Information Notice 1995-19, Failure of Reactor Trip Breaker to Open Because of Cutoff Switch Material Lodged in the Trip Latch Mechanism

Failure of Reactor Trip Breaker to Open Because of Cutoff Switch Material Lodged in the Trip Latch Mechanism

ML031060244
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	03/22/1995
From:	Grimes B K Office of Nuclear Reactor Regulation
To:
References
IN-95-019, NUDOCS 9503160374
Download: ML031060244 (12)

-eUNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555March 22, 1995NRC INFORMATION NOTICE 95-19:FAILURE OF REACTOR TRIP BREAKER TO OPEN BECAUSEOF CUTOFF SWITCH MATERIAL LODGED IN THE TRIPLATCH MECHANISM

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to the possible failure of a circuit breaker toopen because of obstruction by material from a subcomponent switch. It isexpected that recipients will review this information for applicability totheir facilities and consider actions, as appropriate, to avoid similarproblems. However, suggestions contained in this information notice are notNRC requirements; therefore, no specific action or written response isrequired.

Description of Circumstances

On July 14, 1994, during the monthly testing of the logic matrix of thereactor protection system at St. Lucie, Unit 2, a General Electric (GE)Model AK 2-25 circuit breaker failed to open after operating correctly onthree previous steps of the surveillance procedure. This circuit breaker isone of eight reactor trip circuit breakers in a one-out-of-two taken twicereactor trip coincidence logic. Several unsuccessful attempts were made toopen the breaker both electrically and mechanically before the licenseeisolated the breaker as required by the Technical Specifications and shut downthe Unit 2 reactor.The investigation of the problem revealed that a 6-mm-square [1/4-inch-square]piece of phenolic material had jammed the circuit breaker trip latchmechanism, preventing its operation. This piece of phenolic material hadbroken off from the breaker cutoff switch (p/n 622 C 505 GI), which is part ofthe breaker antipump circuitry. The cutoff switch is mounted in the breakerassembly above the trip latch mechanism (Figure 1). A screw holding thecutoff switch had come loose, allowing two halves of the switch to separate,become misaligned, and break during the previous circuit breaker operation.The licensee inspected the remaining Unit 2 trip circuit breakers as well asthe similar motor generator set output breakers. No additional loose screwswere found on the cutoff switch mountings. The licensee has incorporated theinspection of the cutoff switch phenolic block and screw into the maintenanceprocedures for Units I and 2. a o ' 6s b9503160374 PAQ T*tE bo s(A, qf-(otqS I ) 3Hat44 I~ C fl

-V.,IN 95-19March 22, 1995 DiscussionOn April 6, 1989, GE Switchgear Operation issued service advisory letter (SAL)303.0, which dealt with the possibility that the cutoff switch actuator couldcrack and break and lead to breaker coil burnout. The text of SAL 303.0 isshown in Attachment 2. Although these cutoff switches had a differentfailure mode and were installed on different breaker models (Models AKR(U) 30sand AK(U) 25-1), the cutoff switch in question was the same part (p/n 622 C505 GI) as the one that caused the AK2-25 breaker failure at St. Lucie,Unit 2.The majority of the reactor trip breaker failures at power reactors have beencaused by problems with relatively small electrical subcomponents in thebreaker assembly, rather that the malfunction of the main breaker mechanismitself. The failure of the cutoff switch in the trip breaker at St Lucie isanother example of a subcomponent failure resulting in the failure of a tripbreaker. The frequency of reactor trip breaker failures could be reduced ifthese small component problems were made less likely by appropriate inspectionand maintenance.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRP) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: S. Rudisail, Region II S. K. Mitra, NRR(404) 331-5582 (301) 415-2783M. B. Shymlock, Region II(404) 331-5596Attachments:1. Figure 12. GE SAL 303.03. List of Recently Issued NRC Information Notices

KJiAttachment 1IN 95-19March 22, 1995 FIGURE 1AK-2 BREAKER FRONT VIEWf CUTOFF SWITCHTX

CONTACT

OR>PIECE OF CUTOFF SWITCHDROPPED DOWN TO BOlTOM OFTHE TRIP LATCH PREVENTINGTHE LATCH FROM ACTUATING(CUTOFF SWITCH PIN 622 C 505 Gl)

vJAttachment 2IN 95-19March 22, 1995 SWITCHGEAROPERATIONSERVICE ADVICESUBJECT ELECTRICALLY OPERATEDAKR 30S AND AKRU 30S BREAKERSAK 25-1 AND AKU 25-1 BREAKERSCUT OF SWITCH BREAKAGE-- I Ce MAn jnIV nTABuIjsuSWGR OPERO.ba A1U .JUJ .U_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I _ _ _ _ _ _ _ _ _ _ _ _ _ I _ _ _ _ _ _ _ _ _BackqroundThe function ofclosing coil when thethe Cut Off Switch is to interrupt thebreaker is closed.ProblemOn electrically operated AKR(U) 30S and AK(U) 25-1 breakersmanufactured between July 1986 and November 1987 there is apossibility that the cut off switch actuator may crack and break.If this occurs, the closing coil may be overheated and burn upwhen the breaker is closed.Recommended ActionGE recommends that the cut off switch actuator on allaffected breakers be visually checked for cracks at the nextregular breaker maintenance / inspection. This includes allAKR(U) 30S breakers with a Breaker Code Date less than P747+ andall AK(U) 25-1 breakers with a Breaker Date Code P548+ throughP747+. The Breaker Code Date is on the control voltage nameplatelocated to the right of the escutcheon on the breaker frame.Corrective ActionIf a broken or cracked cut off switch is found, contactCustomer Service for a no-charge replacement cut off switch [PartNo. 622C505G1] at:Mary HockettCustomer ServiceGeneral ElectricPO Box 488Burlington, IA 52601Phone: (319) 753-84758*673-6475Telecopier: (319) 753-54798*673-6479Please have Breaker Serial Numbers and Date Codes whenyou contact us.I_ ,_ _ _ ...z p xPREPARED BYGARY SCHULEIIIIIIISSUED BYDON LESNETIIIIIIDATE I bUFtURtULbIISSUE DATED4-06-89 0 (NEW)IIOF1 Attachment 3IN 95-19March 22, 1995 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to95-1895-1795-1695-1595-14Potential Pressure-Lockingof Safety-Related Power-Operated Gate ValvesReactor Vessel Top Guideand Core Plate CrackingVibration Caused byIncreased RecirculationFlow in a Boiling WaterReactorInadequate Logic Testingof Safety-Related CircuitsSusceptibility of Con-tainment Sump Recircula-tion Gate Valves toPressure LockingPotential for DataCollection Equipment toAffect Protection SystemPerformancePotentially NonconformingFasteners Supplied byA&G Engineering II, Inc.Failure of CondensatePiping Because of Erosion/Corrosion at a Flow-Straightening DevicePotential for Loss ofAutomatic EngineeredSafety FeaturesActuation03/15/9503/10/9503/09/9503/07/9502/28/9502/24/9502/21/9502/24/9502/10/95All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsAll holders of OLs or CPsfor boiling water reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.95-1395-1295-1195-10Supp. 1OL = Operating LicenseCP = Construction Permit

IN 95-19March 22, 1995 DiscussionOn April 6, 1989, GE Switchgear Operation issued service advisory letter (SAL)303.0, which dealt with the possibility that the cutoff switch actuator couldcrack and break and lead to breaker coil burnout. The text of SAL 303.0 isshown in Attachment 2. Although these cutoff switches had a differentfailure mode and were installed on different breaker models (Models AKR(U) 30sand AK(U) 25-1), the cutoff switch in question was the same part (p/n 622 C505 Gi) as the one that caused the AK2-25 breaker failure at St. Lucie,Unit 2.The majority of the reactor trip breaker failures at power reactors have beencaused by problems with relatively small electrical subcomponents in thebreaker assembly, rather that the malfunction of the main breaker mechanismitself. The failure of the cutoff switch in the trip breaker at St Lucie isanother example of a subcomponent failure resulting in the failure of a tripbreaker. The frequency of reactor trip breaker failures could be reduced ifthese small component problems were made less likely by appropriate inspectionand maintenance.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Gri fbyiatlI K. rmesDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: S. Rudisail, Region II S. K. Mitra, NRR(404) 331-5582 (301) 415-2783M. B. Shymlock, Region II(404) 331-5596Attachments:1. Figure 12. GE SAL 303.03. List of Recently Issued NRC Information NoticesDOCUMENT NAME: S:\DOPS SEC\95-19.IN *See previous concurrenceOECB:DOPS:NRR* RPB:ADM EELB:DE C/EELB:DEDCKirkpatrick l BCalure, Tech Ed* SKMitra* CEBerlinger*12/22/94 l 12/28/94 01/23/95 01/23/95RII (via e-mail) RII (via e-mail) SC/OECB:DOPS:NRR OECB:DOPS:NRRSRudisail* MBShymlok* EFGoodwin* RJKiessel*01/25/95 01/25/95 Z 01/26/95 02/01/95C/OECB:DOPS:NRR D/J4* 7 =AEChaffee*03/11/95 03// /95OFFICIAL RECORD COPY

v~~IN 95-XXMarch xx, 1995 DiscussionOn April 6, 1989, GE Switchgear Operation issued service advisory letter (SAL)303.0, which dealt with the possibility that the cutoff switch actuator couldcrack and break and lead to breaker coil burnout. The text of SAL 303.0 isshown in Attachment 2. Although these cutoff switches had a differentfailure mode and were installed on different breaker models (Models AKR(U) 30sand AK(U) 25-1), the cutoff switch in question was the same part (p/n 622 C505 Gl) as the one that caused the AK2-25 breaker failure at St. Lucie,Unit 2.The majority of the reactor trip breaker failures at power reactors have beencaused by problems with relatively small electrical subcomponents in thebreaker assembly, rather that the malfunction of the main breaker mechanismitself. The failure of the cutoff switch in the trip breaker at St Lucie isanother example of a subcomponent failure resulting in the failure of a tripbreaker. It follows that the frequency of reactor trip breaker failures couldbe significantly reduced if these small component problems could be eliminatedby careful inspection and maintenance.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:S. Rudisail, Region II(404) 331-5582S. K. Mitra, NRR(301) 504-2783M. B. Shymlock, Region II(404) 331-5596Attachments:1. Figure 12. GE SAL 303.03. List of Recently Issued NRC Information NoticesDOCUMENT NAMF: s!\nlfPS SFC\RRFAKER *See nrev'ious concurrenceOECB:DOPS:NRR* RPB:ADM EELB:DE C/EELB:DEDCKirkpatrick BCalure, Tech Ed* SKMitra* CEBerlinger*12/22/94 12/28/94 01/23/95 01/23/95RII (via e-mail) RII (via e-mail) SC/OECB:DOPS:NRR OECB:DOPS:NRRSRudisail* MBShymlok* EFGoodwin* RJKiessel*01/25/95 01/25/95 01/26/95 02/01/95C/OECB:DOPS:NRR D/DOPS:NRRAEChaffee* BKGrimes03/11/95 0 / j95_OFF IC IAL RECORD COPY

IN 95-xxMarch xx, 1995 DiscussionOn April 6, 1989, GE Switchgear Operation issued service advisory letter (SAL)303.0, which dealt with the possibility that the cutoff switch actuator couldcrack and break and lead to breaker coil burnout. The text of SAL 303.0 isshown in Attachment 2. Although these cutoff switches had a differentfailure mode and were installed on different breaker models (Models AKR(U) 30sand AK(U) 25-1), the cutoff switch in question was the same part (p/n 622 C505 GI) as the one that caused the AK2-25 breaker failure at St. Lucie,Unit 2.The majority of the reactor trip breaker failures at power reactors have beencaused by problems with relatively small electrical subcomponents in thebreaker assembly, rather that the malfunction of the main breaker mechanismitself. The failure of the cutoff switch in the trip breaker at St Lucie isanother example of a subcomponent failure resulting in the failure of a tripbreaker. It follows that the frequency of reactor trip breaker failures couldbe significantly reduced if these small component problems could be eliminatedby careful inspection and maintenance.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:S. Rudisail, Region II(404) 331-5582S. K. Mitra, NRR(301) 504-2783M. B. Shymlock, Region II(404) 331-5596Attachments:1. Figure 12. GE SAL 303.03. List of Recently Issued NRCnnrlMFrNT NAME- n-\nN\RRFAKFRInformation Notices*See nrevious concurrencevvVl r L. v \ --__ ._ .. ____.~. -.._........ __OECB:DOPS:NRR* RPB:ADM* EELB:DE* C/EELB:DE*DCKirkpatrick BCalure, Tech Ed SKMitra CEBerlinger12/22/94 12/28/94 01/23/95 01/23/95RII* (via e-mail) RII* (via e-mail) SC/OECB:DOPS:NRR*SRudisail MBShymlok EFGoodwin01/25/95 01/25/95 01/26/95OECB:DOPS:NRR* C BD N D/DOPS:NRRRJKiessel AEChlree P BKGrimes02/01/95 /11 /95 01/ /95OFFICIAL RECORD COPY

IN 95-xxJanuary xx, 1995 DiscussionOn April 6, 1989, GE Switchgear Operation issued service advisory letter (SAL)303.0, which dealt with the possibility that the cutoff switch actuator couldcrack and break and lead to breaker coil burnout. A copy of SAL 303.0 isattached. Although these cutoff switches had a different failure mode andwere installed on different breaker models (Models AKR(U) 30s and AK(U) 25-1),the cutoff switch in question was the same part (p/n 622 C 505 GI) as the onethat caused the AK2-25 breaker failure at St. Lucie, Unit 2.The majority of the reactor trip breaker failures at power reactors have beencaused by problems with relatively small electrical subcomponents in thebreaker assembly, rather that the malfunction of the main breaker mechanismitself. The failure of the cutoff switch in the trip breaker at St Lucie isanother example of a subcomponent failure resulting in the failure of a tripbreaker. It follows that the frequency of reactor trip breaker failures couldbe significantly reduced if these small component problems could be eliminatedby careful inspection and maintenance.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:S. Rudisail, Region II(404) 331-5582S. K.(301)Mitra, NRR504-2783M. B. Shymlock, Region II(404) 331-5596Attachments:1. Figure 12. GE SAL 303.03. List of Recently Issued NRCnfnrilMrKT IAMEM. r- \n N\RnFAVFRInformation Notices*SeP nrevious concurrenceUV%111L-1% I 111ru-19- U. vuvuW-Xl ---reOECB:DOPS:NRR* RPB:ADM* EELB:DE* C/EELB:DE*DCKirkpatrick BCalure, Tech Ed SKMitra CEBerlinger12/22/94 J 12/28/94 01/23/95 _ 01/23/95RII* (via e-mail) RII* (via e-mail) SC/OECB:DOPS:NRR*SRudisail MBShymlok EFGoodwin01/25/95 01/25/95 01/26/95OECB:DOPS:NRR C/OECB:DOPS:NRR D/DOPS:NRR =RJKiesse AEChaffee BKGrimes*y /95 01/ /95 01/ /95OFFICIAL RECORD COPY

IN 95-xxJanuary xx, 1995 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:S. Rudisail, Region II(404) 331-5582M. B. Shymlock, Region II(404) 331-5596S. K. Mitra, NRR(301) 504-2783Attachments:1. Figure 12. GE SAL 303.03. List of RecentlyMV tf laIssued NRC Information NoticesOECB:DOPS:NRR* l RPB:ADM* EELB:DE C/EELB:DE >DCKirkpatrick BCalure ,Tech Ed SKMitra CEBerlinger 'l12/22/94 12/28/94 1/Z3/95 1/Z/95lREG II I i^ REG II SC/OECB:DOPS:NRRlSRudisail MBShymlok~ -IEFGoodwin0OIi1/95 J 01f)/95 01_ 9_5OECB:DOPS:NRR C/OECB:DOPS:NRR D/DOPS:NRRRJKiessel AEChaffee BKGrimes* 01/ /95 01/ /95 pc/ /95*See previous concurrences

From: Donald C. Kirkpatrick (DCK1)To: SBRDate: Wednesday, January 25, 1995 10:43 amSubject: CONCURNCE W IN:FAILURE OF RX TRIP BREAKRSteve:The attached file contains your proposed IN on the failure of the reactor tripbreaker due to foreign material in the latch. Brian Grimes decided that itshould be issued after all. We added some history on previous problems withthe cutoff switch that was the source of the jamming material.Please review it, concur if possible and pass it on toShymlock. Pleace call me at (301) 504-1849 if you need anything else on this.Thanks,Don Kirkpatrick, OECBFiles: G:\DON\BREAKERFrom: Steven B. Rudisail (SBR)To: AT1:HMS1:HMS2:WN4:DCK1Date: Wednesday, January 25, 1995 3:03 pmSubject: CONCURNCE W IN:FAILURE OF RX TRIP BREAKRMilton Shymlock and I have reviewed the draft notice and we both concur.CC: MBS

1. Contents of GE Service Advisory Letter 303.02. List of Recently Issued NRC Information NoticesOECB:DOPS:NRR RPB:ADM EELB:DE C/EELB:DEDCKirkpatric k , ' 4 9,4 Tech Ed SKMitra CEBerlinger12/2/94 12b??/94 01/ 95REG II REG II SC/OECB:DOPS :NRRSRudisail MBShymlok EFGoodwin01/ /95 01/ /95 01/ /95OECB:DOPS:NRR C/OECB:DOPS:NRR D/DOPS:NRRRJKiessel AEChaffee BKGrimes01/ /95 01/ /95 01/ /952Z