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| {{Adams
| | #REDIRECT [[05000387/LER-2013-001, Regarding Diesel Generator B to Bus 2B Synchronizing Selector Switch Failure]] |
| | number = ML13309A632
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| | issue date = 11/04/2013
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| | title = Regarding Diesel Generator B to Bus 2B Synchronizing Selector Switch Failure
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| | author name = Franke J
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| | author affiliation = PPL Susquehanna, LLC
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| | addressee name =
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| | addressee affiliation = NRC/Document Control Desk, NRC/NRR
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| | docket = 05000387, 05000388
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| | license number = NPF-014, NPF-022
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| | contact person =
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| | case reference number = PLA-7082
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| | document report number = LER 13-001-01
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| | document type = Letter, Licensee Event Report (LER)
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| | page count = 6
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| }}
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| {{LER
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| | Title = Regarding Diesel Generator B to Bus 2B Synchronizing Selector Switch Failure
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| | Plant =
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| | Reporting criterion = 10 CFR 50.73(a)(2)(i)(B), 10 CFR 50.73(a)(2)(i), 10 CFR 50.73(a)(2)(vii), 10 CFR 50.73(a)(2)(ii)(A), 10 CFR 50.73(a)(2)(viii)(A), 10 CFR 50.73(a)(2)(ii)(B), 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), 10 CFR 50.73(a)(2)(x), 10 CFR 50.73(a)(2)(v)(A), 10 CFR 50.73(a)(2)(v)(B), 10 CFR 50.73(a)(2)(i)(A), 10 CFR 50.73(a)(2)(v)
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| | Power level =
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| | Mode =
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| | Docket = 05000387
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| | LER year = 2013
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| | LER number = 1
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| | LER revision = 1
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| | Event date =
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| | Report date =
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| | ENS =
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| | abstract =
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| }}
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| =text=
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| {{#Wiki_filter:NOV 0 4 2013 Jon A. Franke Site Vice President U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.2904 Fax 570.542.1504 jfranke@ pplweb.com SUSQUEHANNA STEAM ELECTRIC STATION (SSES)
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| LICENSEE EVENT REPORT 50-387/2013-001-01 LICENSE NOS NPF-14 and NPF-22 Docket Nos. 50-387 and 50-388 PLA-7082
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| ==Reference:==
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| PPL letter PI.A-7041, J. A. Franke (PPL) to USNRC (Document Control Desk),
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| "Susquehanna Steam Electric Station, License Event Report 50-38712013-001-00, License Nos. NPF-14 and NPF-22," dated July 8, 2013.
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| Attached is supplemental Licensee Event Report (LER) 50-387/2013-001-01, submitted to provide additional information associated with the condition in which the SSES Diesel Generator 'B' to 4.16 kV bus '2B' synchronizing selector switch failed. This resulted in a condition that is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as any operation or condition which was prohibited by the SSES Technical Specifications.
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| There were no actual consequences to the health and safety of the public as a result of this event.
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| There are no regulatory commitments associated with this LER.
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| J A. Franke Attachment: LER 50-387/2013-001-01 Copy:
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| NRC Region I Mr. J. W. Greives, NRC Sr. Resident Inspector Mr. J. A. Whited, NRC Project Manager Mr. L. J. Winker, PA DEP/BRP
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| NRC FORM366 U.S. NUCLEAR REGULATORY
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| \\(PPROVED BY OMS: NO. 3150-0104 EXPIRES:10/31/2013 (1Q-2010)
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| COMMISSION Estimated burden per response to comply with this mandatory collection request: 80 hours. Reported lessons learned are incorporated into the rensing process and fed back to industry. Send comments regarding burden estimate to the FOIA/Privacy Section (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to LICENSEE EVENT REPORT (LER) mfocollects.resources@nrc.nov, and to the Desk Officer, Office of Information land 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
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| ~ollection does not display a currently valid OMS control number, the NRC digits/characters for each block) may not conduct or sponsor, and a person is not required to respond to, the information collection.
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| : 1. FACILITY NAME
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| : 12. DOCKET NUMBER
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| ~-PAGE Susquehanna Steam Electric Station (SSES) Unit 1 05000387 1 OF5
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| ~-TITLE: Diesel Generator 'B' to Bus '28' Synchronizing Selector Switch Failure
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| : 5. EVENT DATE
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| : 6. LER NUMBER
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| : 7. REPORT DATE
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| : 8. OTHER FACILITIES INVOLVED MONTH YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER DAY YEAR MONTH DAY YEAR NUMBER NO.
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| 05000 FACILITY NAME DOCKET NUMBER 05 07 2013 2013
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| :- 001
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| :- 01
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| \\\\
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| 04-2013 Susquehanna Steam Electric Station Unit 2
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| ~5000388
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| : 9. OPERATING MODE
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| : 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
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| Unit 1 -1 D 20.2201 (b)
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| D 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C)
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| D 50.73(a)(2)(vii)
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| Unit 2-5 D 20.2201 (d)
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| D 20.2203(a)(3)(ii)
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| D 50.73(a)(2)(ii)(A)
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| D 50.73(a)(2)(viii)(A)
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| D 20.2203(a)(1)
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| D 20.2203(a)(4) 0 50.73(a)(2)(ii)(B)
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| D 50.73(a)(2)(viii)(B)
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| : 10. POWER LEVEL D 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A)
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| D 50.73(a)(2)(iii)
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| D 50.73(a)(2)(ix)(A)
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| Unit 1 -100%
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| D 20.2203(a)(2)(ii)
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| D 50.36(c)(1)(ii)(A)
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| D 50.73(a)(2)(iv)(A)
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| D 50.73(a)(2)(x)
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| D 20.2203(a)(2)(iii)
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| D 50.36(c)(2)
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| D 50.73(a)(2)(v)(A)
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| D 73.71 (a)(4)
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| Unit2-0%
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| D 20.2203(a)(2)(iv)
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| D 50.46(a)(3)(ii)
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| D 50.73(a)(2)(v)(B)
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| D 73.71 (a)(5)
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| D 20.2203(a)(2)(v)
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| D 50.73(a)(2)(i)(A)
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| D 50.73(a)(2)(v)(C) 0 OTHER D 20.2203(a)(2)(vi) 1:81 50.73(a)(2)(i)(B)
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| D 50.73(a)(2)(v)(D)
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| Specify in Abstract below or in Sequence of Events The following is a summary of the events related to this reportable condition:
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| : 3. PAGE 30F5 5/7/2013 00:40 While performing S0-024-001 B, the synch switch for Unit 2B ESS Bus HS-00040B appears to have failed in the synch position. CR 1700407 written to document this failure.
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| 5/7/2013 00:53 Synchronizing Select Switch DG B to Bus 2B is determined to be broken in the closed position, the synchronizing scope will not work for any other busses. Use of any other synchronizing selector switch will cause the fuse to blow.
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| 5/7/2013 00:56 CR 1706404 written to identify that the synchronizing circuit at Susquehanna needs to be reviewed in accordance with NDAP-QA-0524 for Failure Effect Codes and Single Point Vulnerability mitigation.
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| 5/7/2013 15:48 CR 1700812 written to evaluate an engineering change to electrically jumper out the synch switch for breaker 2A20204 (HS-00040B) from the circuit to allow all other synch switches to function.
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| 5/7/2013 PCWO 1700528 written to determinate I remove the defective synchronizing selector switch from control room panel OC653. PCWO 1700647 written to replace synchronizing selector switch HS-00040B on panel OC653.
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| 5/8/2013 18:10 Power supply de-energized for synchronizing selector switch replacement 5/9/2013 13:17 Completed replacement of HS00040B DG B to Bus 28 Synchronizing Selector Switch on Panel OC653 under WO 1700647 5/14/2013 03:55 The SSES NRC Senior Resident requested clarification related to compliance with the TS SR 3.8.16 surveillance requirement for the HS00040B DG B to Bus 2B Synchronizing Selector Switch failure (documented in CR 1703293) The TS Bases for SR 3.8.1.16 states: "As required by Regulatory Guide 1.9 (Ref.
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| 3)", this Surveillance ensures that the manual synchronization and automatic load transfer from the DG to the offsite source can be made and that the DG can be returned to ready to load status when offsite power is restored.
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| It also ensures that the auto start logic is reset to allow the DG to reload if a subsequent loss of offsite power occurs. The DG is considered to be in ready to load status when the DG is at rated speed and voltage, the DG controls are in isochronous and the output breaker is open.
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| 5/28/2013 16:58 CR 1708912 was written to identify that the condition prohibited by Unit 2 TS 3.8.2 involved OPDRVs. Specifically, LCO 3.8.2 required action A.2.3 to immediately initiate actions to suspend OPDRVs was not followed on Unit 2. As a result, enforcement discretion criteria item 4 of EGM 11-003, Revision 1 was not met because TS Action requirement for Mode 5 OPDRV activities were not followed as required by criteria item 4 for approximately 75 hours. Because criteria item 4 was not met, enforcement discretion under EGM 11-003 was not applicable to any OPDRV activities that were performed while LCO 3.8.2 required action A.2.3 was not met.
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| ==CAUSE OF THE EVENT==
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| The Direct Cause of the event was a failure of the D/G 'B' to Bus '2B' synchonizing selector switch (HS-00040B) which failed in the 'on' position during performance of S0-024-001 B "Monthly Diesel Generator B Operability Test.
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| The Apparent Cause was that Surveillance Procedure S0-024-001 B did not provide guidance that the synchronizing selector switch is required to meet the TS SR 3.8.1.8 and SR 3.8.1.16 surveillance requirements. A Causal Factor was determined to be that the SRO review was limited to the TS surveillance requirements of S0-024-001 B, and it was not recognized that operation of the synchronizing selector switch was necessary to meet these requirements. SR 3.8.1.8 is met by performing SE-1 (2)04-1 (2)01 (2), "24 month 4.16kv Class 1 E Bus to Offsite Supply Transfer Check". SR 3.8.1.16 is met by performing SE-1 (2)24-1 (2)07, "LOCA LOOP Testing" on a two year frequency. Consequently, these SRs are not frequently reviewed and exercised.
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| ==ANALYSIS/SAFETY SIGNIFICANCE==
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| Actual Consequences:
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| There were no actual consequences to the health and safety of the public as a result of this event. The broken synchronizing selector switch caused TS SR's to not be met, which resulted in Unit 1 LCO 3.8.1 and Unit 2 LCO 3.8.2 to not be met. At no time were the A, B, C, or D required D/Gs not capable of performing their safety function to automatically start and load to the Emergency Safety Switchgear (ESS) busses.
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| Additionally, at no time were either of the offsite power sources unable to supply their connected loads or automatically transfer from the preferred to the alternate source or vice versa if necessary. The switch failure affected restoration of power following a LOOP, in which the offsite power source would not be able tore-synchronize to the ESS busses with the loads remaining connected to the D/Gs. Additionally, the switch failure would have prevented manual transfer of the ESS buses from the normal offsite circuit to the alternate offsite circuit if necesssary.
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| Since the inoperable AC power sources were determined to have maintained their ability to perform their necessary shutdown risk function, the impact to OPDRV activities was determined to be of low shutdown risk significance and an adequate level of safety was provided during the performance of the OPDRV activities described in Unit 2 LER 50-388/2013-001-00 (PLA-7018, dated June 14, 2013).
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| Potential Consequences:
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| In the event of a LOOP off site power could not have been re-synchronized to the running loads on the ESS buses, and manual transfer of the ESS buses from the normal offsite circuit to the alternate offsite circuit would have been prevented without repair of the broken synchronizing selector switch or its isolation from the circuit.
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| ==CORRECTIVE ACTIONS==
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| An immediate corrective action was to replace the failed synchronizing selector switch.
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| Longer term corrective actions planned thus far:
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| : 3. PAGE 50F5 Revise the affected surveillance procedures to provide guidance that the synchronizing selector switch is required to meet the surveillance requirements of SR 3.8.1.8 and SR 3.8.1.16.
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| Reclassify all existing synchronizing switches to have the same failure effect and maintenance rule codes, which will establish an equal criticality for all switches.
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| Create a maintenance plan to change out the switches to improve reliability.
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| Evaluate the feasibility of synchronizing circuit design changes.
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| Perform a sampling of surveillances that would lead to a 2 hour LCO if the surveillance failed, to ensure that there are sufficient directions in procedures to alert Operators when performing the TS review.
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| Review Operability Determination Training recently provided for effectiveness.
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| Submit an IN PO Operating Experience Report for this event.
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| ==PREVIOUS SIMILAR EVENTS==
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| No previous similar events in which a single point vulnerability equipment failure resulted in a condition prohibited by TS on both SSES Units were identified.
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| }}
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| {{LER-Nav}}
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