Information Notice 1992-71, Partial Plugging of Suppression Pool Strainers at a Foreign BWR

Partial Plugging of Suppression Pool Strainers at a Foreign BWR

ML031200327
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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:	09/30/1992
Revision:	0
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-92-071, NUDOCS 9209290014
Download: ML031200327 (7)

_~K)UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555September 30, 1992NRC INFORMATION NOTICE 92-71: PARTIAL PLUGGING OF SUPPRESSION POOLSTRAINERS AT A FOREIGN BWR

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 potential-for loss of emergency core coolingsystems (ECCS) that was identified as a result of an event at a Swedishboiling water reactor (BWR). It is expected that recipients will review thelinformation for applicability to their facilities and consider actions, asappropriate, to avoid similar problems. However, suggestions contained inthis information notice are not NRC requirements; therefore, no specificaction or written response is required.

Description of Circumstances

On July 28, 1992, Sydkraft AB, the utility licensed by the Swedish regulatoryagency for the BarsebAck nuclear power plant, was restarting Unit 2 after theannual outage. While the reactor was at 1 or 2 percent power and at 435 psi,a leaking pilot valve caused a safety valve for the reactor vessel to open.This valve discharges directly to the drywell. Reactor scram, high pressuresafety injection, core spray, and containment spray systems initiatedautomatically in response to the event. Steam from the open safety valve,impinging on thermally-insulated equipment, dislodged 440 pounds of metal-jacketed, mineral wool. An estimated 220 pounds of insulating material waswashed into the suppression pool. Two of five strainers on the suction sideof the ECCS pumps were in service and became partially plugged with mineralwool. Plugging caused pressure to decrease significantly across the strainersand caused indications of cavitation in one pump in about an hour after theevent began. The operators successfully back flushed the strainers and shutdown the reactor without additional problems.DiscussionIn the safety analysis for Unit 2 of the Barsebdck plant, the licenseeconcluded that the strainers would not require back flushing during the first10 hours after a loss-of-coolant accident. Because of the event of July 28,the Swedish regulatory agency required Barseback Unit 2 and four other unitsof similar design to remain shut down until this problem is resolved.9209290014 e IIIIN 92-71September 30, 1992 This event at BarsebAck is directly applicable to an earlier study conductedby the NRC. That study evaluated the potential for displaced thermalinsulation to form debris and to be drawn to the sump screen. The results ofthe study are documented in "Containment Sump Performance," NUREG-0897,Revision 1, dated March 1984. The NRC concluded that the risk associated withthe sump clogging concern did not warrant backfitting of domestic plants.However, based on the Barsebdck event, this conclusion is being reevaluated.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.(arles si, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: Robert L. Dennig, NRR(301) 504-1156

Attachment:

List of Recently Issued NRC Information Notices AttachmentIN 92-71September 30, 1992 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to92-7092-6991-29,Supp.92-6892-671Westinghouse Motor-OperatedValve Performance DataSupplied to Nuclear PowerPlant LicenseesWater Leakage from YardArea Through ConduitsInto BuildingsDeficiencies IdentifiedDuring Electrical Dis-tribution System Func-tional InspectionsPotentially SubstandardSlip-On, Welding Neck,and Blind FlangesDeficiency in DesignModifications to Ad-dress Failures ofHiller Actuators UponA Gradual Loss ofAir PressureAccess Denied to NRCInspectors at Five StarProducts, Inc. andConstruction ProductsResearch, Fairfield,ConnecticutSafety System ProblemsCaused by ModificationsThat Were Not AdequatelyReviewed and Tested09/25/9209/22/9209/14/9209/10/9209/10/9209/01/9209/03/9208/28/92All 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 reactorsand all recipients ofNUREG-0040, "Licensee, Con-tractor and Vendor Inspec-tion Status Report" (White.Book).All holders of OLs or CPsfor nuclear power reactors.All holders of -OLs or CPsfor nuclear power reactors.92-6692-6592-64Nozzleon LowReliefRing SettingsPressure Water-ValvesOL = Operating LicenseCP = Construction Permit K><YIN 92-71September 30, 992This event at Barseback is directly applicable to an earlier study conductedby the NRC. That study evaluated the potential for displaced thermalinsulation to form debris and to be drawn to the sump screen. The results ofthe study are documented in "Containment Sump Performance," NUREG-0897,Revision 1, dated March 1984. The NRC concluded that the risk associated withthe sump clogging concern did not warrant backfitting of domestic plants.However, based on the BarsebAck event, this conclusion is being reevaluated.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Original Signed byCharles E. RossiCharles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical conitact: Robert L. Dennig, NRR(301) 504-1156List of Recently Issued NRC Information Notices

Attachment:

Document Name: 92-71.IN*SEE PREVIOUS CONCURRENCES*OEAB:DOEA:NRR*SC/OEAB:DOEA:NRRRWWoodruff RLDennig09/24/92 09/24/92V CEp/azeSC~hLAt_- Jest)o1i A e- ,L .IDO *C/OGCB:DOEA:NRR*RPB:ADMC GHMarcus TechEd09/; 92 09/28/92 09/24/24*C/OEAB:DOEA:NRR*C/SPLB:DST:NRR ICEP/OIPwAChaffee CEMcCracken AKenqeke09/k8/92 09/1r/92 09/dg/92ago,. 4 e, am ASCo-- -I rw W. 4.4a NRCIN 92-XXSeptember xx, 1991 documented in "Containment Sump Performance," NUREG-0897, Revision 1, dated March1984. The NRC concluded that the risk associated with the sump clogging concerndid not warrant backfitting of domestic plants. However, based on the Barsebackevent and NUREG-0897, Revision 1, this conclusion is being reevaluated.This information notice requires no specific action or written response. If youhave any question about the information in this notice, please contact thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.-Charles E. Rossi, DirectorDivision of OperationalEvents AssessmentOffice of Nuclear Reactor RegulationTechnmical Contact:Robert L. Dennig, NRR(301) 504-1156

Attachment:

1. List of Recently Issued Information Notices* See previous page for concurrence.CONCURRENCE:OEAB*RWWoodruff09/24/92D:DOEACERossi09/ /92LevA^-t l40-m'-is -DcNpu P I 0 u; "rcz- NX,-,I- PO T-P'TECH EDITORS*JDMain09/24/92SC:OEAB*RLDennig09/24/92:SPLBCEMcCrcken092/9209 3-1n I -KcBC:OEABAEChaffee09/4&/92BC:OGCBGHMarcus09/ /92Or? oSSC.l1er- Duesc,?/Xl/q;;410a.inCovCO LV V% ecceLpCAPt"XU I4posh4aDSCet.C do Lue g;Al CLL4e.?.-

V- IN 92-71September 29, 992This event at Barseback is directly applicable to an earlier study conductedby the NRC. That study evaluated the potential for displaced thermalinsulation to form debris and to be drawn to the sump screen. The results ofthe study are documented in "Containment Sump Performance," NUREG-0897,Revision 1, dated March 1984. The NRC concluded that the risk associated withthe sump clogging concern did not warrant backfitting of domestic plants.However, based on the Barsebdck event and NUREG-0897, Revision 1, thisconclusion is being reevaluated.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: Robert L. Dennig, NRR(301) 504-1156List of Recently Issued NRC Information Notices

Attachment:

Document Name: 92-71.IN*SEE PREVIOUS CONCURRENCES*OEAB:DOEA:NRR*SC/OEAB:DOEA:NRRRWWoodruff RLDennig09/24/92 09/24/92DOEA:NRR C/OGCB:DOEA:NRR*RPB:ADMCERossi GHMarcus)GLK- TechEd09/ /92 09/,S/92 &o 09/24/24*C/OEAB:DOEA:NRR*C/SPLB:DST:NRR CEP/OIPAChaffee CEMcCracken AKenneke09/ /92 09/ /92 09/ /92 K>-NRCIN 92-XXSeptember xx, 1991 technical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of OperationalEvents AssessmentOffice of Nuclear Reactor Regulation

Technical Contact:

Robert L. Dennig, NRR(301) 504-1156

Attachment:

1. List of Recently Issued Information NoticesCONCTRRENCE:OEAB W'RWWoodruff09 5/92D : DOEACERossi09/ /92TECH EDITORirgaln Pl09/2,1/9209/; f92BC: SPLUCEMcCracken09/ /92BC: OEKBAEChaffee09/ /92BC: KCBGHMarcus09/ /92410.in