Information Notice 1991-68, Careful Planning Significantly Reduces the Potential Adverse Impacts of Loss of Offsite Power Events During Shutdown: Difference between revisions
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==Description of Circumstances== | ==Description of Circumstances== | ||
In November 1990, the licensee for the Turkey Point Plant began an 11-monthdual unit outage to conduct a major electrical system upgrade includinginstalling two additional emergency diesel generators (EDGs). OnMarch 13, 1991, while both units were defueled and the safety-related EDGs wereinoperable, offsite power for Unit 4 was being provided through the startuptransformer. Spent fuel pool cooling pumps were being powered from the"C" load center which was being supplied by the "A" vital bus. Electricalpower for the component cooling water (CCW) pumps and the intake cooling water(ICW) pumps was being provided from vital bus "A". At the time, spent fuelpool cooling was the most significant nuclear safety function.An alternate source of power supply to the CCW, ICW, and spent fuel poolcooling pumps was available from four, non-safety-related (black start) dieselgenerators. Other backup sources of power to the pumps included interconnec-tion with the Unit 3 startup transformer and transfer to another Unit 4 trans-former (after defeating circuit breaker interlocks). An alternate method of(Z91030028 A ;04SAn1 19mit-// | In November 1990, the licensee for the Turkey Point Plant began an 11-monthdual unit outage to conduct a major electrical system upgrade includinginstalling two additional emergency diesel generators (EDGs). OnMarch 13, 1991, while both units were defueled and the safety-related EDGs wereinoperable, offsite power for Unit 4 was being provided through the startuptransformer. Spent fuel pool cooling pumps were being powered from the"C" load center which was being supplied by the "A" vital bus. Electricalpower for the component cooling water (CCW) pumps and the intake cooling water(ICW) pumps was being provided from vital bus "A". At the time, spent fuelpool cooling was the most significant nuclear safety function.An alternate source of power supply to the CCW, ICW, and spent fuel poolcooling pumps was available from four, non-safety-related (black start) dieselgenerators. Other backup sources of power to the pumps included interconnec-tion with the Unit 3 startup transformer and transfer to another Unit 4 trans-former (after defeating circuit breaker interlocks). An alternate method of(Z91030028 A ;04SAn1 19mit-// | ||
IN 91-68October 28, 1991 spent fuel pool cooling, which was available, involved the use of a trailer-mounted diesel generator and a diesel powered fire pump or a non-safety gradescreen wash pump. Detailed procedures for use of the alternative coolingmethods were'available.At 3:30 p.m., a lockout occurred on the Unit 4 startup transformer resulting ina total loss of all vital AC power to Unit 4. A notification of an unusualevent (NOUE) was declared as a result of the loss of vital offsite power. Thelicensee manually started, but did not load, two of the black start dieselgenerators. The other black start diesel generators were not started. All ofthese sources were available to supply power to the cooling pumps for the spentfuel pool if the startup transformer could not be returned to service.The licensee inspected the startup transformer and associated circuit breakersand found no electrical fault indications. At 4:35 p.m., the licensee ener-gized the startup transformer. At 5:27 p.m., power was restored to the CCW,ICW and spent fuel pool cooling pumps and forced cooling to the spent fuel poolwas resumed. The NOUE was then terminated. The temperature of the spent fuelpool had increased from 840F to 87°F during the 2-hour duration of the event.On March 20, 1991, another event of interest occurred at the Indian PointStation. Before the event, Indian Point, Unit 2, (IP2) was in cold shutdownwith all fuel removed from the vessel and stored in the spent fuel pit.Indian Point, -Unit 3, (IP3) was operating-at 100 percent power An a normalplant configuration. At 7:15 p.m., a potential transformer on a 345kV bussection at a remote substation failed catastrophically, creating a ground faulton the 345kV system. Fault isolation circuitry opened the main generatoroutput breaker for IP3, which initiated a reactor trip. The reactor trip wasuncomplicated and offsite power to IP3 vital buses was not interrupted.However, an explosion and subsequent fire in the substation caused circuitbreakers to electrically isolate the 138kV feeder circuit supplying offsitepower to the IP2 6.9kV buses. As a result, the 6.9kV non-vital and 480V vitalbuses that were in service were deenergized. EDG 23 started automatically onbus undervoltage. At the time, the other two IP2 EDGs were tagged out ofservice for maintenance. As designed, EDG 23 did not load to the buses becauseall logic requirements for automatic loading were not satisfied. EDG 23 wasmanually loaded to two vital 480V buses. This action allowed a service waterpump and a component cooling water pump to be started, a battery charger to beplaced in service, and lighting to the auxiliary and containment buildings tobe restored.At the time of the event, offsite power to some vital loads was being supplieddirectly from temporary connections from an Indian Point Unit 1 feeder bus asopposed to being supplied from normal sources. These loads included the spentfuel pit cooling pump, the auxiliary building exhaust fan, and a batterycharger. The licensee established these temporary connections to mitigate theconsequences of a potential loss of the normal offsite source.Since two EDGs were out of service, a temporary EDG was started as a precau-tion. However, the unit was not needed during the event. The licensee had | IN 91-68October 28, 1991 spent fuel pool cooling, which was available, involved the use of a trailer-mounted diesel generator and a diesel powered fire pump or a non-safety gradescreen wash pump. Detailed procedures for use of the alternative coolingmethods were'available.At 3:30 p.m., a lockout occurred on the Unit 4 startup transformer resulting ina total loss of all vital AC power to Unit 4. A notification of an unusualevent (NOUE) was declared as a result of the loss of vital offsite power. Thelicensee manually started, but did not load, two of the black start dieselgenerators. The other black start diesel generators were not started. All ofthese sources were available to supply power to the cooling pumps for the spentfuel pool if the startup transformer could not be returned to service.The licensee inspected the startup transformer and associated circuit breakersand found no electrical fault indications. At 4:35 p.m., the licensee ener-gized the startup transformer. At 5:27 p.m., power was restored to the CCW,ICW and spent fuel pool cooling pumps and forced cooling to the spent fuel poolwas resumed. The NOUE was then terminated. The temperature of the spent fuelpool had increased from 840F to 87°F during the 2-hour duration of the event.On March 20, 1991, another event of interest occurred at the Indian PointStation. Before the event, Indian Point, Unit 2, (IP2) was in cold shutdownwith all fuel removed from the vessel and stored in the spent fuel pit.Indian Point, -Unit 3, (IP3) was operating-at 100 percent power An a normalplant configuration. At 7:15 p.m., a potential transformer on a 345kV bussection at a remote substation failed catastrophically, creating a ground faulton the 345kV system. Fault isolation circuitry opened the main generatoroutput breaker for IP3, which initiated a reactor trip. The reactor trip wasuncomplicated and offsite power to IP3 vital buses was not interrupted.However, an explosion and subsequent fire in the substation caused circuitbreakers to electrically isolate the 138kV feeder circuit supplying offsitepower to the IP2 6.9kV buses. As a result, the 6.9kV non-vital and 480V vitalbuses that were in service were deenergized. EDG 23 started automatically onbus undervoltage. At the time, the other two IP2 EDGs were tagged out ofservice for maintenance. As designed, EDG 23 did not load to the buses becauseall logic requirements for automatic loading were not satisfied. EDG 23 wasmanually loaded to two vital 480V buses. This action allowed a service waterpump and a component cooling water pump to be started, a battery charger to beplaced in service, and lighting to the auxiliary and containment buildings tobe restored.At the time of the event, offsite power to some vital loads was being supplieddirectly from temporary connections from an Indian Point Unit 1 feeder bus asopposed to being supplied from normal sources. These loads included the spentfuel pit cooling pump, the auxiliary building exhaust fan, and a batterycharger. The licensee established these temporary connections to mitigate theconsequences of a potential loss of the normal offsite source.Since two EDGs were out of service, a temporary EDG was started as a precau-tion. However, the unit was not needed during the event. The licensee had | ||
K)IN 91-68October 28, 1991 imported this temporary EDG unit to the site specifically for use as an alter-nate onsite source of emergency power during the shutdown In view of thesignificant number of planned equipment outages. The licensee provided thisunit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water and service water were lost for only2 minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliber-ate, well Informed actions and minimized the safety concerns associated witheach event. If the licensees had been less careful in their planning, theseevents could have been more significant. The technical specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: N. Fields, NRR(301) 492-1173Attachment:List of Recently Issued NRC Information Notices | |||
List of Recently Issued NRC Information Notices 9-9-toCU),CI"If~C0I:IECACCA0I .zaCcoF)go "atAttachmentIN 91-68October 28, 1991Page I of ILIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to90-51. Failures of Voltage-Dropping 10/24/91 All holders of OLs or CPsSupp. I Resistors in the Power for nuclear power reactors.Supply Circuitry of ElectricGovernor Systems91-67 Problems With the Reliable 10/21/91 All holders of OLs or CPsDetection of Intergranular for pressurized-water reactors.Attack (IGA) of StemGenerator Tubing91-66 (1) Erroneous Data in 10/18/91 All fuel cycle licensees,ONuclear Safety Guide critical mass licensees,TID-7016, Revision 2,' interim spent fuel storage(NUREG/CR-O095, ORNL/ licensees, and all holdersNUREG/CSD-6 (1978)) and of operating licenses or(2) Thermal Scattering construction permits forData Limitation in the test, research, and nuclearCross-Section Sets Provided power reactors.with the KENO and SCALE Codes91-65 Emergency Access to 10/16/91 All NRC licensees.Low-Level Radioactivewaste Disposal Facilities91-64 Site Area Emergency 10/09/91 All holders of OLs or CPsResulting From a Loss for nuclear power reactors.of Non-Class IEUninterruptible Power Supplies91-63 Natural Gas Hazards ID/03/91 All holders of OLs or CPsat Fort St. Vramn for nuclear power reactors.Nuclear Generating Station91-62 Diesel Engine Damage 09/30/91 All holders of OLs or CPsCaused by Hydraulic for nuclear power reactors.Lockup Resulting fromFluid Leakage IntoCylindersOL | |||
9-9-toCU),CI"If~C0I:IECACCA0I .zaCcoF)go "atAttachmentIN 91-68October 28, 1991Page I of ILIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to90-51. Failures of Voltage-Dropping 10/24/91 All holders of OLs or CPsSupp. I Resistors in the Power for nuclear power reactors.Supply Circuitry of ElectricGovernor Systems91-67 Problems With the Reliable 10/21/91 All holders of OLs or CPsDetection of Intergranular for pressurized-water reactors.Attack (IGA) of StemGenerator Tubing91-66 (1) Erroneous Data in 10/18/91 All fuel cycle licensees,ONuclear Safety Guide critical mass licensees,TID-7016, Revision 2,' interim spent fuel storage(NUREG/CR-O095, ORNL/ licensees, and all holdersNUREG/CSD-6 (1978)) and of operating licenses or(2) Thermal Scattering construction permits forData Limitation in the test, research, and nuclearCross-Section Sets Provided power reactors.with the KENO and SCALE Codes91-65 Emergency Access to 10/16/91 All NRC licensees.Low-Level Radioactivewaste Disposal Facilities91-64 Site Area Emergency 10/09/91 All holders of OLs or CPsResulting From a Loss for nuclear power reactors.of Non-Class IEUninterruptible Power Supplies91-63 Natural Gas Hazards ID/03/91 All holders of OLs or CPsat Fort St. Vramn for nuclear power reactors.Nuclear Generating Station91-62 Diesel Engine Damage 09/30/91 All holders of OLs or CPsCaused by Hydraulic for nuclear power reactors.Lockup Resulting fromFluid Leakage IntoCylindersOL | |||
* Operating LicenseCP | * Operating LicenseCP | ||
* Construction Permit(C | * Construction Permit(C | ||
IIN 91-68October 28, 1991 imported this temporary EDG unit to the site specifically for use as an alter-nate onsite source of emergency power during the shutdown in view of thesignificant number of planned equipment outages. The licensee provided thisunit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water and service water were lost for only2 minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliber-ate, well informed actions and minimized the safety concerns associated witheach event. If the licensees had been less careful in their planning, theseevents could have been more significant. The technical specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrence Document Name: IN 9168OFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR :____ ___ _ _ _-----_--__-: ------------- _-_ ____ _ __NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVargaDATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91 :OFC : *RI : *RII :*C:OGCB:NRR :*DD:DST:NRR :D:DOEA:NRR :NAME : CHehl : LReyes :CBerlinger :GHolahanDATE : 10/11/91 : 10/11/91 :10/17/91 :10/21/91 :/O/I4W91 : | |||
List of Recently Issued NRC Information Notices*See previous concurrence Document Name: IN 9168OFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR :____ ___ _ _ _-----_--__-: ------------- _-_ ____ _ __NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVargaDATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91 :OFC : *RI : *RII :*C:OGCB:NRR :*DD:DST:NRR :D:DOEA:NRR :NAME : CHehl : LReyes :CBerlinger :GHolahanDATE : 10/11/91 : 10/11/91 :10/17/91 :10/21/91 :/O/I4W91 : | |||
-fIN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation | -fIN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation | ||
===Technical Contact:=== | ===Technical Contact:=== | ||
N. Fields, NRR(301) 492- | N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrenceOFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR__ __ --_ ----_ --_ --_ --_____ :_ _-_-_: _ _: _ _ -------NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVarga-__ - __ ___ ___ -------DATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91A/OFC : *RI : *RII :*C:OGCB:NIR D5 :NRR :D:DOEA:NRR :NAME : CHehl : LReyes :CBerlinger ( olahan :CRossi :DATE :10/11/91 :10/11/91 :10/17/91 ;bLt/91 ://91 :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT. | ||
IN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation | |||
===Technical Contact:=== | ===Technical Contact:=== | ||
N. Fields, NRR(301) 492- | N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrenceOFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR :NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVargaDATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91OFC : *RI : *RII :C:O O9B;J@t :D:DOEA:NRR : :NAME : CHehl : LReyes :CBeFl hger :CRossi Y :DATE: 10/11/91 10/11/91 : ///7/91 , /91OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT. | ||
IN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation | |||
===Technical Contact:=== | ===Technical Contact:=== | ||
N. Fields, NRR(301) 492- | N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrence Owl'OFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :C:4 C),F5J :C :N._- -_ _ _ _ _ _ _ _I , _ _NAME :NFields :JMain :DFischer :FRosa :AChaffee : g_____ --- -- -- ------------ _ _ _ _ _ _:----- ----- ----:-------- --------------: .,£ -------DATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :{./i /91 : / /91OFC : RI : :------- ~ ~ ~ _ '---- -t^ i ----------:- ------------ --------__ _ _ _ _ _ _ _ ----------NAME : CHehl- : LReye CRossi : :DATE :o/,//91 :/0//1/91 : / /91 : :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT. | ||
IN 91-XXSeptember XX, 1991 Document Name: IN/TURKEY PT. & INDIAN PT. | |||
IN 91-XXSeptember XX, 1991 Document Name: IN/TURKEY PT. & INDIAN PT. | |||
If the licensees had been less circumspect in their planning, these eventscould have been more significant. Licensees have considerable flexibility inremoving equipment from service and altering normal system lineups duringshutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation | |||
===Technical Contact:=== | ===Technical Contact:=== | ||
N. Fields, NRR(301) 492- | N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information NoticesOFC :EAB:NRR M fi .eEW:NRR :BC:SELB:NRR :C:EAB:NRR :C:DRPE:NRR :NAME :NF iFelds :JMain :DFischer :FRosa :AChaffee :SVargaDATE :1/1-:91 :: F/i/91 q/2/91 : / /91 : / /91 : / /91 :OFC : RI : RII :D:DOEA:NRR : :NAME: in :S er :CRossi :-----s---:-A----------------:--------- ------- --------DATE: /9 : ://91 : : :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT. | ||
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{{Information notice-Nav}} | {{Information notice-Nav}} | ||
Revision as of 18:53, 6 April 2018
UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555October 28, 1991'NRC INFORMATION NOTICE 91-68: CAREFUL PLANNING SIGNIFICANTLY REDUCESTHE POTENTIAL ADVERSE IMPACTS OF LOSSOF OFFSITE POWER EVENTS DURING SHUTDOWN
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 describe the positive benefits that were derived by two licensees when theiroutage activities were carefully planned, scheduled, and performed. Theselicensees did not rely solely on technical specifications to identify theminimum equipment that should be available under various shutdown configura-tions. Rather, these licensees made additional equipment available and devel-oped special procedures, as appropriate, to mitigate the consequences thatcould result from forced equipment outages. It is expected that recipientswill review the information for applicability to their facilities and considerappropriate actions. However, suggestions contained in this information noticeare not NRC requirements; therefore, no specific action or written response isrequired.
Description of Circumstances
In November 1990, the licensee for the Turkey Point Plant began an 11-monthdual unit outage to conduct a major electrical system upgrade includinginstalling two additional emergency diesel generators (EDGs). OnMarch 13, 1991, while both units were defueled and the safety-related EDGs wereinoperable, offsite power for Unit 4 was being provided through the startuptransformer. Spent fuel pool cooling pumps were being powered from the"C" load center which was being supplied by the "A" vital bus. Electricalpower for the component cooling water (CCW) pumps and the intake cooling water(ICW) pumps was being provided from vital bus "A". At the time, spent fuelpool cooling was the most significant nuclear safety function.An alternate source of power supply to the CCW, ICW, and spent fuel poolcooling pumps was available from four, non-safety-related (black start) dieselgenerators. Other backup sources of power to the pumps included interconnec-tion with the Unit 3 startup transformer and transfer to another Unit 4 trans-former (after defeating circuit breaker interlocks). An alternate method of(Z91030028 A ;04SAn1 19mit-//
IN 91-68October 28, 1991 spent fuel pool cooling, which was available, involved the use of a trailer-mounted diesel generator and a diesel powered fire pump or a non-safety gradescreen wash pump. Detailed procedures for use of the alternative coolingmethods were'available.At 3:30 p.m., a lockout occurred on the Unit 4 startup transformer resulting ina total loss of all vital AC power to Unit 4. A notification of an unusualevent (NOUE) was declared as a result of the loss of vital offsite power. Thelicensee manually started, but did not load, two of the black start dieselgenerators. The other black start diesel generators were not started. All ofthese sources were available to supply power to the cooling pumps for the spentfuel pool if the startup transformer could not be returned to service.The licensee inspected the startup transformer and associated circuit breakersand found no electrical fault indications. At 4:35 p.m., the licensee ener-gized the startup transformer. At 5:27 p.m., power was restored to the CCW,ICW and spent fuel pool cooling pumps and forced cooling to the spent fuel poolwas resumed. The NOUE was then terminated. The temperature of the spent fuelpool had increased from 840F to 87°F during the 2-hour duration of the event.On March 20, 1991, another event of interest occurred at the Indian PointStation. Before the event, Indian Point, Unit 2, (IP2) was in cold shutdownwith all fuel removed from the vessel and stored in the spent fuel pit.Indian Point, -Unit 3, (IP3) was operating-at 100 percent power An a normalplant configuration. At 7:15 p.m., a potential transformer on a 345kV bussection at a remote substation failed catastrophically, creating a ground faulton the 345kV system. Fault isolation circuitry opened the main generatoroutput breaker for IP3, which initiated a reactor trip. The reactor trip wasuncomplicated and offsite power to IP3 vital buses was not interrupted.However, an explosion and subsequent fire in the substation caused circuitbreakers to electrically isolate the 138kV feeder circuit supplying offsitepower to the IP2 6.9kV buses. As a result, the 6.9kV non-vital and 480V vitalbuses that were in service were deenergized. EDG 23 started automatically onbus undervoltage. At the time, the other two IP2 EDGs were tagged out ofservice for maintenance. As designed, EDG 23 did not load to the buses becauseall logic requirements for automatic loading were not satisfied. EDG 23 wasmanually loaded to two vital 480V buses. This action allowed a service waterpump and a component cooling water pump to be started, a battery charger to beplaced in service, and lighting to the auxiliary and containment buildings tobe restored.At the time of the event, offsite power to some vital loads was being supplieddirectly from temporary connections from an Indian Point Unit 1 feeder bus asopposed to being supplied from normal sources. These loads included the spentfuel pit cooling pump, the auxiliary building exhaust fan, and a batterycharger. The licensee established these temporary connections to mitigate theconsequences of a potential loss of the normal offsite source.Since two EDGs were out of service, a temporary EDG was started as a precau-tion. However, the unit was not needed during the event. The licensee had
K)IN 91-68October 28, 1991 imported this temporary EDG unit to the site specifically for use as an alter-nate onsite source of emergency power during the shutdown In view of thesignificant number of planned equipment outages. The licensee provided thisunit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water and service water were lost for only2 minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliber-ate, well Informed actions and minimized the safety concerns associated witheach event. If the licensees had been less careful in their planning, theseevents could have been more significant. The technical specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: N. Fields, NRR(301) 492-1173Attachment:List of Recently Issued NRC Information Notices
9-9-toCU),CI"If~C0I:IECACCA0I .zaCcoF)go "atAttachmentIN 91-68October 28, 1991Page I of ILIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to90-51. Failures of Voltage-Dropping 10/24/91 All holders of OLs or CPsSupp. I Resistors in the Power for nuclear power reactors.Supply Circuitry of ElectricGovernor Systems91-67 Problems With the Reliable 10/21/91 All holders of OLs or CPsDetection of Intergranular for pressurized-water reactors.Attack (IGA) of StemGenerator Tubing91-66 (1) Erroneous Data in 10/18/91 All fuel cycle licensees,ONuclear Safety Guide critical mass licensees,TID-7016, Revision 2,' interim spent fuel storage(NUREG/CR-O095, ORNL/ licensees, and all holdersNUREG/CSD-6 (1978)) and of operating licenses or(2) Thermal Scattering construction permits forData Limitation in the test, research, and nuclearCross-Section Sets Provided power reactors.with the KENO and SCALE Codes91-65 Emergency Access to 10/16/91 All NRC licensees.Low-Level Radioactivewaste Disposal Facilities91-64 Site Area Emergency 10/09/91 All holders of OLs or CPsResulting From a Loss for nuclear power reactors.of Non-Class IEUninterruptible Power Supplies91-63 Natural Gas Hazards ID/03/91 All holders of OLs or CPsat Fort St. Vramn for nuclear power reactors.Nuclear Generating Station91-62 Diesel Engine Damage 09/30/91 All holders of OLs or CPsCaused by Hydraulic for nuclear power reactors.Lockup Resulting fromFluid Leakage IntoCylindersOL
- Operating LicenseCP
- Construction Permit(C
IIN 91-68October 28, 1991 imported this temporary EDG unit to the site specifically for use as an alter-nate onsite source of emergency power during the shutdown in view of thesignificant number of planned equipment outages. The licensee provided thisunit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water and service water were lost for only2 minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliber-ate, well informed actions and minimized the safety concerns associated witheach event. If the licensees had been less careful in their planning, theseevents could have been more significant. The technical specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrence Document Name: IN 9168OFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR :____ ___ _ _ _-----_--__-: ------------- _-_ ____ _ __NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVargaDATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91 :OFC : *RI : *RII :*C:OGCB:NRR :*DD:DST:NRR :D:DOEA:NRR :NAME : CHehl : LReyes :CBerlinger :GHolahanDATE : 10/11/91 : 10/11/91 :10/17/91 :10/21/91 :/O/I4W91 :
-fIN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
Technical Contact:
N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrenceOFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR__ __ --_ ----_ --_ --_ --_____ :_ _-_-_: _ _: _ _ -------NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVarga-__ - __ ___ ___ -------DATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91A/OFC : *RI : *RII :*C:OGCB:NIR D5 :NRR :D:DOEA:NRR :NAME : CHehl : LReyes :CBerlinger ( olahan :CRossi :DATE :10/11/91 :10/11/91 :10/17/91 ;bLt/91 ://91 :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT.
IN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
Technical Contact:
N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrenceOFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :*C:EAB:NRR :*C:DRPE:NRR :NAME :NFields :JMain :DFischer :FRosa :AChaffee :SVargaDATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :10/07/91 :10/18/91OFC : *RI : *RII :C:O O9B;J@t :D:DOEA:NRR : :NAME : CHehl : LReyes :CBeFl hger :CRossi Y :DATE: 10/11/91 10/11/91 : ///7/91 , /91OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT.
IN 91-XXNovember XX, 1991 unit even though there were three gas turbines and a second 138kV feeder thatwere available from off site and that could have been manually aligned toenergize the IP2 vital buses.The licensee restored normal offsite power to IP2 within 30 minutes. Duringthe event, component cooling water, and service water was lost for only 2minutes limiting the interruption to spent fuel cooling.DiscussionThese events illustrate the benefits of carefully planning equipment outagesduring shutdown. Before each event, the licensees had made additional powersources available to augment normal supplies. Furthermore, the licensees haddeveloped written procedures to address anticipated equipment failures. Theseefforts allowed operating personnel to have adequate time to perform deliberate,well informed actions and minimized the safety concerns associated with eachevent. If the licensees had been less circumspect in their planning, theseevents could have been more significant. The Technical Specifications allowlicensees considerable flexibility in removing equipment from service andaltering normal system lineups during shutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
Technical Contact:
N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information Notices*See previous concurrence Owl'OFC :*EAB:NRR :*TECH ED :*SC:EAB:NRR :*C:SELB:NRR :C:4 C),F5J :C :N._- -_ _ _ _ _ _ _ _I , _ _NAME :NFields :JMain :DFischer :FRosa :AChaffee : g_____ --- -- -- ------------ _ _ _ _ _ _:----- ----- ----:-------- --------------: .,£ -------DATE :08/28/91 :08/28/91 :08/29/91 :09/06/91 :{./i /91 : / /91OFC : RI : :------- ~ ~ ~ _ '---- -t^ i ----------:- ------------ --------__ _ _ _ _ _ _ _ ----------NAME : CHehl- : LReye CRossi : :DATE :o/,//91 :/0//1/91 : / /91 : :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT.
IN 91-XXSeptember XX, 1991 Document Name: IN/TURKEY PT. & INDIAN PT.
IN 91-XXSeptember XX, 1991 Document Name: IN/TURKEY PT. & INDIAN PT.
If the licensees had been less circumspect in their planning, these eventscould have been more significant. Licensees have considerable flexibility inremoving equipment from service and altering normal system lineups duringshutdown.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please call thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
Technical Contact:
N. Fields, NRR(301) 492-1173Attachment: List of Recently Issued NRC Information NoticesOFC :EAB:NRR M fi .eEW:NRR :BC:SELB:NRR :C:EAB:NRR :C:DRPE:NRR :NAME :NF iFelds :JMain :DFischer :FRosa :AChaffee :SVargaDATE :1/1-:91 :: F/i/91 q/2/91 : / /91 : / /91 : / /91 :OFC : RI : RII :D:DOEA:NRR : :NAME: in :S er :CRossi :-----s---:-A----------------:--------- ------- --------DATE: /9 : ://91 : : :OFFICIAL RECORD COPYDocument Name: IN/TURKEY PT. & INDIAN PT.