Information Notice 1996-59, Potential Degradation of Post Loss-of-Coolant Recirculation Capability As a Result of Debris

Potential Degradation of Post Loss-of-Coolant Recirculation Capability As a Result of Debris

ML031050557
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:	10/30/1996
Revision:	0
From:	Martin T T Office of Nuclear Reactor Regulation
To:
References
IN-96-059, NUDOCS 9610280088
Download: ML031050557 (6)

October 30, 1996

NRC INFORMATION NOTICE 96-59: POTENTIAL DEGRADATION OF POST LOSS-OF-COOLANT RECIRCULATION CAPABILITY AS ARESULT OF DEBRIS

Addressees

All holders of operating licenses or construction permits for nuclear power reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alertaddressees that the suppression pool and associated components of two boiling-waterreactors (BWRs) have been found to contain foreign objects that could have impairedsuccessful operation of emergency safety systems using water from the suppression pool. Itis expected that recipients will review the information for applicability to their facilities andconsider actions, as appropriate, to avoid similar problems. However, suggestions containedin this information notice are not NRC requirements; therefore, no specific action or writtenresponse is required.

Description of Circumstances

Niagara Mohawk Power Corporation, the licensee for Nine Mile Point Unit 2, reported onOctober 17, 1996, that a significant amount of debris was found during inspection of thedrywell-to-suppression chamber downcomers. Most downcomers were clean or containedminimal debris. However, 17 downcomers contained debris, and 7 of the 8 downcomerslocated directly under the reactor vessel had cleanliness covers installed over the downcomeropening. Some debris was floating on the water inside the downcomers and consisted offoam rubber cleanliness covers, plastic bags, Tygon tubing, hard hats, and so on. Thesuppression pool had been cleaned during the previous refueling outage.Commonwealth Edison Company reported on October 16, 1996, that during the first thoroughcleaning of the LaSalle Unit 2 suppression pool, a significant amount of foreign material hadbeen found under a layer of sludge. Sludge is a generic term for rust particles from thecarbon steel piping connected to the suppression pool. Foreign material was also found inseveral downcomers. The foreign material included a rubber mat, a sheet of gasket material,a nylon bag, and a substantial amount of sludge. The licensee concluded that sufficientmaterial was present to challenge the clogging limit for multiple emergency core coolingsystem (ECCS) strainers. The Unit 2 pool had been inspected previously to remove visibledebris, and the strainers had been cleaned.PD& i0E 0e t 9(0-0 (P WU>9610280088cae nl~ll ( ~t/

IN 96-59October 30, 1996 DiscussionSection 50.46 of Title 10 of the Code of Federal Regulations (10 CFR 50.46)requires that licensees design their ECCSs so that the calculated cooling performancefollowing a loss-of-coolant accident (LOCA) meets five criteria, one of which is to providelong-term cooling capability of sufficient duration following a successful system initiation sothat the core temperature shall be maintained at an acceptably low value and decay heatshall be removed for the extended period required by the long-lived radioactivity remaining inthe core.On October 17, 1995, the NRC issued Bulletin 95-02, "Unexpected Clogging of a ResidualHeat Removal (RHR) Pump Strainer While Operating in Suppression Pool Cooling Mode,"which requested BWR licensees to review the operability of their ECCS and other pumps thatdraw suction from the suppression pool while performing their safety function. Theaddressees' evaluations were to be based on suppression pool cleanliness, suction strainercleanliness, and the effectiveness of their foreign material exclusion practices. In addition,licensees were to implement appropriate procedural modifications and other actions (e.g.,suppression pool cleaning), as necessary, to minimize foreign material in the suppressionpool, the drywell, and systems that interface with the suppression pool. Licensees were toverify their operability evaluation through appropriate testing and inspection.The actions of both licensees were a consequence of the requested actions of Bulletin 95-02.The LaSalle Unit 2 suppression pool was being thoroughly deaned as requested by thebulletin, and the Nine Mile Point Unit 2 suppression pool was being reinspected as part of theenhanced surveillance requested by the bulletin.The NRC has issued a number of generic communications to describe aspects of thepotential for loss of recirculation capability as a result of strainer clogging and debrisblockage. While the past generic communications contain examples that focus on specificconsiderations that are most applicable to either pressurized-water reactors (PWRs) orBWRs, the basic safety concern applies to both BWRs and PWRs. These events as well asthose in previous generic communications demonstrate the need for a thorough cleaning ofall areas of PWRs and BWRs that may contain materials which could adversely affect LOCArecirculation. Visual inspection and spot cleaning cannot ensure that all undesirable andunanticipated foreign material will be eliminated.Related Generic CommunicationsRecent instances of problems with strainer clogging are described in thefollowing generic communications:NRC Generic Letter 85-22: "Potential for Loss of Post LOCA Recirculation CapabilityDue to Insulation Debris Blockage," dated November 22, 1985.NRC Information Notice 89-77: "Debris in Containment Emergency Sumps andIncorrect Screen Configuration," dated November 21, 198 ;jIN 96-59October 30, 1996

• NRC Information Notice 92-71: "Partial Plugging of Suppression PoolStrainers at a Foreign BWR," dated September 30, 1992.* NRC Information Notice 92-85: "Potential Failures of Emergency CoreCooling Systems Caused by Foreign Material Blockage," dated December 23, 1992.* NRC Bulletin 93-02 and Supplement 1: "Debris Plugging of Emergency CoreCooling Suction Strainers," dated May 11, 1993 and February 18, 1994.* NRC Information Notice 93-34 and Supplement 1: "Potential for Loss ofEmergency Core Cooling Function Due to a Combination of Operational andPost-LOCA Debris in Containment," dated April 26, 1993 and May 6, 1993.NRC Information Notice 95-06: "Potential Blockage of Safety-RelatedStrainers by Material Brought Inside Containment," dated January 25, 1995.NRC Information Notice 95-47: "Unexpected Opening of a SafetylReliefValve and Complications Involving Suppression Pool Cooling StrainerBlockage," dated October 4, 1995.NRC Bulletin 95-02: "Unexpected Clogging of a Residual Heat Removal (RHR) PumpStrainer While Operating in Suppression Pool Cooling Mode, dated October 13, 1995.NRC Bulletin 96-03: "Potential Plugging of Emergency Core Cooling SuctionStrainers By Debris in Boiling-Water Reactors," dated May 6, 1996.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contactslisted below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Richard Lobel, NRR(301) 415-2865Email: rml@nrc.govJerry Carter, NRR(301) 415-1153Email: tjcenrc.gov

Attachment:

List of Recently Issued NRC Information Notices IN 96-59October 30, 1996

• NRC Information Notice 92-71: "Partial Plugging of Suppression PoolStrainers at a Foreign BWR," dated September 30, 1992.* NRC Information Notice 92-85: "Potential Failures of Emergency CoreCooling Systems Caused by Foreign Material Blockage," dated December 23, 1992.* NRC Bulletin 93-02 and Supplement 1: "Debris Plugging of Emergency CoreCooling Suction Strainers," dated May 11, 1993 and February 18, 1994.* NRC Information Notice 93-34 and Supplement 1: "Potential for Loss ofEmergency Core Cooling Function Due to a Combination of Operational andPost-LOCA Debris in Containment," dated April 26, 1993 and May 6, 1993.NRC Information Notice 95-06: "Potential Blockage of Safety-RelatedStrainers by Material Brought Inside Containment," dated January 25, 1995.NRC Information Notice 95-47: "Unexpected Opening of a Safety/ReliefValve and Complications Involving Suppression Pool Cooling StrainerBlockage," dated October 4, 1995.NRC Bulletin 95-02: "Unexpected Clogging of a Residual Heat Removal (RHR) PumpStrainer While Operating in Suppression Pool Cooling Mode, dated October 13, 1995.NRC Bulletin 96-03: "Potential Plugging of Emergency Core Cooling SuctionStrainers By Debris in Boiling-Water Reactors," dated May 6, 1996.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contactslisted below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.original signed byThomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Richard Lobel, NRR Jerry Carter, NRR(301) 415-2865 (301) 415-1153Email: rmlenrc.gov Email: tjcenrc.gov

Attachment:

List of Recently Issued NRC Information NoticesTech Editor has reviewed and concurred on 10/24/96 *SEE PREVIOUS CONCURRENCESDOCUMENT NAME: 96-59.INTo receive a copy of this document, Indicate in the box cC-opy wlo attachment/endosure E=Copy with attachment/endosure N = No copyl OFFICE E SCSB E BC:PECB lNAME d IjCBerdingerf AChaffee* TartinIDATE 10/24/96 10/25/96 10125/96 10A506OFFICIAL RECORD COPY

/,_ -f -IN 96-October , 1996 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.Thomas T. Martin. DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Richard Lobel, NRR(301) 415-2865Email: rml@nrc.govJerry Carter, NRR(310 415-1153Email: tjc@nrc.gov

Attachment:

List of Recently Issued NRC Information NoticesDOCUMENT NAME:G:\TJC\31172_IN.FINTo receive a copy of this document, indicate in the box C-Copy w/o attachment/enclosureattachment/e closure 8.- No copyJZC A2ZOLE-Copy withOFFICE JECB I I I SCSB -I BC:PECB f I i lDRPM Z INAME 'arter:jkd CBerlin er j Xhaffee 7 Thartin 1DATE 10/2y/96 9 10t_096 *- L 96 10/ /96 l, rrT T Al IDEI _ VUOFF1U1t KtUUKU LuPTM'J?1fJ

,AttachmentIN 96-59October 30, 1996 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to96-5896-5796-5696-5596-54RCP Seal Replacement withPump on BackseatIncident-Reporting Require-ments Involving Intakes,During a 24-Hour PeriodThat May Cause a TotalEffective Dose Equivalentin Excess of 0.05 Sv(5 rems)Problems Associated withTesting, Tuning, or Reset-ting of Digital ControlSystems While at PowerInadequate Net PositiveSuction Head of EmergencyCore Cooling and Contain-ment Heat Removal PumpsUnder Design Basis AccidentConditionsVulnerability of StainlessSteel to Corrosion WhenSensitizedRetrofit to Amersham 660Posilock RadiographyCamera to Correct Incon-sistency in 10 CFR Part 34Compatibility10130/9610/30/9610/22/9610/22/9610/17/9610/15/96All holders of OLs orCPs for pressurized-waterreactorsAll U.S. NuclearRegulatory CommissionlicenseesAll holders of OLs orCPs for nuclear powerreactorsAll holders of OLs orCPs for nuclear powerreactorsAll materials licenseesAll industrial radio-graphy licensees96-53OL = Operating LicenseCP = Construction Permit