Information Notice 1994-54, Failures of General Electric Magne-Blast Circuit Breakers to Latch Closed
UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555August 1, 1994NRC INFORMATION NOTICE 94-54: FAILURES OF GENERAL ELECTRIC MAGNE-BLASTCIRCUIT BREAKERS TO LATCH CLOSED
Addressees
All holders of operating licenses or construction permits for nuclear powerreactors.PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to a condition in which certain General Electric(GE) medium-voltage Magne-Blast circuit breakers may begin to randomly fail tolatch closed. It is expected that recipients will review the information forapplicability to their facilities and consider actions, as appropriate, toavoid similar problems. However, suggestions contained in this informationnotice are not NRC requirements; therefore, no specific action or writtenresponse is required.
Description of Circumstances
The Maine Yankee Atomic Power Station (Maine Yankee) and the Millstone NuclearPower Station (Millstone) have recently experienced failures of safety-relatedGE Magne-Blast 4160-Vac circuit breakers to latch closed (also called "goingtrip-free"). Failures occurred during post-overhaul, preoperational, andin-service surveillance testing. At Maine Yankee, failures occurred shortlyafter an overhaul of the breakers, during troubleshooting of an indirectlyrelated problem with limit switches. The affected breakers have failed tolatch on a random basis during up to about two-thirds of attempted closures,both electrically and manually. At both plants, the affected breakers wereamong those recently overhauled by the GE Apparatus Service Division ofPhiladelphia, with quality assurance coverage provided by GE Nuclear Energy(NE) Power Delivery Services (PDS) of King of Prussia, Pennsylvania. Failureanalysis, inspection, and testing of one of the affected breakers from MaineYankee were performed at the GE Apparatus Service Division under the directionof GE NE PDS and the design engineer from the breaker manufacturer, GESpecialty Breaker Plant. The results were consistent with onsite testing atboth Millstone and Maine Yankee. The failure analysis activities, observed byNRC and licensee representatives, identified the primary failure mode,apparent principal root causes, and the most effective remedies.9407270127 PmR 2 -O5M qq9 o(up&LB} b gl~lIX v\
IN 94-54-August 1, 1994 DiscussionThe breaker models considered to be potentially affected at the present timeinclude (1) Type AM-4.16-350-1H and (2) Type AM-4.16-250-6, -7, -8, or -9HB.GE is currently evaluating other Magne-Blast models for potentialsusceptibility. Among these models, only breakers equipped with one propreset spring (prop spring), and in which all "Tuf-Loc" (Teflon-coatedfiberglass) bushings (especially the prop bushings) have been replaced withaluminum-bronze bushings, have recently experienced unreliable latching.However, it should be noted that this failure ultimately results from acombination of contributing factors and not all breakers of the potentiallyaffected type and configuration are prone to failure. In addition, there havebeen a few instances (although not recently) of one-prop spring breakers withTuf-Loc prop bushings that have failed to latch due to other unsatisfactoryconditions within the breaker such as excessive wear, hardened or insufficientlubrication, and/or being severely out of adjustment. No failures are knownto GE or the NRC to occur in breakers equipped with two prop springs (includedas original equipment since 1968, or added during maintenance or repair). Thefailure analysis testing appeared to confirm the GE position that breakerswith two prop springs should not experience this problem. The details of thefailure mode are discussed in Attachment 1 to this information notice.Attachment 2 shows the prop springs.It should be noted that, depending on the severity of the various contributingconditions, the onset of failure to latch reliably in these breakers may vary,and a breaker that has successfully passed rigorous post-maintenance testingand further receipt inspection and preoperational testing may subsequentlystart failing to latch reliably in service. In recent instances, failures tolatch have begun to occur after about 35-50 operations (cycles) followingoverhaul or repair of the operating mechanism. Once started, the failurefrequency has been observed during testing, to vary from 1 failure to latch inas many as 50 consecutive operations to 16 failures in 24 attempts. Theoperating characteristics of a given breaker (in particular, adequacy andconsistency of prop action as explained in Attachment 1) can indicate thelikelihood of unreliable latching. According to GE, the desired prop actionpositions the prop fully forward against its stop, thus providing maximumengagement under the prop pin (called prop wipe). However, affected breakersthat start (or are likely to start) failing to latch reliably typicallyexhibit inconsistent (and often less than the design minimum) prop wipe evenwhen they do latch.The NRC and licensees have expressed concerns regarding increased suscepti-bility to unwanted tripping with less than minimum design prop wipe caused byvibration or shock (e.g., during a seismic event). The Magne-Blast designengineer has stated that because of the geometry and magnitude of forcesacting on the prop, once the mechanism has successfully latched (even if onlybarely), it would be extremely unlikely for the shocks or vibration associatedwith seismic events to cause the prop to move backwards and olut from under theprop pin. Nevertheless, a breaker that is latched, but with less than thedesign minimum prop wipe, is not in a condition for which it was analyzed orin which it was tested during seismic qualification.
IN 94-54August 1, 1994 Normal prop wipe can be confirmed with the breaker in its cubicle and closed(in test position if necessary) in most installations by visual inspection(using an inspection mirror and light) without having to get too close toenergized components or hazardous mechanism parts if the switchgear cabinetdoor can be opened with appropriate safety precautions. Pending issuance of aservice advice letter (SAL) by the manufacturer on this problem or a safetycommunication by GE NE, Attachment 2 illustrates an inspection hole in theright side of the mechanism frame through which the prop and prop pin positionmay be viewed. While the fully forward prop position (to the stop) is thedesired condition (maximum wipe), the absence of failures to latch along withconsistent and greater than minimum allowed prop wipe is, according to GE,indicative of continued reliable latching. However, because minimum prop wipeis not a published design specification, and because certain other factors(e.g., opening spring adjustment) may influence latching reliability, GE hasrequested that any licensee experiencing Magne-Blast breaker latching problemsor noticing changed, inconsistent or apparently abnormally low prop wipe,particularly following overhaul or repair including prop bushing replacement,contact GE NE PDS at (610) 992-6049.Pending installation of a second prop spring in affected breakers, MaineYankee has shifted, to the extent possible, its available dual prop springbreakers to locations where operability requires assured latching reliabilityfor closure or reclosure during a design-basis event. For the remainingpotentially affected breakers, Maine Yankee is planning expedited inspectionswith the assistance of GE NE PDS to aid in its operability determinations.Related Generic CommunicationsInformation Notice 84-29, "General Electric Magne-Blast Circuit BreakerProblems," dated April 29, 1984.Information Notice 90-41, "Potential Failure of General Electric Magne-BlastCircuit Breakers and AK Circuit Breakers," dated June 12, 1990.Information Notice 93-91, "Misadjustment Between General Electric 4.16-KYCircuit Breakers and Their Associated Cubicles," dated December 3, 1993.Information Notice 94-02, "Inoperability of General Electric Magne-BlastBreaker Because of Misalignment of Close-Latch Spring," dated January 7, 1994.
IN 94-54: August 1, 1994 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 Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts: Stephen Alexander, NRR(301) 504-2995Kamalakar Naidu, NRR Sikindra Mitra, NRR(301) 504-2980 (301) 504-2783Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued NRC Information Notices47 g ^d AnJ-L
Attachment 1IN 94-54August 1, 1994 DETAILS OF THE FAILURE MODE AND CONTRIBUTING FACTORSThe cause of the failures to latch cited in the body of the Information Noticeis related to a component of the Type ML-13 breaker operating mechanism calledthe prop (see Attachment 2). The breaker will fail to latch closed when theprop does not travel forward fast enough (relative to the motion of theclosing linkage) to be in the proper position under the prop pin of theclosing linkage as it rises above then descends onto the prop during theclosing cycle (whether manually or electrically initiated). Absent a tripcondition upon closing, the prop is permitted (by the rotation of the maincam) to be pulled forward under the prop pin by the prop reset spring (orsprings when two are fitted). If the slower speed of the prop relative to thepin is such that the pin passes down in front of the prop instead of landingon top of it (called latching) as it is supposed to, the linkage will"collapse" causing the moving contact arms to immediately drop down to theopen position. This condition or action is also called the trip-freecondition because it occurs in the same manner as if a trip signal werepresent at the breaker tripping mechanism when the breaker attempts to close,thus preventing the prop from moving forward and latching.According to GE, and as apparently confirmed by testing, several conditionsmust be present to render a given breaker susceptible to this failure mode.Most fundamental are the individual breaker model and configuration, mechanismtype, and vintage. Within these constraints, certain modifications orupgrades that have (or have not) been performed on a given breaker influenceits susceptibility. Finally, the condition of the breaker mechanism in termsof age and type of moving parts, wear, lubrication, and adjustment canultimately be the determining factor with regard to latching reliability.Due to their particular combination of operating (opening and closing) springconfigurations, all 4.16-kilovolt (Kv)-rated, vertical-lift, air-magnetic(Magne-Blast) breakers of 350-million volt-ampere (MVA) interrupting rating(Type AM-4.16-350-1H) that are fitted with only one prop spring are consideredby GE to be potentially affected. Also potentially affected, owing also totheir particular operating spring configurations, are those 4.16-Kv, 250-MVA-rated Magne-Blast breakers with one prop spring that have a 78-kilo-ampere(kA) close-latch rating (called a "high momentary" rating), which includesModels AM-4.16-250-6, -7, -8, or -9HB (the "H" suffix indicates the ML-13 typemechanism and the "B" indicates the high momentary rating).Within this population, the major factor determining susceptibility is thenumber of prop springs installed. With one anomalous exception (a breakersuspected of being grossly out of adjustment), only breakers with one propspring have thus far been reported to experience unreliable latching.Breakers of these models built before about 1968 were originally fitted at thefactory with a single prop spring. After this time, breakers with close andlatch ratings of 77 Ka or 78 Ka were factory fitted with two prop springs, inorder, according to GE, to make the breakers less sensitive to fit andadjustment tolerances and to facilitate factory setup. The failure analysistesting indicated that breakers built with or modified subsequently to add asecond (upper) prop spring, and that are not otherwise in severely out oftolerance condition, should not be susceptible to this failure mode.
Attachment 1: IN 94-54August 1, 1994 The breaker manufacturer, in GE Service Advice Letter (SAL) No. 073-348.1,issued in December 1990, recommended replacement of the main (lower) propspring with an improved spring (called the "gold" prop spring because of thecolor of its cadmium plating). NRC Information Notice 90-41, "PotentialFailure of General Electric Magne-Blast Circuit Breakers and AK CircuitBreakers," also addressed this problem. The gold prop spring has been fittedin breakers built since 1971, due to fatigue failures reported in the originalspring. Although SAL 073-348.1 did describe the dual prop springconfiguration, it did not address the addition of a second prop spring. SeeAttachment 2.Recent breaker overhauls/repairs that included replacement of the Tuf-Loc(Teflon-coated fiberglass) prop bushings with aluminum-bronze prop bushings,in conjunction with cleaning and relubrication of the closing linkage andrenewal of worn parts have not been demonstrated conclusively to be the solecause of the recently reported failures to latch. However, they appear tohave been the common precipitating events. In breakers of the affected modelswith one prop spring that have had all the Tuf-Loc bushings (except for theprop bushings) replaced with aluminum-bronze, the recently reported failuresto latch have begun to occur after about 35-50 operations (cycles) aftercompletion of overhaul or repair that included replacement of the Tuf-Loc propbushings with aluminum-bronze. Since 1975, these breakers have been fittedwith aluminum-bronze sleeve bearings or bushings in their mechanisms (exceptfor the prop bushings) for improved wear characteristics. Many of the olderMagne-Blast breakers, in accordance with GE SAL 073-318.1 (and .1A), issued in1977, and 318.2, issued in 1979, have had their original Tuf-Loc bushingsreplaced with the aluminum-bronze bushings. IE Information Notice 84-29, "GEMagne-Blast Circuit Breaker Problems," also addressed this issue. The factorybushing replacement kits, supplied under catalog no. 0156C9403G001, did notinclude replacement bushings for the prop. Hence, most prop bushingreplacements have been performed only recently.When other conditions in a breaker are conducive to marginal latching, itappears that the new bushings, in conjunction with reduced friction in theclosing linkage from the overhaul, cleaning and new lubricant, may shift theforce and speed balance in the mechanism. The shift can be sufficient tospeed up the motion of the closing linkage and prop pin relative to the prop(which also may actually be slightly retarded) beyond design margins. Underthese conditions, a single prop spring can no longer move the prop forwardfast enough to latch reliably, or if it does latch, to ensure the desired propwipe. Where the second prop spring has been installed in conjunction with themechanism overhaul, failure to latch reliably in the manner described hereinhas not been reported, and according to GE, as confirmed by testing, would notbe expected to occur. Disassembly and detailed inspection of the Maine Yankeebreaker operating mechanism after testing revealed no additional significantfactors contributing to the failures to latch experienced by the test breaker.Therefore, the test results appear to have confirmed the factors to whichclose-latch reliability is most sensitive.
Attachment 21, IN 94-54August 1, 1994Page 1 of IMAGNE-BLAST OPERATING MECHANISM PROP DIAGRAMS1.2.3.4.5.5A.6.7.8.9.10.11.12.13.14.15.16.17.HandleTrip Coil SupportTrip CoilTrip ArmaturePROP SPRINGSECOND PROP SPRING(if fitted)Cam Follower RollerTrip ShaftTrip LatchTrip Latch RollerRoller SupportCrank ShaftCranksPROP PINPROPDrive ShaftCamPROP BUSHINGFRONT OF BREAKERFigure 1 (Adapted From Figure 7 of GE Instruction Book GEI-88761)Figure 2: Right Side View of ML-13 Operating Mechanism(From Figure 4 of GE Instruction Book GEI-88761)
Attachment 3' IN 94-54August 1, 1994 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to91-45,Supp. 1Possible Malfunction ofWestinghouse ARD, BFD,and NBFD Relays, andA200 DC and DPC 250Magnetic Contactors07/29/94All holders of OLs or CPsfor nuclear power reactors.94-42,Supp. 1Cracking in the LowerRegion of the Core Shroudin Boiling-Water Reactors07/19/94All holdersfor boiling(BWRs).of OLs or CPswater reactors94-5394-5294-5194-5094-49Hydrogen Gas Burn InsidePressurizer During WeldingInadvertent ContainmentSpray and Reactor VesselDraindown at MillstoneUnit 1Inappropriate Greasingof Double Shielded MotorBearingsFailure of GeneralElectric Contactorsto Pull in at theRequired VoltageFailure of TorqueSwitch Roll PinsSnubber LubricantDegradation in High-Temperature EnvironmentsUnanticipated and Unin-tended Movement of FuelAssemblies and otherComponents due to ImproperOperation of RefuelingEquipment07/18/9407/15/9407/15/9407/14/9407/06/9406/30/9406/28/94All 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.All holders of OLs or CPsfor nuclear power reactors.94-4894-13,Supp. 1OL = Operating LicenseCP = Construction Permit
IN 94-54August 1, 1994 94-54. INNOTE: The PMs for Maine Yankee (E. Trottier) and Millstone-1 (J. Andersen)have been informed of the development of this information notice, andtheir comments have been incorporated.Steve Alexander of the Vender Inspection Branch hasthe technical accuracy of this information notice.been incorporated.consulted with GE onGE's comments havePeter Wen, 7/13/94 IN 94-XXJuly XX, 1994 NOTE: The PMs for Maine Yankee (E. Trottier) and Millstone-I (J. Andersen)have been informed of the development of this information notice, andtheir comments have been incorporated.Steve Alexander of the Vender Inspection Branch has consulted with GE onthe technical accuracy of this information notice. GE's comments havebeen incorporated.Peter Wen, 7/13/94 IN 94-XXJuly XX, 1994 Normal prop wipe can be confirmed with the breaker in its cubicle and closed(in test position if necessary) in most installations by visual inspection(using an inspection mirror and light) without having to get too close toenergized components or hazardous mechanism parts if the switchgear cabinetdoor can be opened with appropriate safety precautions. Pending issuance of aservice advice letter (SAL) by the manufacturer on this problem or a safetycommunication by GE NE, Attachment 2 illustrates an inspection hole in theright side of the mechanism frame through which the prop and prop pin positionmay be viewed. While the fully forward prop position (to the stop) is thedesired condition (maximum wipe), the absence of failures to latch along withconsistent and greater than minimum allowed prop wipe is, according to GE,indicative of continued reliable latching. However, because minimum prop wipeis not a published design specification, and because certain other factors(e.g., opening spring adjustment) may influence latching reliability, GE hasrequested that any licensee experiencing Magne-Blast breaker latching problemsor noticing changed, inconsistent or apparently abnormally low prop wipe,particularly following overhaul or repair including prop bushing replacement,contact GE NE PDS at 610-992-6049.Pending installation of a second prop spring in affected breakers, MaineYankee has shifted, to the extent possible, its available dual prop springbreakers to locations where operability requires assured latching reliabilityfor closure or reclosure during a design-basis event. For the remainingpotentially affected breakers, Maine Yankee is planning expedited inspectionswith the assistance of GE NE PDS to aid in its operability determinations.NRC Information Notice 94-XX, issued May XX, 1994, discusses other recentlyidentified problems impacting Magne-Blast operability, related to defectiveand improperly installed GE CR2940 limit switches.This information notice requires no specific action or written response.If you 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.ORIG /S/'D BY BKGRIMESBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts: Stephen Alexander, NRR Kamalakar Naidu, NRR(301) 504-2995 (301) 504-2980Sikindra Mitra, NRR (301) 504-2783Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued NRC Information NoticesVIB:DRIL VIB:DRIL SC/VIB:DRILSAlexander* KNaidu* GCwalina*05/19/94 04/14/94 05/19/94C/VIB:DRIL:NRR D/DRIL:NRR EELB:DE(PR,1LNorrholm* CERossi* Smitya afb'05/24/94 05/27/94 cuff /94OGCB:DORS:NRR AC/OGCB:DORS:NRR D7:DORS:NRRPWen BKGrimes07/ /94 07/ /94 07/ /94OFFICIAL RECORD COPY DOCUMENT NAME: I*See previous concurrenceTECHEDMMejac*04/18/94C/EELB:DE:N f )CjerlingerOV/tt/94MAGNE3AT.GE
IN 94-XXMay XX, 1994 Normal prop wi can be confirmed with the breaker in its cubicle and closed(in test position if necessary) in most installations by visual inspection(using an inspectio mirror and light) without having to get too close toenergized components r hazardous mechanism parts if the switchgear cabinetdoor can be opened wit appropriate safety precautions. Pending issuance of aservice advice letter (SAL) by the manufacturer on this problem or a safetycommunication by GE NE, Attchment 2 illustrates an inspection hole in theright side of the mechanism ame through which the prop and prop pin positionmay be viewed. While the fully forward prop position (to the stop) is thedesired condition (maximum wipe), the absence of failures to latch along withconsistent and greater than minim allowed prop wipe is, according to GE,indicative of continued reliable la thing. However, because minimum prop wipeis not a published design specificatio, and because certain other factors(e.g., opening spring adjustment) may i'hluence latching reliability, GE hasrequested that any licensee experiencing 14 gne-Blast breaker latching problemsor noticing changed, inconsistent or appare tly abnormally low prop wipe,particularly following overhaul or repair in uding prop bushing replacement,contact GE NE PDS at 610-992-6049.Pending installation of a second prop sprin in affected breakers, MaineYankee has shifted, to the extent possible, its aailable dual prop springbreakers to locations where operability requires assured latching reliabilityfor closure or reclosure during a design-basis event. For the remainingpotentially affected breakers, Maine Yankee is plannin expedited inspectionswith the assistance of GE NE PDS to aid in its operabilMty determinations.NRC Information Notice 94-XX, issued May XX, 1994, discusles other recentlyidentified problems impacting Magne-Blast operability, rela ed to defectiveand improperly installed GE CR2940 limit switches.This information notice requires no specific action or w *tten response.If you have any questions about the information in this notice, lease contactone of the technical contacts listed below or the appropriate Of ce ofNuclear Reactor Regulation (NRR) project manager.ORIG /S/'D BY BKGRIMESBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts: Stephen Alexander, NRR Kamalakar Naidu, NRR(301) 504-2995 (301) 504-2980Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued NRC Information NoticesVIB:DRIL VIB:DRIL SC/VIB:DRILSAlexander* KNaidu* GCwalina*05/19/94 04/14/94 05/19/94C/VI BDRIL:NRR D/D I *N ChftA EELB:DE:NRRLN I film SMitra'05JK 1 /94 05/17g 4\ 05/ /94OGCB:DORS:NRR AC/OGCB:DORS :NRR D/:DORS:NRRPWen AJKugler BKGrimes05/ /94 05/ /94 05/ /94OFFICIAL RECORD COPY DOCUMENT NAME: I*See previousTECHEDMMeJac*04/18/94C/EELB:DE:NRFCBerlinger05/ /94concurrenceMAGNE3AT.GE
IN 94-XXMay XX, 1994 Normal prop wipe can be confirmed with the breaker in its cubicle and closed(in test position if necessary) in most installations by visual inspection(using an inspection mirror and light) without having to get too close toenergized components or hazardous mechanism parts if the switchgear cabinetcan be opened with appropriate safety precautions. Pending issuance of aserv' advice letter (SAL) by the manufacturer on this problem or a safetycommunic ion by GE NE, Attachment 2 illustrates an inspection hole in theright side the mechanism frame through which the prop and prop pin positionmay be viewed. hile the fully forward prop position (to the stop) is thedesired condition aximum wipe), the absence of failures to latch along withconsistent and grea than minimum allowed prop wipe is, according to GE,indicative of continue reliable latching. However, because minimum prop wipeis not a published desig specification, and because certain other factors(e.g., opening spring adjus ent) may influence latching reliability, GE hasrequested that any licensee e eriencing Magne-Blast breaker latching problemsor noticing changed, inconsiste or apparently abnormally low prop wipe,particularly following overhaul o repair including prop bushing replacement,contact GE NE PDS at 215-992-6049.Pending installation of a secon rop spring in affected breakers, MaineYankee has shifted to the extent possibe, its available dual prop springbreakers to locations where operability quires assured latching reliabilityfor closure or reclosure during a design-b is event. For the remainingpotentially affected breakers, Maine Yankee planning expedited inspectionswith the assistance of GE NE PDS to aid in it operability determinations.NRC Information Notice 94-XX, issued May XX, 19 , discusses other recentlyidentified problems impacting Magne-Blast operab ity, related to defectiveand improperly installed GE CR2940 limit switches.This information notice requires no specific ac ion or written response.If you have any questions about the information in th notice, please contactone of the technical contacts listed below or the appro late Office ofNuclear Reactor Regulation (NRR) project manager.ORIG /S/'D BY BKGRIMESBrian K. Grimes, DirectoDivision of Operating Reac or SupportOffice of Nuclear Reactor RegulationTechnical contacts: Stephen Alexander, NRR Kamalakar Naidu, NRR(301) 504-2995 (301) 504-2980Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued NRC Information NoticesVIB:DRIL VIB:DRIL SC V :DRIL TECHEDS~lexanderl'J K &aicu , G & S1na MMejac*05/(9/94 04/ W 94* O'5/94 04/18/94C VIB:DRIL:NRR D/DRIL:NRR EELB:DE:NRR CIEELB:DE:NRRLgrrholm CERossi SMitra Caerlinger05/ /94 05/ /94 05/ /94 05/ /94OGCB:DORS:NRR AC/OGCB:DORS:NRR D/:DORS:NRRPWen AJKugler BKGrimes05/ /94 05/ /94 05/ /94OFFICIAL RECORD COPY DOCUMENT NAME: MAGNE3AT.GE<&c rfmtC'al Cak"vyc.t
IN 94-XXApril XX, 1994 Prop wipe can be etermined in most installations by visual inspection withouthaving to get too lose to hazardous mechanism parts if the switchgear cabinetdoor can be opened fely. Pending issuance of a SAL by the manufacturer onthis problem (and/or Service Information Letter by GE NE), Attachment 2illustrates one locatlo where the prop position may be seen. While fullyforward prop position (t the stop) is the desired condition (maximum wipe),the absence of failures to latch along with consistent and greater thanminimum allowed prop wipe is according to GE, indicative of continuedreliable latching. However, cause minimum prop wipe is not a publisheddesign specification, and becau certain other factors (e.g. opening springadjustment) may influence latchin reliability, GE has requested that anylicensee experiencing Magne-Blast eaker latching problems or noticingchanged, inconsistent or what appear to be abnormally low prop wipe, parti-cularly following prop bushing replacemnt, contact GE NE PDS at 215-992-6049.In the meantime, pending installat n of a second prop spring in itsaffected breakers, Maine Yankee has shift to the extent possible, itsavailable dual prop spring breakers to loca Ions where operability requiresassured latching reliability for closure or closure during a design basisevent. For the remaining suspect breakers, Mane Yankee has undertakenexpedited inspections with the assistance of G E PDS to aid in its operabil-ity determinations. NRC Information Notice 94-X issued April XX, 1994, dis-cusses other recently identified problems impactin Magne-Blast operability,related to defective and improperly installed GE CR 940 limit switches.This information notice requires no specific ac on or written response.If you have any questions about the information in thi notice, please contactthe technical contacts listed below or the appropriate ffice of NuclearReactor Regulation (NRR) project manager.ORIG /S/'D BY BKGRIMESBrian K. Grimes, DirectoDivision of Operating Reac or SupportOffice of Nuclear Reactor R ulationTechnical contacts: Stephen Alexander, NRR(301) 504-2995Kamalakar Naidu, NRR(301) 504-2980Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued NRC Information NoticesVIB:DRIL VIB:DRIL SC/VIB:DRIL TECHEDSalexander Knaidu Gcwalina 41./V (,AA-04/ /94 04/ /94 04/ /94 04/AR/94C/VIB:DRIL:NRR D/DRIL:NRR EELB:DE:NRR C/EELB:DE:NRRLnorrholm CERossi SMitra Cberlinger04/ /94 04/ /94 04/ /94 04/ /94OGCB:DORS:NRR AC/OGCB:DORS:NRR D/:DORS:NRRPWen AJKugler BKGrimes04/ /94 04/ /94 04/ /94OFFICIAL RECORD COPYDOCUMENT NAME:MAGNBLST.IN
IN 94-XXApril XX, 1994 Prop wipe can be termined in most installations by visual inspection withouthaving to get too c eto hazardous mechanism parts if the switchgear cabinetdoor can be opened sa ly. Pending issuance of a SAL by the manufacturer onthis problem (and/or a rvice Information Letter by GE NE), Attachment 2illustrates one location ere the prop position may be seen. While fullyforward prop position (to t stop) is the desired condition (maximum wipe),the absence of failures to lat h along with consistent and greater thanminimum allowed prop wipe is, a cording to GE, indicative of continuedreliable latching. However, bec se minimum prop wipe is not a publisheddesign specification, and because ertain other factors (e.g. opening springadjustment) may influence latching eliability, GE has requested that anylicensee experiencing Magne-Blast breker latching problems or noticingchanged, inconsistent or what appears o be abnormally low prop wipe, parti-cularly following prop bushing replacem t, contact GE NE PDS at 215-992-6049.In the meantime, pending installatlo of a second prop spring in itsaffected breakers, Maine Yankee has shifte to the extent possible, itsavailable dual prop spring breakers to loca ions where operability requiresassured latching reliability for closure or eclosure during a design basisevent. For the remaining suspect breakers, M ne Yankee has undertakenexpedited inspections with the assistance of G NE PDS to aid in its operabil-ity determinations. NRC Information Notice 94- , issued April XX, 1994, dis-cusses other recently identified problems impact g Magne-Blast operability,related to defective and improperly installed GE R2940 limit switches.This information notice requires no specific ction or written response.If you have any questions about the information in \this notice, please contactthe technical contacts listed below or the appropri te Office of NuclearReactor Regulation (NRR) project manager.ORIG /S/'D BY BKG IMESBrian K. Grimes, irectorDivision of Operat ng Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:Stephen Alexander, NRR(301) 504-2995Kamalakar Naidu, NRR(301) 504-2980Attachments:1. Details of Failure Mode and Contributing Factors2. Magne-Blast Prop Mechanism Diagram3. List of Recently Issued_ RC Information NoticesVIB:DRIL VIB:DRI SC/VIB:DRILSalexand 9k Knaidu Gcwalina04//5'/94 04/14/94 s '4, 04/ /94C/VIB:DRIL:NRR D/DRIL:NRR EELB:DE:NRRLnorrholm CERossi SMitra04/ /94 04/ /94 04/ /94OGCB:DORS:NRR AC/OGCB:DORS:NRR D/:DORS:NRRPWen AJKugler BKGrimes04/ /94 04/ /94 04/ /94TECHED04/ /94C/EELB:DE:NRRCberlinger04/ /94OFFICIAL RECORD COPYDOCUMENT NAME:MAGNBLST.IN