Information Notice 1993-25, Electrical Penetration Assembly Degradation

Electrical Penetration Assembly Degradation

ML031080020
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:	04/01/1993
From:	Grimes B K Office of Nuclear Reactor Regulation
To:
References
IN-93-025, NUDOCS 9303250146
Download: ML031080020 (12)

I'- 'UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555April 1, 1993NRC INFORMATION NOTICE 93-25: ELECTRICAL PENETRATION ASSEMBLY DEGRADATION

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 problems that could result in degradation ofelectrical penetration assembly seals. This information notice focuses on thecontainment integrity function of these seals. It is expected that recipientswill review the information for applicability to their facilities and consideractions, as appropriate, to avoid similar problems. However, suggestionscontained in this information notice are not NRC requirements; therefore, nospecific action or written response is required.

Description of Circumstances

In July 1987 and in October 1989, the licensee for the Trojan Nuclear Plant,the Portland General Electric Company, reported problems with containment airleakage through its Bunker-Ramo electrical penetration assembly seals[licensee event reports (LERs) 50-344/87-11 and 50-344/89-23]. In July andAugust 1991, the NRC inspected the use of containment electrical penetrationassembly seals at Trojan and concluded that the licensee had not establishedan effective program for trending and evaluating electrical penetrationassembly seal leakage (Inspection Report 50-344/91-27). On October 28, 1991,while the plant was in a refueling outage, the licensee reported to the NRCthat in the originally installed electrical penetration assemblies, the seal(polyurethane) and lubricant (Celvacene or Glycerin) materials wereinappropriate for the application (LER 50-344/91-11-01). The licenseeconcluded that these materials may cause seal degradation and that the sealsmay become degraded if subjected to design basis accident conditions formoisture or temperature. The licensee replaced the electrical penetrationassembly seal with an environmentally qualified ethylene propylene rubber sealand added a silicone rubber backup O-ring to the outer face of each electricalpenetration assembly module. The licensee subsequently replaced all theBunker-Ramo electrical penetration assemblies with Conax assemblies.DiscussionElectrical penetration assemblies provide electrical continuity for fieldcables penetrating the containment and maintain containment integrity.9303250146 -PW a: f1) t arC;02S ISoC'aoII \l

.aIN 93-25April 1, 1993 Degraded electrical penetration assemblies can adversely affect containmentintegrity by allowing excessive leakage from the containment under accidentconditions.The Bunker-Ramo electrical penetration assembly consists of a cylindricalstructure with circular header plates at each end. One header plate isdesigned to be bolted to a flange on the containment liner plate penetrationnozzle. Containment integrity is achieved by two C-cup seals between theflanges. In the Bunker-Ramo design, a helical spring-loaded polyurethane sealis mounted at each end of the-electrical penetration assembly. Eachelectrical penetration assembly has two seals, an outer one, nominally of8.9 cm [3.5 inch] diameter, and an inner one, of nominally 6.4 cm [2.5 inch]diameter. The outer seal functions as part of the containment boundary whilethe inner seal functions as an outer seal test pressure boundary. Theelectrical penetration assembly header plate is equipped with a connection towhich a pressure indicating gauge can be attached to monitor seal leakage.At the Trojan plant, the qualified life of the seal had not been accuratelyestablished. The simultaneous effects of corrosion and moisture at normaltemperature had not been taken into account. The established longevity wasnot corrected after factoring in the actual degradation observed duringperiodic surveillance of the individual seals.' Also, an administrativemechanism was not in place to replace the seals before their estimatedqualified life expired. The original seal material in the Bunker-Ramoelectrical penetration assembly has polyesterurethane manufactured by ParkerPacking Company (Parker) under the trade name of Parkerthane (Parker CompoundNo. P4611). Parker, which manufactures both polyester urethane and polyetherurethane seals, indicated in its catalog that polyester urethane maintainscritical characteristics up to 6 years while polyether urethane maintainscritical characteristics up to 10 years.The polyester urethane (the originally installed seal material) was determinedinadequate for several reasons:Short expected life (independently estimated at 2-5 years under someconditions)Incompatibility with water (hydrolysis shortens life)Incompatibility with high temperature (acceleration of hydrolysis)Susceptibility to compression-set (a slowly acquired permanentdeformation)The licensee used different lubricants over the years. In 1987, the licenseedetermined that three seals had failed because they were erroneouslylubricated with an incompatible (silicone) grease. After examination of sealfailures that occurred in 1991, Parker determined that the failed seals hadcastor oil residue on the exterior, indicative of the use of Celvacenelubricant', which'includes castor oil and cellulose acetate butyrate.Celvacene, specified for use by the original penetration supplier, can cause IN 93-25April 1, 1993 degradation of polyurethane as follows. The cellulose acetate butyratecomponent breaks down in the presence of moisture, producing butyric acid,which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowlydegrades the polyurethane material. Under accident conditions, the sealdegradation may be accelerated.The original penetration supplier, Bunker-Ramo, no longer supplies suchassemblies. Similar electrical penetration assemblies have been supplied byAmphenol, but this company also no longer supplies such assemblies.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: C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachment:

List of Receitly Issued NRC Information Notices 14AttachmentIN 93-25April 1, 1993Page I of ILIST OF RECENTLY ISSUEDKRC INFORMlATION NOTICESa4c40L '0I UJ :30A.UflU InrormationNotice No.93-2493-2393-2293-2193-2093-1993-18)93-1793-16SubjectDistribution ofRevision 7 of PURE6-1021.0Operator LicensingExaminer Standards"Weschler InstrumentsNodel 252 SwitchboardPetersTriping of Klockner-Nfoeller Molded-CaseCircuit Breakers due toSupport Level FailureSummary of NRC StaffObservations Compiledduring Engineering Auditsor Inspections of Licen-see Erosion/CorrosionProgramsThermal Fatigue Crackingof Feedwater Piping to*Steam GeneratorsSlab Hopper BulgingPortable Moisture-DensityGauge User Responsibilitiesduring Field OperationsSafety Systems Responseto Loss of Coolant andLoss of Offs1te PowerFailures of Nut-LockingDevices in Check ValvesIssuane Issued to03/31/93 All holders of orater andsenior operator eienses atnuclear power reactors.03/31/93 All holders of OLs or CPsfor nuclear power reactors.03/26/93 All holders of OLs or CPsfor nuclear power reactors.03/25/93 All holders of OLs or CPsfor light water nuclearpower reactors.Ii03/24/93 All holders of OLs or CPsfor PWRs supplied byWestinghouse or CombustionEngineering.03/17/92 All nuclear fuel cyclelicensees.03/10/93 All U.S. Nuclear RegulatoryCommission licensees thatpossess moisture-densitygauges.03/08/93 All holders of OLs or CPsfor nuclear power reactors.02/19/93 All holders of OLs or CPsfor nuclear power reactors.2I(0000W O1 c1n 2IL I-I U4):zUZ aFA.~OL -Operating LicenseCP -Construction Permit IN 93-25April 1, 1993 degradation of polyurethane as follows. The cellulose acetate butyratecomponent breaks down in the presence of moisture, producing butyric acid,which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowlydegrades the polyurethane material. Under accident conditions, the sealdegradation may be accelerated.The original penetration supplier, Bunker-Ramo, no longer supplies suchassemblies. Similar electrical penetration assemblies have been supplied byAmphenol, but this company also no longer supplies such assemblies.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.orig /s/'d by BKGrimesBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachment:

List of Recently Issued NRC Information Notices*SEE PRMV a CONCURRENCES*C/OGCB:DORS:NRR*RPB:ADMGHMarcus TechEd03/05/93 04/13/92*D/DRIL:NRRCERossi03/03/93*C/RVIB:DRIL:NRRLJNorrholm02/27/93*OGCB: DORS:NRRCVHodge06/03/92*RESINSP/RVRBarr06/03/92*RVIB:DRIL:NRRKNaidu01/11/93*SC/RVIB:DRIL:NRRGCwallna02/27/93DOCUMENT NAME: 93-25.IN IN 93-XXMarch xx, 1993 castor oil residue on the exterior, indicative of the use of Celvacenelubricant, which includes castor oil and cellulose acetate butyrate.Celvacene, specified for use by the original penetration supplier, can causedegradation of polyurethane as follows. The cellulose acetate butyratecomponent breaks down in the presence of moisture, producing butyric acid,which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowlydegrades the polyurethane material. Under accident conditions, the sealdegradation may be accelerated.The original penetration supplier, Bunker-Ramo, no longer supplies suchassemblies. Si ilar electrical penetration assemblies have been supplied byAmphenol6w-butThis company also no longer supplies such assemblies. -AThis 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: C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachment:

List of Recently Issued NRC Information NoticesDocument Name: PRESBOUN.IN*SEE PREVIOUS CONCURRENCESD/DORS:NRRBKGrimes03/ /93U*C/OGCB:DORS:NRR*RPB:ADM *D/DRIL:NRR C/RVIB:DRIL:NRRGHMarcus TechEd CERossi LJNorrholm03/05/93 04/13/92 03/03/93 02/271/93*OGCB:DORS:NRR *RESINSP/RV *RVIB:DRIL:NRR *SC/RVIB:DRIL:NRRCVHodge RBarr KNaidu GCwalina06/03/92 06/03/92 01/11/93 02/27/93 IN 93-XXMarch xx, 1993 degradation of polyurethane as follows. Ihe cellulose acetate butyrateccuponent breaks dawm in the presence of irsture, producing butyric acid,whici in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowlydegrades the polyurethane material. Mier accident cmditins,, the sealdegradation may be accelerated.The original penetration supplier, Bunker-Ramo, is no longer in the business.Similar electrical penetraticn assemblies have been splied -by Anphenol, butthis ccapany also is no lcnger in the hksiness. Ihe licensee at Trojanreplaced its Eunker-Ramo electrical penetration assemblies with Ckmaxelectrical penetration assemblies.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 aPqrcpriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Cperating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts: C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naid, NRR(301) 504-2980

Attachment:

List of Recently Issued NR Information NoticesD x:mnt Name: PRESBCEXI IN*SEE PREVIOUS aONCNRRENcSD/DORS:NRR C/OGCB:DORS:MMR*RPB:ADM *D/MlUL:NfRBI~rimes Grfrcus64W Tech~d CEossi02/ /93 03/S /93 04/13/92 03/03/93*OGCB:DORS:NRR *PMINSP/RV *REV :RI:NR:R *SC/RVIB:DR:M;R*C/RIB:WIL:NRRCvHodge RBarr .Naidu Gwalina mJ~orrhobii06/03/92 06/03/92 01/11/93 02/27/93 02/27/93

-IN 93-XXFebruary xx, 1993 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:C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachment:

List of Recently Issued NRC Information NoticesDocument Name:PRESBOUN.IN*SEE PREVIOUS CONCURRENCES*OGCB:DORS:NRRCVHodge06/03/92D/DORS:NRRBKGrimes02/ /93*RESINSP/RVRBarr06/03/92C/OGCB:DORS:NRR*RPB:ADMGHMarcus TechEd02/ /93 04/13/92*RVIB:DRIL:NRR SC/RVIB:DRIL:NRRKNaidu GCwalina01/11/93 02/ /93CYRU:DRIL:NRRLJNorrholm02/ /93 IN 93-XXJanuary xx, 1993 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:C. Vernon Hodge,(301) 504-1861NRRRobert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachment:

List of Recently Issued NRC Information NoticesDocument Name:PRESBOUN.IN*SEE PREVIOUS*OGCB: DORS:NRFCVHodge06/03/92CONCURRENCESD/DORS:NRRBKGrimes01/ /93Z *RESINSP/RVRBarr06/03/92C/OGCB:DORS:NRR*RPB:ADMGHMarcus TechEd01/ /93 04/13/92*RVIB:DRIL:NRR IB:DRIL:NRRKNaidu Gaina01/11/93 /93D/DRIL:NRR C--#-CERossig gmlL:NRR01/j /93DD:DRIL:NRRRZimmerman01/ /93 IN 93-XXJanuary , 1993 .,under loss of coolant accident (LOCA) conditions. Premature degradation ofthe insulation covering the electrical connections can expose the connectionsto an adverse environment during a LOCA. A brief survey of these LERs isincluded in Attachment 1.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 Off ce ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating ReactorOffice of Nuclear Reactor ReguSupportlationTechnical contacts:C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal(301)Naidu, NRR504-2980

Attachments:

1. Survey of Licensee Event Reports (LERs)2. List of Recently Issued NRC Information NoticesDocument Name: PRESBOUN.IN*SEE PREVIOUS CONCURRENCES*OGCB:DORSONRR *RESINSP/RVCVHodge USA RBarr06/03/92 0413 06/03/92D/DORS:NRRBKGrimes01/f /93! n IB:DRIL:NRRKNai du01/11/93C/OGCB:DORS:NRR*RPB:ADMGHMarcus TechEd01/ /93 04/13/92C/RVIB:DRIL:NRR D/DRIL:NRRLJNorrholm CERossi01/ /93 01/ /93..I zi' k I '. ,.-: I , :

K>IN 93-XXJanuary xx, 993identify excessive leakage of EPA seals indicating possible degradation frommoisture intrusion. Degraded seals can cause breach of containment integrityunder loss of coolant accident (LOCA) conditions. Premature degradation ofthe insulation covering the electrical connections can expose the connectionsto an adverse environment during a LOCA. A brief survey of these LERs isincluded in Attachment 1.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:C. Vernon Hodge, NRR(301) 504-1861Robert C. Barr, Region V(509) 377-2627Kamal Naidu, NRR(301) 504-2980

Attachments:

1. Survey of Licensee Event Reports (LERs)2. List of Recently Issued NRC Information NoticesDocument Name:PRESBOUN.IN*SEE PREVIOUS CONCURRENCESOGCB:DORS:NRRCVHodge V@06/o3/9201 /Iq/3D/DORS:NRRBKGrimes01/ /93RESINSP/RVRBarr wC/OGCB:DORS:NRR*RPB:ADMGHMarcus TechEd01/ /93 04/13/92*RVIB:DRIL:NRR SC/RVIB:DRIL:NRRKNaidu GCwalina01/11/93 01/ /93D/DRIL:NRRCERossi01/ /93C/RVIB:DRIL:NRRLJNorrholm01/ /93 of EPA seals represent violations of Containment integrity and environmentalqualification deficiencies in EPA components indicatepe s m -/~u4n-deiiP coddia")loss~bf(oolant accident (LOCA) co'nditions. A brief survey of these LERs I4B'Cincluded in .ttachmet A imThis information notice requiresyou have any questions about theof the technical contacts listedReactor Regulation (NRR) projectno specific action or written response. Ifinformation in this notice, please contact onebelow or the appropriate Office of Nuclearmanager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contacts:Vern Hodge, NRR(301) 504-1861Rob Barr, RV(503) 556-3751

Attachments:

1. Survey of Licensee Event Reports (LERs)2. List of Recently Issued NRC Information NoticesDocument Name: BUNK0403 REV 19OGCB:DOEA:NRRCVHodge04/ /92RESINSP/RVRBarr04/ /92D/DOEA:NRRCERossi04/ /92RVIB:DRIS:NRRKNaidu04/ /92C/OGCB:DOEA:NRRCHBerlinger04/ /92RPB:ADMTechEd J'Ma;, )04/13 /92ROAB:DSP:NRRSMazumdar04/ /92