05000446/LER-2004-002, For Comanche Peak, Unit 2 Re Actuation of Specified System: Emergency Diesel Generator and Turbine Driven Auxiliary Feedwater Pump
| ML043640406 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/20/2004 |
| From: | Madden F TXU Power |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CPSES-200402777, TXX-04192 LER 04-002-00 | |
| Download: ML043640406 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4462004002R00 - NRC Website | |
text
- %TXU
~ "w Power TXU Power Comanche Peak Steam Electric Station P. O. Box 1002 (EO1)
Glen Rose, TX 76043 Tel: 254 897 5209 Fax: 254 897 6652 mike.blevinsbtxu.com Mike Blevins Senior Vice President &
Chief Nuclear Officer Ref: 10CFR50.73(a)(2)(iv)(A)
CPSES-200402777 Log# TXX-04192 December 20, 2004 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 SPECIFIED SYSTEMS:
EMERGENCY DIESEL GENERATOR AND TURBINE DRIVEN AUXILIARY FEEDWATER PUMP LICENSEE EVENT REPORT 446/04-002-00 Gentlemen:
Enclosed is Licensee Event Report (LER) 04-002-00 for Comanche Peak Steam Electric Station Unit 2, "Auto Start of the CPSES Unit 2 Train B Emergency Diesel Generator and the Turbine Driven Auxiliary Feedwater Pump."
This communication contains no new licensing basis commitments regarding CPSES Units 1 and 2.
/'
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
TXX-041 92 Page 2 of 2 Sincerely, TXU Generation Company LP By:
TXU Generation Management Company LLC Its General Partner Mike Blevins
/Fi'ed W. Madden Director, Regulatory Affairs TJE/te Enclosures c -
B. S. Mallett, Region IV W. D. Johnson, Region IV M. C. Thadani, NRR Resident Inspectors, CPSES
"Enclosure to TXX-04192 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMIB NO. 31500104 EXPIRES 06/302007 (6-2004)
Estimated the NRC may not conduct or
- sponsor, and a person is not required to respond to. the infoirnation collection Facility Name (I)
Docket Number (2)
Page (3)
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 1 OF 6 Tite (4)
ACTUATION OF SPECIFIED SYSTEM: EMERGENCY DIESEL GENERATOR AND TURBINE DRIVEN AUXILIARY FEEDWATER PUMP Event Date (5)
LERNumber (6)
Repor Date(7
- 1)
OtherFacilitieslnvolved(8)
Month Dsy Year Year Sequential Revision Month Day l
Year Facility Name Docket Numbers INumber I
Number I
I N/A 05000 10 19 04 04 002 12 20 04 05000 Operastig This ipot is submited pursuant to the requvements of 10 CFR* (Check altl that appry) (I 1_
Mode (9) 1 20.2201(b) 20.2203(a)(3Xi) 50.73(aX2Xi)(C) 50.73(aX2)Xvii)
Po" I
1 20.2201(d) 20.2203(X3Xii) 50.73(aX2)XiiXA) 50.73(a)(2 XviiiXA) f o 0
20.2203(a)(1) 20.2203(a)K4)
=
50.73(aX2Xii)(B)
=
50.73(aX2XViiiXB) 20.2203(aX2xi) 50.36(cX2XiXA) 50.73(aX)2Xiii) 50.73(a)X2XixX A) 20.2203(aX2Xii) 50.36{cX) 1)ii)A)
X 50.73(aX2)(iyXA) 50.72(a)X2Xx) 20.2203(aX)2Xiii) 50.36(cX2) 50.73(aX2XvXA)
I 73.71(aX4) 20.2203(aX2Xiv)
S0.46{aX3Xii)
=
50.73(aX2XvXB)
=
73.71(aXS) 20.2203(aX2Xv) 50.73(aX2)(i)(A)
=
50.73(aX2XvXC)
=
OTHER 20.2203(aX2Xvi) 50.73(aX2XiXB) 50.73(a)(2Xv)D)
Specify in Abstract below or in SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On October 19,2004 and before 0520, the DeCordova feeder line to the CPSES 138 kV switchyard was out of service due to maintenance on the CPSES switchyard circuit breaker [EIIS: (FD)(52)] and the associated DeCordova switchyard circuit breaker relays. The Stephenville feeder line was in service.
The two feeder lines to the CPSES 138 kV switchyard are from DeCordova and Stephenville switchyards. All five feeder lines to the CPSES 345 kV switchyard were in service.
At approximately 0520 on the same day, a circuit breaker in the Stephenville 138 kV switchyard tripped and failed to reclose causing the loss of power to the CPSES 138 kV switchyard. Loss of power to the 138 kV switchyard caused the loss of offsite power to the Unit 2 138/6.9 kV Startup Transformer XST1.
(If more space is required us Ca ional copies of (If more space is required, use addtional copies of (If more spce i require use addiional copies of NRC Fonm 366A) (17)
B.
DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY Not applicable -- However, the offsite 138 kV switchyard was inoperable from 0520 to 0606.
C.
SAFETY CONSEQUENCES AND IMPLICATIONS
Both Unit 2 Trains A and B blackout sequencers started which function to reload the associated 6.9 kV safeguards bus in a pre-established sequence following the undervoltage condition on the bus and re-energization from the alternate power source. When the time delay relay 27BX-l/STl was slow to time out at approximately 30 seconds instead of less than or equal to one-half second, as designed, the preferred 6.9 kV Train B feeder breaker did not open as expected and the Unit 2 Train B EDG started, but was not required to load because alternate 6.9 kV power was supplied from the CPSES 345 kV switchyard via the Startup Transformer XST2. As a result of the slow transfer to the alternate 6.9 kV source, the Unit 2 Train B safety bus lost power for approximately 30 seconds. The unanticipated start of the EDG is attributed to the delay in the tripping of the Train B 6.9 kV switchgear preferred feeder breaker during slow transfer of the Safeguards buses to their alternate source.
Because the Train A safeguards bus was unaffected by this event, this condition did not result in a safety system functional failure, under 10 CFR 50.73 (a)(2)(v).
Furthermore, there was no disruption in the non-safeguards loads required for normal plant operations because normal plant operations are unaffected by the loss of the 138 kV switchyard. Therefore, this event did not adversely affect the safe operation of CPSES Unit 2 or the health and safety of the public.
The Turbine Driven Auxiliary Feedwater Pump start is bounded within the existing accident analysis.
NRC FURlM 366A (i-200I)
I ' Enclosure to TXX-04192 NRC FORMI 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
Factliy Name (1)
Docket LER Nurnber(6)
Page(3)
Year Sequeltial RisRa i
on COMANCHE PEAK STEAM ELECTRC STATION UNIT 2 05000446 umbe P
05000446 04 H 002 00 6 OF 6 NARRATIVE (If more space is requirwed, us a ional copies of NRC Form 366A) (I 7)
IV.
CAUSE OF THE EVENT
The bus undervoltage relays should have caused both Train A 2EAI-1 and Train B 2EA2-1 circuit breakers to open in less than or equal to one-half second. 2EA1-1 operated correctly, but 2EA2-1 did not open for approximately 30 seconds. The Unit 2 Train B EDG started due to the bus undervoltage, but was not allowed to close its output breaker due to 2EA2-1 breaker remaining closed. TXU Power believes that the 27BX-1/STI undervoltage relay for 2EA2-1 was operating erratically causing the start of the Train B EDG.
The Turbine Driven Auxiliary Feedwater Pump started as designed.
V.
CORRECTIVE ACTIONS
The relay 27BX-1/ST was replaced with a new relay. The new relay was tested and within design specifications and subsequently placed in service. The defective relay was sent off site for a more detailed failure analysis to provide further understanding of the failure mechanism and potential extent of conditions for other similar Agastat relays on site.
VI.
PREVIOUS SIMILAR EVENTS
There was a previous event involving an Agastat relay on October 7, 2002. Specifically, LER 02-003-00 is related to the erratic behavior of an Agastat relay causing the unexpected auto start of the Unit 1 Train B EDG. Corrective actions from the previous 2002 event included development of a schedule to replace all of the 212 safety related relays and approximately 55% of the relays have been replaced. The schedule was based on availability and on risk of failure of these relays based on past calibration data and failure history.
This specific relay was scheduled to be tested and replaced, if required, on October 25, 2004 as a result of the previous event. This relay has been sent offsite for detailed failure analysis. The current completion date to replace the remaining safety related relays is December 31, 2005.