Information Notice 1995-33, Switchgear Fire and Partial Loss of Offsite Power at Waterford Generating Station, Unit 3

Switchgear Fire and Partial Loss of Offsite Power at Waterford Generating Station, Unit 3

ML031060305
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:	08/23/1995
From:	Crutchfield D M Office of Nuclear Reactor Regulation
To:
References
IN-95-033, NUDOCS 9508180092
Download: ML031060305 (7)

K>UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555August 23, 1995NRC INFORMATION NOTICE 95-33: SWITCHGEAR FIRE AND PARTIAL LOSS OF OFFSITEPOWER AT WATERFORD GENERATING STATION, UNIT 3

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice (IN) to alert addressees to a switchgear fire and subsequent partialloss of offsite power at Waterford Generating Station, Unit 3. It is expectedthat recipients will review the information for applicability to theirfacilities and consider actions, as appropriate, to avoid similar problems.However, suggestions contained in this information notice are not NRCrequirements; therefore, no specific action or written response is required.

Description of Circumstances

On June 10, 1995, Waterford 3 was operating at 100 percent power with anoperations staff consisting of a shift supervisor (SS), a control roomsupervisor (CRS), and two reactor operators. At 8:58 a.m. a generator tripoccurred in response to failure of a lightning arrester on a remote offsitesubstation transformer. The generator trip resulted in a fast transferactivation. All 6.9 kV and 4.16 kV buses transferred as designed except the4.16 kV A2 bus. A fire and electrical fault on the 4.16 kV A2 bus normalpower supply breaker caused a voltage and frequency perturbation on the 6.9 kVAl bus, which caused an underspeed condition on rector coolant pumps IA and2A. This circumstance resulted in a reactor trip and a loss of offsite powerto the 4.16 kV nonsafety-related A2 bus and the associated 4.16 kV safety-related A3 bus. Emergency Diesel Generator A started and loaded to power theA3 bus. At 9:06 a.m., an auxiliary operator informed the control room ofheavy smoke within the turbine generator building. At that time, the SS didnot activate the plant fire alarm or dispatch the fire brigade, but directedtwo auxiliary operators to don protective gear and investigate whether a fireexisted. At 9:35 a.m., the operators reported seeing flames above the A2switchgear and the SS activated the fire brigade. Operators requestedassistance from the local offsite fire department and declared an UnusualEvent in accordance with emergency response procedures. The fire brigade wasunable to suppress the fire using portable fire extinguishers. The offsitefire department arrived on the scene at 9:58 a.m. and extinguished the firewith water at 10:22 a.m., after the A2 bus was deenergized. During thecooldown transition from Mode 4 to Mode 5, operators discovered that theisolation valves for both trains of shutdown cooling did not operate properly.9508180092PDR It 9S-.o33 9,s5T3 tJ <J IN 95-33August 23, 1995 The plant cooldown to Mode 5 was delayed approximately 38 hours4.398148e-4 days <br />0.0106 hours <br />6.283069e-5 weeks <br />1.4459e-5 months <br /> while thesevalves were repaired.DiscussionDuring the period of June 13-16, 1995, the NRC conducted an augmentedinspection team (AIT) inspection to determine the causes, conditions, andcircumstances relevant to this event. The results of this AIT inspection aredocumented in NRC Inspection Report 50-382/92-15, dated July 7, 1995. The AITidentified three primary issues: fire protection, fast bus transfer design,and shutdown cooling valve inoperabilit). These three issues are discussed ingreater detail in the following sections.Fire ProtectionSeveral recent events at U.S. nuclear power plants have included a fireconcurrent with a plant transient. The fire at Waterford 3 highlights theimportance of (1) training for timely and effective response to initialindications of a plant fire, (2) ensuring personnel are not assignedpotentially conflicting duties, and (3) plant staffing.An auxiliary operator (a trained fire brigade member) noticed heavy smoke inthe turbine generator building and notified the control room. The auxiliaryoperator was asked if there was a fire in the room and responded that he didnot see flames because of the presence of heavy smoke. The CRS did notdeclare a fire until 29 minutes after receiving the report of heavy smoke.Activating the fire brigade required the SS to assume the responsibilities ofthe CRS (the designated fire brigade leader), who was directing plantpersonnel responding to the event. Following the event, operators stated thatthe loss of the CRS from the control room did not adversely affect theirability to respond to this event and noted that a fire scenario, whichrequires that the CRS leave the control room, is routinely used duringrequalification training.Before the local offsite fire department was allowed to extinguish the firewith water, the fire brigade attempted to extinguish the fire using portablecarbon dioxide (CO ), halon, and dry chemical fire extinguishers. The use ofportable extinguishers was not effective in extinguishing the fire. When thefire department arrived, it recommended the use of water to extinguish thefire. The fire brigade leader did not allow the use of water until about20 minutes later. The fire was finally extinguished by the offsite firedepartment within 4 minutes of using water. The use of water is consistentwith documented NRC staff positions. The AIT determined that the operatorswere reluctant to apply water to an electrical fire based on previous trainingthat had emphasized the use of water as a last resort on electrical fires.Although the appropriate fire alarms had activated in the control room, thecontrol room crew was not aware of the alarms because of (1) other auditoryalarms caused by the event and (2) the lack of a visual fire alarm signal on afront panel of the control room. Control room operators did not refer to thefire alarm panel when the auxiliary operator reported seeing heavy smoke. Inthis instance, the ineffectiveness of the fire alarms did not directly affect KJ-J IN 95-33August 23, 1995 the response to the fire because an auxiliary operator alerted the controlroom to heavy smoke in the turbine building. Nevertheless, fire alarms thatare inaudible under actual operational conditions and lack redundant visualsignals can inhibit prompt identification of, and response to, plant fires.Also, it is important for operators to refer to the fire alarm panel upon anyverbal report of a potential fire, in order to ensure that the fire is notwider spread than visually reported. NRC fire protection requirements andguidelines specify that fire drills include an assessment of fire alarmeffectiveness.IN 91-77 'shift staffing at Nuclear Power Plants', reminded licensees thatSection 50.54(m) of Title 10 of the Code of Federal Regulations(10 CFR 50.54 (m)) addresses minimum staffing levels for licensed personnel.It does not address availability of personnel for performing all actionsspecified in the licensee's administrative procedures required during anevent. NRC fire protection requirements and guidelines provide flexibility inassigning personnel to a fire brigade (e.g., the brigade leader may possesseither an operator's license or an equivalent knowledge of plant safety-related systems). The potential exists for personnel to be assigned dutiesthat, during certain events, may present concurrent and conflicting demands.Such conditions could significantly delay or degrade the response of thoseindividuals.Fast Bus Transfer DesignThe Waterford 3 fast bus transfer design consists of an automatic transfer ofsafety and nonsafety-related station auxiliary loads from the normal powersupply (from the main generator through the unit auxiliary transformer) to thealternate power supply (from the offsite transmission network through thestartup transformer). All supply breakers are General Electric, Magne-Blasttype. During a fast bus transfer, the normal supply breakers are designed toopen in five cycles and the alternate supply breakers are designed to close inseven cycles, resulting in a two-cycle deadband on the respective buses. Toprevent simultaneous closing of both the supply breakers, some other fast bustransfer designs include mechanical or electrical interlocks. The Waterford 3design does not include interlocks.During this event, when the fast bus transfer was initiated, the A2 bus normalsupply breaker did not open in five cycles but the alternate supply breakerclosed within seven cycles. As a result, (1) the A2 bus was connected to boththe offsite transmission network and the main generator, (2) both supplybreakers to the A2 bus received overcurrent trip signals, (3) while the A2 busalternate supply breaker adequately isolated the offsite transmission network,the A2 bus normal supply breaker did not isolate the main generator, (4) theA2 switchgear cubicle for the normal supply breaker caught fire, and (5) thecable bus for the normal supply breaker also caught fire.Shutdown Cooling ValvesDuring the plant cooldown to Mode 5, the shutdown cooling isolation valvesfailed to operate properly when operators attempted to align low-temperatureoverpressure protection relief valves in preparation for placing shutdown IN 95-33August 23, 1995 cooling into service. The Loop 1 shutdown cooling suction header isolationvalve (SI-405B) failed to fully open and automatically closed afterapproximately 15 minutes. The Loop 2 shutdown cooling suction headerisolation valve (SI-405A) fully opened; however, several hours later, thevalve hydraulic pump was observed to be running continuously instead ofcycling as designed. These two valves isolate low-pressure portions of theshutdown cooling system from the reactor coolant system and must be opened inorder to complete plant cooldown below 200 OF (Mode 5). Troubleshootingrevealed that both valves contained inadequate hydraulic oil levels in thevalve actuator reservoirs. The cause of the low levels was inadequateinstructions for a periodic maintenance task for the valves.Related Generic CommunicationsBUL 75-04, wCable Fire at Browns Ferry Nuclear Power Station," dated March 24,1975.BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3,1975BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," datedNovember 3, 1975.IN 85-80, "Timely Declaration of an Emergency Class, Implementation of anEmergency Plan, and Emergency Notifications," dated October 15, 1985.IN 91-57, "Operational Experience on Bus Transfers," dated September 19, 1991.IN 91-77, "Shift Staffing at Nuclear Power Plants," dated November 26, 1991.IN 93-44, "Operational Challenges During a Dual-Unit Transient," datedJune 15, 1993.IN 93-81, "Implementation of Engineering Expertise on Shift," datedOctober 12, 1993.This information notice requires no specific or written response. If you haveany questions about the information in this notice, please contact thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.DennvsWM. CrutchfieldP DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact: Eric J. Benner, NRR(301) 415-1171

Attachment:

List of Recently Issued NRC Information Notices@-gL~5~ 44yAGgQ K>KreachmentIN 95-33August 23, 1995 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to95-10,Supp. 295-3295-3195-3094-66,Supp. 195-2995-2895-27Potential for Loss ofAutomatic EngineeredSafety Features ActuationThermo-Lag 330-1 FlameSpread Test ResultsMotor-Operated ValveFailure Caused by StemProtector Pipe Inter-ferenceSusceptibility of Low-Pressure Coolant Injectionand Core Spray InjectionValves to Pressure LockingOverspeed of Turbine-Driven Pumps Caused byBinding in Stems ofGovernor ValvesOversight of Design andFabrication Activitiesfor Metal Components Usedin Spent Fuel Dry StorageSystemsEmplacement of SupportPads for Spent Fuel DryStorage Installations atReactor SitesNRC Review of NuclearEnergy Institute,"Thermo-Lag 330-1Combustibility EvaluationMethodology Plant ScreeningGuide"08/11/9508/10/9508/09/9508/03/9506/16/9506/07/9506/05/9505/31/95All 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 reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power plants.OL -Operating LicenseCP = Construction Permit

-11IN 95-XXAugust xx, 1995 order to complete plant cooldown below 200 *F (Mode 5). Troubleshootingrevealed that both valves contained inadequate hydraulic oil levels in thevalve actuator reservoirs. The cause of the low levels was inadequateinstructions for a periodic maintenance task for the valves.Related Generic CommunicationsBUL 75-04, "Cable Fire at Browns Ferry Nuclear Power Station," dated March 24,1975.BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3,1975BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," datedNovember 3, 1975.IN 85-80, "Timely Declaration of an Emergency Class, Implementation of anEmergency Plan, and Emergency Notifications," dated October 15, 1985.IN 91-57, "Operational Experience on Bus Transfers," dated September 19, 1991.IN 91-77, -Shift Staffing at Nuclear Power Plants," dated November 26, 1991.IN 93-44, "Operational Challenges During a Dual-Unit Transient," datedJune 15, 1993.IN 93-81, "Implementation of Engineering Expertise on Shift," datedOctober 12, 1993.This information notice requires no specific or written response. If you haveany questions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Eric J. Benner, NRR(301) 415-1171

Attachments:

1. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\IN\WATERFOR.INR *See Previous ConcurrenceTo receive a copy of this document, Indicate In the box: 'C' = Copy without attachment/enclosure 'E' = Copy with attachment/enclosure 'N" = No copy---------IOFFICE PECB:DRPM ADM:PUB C/PECB:DRPM C/SPLB:DSSA C/EELB:DE INAME EBenner* Tech Editor* EGoodwin* CMcCracken* JCalvo*DATE 07/21/95 7/24/95 8/2/95 7/25/95 7/27/95OFFICE C/HHFB:DRCH RI D/DSSA I1> PECB:DRPM J A C/0&.DRPM lNAME CThomas* RHuey* AGHolahan Wb! Riiessel M1AC~affeeDATE 8/1/95 8/2/95 /95 /95 95jOFFICE D/DRPMNAME DCrutchfieldDATE / /95OFFICIAL RECORD COPY IN 95-XX'__ _ July xx, 1995 Related Generic CommunicationsBUL 75-04, "Cable Fire at Browns Ferry Nuclear Power Station," dated March 24,1995BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," datedNovember 3, 1995BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3,1995IN 85-80, "Timely Declaration of an Emergency Class, Implementation of anEmergency Plan, and Emergency Notifications, " dated October 15, 1985IN 91-57, "Operational Experience on Bus Transfers," dated September 19, 1991IN 91-77, "Shift Staffing at Nuclear Power Plants," dated November 26, 1991IN 93-44, "Operational Challenges During a Dual Unit Transient," datedJune 15, 1993IN 93-81, Implementation of Engineering Expertise on Shift," datedOctober 12, 1993This information notice requires no specific or written response. If you haveany questions about the information in this notice, please contact one of thetechnical contacts below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Forrest R. Huey, RIV(510) 975-0342Eric J. Benner, NRR(301) 415-1171Amarjit Singh, NRR(301) 415-1237David(301)R. Desaulniers, NRR415-1043Sikhindra K. Mitra, NRR(301) 415-2783Thomas A. Bergman, NRR(301) 415-1021

Attachments:

A.1. List of Recently Issued NRC Information Notices If- MDOCUMENT NAME: G:\IN\WATERFOR.INTo rocalva a ca at ofis docunm Indicatae I Oem box: ' -COY wilthout atachment/enrcbsum T a Cov with Irtthnt/encosure W -No copy*. 4tDSW07teV1_FOFFICE PECB:DRPM ADM:PUB SC/PECB:DRPM I C/SWA C/EELB:DENAME EBenner _ Tech Editors EGoodwin I McC__;_____ JCavo /_T-DATE 07/21/95 '/-r//95 /I&2J95 'I / 3795 "A 12/27 /95 l"a'OFFICE /"ff:DRCgL D/DRCH C/TQMB:DOTS RIV PECB:DRPMNAME h [BBoger SBlack RHueyQ! A k~ RKiesselDATE I /95 / 95 /95 J 1/-> /95 I / /95OFFICE PECB:DRPM D/DRPMNAME AChaffee DCrutchfield _DATE / /95 R D/95 OOFF ICIA L RECORD COPY