05000416/LER-2009-002, Regarding Emergency Diesel Actuation Caused by Degraded DC Control Battery
| ML091831263 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 07/02/2009 |
| From: | Perino C Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GNRO-2009/00034 LER 09-002-00 | |
| Download: ML091831263 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(x)(2) 10 CFR 50.73(x)(2)(iv) 10 CFR 50.73(x)(2)(v)(B) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2) 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)(iv)(A), System Actuation 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)(i)(B), Prohibited by Technical Specifications |
| 4162009002R00 - NRC Website | |
text
July 02, Dear S CLP/MJL ct :
r ched is 009 Regulatory Commix Document Control Desk gton, DC 20555-0001 report, please co Sincerely, t:
Grand G Docket ~
License No. NPF-29 2009-002 Emergency Diesel Actuation Caused by Degraded DC Control Battery If Nuclear Station, nsee Event Report {HER} 2009-002-00 which is a final This letter does not contain any commitme ext Page) any questions regarding this GNRO-2009/00034 July 02, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
LER 2009-002 Emergency Diesel Actuation Caused by Degraded DC Control Battery Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29
Dear Sir or Madam:
Attached is Licensee Event Report (LER) 2009-002-00 which is a final report.
This letter does not contain any commitments. Should you have any questions regarding this report, please contact Christina L. Perino at 601-437-6299.
Sincerely, CLP/MJL
attachment:
cc:
LER 2009~002-00 (See Next Page)
Page 2 U. S. Nuclear Regulatory Commission ATTN : Mr. Elmo E. Collins (w/a}
Regional Administrator, Region IV 612 East Lamar Drive. Suite 400 05 Regulatory NRR/ADRO/DORL (w/2)
ATTN : ADDRESSEE ONLY Delivery Only Rockville, MD 2085 GNRO-2009/00034 Page 2 cc:
NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 u. S. Nuclear Regulatory Commission ATTN: Mr. Elmo E. Collins (w/a)
Regional Administrator, Region IV 612 East Lamar Drive, Suite 400 Arlington, TX 76011-4005 u.S. Nuclear Regulatory Commission ATTN: Mr. Carl F. Lyon, NRR/ADRO/DORL (w/2)
ATTN: ADDRESSEE ONLY ATTN: Courier Delivery Only Mail Stop OWFN/8 81 11555 Rockville Pike Rockville, MD 20852-2378
NRC FORM 366 (9-2007)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
LEAR REGULATORY COMMISSION MONTH 05 DAY 05 YEAR 2009 100
- 6. LER NUMBER 2009 NIA SEQUENTIAL NUMBER 00 REPORT DATE MONTH 07 DAY 02 YEAR 2009 APPROVED BY OMB: NO. 3150-0104
, the not conduct or sponsor, and a person is not required to respond to, information collection.
GE 1 OF 4 Diesel Generator Actuation Caused by a Degra ER FACILITIES INVOLVED FACILITY NIA NAME FACILITY NAME NIA 11.T 20.2203(x) 20.2203(x)(2)(
p 20.2203(a)(2)(iv)
© 20.2203(a)(2)(v) p 20.2203(x)(2)
REQUIREMENTS OF 10 CFR§ : (Check all that apply) 50.
50 50.73(x)(2)(
50.73(x)(2)(iv) 50.73(x)(2)(v)(B) 50.73(a)(2)(v)(G) 50.73(a)(2)(v)(D) low LITY NAME L. Perino alter PPLEMENTAL REPORT EXPECTED YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO DOCKET NUMBER NIA DOCKET NUMBER NIA 601-4 7-6299 ude Area Code)
COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM ICOMPONENT I MA FACTURER RTABLE O EPIX MONTH DAY YEAR occurred. The actu ated a Load Shed and erator and Standby Service a degraded voltage con failing to open and clear a fault on over current in the required 3 to 5 cycles. The r and main breaker did not open due to low DD control voltage whi cted one ce cells were found to have u placed with a new 48 VDC battery ban ten DC
[~ 20.2203(x)(3)(
[:1 p 20.2203(a)(3)(ii)
© 20.2203(x)(4)
[]
n 50.36(c)(1)(i)(A)
[]
[] 50.36(c)(1)(ii)
© 50.36(
[l 50.46(a)(3)(ii)
[]
[l 50.73(a)(2)(i A)
[] 50.73(x)(2) )(B) 0 LICENSEE CON U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 NRC FORM 366 (9-2007)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
EXPIRES: 08/31/2010 the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 13. PAGE Grand Gulf Nuclear Station, Unit 1 05000416 1 OF 4
- 4. TITLE Emergency Diesel Generator Actuation Caused by a Degraded DC Control Battery
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR N/A N/A FACILITY NAME DOCKET NUMBER 05 05 2009 2009
- 002
- 00 07 02 2009 N/A N/A 1
100
- 10. POWER LEVEL
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) o 20.2201(d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) o 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B)
__------....0 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A) o 20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A)
~ 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) o 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 73.71 (a)(4) o 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) o 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
OTHER o 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME I
TELEPHONE NUMBER (InclUde Area Code)
Christina L. Perino, Licensing Manager 601-437-6299CAUSE MANU-REPORTABLE SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
MANU-SYSTEM COMPONENT FACTURER REPORTABLE TO EPIX N/A
- 14. SUPPLEMENTAL REPORT EXPECTED o YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
~NO
- 15. EXPECTED SUBMISSION DATE MONTH DAY YEAR ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On May 5, 2009 at 2327 hours0.0269 days <br />0.646 hours <br />0.00385 weeks <br />8.854235e-4 months <br /> Central Daylight Time, Grand Gulf Nuclear Station was in Mode 1 operating at approximately 100 percent power when a valid Engineered Safety Feature (ESF) actuation of the Division 1 Emergency Diesel Generator and Standby Service Water A occurred. The actuation occurred due to a degraded voltage condition on ESF Transformer 12 which initiated a Load Shed and Sequence on the 15AA bus, which required the EDG to start and supply AC power to the bus. The cause of the ESF actuation was a 90% bus undervoltage condition that lasted for greater than nine seconds due to feeder breaker 5X01 and main breaker 5X22 failing to open and clear a fault on over current in the required 3 to 5 cycles. The feeder breaker and main breaker did not open due to low DC control voltage which was caused by a degraded 48 VDC battery bank. The battery bank (24 cells) was inspected and found to have visual cell damage in one cell. Additional cell testing was performed on the battery bank and two of the tested cells were found to have unsatisfactory results. The degraded 48 VDC battery bank was replaced with a new 48 VDC battery bank on May 11, 2009 and the new battery is working properly. Additionally, breaker maintenance and testing was performed on breakers 5X01 and 5X22.
NRC FORM 366 (9-2007)U.S. NUCLEAR REGULATORY COMMISSI (9-2007)
LICENSEE EVENT REPORT (LER}_
operating the Divisio d. The a Nuclear Station Diesel Generator (Referen ESF actuation of SSW A (Referen CILI rs Central Daylight Time (C rcent power when a v ification was made to the NRC's Emergency Station was in Mode 1 neered Safety Feature (ESF) actuation of ndby Service Water (SSW) [BS] A d due to a degraded voltage condition on ESF Transformer 12 [XFMR]
nd Sequence (LSS) on the 15AA bus [EB], which required the EDG to start The following occurrences were considered reportable :
At the time of the event, the reactor was in OPERATIONAL MODE 1 with reactor power at approximately There were no additional inoperable structures, systems, or components at the start of the ion of the event. At the time of the event, Service Transformer 21 was nce. but did not contribute to the initiation of the event.
INITIAL CONDITIONS required loads DESCRIPTION OF OCCURRENCE d Engineered Safety Feature actuation for Division 1 Emergency AC power for the 15AA bus occurred at 2327 hours0.0269 days <br />0.646 hours <br />0.00385 weeks <br />8.854235e-4 months <br /> CDT on May 5, 2009 due to a degraded voltage condition on ESF Transformer Figure 1. ESF Transformer 12 was out of service for maintenance. A X22 provided to assist wi supplying power to the 15AA bus due to Service Transformer fault occurred on the site power loop at switch 389-2901 S i
When power switch 389-2901 S faulted, both breakers failed to trip at the prescri about 21 seconds later, the site power onded and caused the transformer nd the motor operated air breaker 2.
t UENTIAL breakers should have cleared the fault in 3 to 5 cycles.
loop 115 kV/1 3.8 kV transformer high over current backup differential lockout relay to activate, sending trips to main brea switch J3872 at which point the fault cleared.
REV 002 --
00 1
2 of ystem {ENS} reporting this condition pursuant d this event is reported under 10 CFR edition, the voltage on the incoming 115 kV offsite power circuit from Port Gibson degraded t Undervoltage-PU or 88.3%) and persisted for approximately 21 seconds until the fault cleared. Since the Division 1 ESF 15AA bus was aligned to receive power from the ESF Transformer 12 and the 115 kV line offsite power circuit from Port Gibson, the protective settings for the 15AA bus Division 1 Load Shed and Sequencing panel were met for the sustained (21 seconds) degraded lues of 0.9 PU for 9 seconds. This resulted in the LSS panel tripping the incoming feeder breaker
- - 1511) to the 15AA bus from ESF Transformer 12, stripping the loads from the bus, starting the Division the EDG to the 15AA bus when voltage and frequency were st e bus.
I U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I SEQUENTIAL I REV YEAR NUMBER NO.
Grand Gulf Nuclear Station Unit 1 05000416 2009 002 --
00 2
of 4
A. REPORTABLE OCCURRENCE On May 5, 2009 at 2327 hours0.0269 days <br />0.646 hours <br />0.00385 weeks <br />8.854235e-4 months <br /> Central Daylight Time (CDT), Grand Gulf Nuclear Station was in Mode 1 operating at approximately 100 percent power when a valid Engineered Safety Feature (ESF) actuation of the Division 1 Emergency Diesel Generator (EDG) [EK] and Standby Service Water (SSW) [8S] A occurred. The actuation occurred due to a degraded voltage condition on ESF Transformer 12 [XFMR]
which initiated a Load Shed and Sequence (LSS) on the 15M bus [EB], which required the EDG to start and supply AC power to the bus. The following occurrences were considered reportable:
ESF actuation of Emergency Diesel Generator (Reference: 10 CFR 50.73(a)(2)(iv) (A) & (B)(8))
ESF actuation of SSW A (Reference: 10 CFR 50.73(a)(2)(iv) (A) &(B)(9))
Notification was made to the NRC's Emergency Notification System (ENS) reporting this condition pursuant to 10 CFR 50.72(b)(3)(iv)(A) and 10CFR50.72(b)(3)(iv)(B)(8) and this event is reported under 10 CFR 50.73(a)(2)(iv)(A).
B.
INITIAL CONDITIONS At the time of the event, the reactor was in OPERATIONAL MODE 1 with reactor power at approximately 100 percent. There were no additional inoperable structures, systems, or components at the start of the event that contributed to initiation of the event. At the time of the event, Service Transformer 21 was removed from service for planned maintenance, but did not contribute to the initiation of the event.
C.
DESCRIPTION OF OCCURRENCE A valid Engineered Safety Feature actuation for Division 1 Emergency AC power for the 15M bus occurred at 2327 hours0.0269 days <br />0.646 hours <br />0.00385 weeks <br />8.854235e-4 months <br /> CDT on May 5, 2009 due to a degraded voltage condition on ESF Transformer 12. A simplified drawing is provided to assist with explanation of the event in Figure 1. ESF Transformer 12 was supplying power to the 15M bus due to Service Transformer 21 being out of service for maintenance. A fault occurred on the site power loop at switch 389-2901 S initiating trip signals to breakers 5X01 and 5X22.
When power switch 389-2901 S faulted, both breakers failed to trip at the prescribed settings. These breakers should have cleared the fault in 3 to 5 cycles. However, about 21 seconds later, the site power loop 115 kV/13.8 kV transformer high over current backup circuitry responded and caused the transformer differential lockout relay to activate, sending trips to main breaker 5X22 and the motor operated air breaker switch J3872 at which point the fault cleared.
During the fault condition, the voltage on the incoming 115 kV offsite power circuit from Port Gibson degraded to 101.5 KV (approximately 0.883 Percent Undervoltage-PU or 88.3%) and persisted for approximately 21 seconds until the fault cleared. Since the Division 1 ESF 15M bus was aligned to receive power from the ESF Transformer 12 and the 115 kV line offsite power circuit from Port Gibson, the protective settings for the 15M bus Division 1 Load Shed and Sequencing panel were met for the sustained (21 seconds) degraded grid values of 0.9 PU for 9 seconds. This resulted in the LSS panel tripping the incoming feeder breaker (152-1511) to the 15M bus from ESF Transformer 12, stripping the loads from the bus, starting the Division 1 EDG, connecting the EDG to the 15M bus when voltage and frequency were stable, and sequencing the required loads to the bus.
/U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE RT (LER) 1. FACILITY NAME KET ER I
SEQUENTIAL REV YEAR NUMBER I
NO.
05000416 2009
-- 002 of 4
ly the SSW A system automatically started due to the required cooling water to support EDG operation.
DESCRIPTION OF OCCURRENCE (co Operators implemented appropriate off normal event procedures to mitigate the transient and all systems following the event, responded as designed. The faulted electrical switch 389-2109S was found smol fire brigade was di and emitting s due to the fire s APPARENT CAUSE
CORRECTIVE ACTIONS
SAFETY ASSESSMENT
ADDITIONAL INFORMATION
hing.
The cause of the ESF actuation was a 90% bus undervoltage condition that lasted for greater seconds due to feeder breaker 5XO1 and main breaker 5X22 failing to open and clear a fault on over current fired 3 to 5 cycles. The 5XO1 and 5X22 breakers did not open in the requi which was caused by a degraded 48 VDC battery bank [BTRY]. The battery bank (24 cells) was inspected and found to have visual cell damage in one cell. Additional cell, testing was performed on the battery bank and two of the tested cells were found to have unsatisfactory results battery bank in question is 13 years old, located in an outside metal building, and maintained by Entergy Immediate Corrective Actions - The degraded 48 VDC battery bank was replaced with a new 48 VDC battery bank on May 11, 2009 and the new battery is working properly. Additionally, breaker main and testing was performed on breakers 5XO1 and 5X22.
Long Term Corrective Actions - Condition Report GGN-2009 additional actions.
23 failures. The Division 1 LSS initiation, EDG start to supp Standby Service Water A system to cool the EDG, all respon provided, the health and safety of the public was not compromise 7 was written an will address any were no safety system functional 15AA bus. and start of the on the discussion Previous Similar Events - There has not been any occurrence of the same underlying concern in the pas years at Grand Gulf Nuclear Station. U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I SEQUENTIAL I
~~~
YEAR NUMBER Grand Gulf Nuclear Station Unit 1 05000416 2009 002 --
00 3
of 4
C.
DESCRIPTION OF OCCURRENCE (cont.)
Additionally the SSW A system automatically started due to the Division 1 EDG starting. It provided the required cooling water to support EDG operation.
Operators implemented appropriate off normal event procedures to mitigate the transient and all systems, following the event, responded as designed. The faulted electrical switch 389-21 09S was found smoldering and emitting smoke. The onsite fire brigade was dispatched but no extinguishing agents were administered due to the fire self-extinguishing.
D.
APPARENT CAUSE The cause of the ESF actuation was a 90% bus undervoltage condition that lasted for greater than nine seconds due to feeder breaker 5X01 and main breaker 5X22 failing to open and clear a fault on over current in the required 3 to 5 cycles. The 5X01 and 5X22 breakers did not open in the required 3 to 5 cycles due to low DC control voltage, which was caused by a degraded 48 VDC battery bank [BTRY]. The battery bank (24 cells) was inspected and found to have visual cell damage in one cell. Additional cell-testing was performed on the battery bank and two of the tested cells were found to have unsatisfactory results. The battery bank in question is 13 years old, located in an outside metal building, and maintained by Entergy, Mississippi personnel.
E.
CORRECTIVE ACTIONS
Immediate Corrective Actions - The degraded 48 VDC battery bank was replaced with a new 48 VDC battery bank on May 11, 2009 and the new battery is working properly. Additionally, breaker maintenance and testing was performed on breakers 5X01 and 5X22.
Long Term Corrective Actions - Condition Report GGN-2009-2347 was written and will address any additional actions.
F.
SAFETY ASSESSMENT
This event did not prevent the fulfillment of a safety function and there were no safety system functional failures. The Division 1 LSS initiation, EDG start to supply AC power to the 15M bus, and start of the Standby Service Water A system to cool the EDG, all responded as expected. Based on the discussion provided, the health and safety of the public was not compromised by this event.
G.
ADDITIONAL INFORMATION
Previous Similar Events There has not been any occurrence of the same underlying concern in the past five years at Grand Gulf Nuclear Station.(9-2007)
LICENSEE EVENT REPORT (LER)
LI Grand Gulf Nuclear 05000416 U.S. NUCLEAR REGULATORY COMMISSION YEAR NTIAL REV BER NO,
__ 002 --
00 of T=sf rm F 1'121 Bus Motor Operated Tr f r 5kvll!
OWER LOOP AROUND SI OHER SWITCHES SURROUND SITE l7A BAY L U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I SEQUENTIAL I REV YEAR NUMBER NO.
Grand Gulf Nuclear Station Unit 1 05000416 2009 002 00 4
of 4
Figure 1 - Simplified Drawing Motor BACK-UP SITE POWER *LOOP 115kv TI3DSfOJJIlel' 115kv113~8 BAY # 7 SITE POWER lOOP AROUND SITE OHfR §;W1TCHES SURROUND SITE
...." 7