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{{Adams
#REDIRECT [[05000247/LER-2009-001]]
| number = ML12334A485
| issue date = 07/20/2009
| title = Official Exhibit - NYS000025-00-BD01 - Exelon Nuclear, Licensee Event Report 09-001-00, Automatic Reactor Scram Due to Failure of Main Power Transformer Surge Arrestor, LaSalle County Station Unit 1 (Jul. 20, 2009)
| author name = Rhoades D
| author affiliation = Exelon Generation Co, LLC, Exelon Nuclear
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000247, 05000286
| license number =
| contact person = SECY RAS
| case reference number = RAS 21523, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01
| document report number = LER-09-001-00
| document type = Legal-Exhibit
| page count = 5
}}
 
=Text=
{{#Wiki_filter:United States Nuclear Regulatory Commission Official Hearing Exhibit In the Matter of:
Entergy Nuclear Operations, Inc.                            NYS000025 (Indian Point Nuclear Generating Units 2 and 3)
Submitted: December 12, 2011 ASLBP #: 07-858-03-LR-BD01 Docket #: 05000247 l 05000286 Exhibit #: NYS000025-00-BD01                  Identified: 10/15/2012 Admitted: 10/15/2012                        Withdrawn:
Rejected:                                      Stricken:
~  __-=========================================~____________________~==~~~~~~SM Other:
Exelon Generation Company, LLC LaSalle County Station www.exeloncorp.com Nuclear 2601 North 21" Road Marseilles, IL 61341-9757 July 20, 2009 10 CFR 50.73 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 LaSalle County Station, Units 1 and 2 Facility Operating License No. NPF 11 and 18 NRC Docket No. 50-373 and 50-374
 
==Subject:==
Licensee Event Report In accordance with 10 CFR 50.73 (a)(2)(iv)(A), Exelon Generation Company, (EGC), LLC, is submitting Licensee Event Report Number 09-001-00, Docket No. 050-373.
Should you have any questions concerning this letter, please contact Mr. Terrence W. Simpkin, Regulatory Assurance Manager, at (815) 415-2800.
Respectfu Ily, David P. Rhoades Plant Manager LaSalle County Station
 
==Attachment:==
Licensee Event Report cc:        Regional Administrator - NRC Region III NRC Senior Resident Inspector - LaSalle County Station OAGI0001042_00001
 
NRC FORM 366                            U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104                                          EXPIRES: 08/31/2010 (9-2007)
Estimated burden per response to comply with this mandatory collection request: 80 hours. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIAlPrivacy Service Branch (T-5 F52), U.S.
LICENSEE EVENT REPORT (LER)                                            Nuclear Regulatory CommisSion, Washington, DC 20555-0001, or by internet e-mail to infocollects@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information (See reverse for required number of                                  collection does not display a currently valid OMB control number, the NRC may digits/characters for each block)                                not conduct or sponsor, and a person is not required to respond to, the infnrm::ltinn r.oIlAr.tinn.
: 1. FACILITY NAME                                                                          2. DOCKET NUMBER                      13. PAGE LaSalle County Station Unit 1                                                                      05000373                                1 OF 4
: 4. TITLE Automatic Reactor Scram Due to Failure of Main Power Transformer Surge Arrestor
: 5. EVENT DATE                6. LER NUMBER                7. REPORT DATE                                    8. OTHER FACILITIES INVOLVED FACILITY NAME                                        DOCKET NUMBER MONTH      DAY      YEAR    YEAR I SEQUENTIAL I REV      MONTH      DAY          YEAR      LaSalle County Station Unit 2                            05000374 NUMBER      NO.
FACILITY NAME                                        DOCKET NUMBER 05      21      2009 2009         - 001     - 00      07      20          2009
: 9. OPERATING MODE                  11. THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) o  20.2201 (b)                  o  20.2203(a)(3)(i)                o 50.73(a)(2)(i)(C)                  o  50.73(a)(2)(vii) 1              o  20.2201 (d)                  o  20.2203(a)(3)(ii)                o 50.73(a)(2)(ii)(A)                o  50.73(a)(2)(viii)(A) o  20.2203(a)(1)                o  20.2203(a)(4)                    o 50.73(a)(2)(ii)(S)                o  50.73(a)(2)(viii)(S) o  20.2203(a)(2)(i)              o  50.36(c)(1 )(i)(A)              o 50.73(a)(2)(iii)                  o  50.73(a)(2)(ix)(A)
: 10. POWER LEVEL              o  20.2203(a)(2)(ii)            o  50.36(c)(1 )(ii)(A)              181 50.73(a)(2)(iv)(A)              o  50.73(a)(2) (x) o  20.2203(a)(2)(iii)            o  50.36(c)(2)                      o 50.73(a)(2)(v)(A)                  o  73.71 (a)(4) 100              o  20.2203(a)(2) (iv)            o  50.46(a)(3)(ii)                  o 50.73(a)(2)(v)(S)                  o  73.71 (a)(5) o  20.2203(a)(2)(v)              o  50.73(a) (2) (i)(A)              o 50.73(a)(2)(v)(C)                  o  OTHER o  20.2203(a)(2)(vi)            o  50.73(a)(2)(i)(S)                o 50.73(a)(2)(v)(D)                    Specify in Abstract below or in NRC Form 366A
: 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME                                                                                                                I~ELEPHONE NUMBER (Include Area Code)
Cindy Snyder, Design Engineering                                                                                          815-415-2919
: 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT MANU-        REPORTABLE                                                                MANU-          REPORTABLE CAUSE        SYSTEM    COMPONENT                                                CAUSE            SYSTEM COMPONENT FACTURER          TO EPIX                                                                FACTURER          TO EPIX B            EL          LAR          Joslyn              y
: 14. SUPPLEMENTAL REPORT EXPECTED                                                    15. EXPECTED            MONTH        DAY        YEAR SUBMISSION DYES (/fyes, complete 15. EXPECTED SUBMISSION DATE)                                181 NO                        DATE ASSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On May 21, 2009, at 1635 COT, LaSalle Unit 1 automatically scrammed from 100% power. The scram was due to a generator lockout signal caused by a failure of the surge arrester on the 'A' phase of the Unit 1 West Main Power Transformer (1W MPT).
The safety significance of this event was minimal. All control rods fully inserted, all systems responded as expected to the scram, and Emergency Core Cooling Systems were not challenged. The voltage transient caused by the arrestor failure resulted in a number of invalid alarms and isolations on both Units.
The cause of the surge arrester failure was determined to be a manufacturing defect. Corrective actions included verifying that the 1W MPT had not been damaged by the event, and replacing the failed surge arrester. Additionally, future procurements of station surge arresters will require that the vendor supply the test data.
NRC FORM 366 (9-2°07)                                                                                                                      PRINTED ON RECYCLED PAPER OAGI0001042 00002
 
NRC FORM 366A                          LICENSEE EVENT REPORT (LER) u.s. NUCLEAR REGULATORY COMMISS (9-2007)
CONTINUATION SHEET
: 1. FACILITY NAME          2. DOCKET            6. LER NUMBER                  3. PAGE LaSalle County Station Unit 1                  05000373 YEAR 1    SEQUENTIAL NUMBER 1REV NO.
2      OF    4 2009      -    01    -  00 NARRATIVE A.        PLANT AND SYSTEM IDENTIFICATION General Electric - Boiling Water Reactor, 3489 Megawatts Thermal Rated Core Power CONDITION PRIOR TO EVENT Unit(s): 1                    Event Date: 5/21/09                Event Time: 1635 Reactor Mode(s): 1            Power Level(s): 100 Mode(s) Name: Power Operation B.        DESCRIPTION OF EVENT On May 21,2009, at 1635 CDT, LaSalle Unit 1 automatically scrammed from 100% power. The scram was due to a generator lockout signal caused by a failure of the surge arrester on the 'A' phase of the Unit 1 West Main Power Transformer (1W MPT) (MP)[EL]. Deluge protection of the 1W MPT actuated and no fire resulted from the arc caused by the surge arrester failure.
Following the scram, reactor water level was restored using the Motor Driven Reactor Feed Pump (FW)[SJ], and pressure control was established with the Main Condenser (CD)[SG] via the turbine bypass valves.
The surge arrester failure caused a voltage transient on both LaSalle Units. On Unit 2, the 24B and 25B Low Pressure Feedwater Heaters (HD)[SM] and the 24C Low Pressure Heater Normal Drain tripped, which forced a reduction in reactor power to approximately 85%. The voltage transient also resulted in a number of other non-valid isolation signals, including Reactor Water Cleanup (RT) [CE] and Reactor Building Ventilation (VR)[VA]. The VR system isolated on both Units 1 and 2.
Unit 2 returned to full power on May 22,2009, at 1100 CDT. Following replacement of the 1W MPT 'A' phase surge arrester and verification that the MPT had not been damaged, Unit 1 was restarted on May 23,2009, and was synchronized to the grid on May 25,2009. The Unit returned to full power at 1412 CDT on May 27,2009.
An Emergency Notification System call was made at 1946 CDT on May 21, 2009, in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an event or condition that resulted in actuation of the reactor protection system when the reactor was critical.
C.        CAUSE OF EVENT A forensic analysis was performed on the failed surge arrester. The analysis determined that the root cause was a manufacturing defect. The glass tape used to hold together the metal oxide blocks inside the arrester was folded and wedged between the metal oxide blocks in two
* NRC FORM 366A (9-2007)                                                                        PRINTED ON RECYCLED PAPE OAGI0001042 00003
 
NRC FORM 366A                            LICENSEE EVENT REPORT (LER) u.s. NUCLEAR REGULATORY COMMISS (9-2007)
CONTINUATION SHEET
: 1. FACILITY NAME            2. DOCKET            6. LER NUMBER                  3. PAGE LaSalle County Station Unit 1                    05000373 YEAR    I  SEQUENTIAL NUMBER I REV NO.
3      OF    4 2009      -    01    -  00 NARRATIVE different areas, which prevented face-to-face contact between the blocks. As a consequence, under normal operating conditions an air gap existed between the blocks, leading to uneven current flow through adjacent blocks. Surges from normal switching operation and lightning strikes in the years following the installation caused punctures near the edge of the affected blocks.
Although all arresters are tested prior to shipping, the defect in this arrester was either not detected by the factory testing or the defective arrester was not discarded upon identification of the defect. It is the opinion of the vendor that this defect should have been identified in production testing. Retrieval of the original Joslyn test reports is no longer possible. The arresters were satisfactorily Doble tested on site prior to installation, but this test was not capable of identifying the defect.
As a result of Doble test results in 2004, the original1W MPT 'A' phase surge arrester was replaced, along with the 1 East (1 E) MPT 'A' phase surge arrester. The Joslyn Manufacturing Co. (now Maclean Power System) ZSH series (MOV-Metal Oxide Varistor) station class surge arresters were selected to replace the original Westinghouse CPl series silicon carbide gapped surge arresters because they use metal oxide technology, which represented an improved design over the silicon carbide gap type arresters.
These arresters performed without problems until the day of the event. On April 30, 2009, a temperature scan of the Unit 1 transformers was performed and no differential temperatures were noted on either the MOV or silicon carbide arresters. Due to the manufacturer defect, degradation of the arrester would have started with the installation in 2004, but the degradation did not result in significant heat generation due to the low current in the arrester. Therefore, thermography did not identify the defect.
D.        SAFETY ANALYSIS The safety significance of this event was minimal. All control rods fully inserted and all systems responded as expected to the scram. The Emergency Core Cooling Systems were not challenged. This event did not meet the NEI 99-02 definition of an unplanned scram with complications. There were no safety system functional failures.
E.      CORRECTIVE ACTIONS Corrective Actions:
* The 'A' phase arresters were replaced on both the 1E and 1W MPT.
* The 1E and 1W MPTs were tested to verify that they had not been degraded as a result of the transient.
NRC FORM 366A (9-2007)                                                                            PRINTED ON RECYCLED PAPE OAGI0001042 00004
 
NRC FORM 366A                              LICENSEE EVENT REPORT (LER)          U_S_ NUCLEAR REGULATORY COMMISS (9-2007)
CONTINUATION SHEET
: 1. FACILITY NAME              2. DOCKET          6. LER NUMBER                  3. PAGE LaSalle County Station Unit 1                        05000373 YEAR  I  SEQUENTIAL NUMBER      I REV NO.
4      OF    4 2009      -  01      -  00 NARRATIVE Corrective Action to Prevent Recurrence:
* Procurement requirements will be changed to require that vendor test data be supplied for future station surge arrester purchases. (AT# 923160-15)
F.        PREVIOUS OCCURENCES LaSalle Station has not previously experienced a failure of a surge arrester.
G.        COMPONENT FAILURE DATA Joslyn ZSH Metal Oxide Arrester with 264kV Rating NRC FORM 366A (9-2007)                                                                            PRINTED ON RECYCLED PAPE OAGI0001042 00005}}

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