Information Notice 1990-02, Potential Degradation of Secondary Containment

Potential Degradation of Secondary Containment

ML031130355
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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	01/22/1990
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-90-002, NUDOCS 9001160420
Download: ML031130355 (9)

I ft Ii-UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555January 22, 1990NRC INFORMATION NOTICE NO. 90-02: POTENTIAL DEGRADATION OF SECONDARYCONTAINMENT

Addressees

All holders of operating licenses or construction permits for boiling waterreactors (BWRs).

Purpose

This information notice is intended to alert addressees to potential problemsinvolving degradation of secondary containment as a result of unforeseen inter-actions with various normal plant ventilation systems and inadequate surveillancetesting of secondary containment integrity. It is expected that recipients willreview the information for applicability to their facilities and consider actions,as appropriate, to avoid similar problems. However, suggestions contained inthis information notice do not constitute NRC requirements; therefore, no specificaction or written response is required.Detcription of Circumstances:Duane Arnold Energy CenterDuring a reactor building exhaust ventilation inspection, an Iowa Electricsystem engineer discovered a large hole in the duct work (see Figure 1).This hole allowed the main plant ventilation system to communicate directlywith the reactor building ventilation system, thus bypassing the standby gastreatment system (SGTS) and providing a direct path for an untreated releaseof radioactive effluents to the environment. This pathway would have existedeven with an automatic Engineered Safety Feature (ESF) isolation of the reactorbuilding ventilation system and an autostart of the SGTS. The licensee dis-covered that .its normal secondary containment integrity surveillance test(which requires a measurement of 0.25 inch water vacuum with one train ofSGTS operating) was still apparently satisfied with the main plant ventilationfans running. This has been the test configuration used at the plant sinceinitial startup in 1974. However, upon conducting the test with the SGTSoperating as designed and the main plant ventilation secured, the 0.25-inchvacuum could not be achieved because of numerous secondary containment leaks.A 10 CFR 50.72 4-hour notification was made to the NRC upon this discovery.The licensee determined that during the performance of the secondary contain-ment integrity surveillance as it was previously conducted, the main plant9001160420 Zjl_ _v c

IN 90-02January 22, 1990 ventilation, turbine building ventilation, and the radwaste building ventila-tion exhaust fans had aided the SGTS in drawing the required vacuum. Becausesurveillance tests performed since initial unit startup usually indicated thatthe required negative pressure had been obtained, numerous secondary contain-ment integrity deficiencies went undetected and uncorrected. The maintenanceto correct this overall degradation of the secondary containment required morethan 3 weeks of effort to locate and repair numerous door seals, electricalpenetrations, steam tunnel boot seals, dampers, building seals, and duct systems.These repairs resulted in an improvement in the measured secondary containmentvacuum from less than 0.08 inch of water to greater than 0.25 inch of water, asdetermined by retesting with a new surveillance test procedure. This test nowrequires all major plant exhaust ventilation fans that potentially communicatewith secondary containment to be secured.Continued testing after repairs has shown that one main plant exhaust ventilationfan can still draw an approximate 500 to 1000 standard cubic feet-per-minute (SCFM)volume' from the reactor building ventilation system (the secondary containmentboundary) when the ESF-required isolation is in effect. As this circumstancecould result in an untreated ground-level release under certain accident scenarios,the licensee developed alarm response procedures designed to secure the mainplant ventilation fans when secondary containment isolation is initiated andmain plant exhaust ventilation radiation monitors reach specified values. IowaElectric is also considering long-term corrective action involving hardwaremodifications that would prevent main plant ventilation from drawing air outof the reactor building under accident conditions.MonticelloAs a result of the secondary containment deficiencies identified at Duane Arnold,the NRC resident inspector contacted the licensee for the Monticello plant con-cerning the procedures and practices for testing the secondary containment system.The licensee had normally tested the secondary containment integrity with themain plant exhaust fans running and isolated both supply and exhaust fans inthe reactor building. However, on October 14, 1989, the licensee conductedthe secondary containment integrity test with the main plant exhaust fanssecured and was not able to maintain the 0.25-inch water vacuum required bythe technical specifications. The vacuum reached in the reactor building wasonly 0.1 inch of water. Preliminary investigation revealed that failure ofthe test was due to leaks in the reactor building supply and exhaust systemdampers and various other secondary containment leaks. The licensee alsobelieves that the operation of the main plant exhaust fans assisted the SGTSin drawing the required vacuum on the secondary containment, thus establishinga path that bypassed the SGTS. A 10 CFR 50.72 notification was made to the NRC.Discussion of Safety Significance:Plant heating, ventilation, and air conditioning (HVAC) systems are diverseamong boiling water reactors. Interactions between these systems and thestandby gas treatment system could mask degradation of the secondary contain-ment boundary during surveillance testing and could exacerbate such degradatiof+t'by diverting flow from the SGTS following an accident. -

K>IN 90-02January 22, 1990 For those plants discussed above, a portion of the secondary containmentboundary is formed by the ductwork and isolation dampers of the reactor build-ing ventilation system. This system exhausts to a common plenum area withinthe reactor building, but outside secondary containment, where ventilationflows from other plant HVAC systems are also directed. The high-capacity mainplant ventilation exhaust fans take suction from the plenum area and dischargethe flow through the reactor building roof stacks. Because of the high capa-city of the main plant exhaust fans and their proximity to the reactor buildingventilation system components that form part of the secondary containmentboundary, the potential exists for air flow to bypass the SGTS even when thesecondary containment is isolated. Further, if the main plant ventilation fansare operated during surveillance testing, degradation of secondary containmentcould go undetected as the main plant fans and the SGTS fans could collectivelydraw the required vacuum.In view of the possibility of the main plant ventilation systems maskingdeficiencies in SGTS and/or secondary containment integrity and of creatingpossible untreated release paths under accident conditions, licensees for otherBWR plants may wish to review the design and operation of major plant ventila-tion systems and to review their secondary containment integrity surveillanceprocedures.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact oneof the technical contacts listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: William L. Axelson, Region III(708) 790-5574John A. Kudrick, NRR(301) 492-0871James R. Hall, NRR(301) 492-1391Attachments:1. Figure 1 -Reactor Building Ventilation2. List of Recently Issued NRC Information Notices

Attachment 1IN 90-02January 22, 1990 Failed DucUngIsolatlon DampersReactor BuidingVentShaftFgure 1Reactor Building VentilationIw/I1-89A1087 K>Attachment 2IN 90-02January 22, 1990 ti e.-..11 -1..,-1-LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to90-0189-9089-8989-8889-8789-45,Supp. 289-8689-8589-84Importance of ProperResponse to Self-IdentifiedViolations by LicenseesPressurizer Safety ValveLift Setpoint ShiftEvent NotificationWorksheetsRecent NRC-SponsoredTesting of Motor-OperatedValvesDisabling of EmergencyDiesel Generators byTheir Neutral Ground-FaultProtection CircuitryMetalclad, Low-VoltagePower Circuit BreakersRefurbished withSubstandard PartsType HK Circuit BreakersMissing Close Latch Anti-Shock Springs.EPA's Interim Final Ruleon Medical Waste Trackingand ManagementFailure of Ingersoll RandAir Start Motors as a Resultof Pinion Gear AssemblyFitting Problems1/12/9012/28/8912/26/8912/26/8912/19/8912/15/8912/15/8912/15/8912/12/89All holders of NRCmaterials licenses.All holders of OLsor CPs for PWRs.All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for nuclearpower reactors.All holders of OLsor CPs for nuclearpower reactors.All medical, academic,industrial, wastebroker, and wastedisposal site licensees.All holders of OLsor CPs for nuclearpower reactors.OL = Operating LicenseCP = Construction Permit

IN 90-02January 22, 1990 For those plants discussed above, a portion of the secondary containmentboundary is formed by the ductwork and isolation dampers of the reactor build-ing ventilation system. This system exhausts to a common plenum area withinthe reactor building, but outside secondary containment, where ventilationflows from other plant HVAC systems are also directed. The high-capacity mainplant ventilation exhaust fans take suction from the plenum area and dischargethe flow through the reactor building roof stacks. Because of the high capa-city of the main plant exhaust fans and their proximity to the reactor buildingventilation system components that form part of the secondary containmentboundary, the potential exists for air flow to bypass the SGTS even when thesecondary containment is Isolated. Further, if the main plant ventilation fansare operated during surveillance testing, degradation of secondary containmentcould go undetected as the main plant fans and the SGTS fans could collectivelydraw the required vacuum.In view of the possibility of the main plant ventilation systems maskingdeficiencies in SGTS and/or secondary containment integrity and of creatingpossible untreated release paths under accident conditions, licensees for otherBWR plants may wish to review the design and operation of major plant ventila-tion systems and to review their secondary containment integrity surveillanceprocedures.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact oneof the technical contacts listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: William L. Axelson, Region III(708) 790-5574John A. Kudrick, NRR(301) 492-0871James R. Hall, NRR(301) 492-1391Attachments:1. Figure 1 -Reactor Building Ventilation2. List of Recently Issued NRC Information NoticesDocument Name: INFO NOTICE -JACKIW, KIESSEL*SEE PREVIOUS CONCURRENCESD *C/OGCB:DOEA:NRR *RPB:ARM *D/DST:NRRE CHBerlinger TechEd AThadani01//190 01/10/90 12/21/89 12/18/89*OGCB:DOEA:NRR*RIII *PD33:DRSP:NRR *SPLB:DST:NRR*C/SPLB:DST:NRRRJKiessel EGGreenman JRHall JKudrick CEMcCracken11/16/89 11/21/89 11/16/89 12/12/89 12/12/89 IN 90-XXJanuary xx, 1990 For those plants discussed above, a portion of the secondary containmentboundary is formed by the ductwork and isolation dampers of the reactor build-ing ventilation system. This system exhausts to a common plenum area withinthe reactor building, but outside secondary containment, where ventilationflows from other plant HVAC systems are also directed. The high-capacity mainplant ventilation exhaust fans take suction from the plenum area and dischargethe flow through the reactor building roof stacks. Because of the high capa-city of the main plant exhaust fans and their proximity to the reactor buildingventilation system components that form part of the secondary containmentboundary, the potential exists for air flow to bypass the SGTS even when thesecondary containment is isolated. Further, if the main plant ventilation fansare operated during surveillance testing, degradation of secondary containmentcould go undetected as the main plant fans and the SGTS fans could collectivelydraw the required vacuum.In view of the possibility of the main plant ventilation systems' maskingdeficiencies in SGTS and/or secondary containment integrity and of creatingpossible untreated release paths under accident conditions, licensees for otherBWR plants may wish to review the design and operation of major plant ventila-tion systems and to review their secondary containment integrity surveillanceprocedures.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contacts listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: William L. Axelson, Region III(708) 790-5574John A. Kudrick, NRR(301) 492-0871James R. Hall, NRR(301) 492-1391Attachments:1. Figure 1 -Reactor Building Ventilation2. Figure 2 -Exhaust Fan Room3. List of Recently Issued NRC Information NoticesDocument Name: INFO NOTICE -JACKIW, KIESSEL*SEE PREVIOUS CONCURRENCESD/DOEA:NRR C/OGCB:D C Byt;*RPB:ARM *D/DST:NRRCERossi CHBerline j) TechEd AThadani01/ /90 01/Y,/90- ' 12/21/89 12/18/89*OGCB:DOEA:NRR*RIII *PD33:DRSP:NRR *SPLB:DST:NRR*C/SPLB:DST:NRRRJKiessel EGGreenman JRHall -lf JKudrick CEMcCracken11 11/21 11/16/8w 12/12/89 12/12/89441/44s~4 IN 89-XX%2 ~November xx, 1989 standby gas treatment system could mask degradation of the secondary contain-ment boundary during surveillance testing and could exacerbate such degradationby diverting flow from the SGTS following an accident.For those plants discussed above, a portion of the secondary containmentboundary is formed by the ductwork and isolation dampers of the reactor build-ing ventilation system. This system exhausts to a common plenum area withinthe reactor building, but outside secondary containment, where ventilationflows from other plant HVAC systems are also directed. The high capacity mainplant ventilation exhaust fans take suction from the plenum area and dischargethe flow out through the reactor building roof stacks. Due to the high capa-city of the main plant exhaust fans and their proximity to the reactor buildingventilation system components that form part of the secondary containmentboundary, the potential exists for air flow to bypass the SGTS even when thesecondary containment is isolated. Further, if the main plant ventilation fansare operated during surveillance testing, degradation of secondary containmentcould go undetected as the main plant fans and SGTS fans could collectivelydraw the required vacuum.In view of the possibility of main plant ventilation systems masking deficien-cies in SGTS and/or secondary containment integrity and of creating possibleuntreated release paths under accident conditions, other BWR plants may wish toreview the design and operation of major plant ventilation systems and toreview their secondary containment integrity surveillance procedures.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contacts listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:William L. Axelson, Region III(708) 790-5574John A. Kudrick, NRR(301) 492-0871James R. Hall, NRR(301) 492-1391Attachments:1. Figure 1 -Reactor Building Ventilation2. Figure 2 -Exhaust Fan Room3. List of Recently Issued NRC Information NoticesDocument Name: INFO NOTICE -JACKIW, KIESSEL*SEE PREVIOUS CONCURRENCES sitD/DOEA:NRR C/OGCB:DOEA:NRR RPB:ARO'CERossi CHBerlinger TechEd11/ /89 11/ /89 ftH/.Zf/*OGCB:DOEA:NRR*RIII *PD33:DRSP:NRR SPLB: RRJKiessel EGGreenman JRHall *udri11/16/89 11/21/89 11/16/89 WMIAl'D/DST:NRRniMAK /89C/SPLB:DST: WG9CEMcCracken,_ --/d 89