Information Notice 2003-18, General Electric Type SBM Control Switches with Defective Cam Followers
| ML032520011 | |
| Person / Time | |
|---|---|
| Issue date: | 09/26/2003 |
| Revision: | 0 |
| From: | Beckner W D NRC/NRR/DIPM |
| To: | |
| References | |
| IN-03-018 | |
| Download: ML032520011 (10) | |
September 26, 2003
NRC INFORMATION NOTICE 2003-18:GENERAL ELECTRIC TYPE SBM CONTROLSWITCHES WITH DEFECTIVE CAM FOLLOWERS
Addressees
All holders of operating licenses for nuclear power reactors, except those who havepermanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to informaddressees of recent and long-term operational experience with control switches and relays incorporating a polycarbonate plastic material manufactured by General Electric known as Lexa It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
On January 5, 2003, at Calvert Cliffs Unit 1, an emergency diesel generator (EDG) outputbreaker failed to close on deman The licensee found that a single block module (SBM) type auxiliary switch on the General Electric (GE) Magne-Blast type breaker had a broken cam followe The cam follower consists of a steel pivot pin centered in clear Lexa The pin had sheared and fallen to the bottom of the switc At the pin location, the Lexan was cracked with some pieces missin Because the cam follower was broken, contact 152/b in the closing coil circuit failed open, preventing the completion of the logic permitting closure of the breaker.The licensee inspected individual breaker components affected by this deficienc Of the 24breakers inspected, 5 had defective SBM switche At Unit 1, the defective switches were on the EDG output breaker discussed above and a service water pump breaker; at Unit 2, a service water pump breaker, a high-pressure injection system breaker, and an EDG output breake All these switches had noticeably cracked Lexan but were not in as bad a condition as the switch on the Unit 1 EDG output breake The licensee replaced these switches with GE Type SB-12 switche Both SBM and SB-12 switches contain Lexan cam followers but the SB-12 switch was fabricated with Lexan not exposed to hydrocarbons, a potential failure mechanism discussed in Information Notice 80-13, General Electric Type SBM ControlSwitches with Defective Cam Followers." BackgroundIn 1976, GE recognized this problem (GE Service Information Letter [SIL] No. 155). The SILstated that the material used for the cam followers prior to July 1972 was an acetyl resin composition called Delri Delrin is easily distinguishable by its milky opaque appearancefrom the clear Lexa The SIL recommends replacement of the SBM switches in safetyapplication GE replaced Lexan in these switches with Valox, which has a white opaqueappearance similar to Delrin.No failures of SBM switches have been reported attributable to cam followers made of Delrinor Valo However, properties of these or related materials have been discussed in NRCgeneric communications, as noted below.The cause of the Lexan failures was believed to be exposure of the switches to hydrocarbonchemicals during manufacture or maintenanc With respect to the manufacturing process, switches made between July 1972 and May 1975 were believed to be suspec GE SIL No. 155 provided date codes to aid in the identification of suspect switches.The Maine Yankee licensee had previously (in 1972) experienced failures of SBM switchesduring maintenance when using contact cleaner and discontinued use of any type of contact cleaner on SBM switche In 1976, GE supplemented SIL No. 155, adding a recommendation to inspect all SBM switchesthat have polycarbonate cam followers and to replace those found to have severely cracked cam followers.In 1979, GE again supplemented SIL No. 155, reminding BWR operators of the need to inspectthe SBM switches according to Supplement 1 and discussing manufacturing changes made since January 1976: discontinuing use of nonvirgin Lexan materials, discontinuing use ofhydrocarbons, and reducing stress during roll pin insertion.In 1980, NRC issued Information Notice 80-13 to describe the SBM switch cam follower defectsfound at Cooper and Diablo Canyon Unit These switches are used broadly and thus represent a potential common-mode failure affecting multiple safety-related system At Cooper, SBM switches are used primarily as hand control switches in the control roo At Diablo Canyon Unit 1, they provide auxiliary contacts in three switch applications on 4 kV and 12 kV Magne-Blast breakers: a breaker-mounted auxiliary switch, a cell-mounted auxiliary switch, and a cell interlock switc These defects were described as severe cracking with a rock salt appearance that could ultimately progress to mechanical failure.Additional, more recent operating experience may be cite In 1998, the Perry licenseemistakenly determined that IN 80-13 and SIL No. 155 did not apply to local control switches on installed ABB HK breaker The licensee committed to reevaluate the applicability and take appropriate corrective action.In 1996, the LaSalle licensee experienced problems while downshifting the recirculation pump. The licensee failed to take appropriate corrective action for safety-related SBM switch degradation concerns identified in 1979, 1990, and 199 Also in 1996, the Turkey Point licensee observed that a 4 kV bus clearing relay failed to actuatein tes An intake cooling water system pump motor breaker stationary switch failed to operate its contacts as require The licensee found a cracked internal cam follower on this switc The licensee also observed that all four 4 kV buses contained SBM switches but concluded that all four 4KV buses were operable, characterizing the problem as an isolated random failure and noting the manufacturer's assessment that the switches would function 45,000 cycles withexisting cracks and the licensee's plans to replace the switches at the next opportunity.In 1995, the Maine Yankee licensee found three broken cam followers in SBM switches onmedium-voltage breaker Two did not prevent switch function and the third affected only a spare contac The licensee did not identify a safety concern but did identify a need for more effective communications with GE, including obtaining an index of all GE service letters to evaluate against the affected components in the plant.Also in 1995, the Pilgrim licensee encountered an SBM switch cam follower failure of the high-pressure coolant injection system suction valve from the toru A similar failure occurred in 199 The NRC cited the licensee for not promptly correcting the 1992 failure and noted that the 1995 failure was corrected satisfactoril Previous similar failures at this plant can be cited as well: a core spray inboard injection valve in 1988, and a hydrogen analyzer sample flow line in 1993. In 1994, the Cooper licensee inspected 130 SBM switches and found cracking, opaqueness,and missing pieces of cam followers on 34 of them.In 1992, the Fort Calhoun licensee experienced a failed switch for a raw water pump becauseof a cracked cam followe At the time, the licensee was replacing switches with open cracks or missing pieces.DiscussionThough failure of SBM switches because of cracked or broken cam followers was noted some30 years ago, problems persis Guidance on avoiding the problem is available.Licensees have found SBM switches with degraded Lexan cam followers of the affected datecodes among their stored components in addition to those installed in the plan In addition to replacing the affected switches in service, licensees have determined that eliminating affected switches, whether degraded or not, from the stored components effectively prevents inadvertent use of such defective switches.Other operating experience that differs from the above in one or more respects mightnevertheless apply to the general problem of degradation of plastic materials used in nuclear power plant Degradation of Delrin-related materials in applications different from controlswitches is described in NRC Information Notices 83-45 and 92-8 Thermal properties of Valox or related material are discussed in NRC Bulletin 78-01. In 2003, NRC inspectors at the Surry plant learned of degradation of zippertubing, a plasticproduct of Zippertubing Company, used to bundle electric cable inside the safety injection cabinets at both Units 1 and This product was qualified and delivered as part of the original equipment during plant constructio Zippertubing sold the product as ZIP-31 at that time,discontinued its manufacture 10-12 years ago, and now markets a similar product as ZIP-4 The Surry licensee removed this coverin This operating experience relates to NRC Information Notice 91-20 Electrical Wire Insulation Degradation Caused Failure in a Safety-Related Motor Control Center."In 2002, the San Onofre licensee reported degradation of contacts due to excessive use ofInhibisol, a cleaning solvent based on trichloroethane (TCE). The cleaning solvent caused the plastic housing for the contacts to break dow Over time, small amounts of the plastic came loose and interfered with the contacts, resulting in linestarter degradation and the failure of safety-related valve The NRC issued Information Notice 2003-06, Failure of Safety-RelatedLinestarter Relays at San Onofre Nuclear Generating Station." Information Notice 93-76,Inadequate Control of Paint and Cleaners for Safety-Related Equipment," may also apply.In 1995, the Browns Ferry licensee reported GE Type HFA 51 Series AC relay failures involvingshorting of coil wire insulation made of nylon or Lexa After its review, the licensee replaced308 such relays at Unit The NRC issued Information Notice 81-01, Possible Failures ofGeneral Electric Type HFA Relays" and Bulletin 84-02, Failures of General Electric Type HFARelays in Use in Class 1E Safety Systems."This information notice requires no specific action or written respons If you have anyquestions about this notice, contact one of the persons listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Chief Reactor Operations Branch Division of Inspection Program Management Office of Nuclear Reactor RegulationTechnical Contacts: Vernon Hodge, NRRJoe O'Hara, Region I 301-415-1861410-495-4669 E-mail: cvh@nrc.gov E-mail: jmo@nrc.govStephen Alexander, NRR301-415-2995 E-mail: sda@nrc.gov
Attachment:
List of Recently Issued NRC Information Notices equipment during plant constructio Zippertubing sold the product as ZIP-31 at that time,discontinued its manufacture 10-12 years ago, and now markets a similar product as ZIP-4 The Surry licensee removed this coverin This operating experience relates to NRC Information Notice 91-20 Electrical Wire Insulation Degradation Caused Failure in a Safety-Related Motor Control Center."In 2002, the San Onofre licensee reported degradation of contacts due to excessive use ofInhibisol, a cleaning solvent based on trichloroethane (TCE). The cleaning solvent caused the plastic housing for the contacts to break dow Over time, small amounts of the plastic came loose and interfered with the contacts, resulting in linestarter degradation and the failure of safety-related valve The NRC issued Information Notice 2003-06, Failure of Safety-RelatedLinestarter Relays at San Onofre Nuclear Generating Station." Information Notice 93-76,Inadequate Control of Paint and Cleaners for Safety-Related Equipment," may also apply.In 1995, the Browns Ferry licensee reported GE Type HFA 51 Series AC relay failures involvingshorting of coil wire insulation made of nylon or Lexa After its review, the licensee replaced308 such relays at Unit The NRC issued Information Notice 81-01, Possible Failures ofGeneral Electric Type HFA Relays" and Bulletin 84-02, Failures of General Electric Type HFARelays in Use in Class 1E Safety Systems."This information notice requires no specific action or written respons If you have anyquestions about this notice, contact one of the persons listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Chief Reactor Operations Branch Division of Inspection Program Management Office of Nuclear Reactor RegulationTechnical Contacts: Vernon Hodge, NRRJoe O'Hara, Region I 301-415-1861410-495-4669 E-mail: cvh@nrc.gov E-mail: jmo@nrc.govStephen Alexander, NRR301-415-2995 E-mail: sda@nrc.gov
Attachment:
List of Recently Issued NRC Information NoticesDISTRIBUTION:IN File ADAMSADAMS ACCESSION NUMBER: ML032520011*See previous concurrenceDOCUMENT NAME: C:\ORPCheckout\FileNET\ML032520011.wpdOFFICEIROB:DIPMTech EditorIEPM:DIPMRGN-IRGN-INAMECVHodge*PKleene*SAlexander*JO'HaraJTrappDATE09/08/200308/29/2003 09/08/200309/15/200309/15/2003OFFICESC:IROB:DIPMBC:IROB:DIPMNAMETReisWDBecknerDATE09/25/200309/26/2003 / /2003 / /2003 / /2003OFFICIAL RECORD COPY
______________________________________________________________________________________OL = Operating License CP = Construction PermitAttachment 1 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES_____________________________________________________________________________________InformationDate of Notice N SubjectIssuanceIssued to_____________________________________________________________________________________2003-17Reduced Service Life ofAutomatic Switch Company (ASCO) Solenoid Valves With Buna-N Material09/29/2003All holders of operating licensesfor nuclear power reactors.2003-16Icing Conditions BetweenBottom of Dry Storage System and Storage PadPendingAll 10 CFR Part 72 licensees andcertificate holders.2003-15Importance of FollowupActivities in Resolving Maintenance Issues09/05/2003All holders of operating licensesfor nuclear power reactors except those who have permanently ceased operation and have certified that fuel has been permanently removed from the reactor vessel.2003-14Potential Vulnerability of PlantComputer Network to Worm Infection08/29/2003All holders of operating licensesfor nuclear power reactors, except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vesse Steam Generator TubeDegradation at Diablo Canyon08/28/2003All holders of operating licensesfor pressurized-water reactors (PWRs), except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor.Note:NRC generic communications may be received in electronic format shortly after they areissued by subscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the followingcommand in the message portion:subscribe gc-nrr firstname lastname