Information Notice 1992-06, Reliability of ATWS Mitigation System and Other NRC Required Equipment not Controlled by Plant Technical Specifications

Reliability of ATWS Mitigation System and Other NRC Required Equipment not Controlled by Plant Technical Specifications

ML031200738
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:	01/15/1992
Revision:	0
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-92-006, NUDOCS 9201080305
Download: ML031200738 (7)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555January 15, 1992NRC INFORMATION NOTICE 92-06: RELIABILITY OF ATWS MITIGATION SYSTEM ANDOTHER NRC REQUIRED EQUIPMENT NOT CONTROLLEDBY PLANT TECHNICAL SPECIFICATIONS

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information noticeto alert addressees of the importance of maintaining the reliability ofequipment required by NRC regulations but not addressed in plant technicalspecifications. It is expected that recipients will review this informationfor applicability to their facilities and consider actions, as appropriate, toavoid similar problems. However, suggestions contained in this informationnotice are not NRC requirements; therefore, no specific action or writtenresponse is required.BackgroundIn 1983, the Salem Nuclear Generating Station experienced an anticipatedtransient without scram (ATWS) event. Following this event, efforts thenin progress to establish requirements to address ATWS events were completed,and the NRC issued, on June 1, 1984, Section 50.62 of Title 10 of theCode of Federal Regulations (10 CFR 50.62), "Requirements for reduction of riskfrom anticipated transients without scram (ATWS) events for light-water-coolednuclear power plants." This regulation required that each reactor have equip-ment, diverse from the reactor trip system, that would automatically initiateactions to mitigate the consequences of an ATWS. The regulation also requiredthat the equipment for this system be independent from the existing reactortrip system and be designed to perform its function in a reliable manner. TheNRC did not require licensees to address the operability of this equipment inplant technical specifications nor did the NRC require that this equipment bedesignated as safety-related.

Description of Circumstances

To meet the requirements of 10 CFR 50.62, the Houston Lighting and PowerCompany, the licensee for the South Texas Project (STP), installed ATWSmitigation system actuation circuitry (AMSAC). In May and June of 1991,a\\\O3O5Z/

IN 92-06January 15, 1992 the NRC inspected the implementation of this system at STP, Units 1 and 2, andidentified three situations in which the reliability of the ATWS mitigationsystem had been compromised.While inspecting Unit 2, the NRC found that the licensee had left open theswitches for the interface circuit between the AMSAC system and the auxiliaryfeedwater (AFW) system. These open switches disabled the automatic AFW flowInitiation feature of the AMSAC, an important part of the ATWS mitigationsystem. The NRC also found that the licensee had bypassed the automaticinitiation feature of the AMSAC system, causing the system to be inoperable, atleast 15 percent of the time that the system was designed to be operable.While inspecting Unit 1, the NRC found that the licensee had bypassed theautomatic initiation feature of the AMSAC system 36 percent of the time thatthe system was designed to be operable. The NRC issued the licensee a SeverityLevel III violation and assessed a civil penalty.The NRC also issued the licensee for Comanche Peak a Severity Level IV violationbecause the ATWS mitigation system was bypassed for approximately 10 days whilethe reactor was operating at full power.DiscussionIn April 1985, the staff issued Generic Letter 85-06, "Quality AssuranceGuidance For ATWS Equipment That Is Not Safety-Related," to provide explicitquality assurance guidance for the nonsafety-related equipment encompassed bythe ATWS rule_ Although-much of the equipment- required-by-10-cR-50.62-is not- -designated safety-related, it does perform an important safety function if theplant's primary reactor protection system fails. The regulation was issued toreduce the risk posed by such an event. The NRC considers the failure oflicensees to comply with this regulation and to ensure that the ATWS mitigationsystem and equipment function reliably to be a significant regulatory concern.The events described above indicate that licensees may not place an appropriatelevel of priority on resolving problems with the ATWS mitigation system becauseit is not a safety-related system and because the plant's technical specific-ations do not govern its operability. However, maintenance of this system isof high priority and appropriate because such action assures the importantsafety function of the system and satisfies the requirements of 10 CFR 50.62for the system to function reliably. Actions taken by licensees to ensure thereliability of the ATWS mitigation system have included performing timelysurveillance testing, completing repairs and preventive maintenance promptly,implementing necessary modifications, and updating procedures to reflect systemchanges.Plant technical specifications only address the minimum personnel and equipmentrequirements for the various modes of plant operations. However, it is importantthat licensees maintain equipment and systems required by NRC regulations, toensure their reliability, even though they are not addressed by a plant'stechnical specification IN 92-06January 15, 1992 This 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.arls't. Rossi, Director /Division of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contacts:R. Evans, RIV(512) 972-2507C. Paulk, RIV(817) 860-8236J. Mauck, NRR(301) 504-3248

Attachment:

List of Recently Issued NRC Information NoticesAttciment11 92-06January IS. 1992 LIST OF RECCEITLY ISS1EDSRC INFOWATIOR WTICESInformation Date ofNotice no. Subject Issuance Issued to92-45 Potential Coil Insuletion 02/08/92 All holders of OLs or CPsBreakdown 1 ABB RJDH2 Relays for nuclear power reactors.92-04 Potter S Bruefitld Model 01/06/92 All holders of OLs or CPsMtDR Rotary Relay Failures for miclear power reactors.92-03 R ote Trip Function 01/06/92 All holders of OLs or CPsFailures in General Electric for nuclear power reactors.F-Frae Molded-Case CircuitBreakers92-02 Relp5/NWo3 tComuter Code 01/03/92 All holders of OLs or CPsError Associated with the for nuclear power reactors.Conservation of EnergyEquation92-01 Cable Damage Caused by 01/03/92 All holders of 0Ls or CPsInadequate Cable Installa- for nuclear power reactors.tion Procedures and Controls91-87 Hydrogen Embrittlement of 12/27/91 All holders of OL or cpsRaychee Cryofit Couplings for nuclear power reactors.91486 kw Reporting Requireents 12/27/91 All licensees authorizedfor Contauination Events at to use byproduct materialsMedical Fecilities for humus use.(10 tFR 30.10)9145 Potential Failures of 12/26/91 All holders of OLc or CPsThermostatic Control valves for nuclear power reactors.for Diesel generator JacketCooling Water9144 Problems uith Criticality 12/26/91 All Muclear RegulatoryAlarm Cot onents/Systems Commission (NRC) fuelcycle licensees. interimspent fuel atorage licens-ees and critical masslicnsees.OL

• Operating LicenseCP

• Construction Permit IN 92-06January 15, 1992 This 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.Orig /s/'d by CERossiCharles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contacts:R. Evans, RIV(512) 972-2507C. Paulk, RIV(817) 860-8236J. Mauck, NRR(301) 504-3248

Attachment:

List of Recently Issued NRC Information NoticesD/ OE~rtR51 *C/OGCB:DOEA:NRR*RPB:ADM *C/SICB:IYST:NRR *SC/SICB:DST:NRRCHBerlinger TechEd SNewberry JMauck01/06/92 11/26/91 12/20/91 12/20/91*OGCBI.DOEA:NRR *RESINSP:RIV *DRS:RIy *SC/DRS:RIV *D/DRS:RIVJLBirmingham REvans CPaulk TWesterman SCollins12/17/91 12/17/91 12/17/91 12/18/91 12/18/91DOCUMENT NAME: IN 92-06 IN 91-XXDecember xx, 1991 This 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:R. Evans, RIV(512) 972-2507C. Paulk, RIV(817) 860-8236J. Mauck, NRR(301) 504-3248

Attachment:

List of Recently Issued NRC Information NoticesDocument Name: ATWS-IN.RFT*SEE PREVIOUS CONCURRENCES/D/DOEA:NRR C/OGC 1fldLA:NRR*RPB:ADMCERossi W'-' CHBerlinger TechEd01/ /92 4 01/VP/92 11/26/91*OGCB:DOEA:NRR *RESINSP:RIV *DRS:RIVJLBirmingham REvans CPaulk12/17/91 12/17/91 12/17/91*C/SICB:DST:NRRSNewberry12/20/91*SC/DRS:RIVTWesterman12/18/91*SC/SICB:DST:NRRJMauck12/20/91*D/DRS:RIVSCollins12/18/91 IN 91-XXDecember xx, 1991 This 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:R. Evans, RIV(512) 972-2507C. Paulk, RIV(817) 860-8236L.t tIc NRCInorati ion N otList of R ecent W Issuel NRC Information Notices/A

Attachment:

Document Name:ATWS-IN.RFT*SEE PREVIOUS CONCURRENCESD/DOEA:NRR C/OGCB:DOEA:NRR*RPB:ADMCERossi CHBerlinger TechEd12/ /91 12/ /91 11/26/91*OGCB:DOEA:NRR *RESINSP:RIV *DRS:RIVJLBirmingham REvans CPaulk12/17/91 12/17/91 12/17/91C/SICB ST:NRRSNe fry&sk4512 /91 C12*SC S:RIVTWesterman12/18/91J12/ /91*D/DRS:RIVSCollins12/18/91 IN 91-XXDecember xx, 1991 This 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:R. Evans, RIV(512) 972-250764'JC. Paulk, RIV(817) 860-8236

Attachment:

List of Recently Issued NRC Information NoticesDocument Name:ATWS-IN.RFT*SEE PREVIOUS CONCURRENCESOGCB:DOEA:NRRJirming ym12/17/91RESINSP:RIYREvans,, f12/17/1eD/DOEA:NRRCERossi12/ /91DRS:RIVCPaulk iJd12/l/91 /DPlC/OGCB:DOEA:NRR*RPB:ADMCHBerlinger TechEd12/ /91 11/26/91SC/DRS:RIV D/DRS:RIVTWesterman V SCollins12/1I/91 o 12/;r/91 (