Unit 2 momentarily lost power to the Trains A and B safeguards buses during the automatic transfer to the alternate offsite power source. The loss of power to XST1 caused a signal to be sent to the Unit 2 Trains A and B Blackout Sequencers (BOSs) [ElIS: (JE)]. The BOSs then started the Unit 2 engineered safety feature equipment, including both motor-driven Auxiliary Feedwater (AFW) pumps [ElIS: (BA)] and the Turbine-Driven AFW pump [EIIS: (BA)]. CR Operators (Utility, Licensed) responded and reduced the Unit 2 output power by 50 mega-watts electric. Furthermore, the Spent Fuel Pool (SPF) cooling pumps [EIIS: (DA)] which are common to both Units 1 and 2 were automatically load shed by the BOS as designed.
The SFP pumps are common to both Units and were shutdown as designed. At that time, the Unit 1 core was off loaded into the SPF with a time to boil of 6.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The SFP cooling pumps were restored by procedure within six minutes.
During this event, CPNPP equipment operators (Utility, Non-Licensed) were observing the satisfactory starts on various safeguard equipment; however, the equipment operators reported vapor in the vicinity of the outboard pump shaft packing in the area of the Unit 2, Train A, motor-driven AFW pump. Not knowing the exact condition of the motor-driven AFW pump, the CR Operators (Utility, Licensed) conservatively entered TS LCO 3.7.5, Condition B for one Train of AFW inoperable.
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
IV. CAUSE OF THE EVENT
Investigation determined that the phase B insulator on a 138kV transmission tower between XST1 and the 138kV switchyard had black marks and foreign material hanging down on the north side of
- the insulator. The foreign material turned out to be'a vine that contacted the top and bottom skirt of the insulator, precipitating the fault. The vine was brought tothe insulator's mounting adaptor by a bird for nest building. The design of the mounting adapter used as a connection mechanism between the under-slung insulators and tower pedestal allows birds to use the mounting adapter openings as sites for nest building. The nest building material came in contact with the top and bottom skirt of the phase B insulator on the 138kV line.
V. CORRECTIVE ACTIONS
Immediate actions included replacement of the insulator and restoration of XST1 as the preferred offsite power source to the Unit 2 Class 1 E buses. The insulator mounting adapters will be modified to reduce the probability of nest building.
VI. PREVIOUS SIMILAR EVENTS
There have been no previous similar reportable events at CPNPP in the last three years.PRINTED ON RECYCLED PAPER