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Category:NRC Information Notice
MONTHYEARInformation Notice 1991-09, Counterfeiting of Crane Valves2007-09-25025 September 2007 Counterfeiting of Crane Valves Information Notice 2007-28, Potential Common Cause Vulnerabilities in Essential Service Water Systems Due to Inadequate Chemistry Controls2007-09-19019 September 2007 Potential Common Cause Vulnerabilities in Essential Service Water Systems Due to Inadequate Chemistry Controls Information Notice 2006-04, Design Deficiency in Pressurizer Heaters for Pwrs2006-02-13013 February 2006 Design Deficiency in Pressurizer Heaters for Pwrs Information Notice 2006-04, Design Deficiency in Pressurizer Heaters for PWRs2006-02-13013 February 2006 Design Deficiency in Pressurizer Heaters for PWRs Information Notice 2005-15, Three-Unit Trip and Loss of Offsite Power at Palo Verde Nuclear Generating Station2005-06-0101 June 2005 Three-Unit Trip and Loss of Offsite Power at Palo Verde Nuclear Generating Station Information Notice 1999-28, Recall of Star Brand Fire Protection Sprinkler Heads1999-09-30030 September 1999 Recall of Star Brand Fire Protection Sprinkler Heads Information Notice 1999-27, Malfunction of Source Retraction Mechanism in Cobalt-60 Teletherapy Treatment Units1999-09-0202 September 1999 Malfunction of Source Retraction Mechanism in Cobalt-60 Teletherapy Treatment Units Information Notice 1999-26, Safety and Economic Consequences of Misleading Marketing Information1999-08-24024 August 1999 Safety and Economic Consequences of Misleading Marketing Information Information Notice 1999-25, Year 2000 Contingency Planning Activities1999-08-10010 August 1999 Year 2000 Contingency Planning Activities Information Notice 1999-24, Broad-Scope Licensees' Responsibilities for Reviewing and Approving Unregistered Sealed Sources and Devices1999-07-12012 July 1999 Broad-Scope Licensees' Responsibilities for Reviewing and Approving Unregistered Sealed Sources and Devices Information Notice 1999-23, Safety Concerns Related to Repeated Control Unit Failures of the Nucletron Classic Model High-Dose-Rate Remote Afterloading Brachytherapy Devices1999-07-0606 July 1999 Safety Concerns Related to Repeated Control Unit Failures of the Nucletron Classic Model High-Dose-Rate Remote Afterloading Brachytherapy Devices Information Notice 1999-20, Contingency Planning for the Year 2000 Computer Problem1999-06-25025 June 1999 Contingency Planning for the Year 2000 Computer Problem Information Notice 1999-21, Recent Plant Events Caused by Human Performance Errors1999-06-25025 June 1999 Recent Plant Events Caused by Human Performance Errors Information Notice 1999-22, 10CFR 34.43(a)(1); Effective Date for Radiographer Certification and Plans for Enforcement Discretion1999-06-25025 June 1999 10CFR 34.43(a)(1); Effective Date for Radiographer Certification and Plans for Enforcement Discretion Information Notice 1999-19, Rupture of the Shell Side of a Feedwater Heater at the Point Beach Nuclear Plant1999-06-23023 June 1999 Rupture of the Shell Side of a Feedwater Heater at the Point Beach Nuclear Plant Information Notice 1999-18, Update on Nrc'S Year 2000 Activities for Material Licensees and Fuel Cycle Licensees and Certificate Holders1999-06-14014 June 1999 Update on Nrc'S Year 2000 Activities for Material Licensees and Fuel Cycle Licensees and Certificate Holders Information Notice 1999-17, Problems Associated with Post-Fire Safe-Shutdown Circuit Analyses1999-06-0303 June 1999 Problems Associated with Post-Fire Safe-Shutdown Circuit Analyses Information Notice 1999-16, Federal Bureau of Investigation'S Nuclear Site Security Program1999-05-28028 May 1999 Federal Bureau of Investigation'S Nuclear Site Security Program Information Notice 1999-15, Misapplication for 10CFR Part 71 Transportation Shipping Cask Licensing Basis to 10CFR Part 50 Design Basis1999-05-27027 May 1999 Misapplication for 10CFR Part 71 Transportation Shipping Cask Licensing Basis to 10CFR Part 50 Design Basis Information Notice 1999-14, Unanticipated Reactor Water Draindown at Quad Cities Unit 2, Arkansas Nuclear One Unit 2, & FitzPatrick1999-05-0505 May 1999 Unanticipated Reactor Water Draindown at Quad Cities Unit 2, Arkansas Nuclear One Unit 2, & FitzPatrick Information Notice 1999-13, Insights from NRC Inspections of Low-and Medium-Voltage Circuit Breaker Maintenance Programs1999-04-29029 April 1999 Insights from NRC Inspections of Low-and Medium-Voltage Circuit Breaker Maintenance Programs Information Notice 1999-12, Year 2000 Computer Systems Readiness Audits1999-04-28028 April 1999 Year 2000 Computer Systems Readiness Audits Information Notice 1999-11, Incidents Involving the Use of Radioactive Iodine-1311999-04-16016 April 1999 Incidents Involving the Use of Radioactive Iodine-131 Information Notice 1999-08, Urine Specimen Adulteration1999-03-26026 March 1999 Urine Specimen Adulteration Information Notice 1999-09, Problems Encountered When Manually Editing Treatment Data on the Nucletron Microselectron-HDR (New) Model 105-9991999-03-24024 March 1999 Problems Encountered When Manually Editing Treatment Data on the Nucletron Microselectron-HDR (New) Model 105-999 Information Notice 1999-07, Failed Fire Protection Deluge Valves & Potential Testing Deficiencies in Preaction Sprinkler Systems1999-03-22022 March 1999 Failed Fire Protection Deluge Valves & Potential Testing Deficiencies in Preaction Sprinkler Systems Information Notice 1999-06, 1998 Enforcement Sanctions as a Result of Deliberate Violations of NRC Employee Protection Requirements1999-03-19019 March 1999 1998 Enforcement Sanctions as a Result of Deliberate Violations of NRC Employee Protection Requirements Information Notice 1999-06, 1998 Enforcement Sanctions As a Result of Deliberate Violations of NRC Employee Protection Requirements1999-03-19019 March 1999 1998 Enforcement Sanctions As a Result of Deliberate Violations of NRC Employee Protection Requirements Information Notice 1999-05, Inadvertent Discharge of Carbon Dioxide Fire Protection System and Gas Migration1999-03-0808 March 1999 Inadvertent Discharge of Carbon Dioxide Fire Protection System and Gas Migration Information Notice 1999-04, Unplanned Radiation Exposures to Radiographers, Resulting from Failures to Follow Proper Radiation Safety Procedures1999-03-0101 March 1999 Unplanned Radiation Exposures to Radiographers, Resulting from Failures to Follow Proper Radiation Safety Procedures Information Notice 1999-03, Exothermic Reactors Involving Dried Uranium Oxide Powder (Yellowcake)1999-01-29029 January 1999 Exothermic Reactors Involving Dried Uranium Oxide Powder (Yellowcake) Information Notice 1999-02, Guidance to Users on the Implementation of a New Single-Source Dose-Calculation Formalism and Revised Air-Kerma Strength Standard for Iodine-125 Sealed Sources1999-01-21021 January 1999 Guidance to Users on the Implementation of a New Single-Source Dose-Calculation Formalism and Revised Air-Kerma Strength Standard for Iodine-125 Sealed Sources Information Notice 1999-01, Deterioration of High-Efficiency Particulate Air Filters in a Pressurized Water Reactor Containment Fan Cooler Unit1999-01-20020 January 1999 Deterioration of High-Efficiency Particulate Air Filters in a Pressurized Water Reactor Containment Fan Cooler Unit Information Notice 1998-45, Cavitation Erosion of Letdown Line Orifices Resulting in Fatigue Cracking of Pipe Welds1998-12-15015 December 1998 Cavitation Erosion of Letdown Line Orifices Resulting in Fatigue Cracking of Pipe Welds Information Notice 1998-44, Ten-Year Inservice Inspection (ISI) Program Update for Licensees That Intend to Implement Risk-Informed ISI of Piping1998-12-10010 December 1998 Ten-Year Inservice Inspection (ISI) Program Update for Licensees That Intend to Implement Risk-Informed ISI of Piping Information Notice 1998-43, Leaks in Emergency Diesel Generator Lubricating Oil & Jacket Cooling Water Piping1998-12-0404 December 1998 Leaks in Emergency Diesel Generator Lubricating Oil & Jacket Cooling Water Piping Information Notice 1998-42, Implementation of 10 CFR 55.55a(g) Inservice Inspection Requirements1998-12-0101 December 1998 Implementation of 10 CFR 55.55a(g) Inservice Inspection Requirements Information Notice 1998-41, Spurious Shutdown of Emergency Diesel Generators From Design Oversight1998-11-20020 November 1998 Spurious Shutdown of Emergency Diesel Generators From Design Oversight Information Notice 1998-41, Spurious Shutdown of Emergency Diesel Generators from Design Oversight1998-11-20020 November 1998 Spurious Shutdown of Emergency Diesel Generators from Design Oversight Information Notice 1998-39, Summary of Fitness-for-Duty Program Performance Reports for Calendar Years 1996 and 19971998-10-30030 October 1998 Summary of Fitness-for-Duty Program Performance Reports for Calendar Years 1996 and 1997 Information Notice 1998-40, Design Deficiencies Can Lead to Reduced ECCS Pump Net Positive Suction Head During Design-Basis Accidents1998-10-26026 October 1998 Design Deficiencies Can Lead to Reduced ECCS Pump Net Positive Suction Head During Design-Basis Accidents Information Notice 1990-66, Incomplete Draining and Drying of Shipping Casks1998-10-25025 October 1998 Incomplete Draining and Drying of Shipping Casks Information Notice 1998-38, Metal-Clad Circuit Breaker Maintenance Issues Identified by NRC Inspections1998-10-15015 October 1998 Metal-Clad Circuit Breaker Maintenance Issues Identified by NRC Inspections Information Notice 1998-37, Eligibility of Operator License Applicants1998-10-0101 October 1998 Eligibility of Operator License Applicants Information Notice 1998-36, Inadequate or Poorly Controlled, Non-Safety-Related Maintenance Activities Unnecessarily Challenged Safety Systems1998-09-18018 September 1998 Inadequate or Poorly Controlled, Non-Safety-Related Maintenance Activities Unnecessarily Challenged Safety Systems Information Notice 1998-34, Configuration Control Errors1998-08-28028 August 1998 Configuration Control Errors Information Notice 1998-33, NRC Regulations Prohibit Agreements That Restrict or Discourage an Employee from Participating in Protected Activities1998-08-28028 August 1998 NRC Regulations Prohibit Agreements That Restrict or Discourage an Employee from Participating in Protected Activities Information Notice 1998-31, Fire Protection System Design Deficiencies and Common-Mode Flooding of Emergency Core Cooling System Rooms at Washington Nuclear Project Unit 21998-08-18018 August 1998 Fire Protection System Design Deficiencies and Common-Mode Flooding of Emergency Core Cooling System Rooms at Washington Nuclear Project Unit 2 Information Notice 1998-30, Effect of Year 2000 Computer Problem on NRC Licensees and Certificate Holders1998-08-12012 August 1998 Effect of Year 2000 Computer Problem on NRC Licensees and Certificate Holders Information Notice 1998-29, Predicted Increase in Fuel Rod Cladding Oxidation1998-08-0303 August 1998 Predicted Increase in Fuel Rod Cladding Oxidation 2007-09-25
[Table view] |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 June 1, 2005 NRC INFORMATION NOTICE 2005-15: THREE-UNIT TRIP AND LOSS OF OFFSITE
POWER AT PALO VERDE NUCLEAR
GENERATING STATION
ADDRESSEES
All holders of operating licensees for nuclear power reactors, except those who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor vessel.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
addressees to electrical equipment failures and design deficiencies identified following recent
transients at Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2, and 3. As a result, the units lost offsite power, tripped, and experienced other problems, including the loss of an
emergency diesel generator (EDG). It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate, to avoid similar problems.
However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.
DESCRIPTION OF CIRCUMSTANCES
On June 14, 2004, at 7:41 a.m. Mountain Standard Time (MST), the 500 kV system upset at
the PVNGS switchyard originated with a fault across a degraded insulator on a 230 kV
transmission line. Protective relaying detected the fault and isolated the line from the remote
substation. The protective relaying scheme at the other substation received a transfer trip
signal actuating an auxiliary relay (Westinghouse Type AR) in the tripping scheme for two
breakers connected to the faulted line. The AR relay had four output contacts, all of which were
actuated by a single lever arm. The tripping scheme used two contacts in redundant trip coils
for each breaker.
One breaker tripped, demonstrating that the AR relay coil picked up, and at least one of the AR
relay contacts closed. The other breaker did not trip. Bench testing of the AR relay
showed that, even with normal voltage applied to the coil, neither of the tripping contacts for the
failed breaker closed. The breaker failure scheme for the failed breaker featured a design
where the tripping contacts for the respective redundant trip coils also energized redundant
breaker failure relays. Since the tripping contacts for the failed breaker apparently did not
close, the breaker failure scheme was not activated, resulting in a persistent uncleared fault on
the 230 kV line.
Various transmission system event recorders show that, during approximately the first
12 seconds after fault inception, several transmission lines on the interconnected 69 kV, 230
kV, 345 kV, and 500 kV systems tripped on overcurrent. Also during the first 12 seconds, three
cogeneration plants tripped, two with combustion turbines and one with a steam turbine, and
the fault alternated between a single-phase-to-ground fault and a two-phase-to-ground fault, apparently as a result of a failed shield wire bouncing on the faulted line. After 12 seconds, the
fault became a three-phase-to-ground fault and additional 500 kV lines tripped.
Approximately 17 seconds after fault inception, the three transmission lines between the
PVNGS switchyard and the nearby 500 kV substation tripped simultaneously due to the action
of their negative sequence relaying, thereby isolating the fault from the several cogeneration
plants connected to that substation. Approximately 24 seconds after fault inception, the last two
500 kV lines connected to the PVNGS switchyard tripped, isolating the PVNGS switchyard from
the transmission system. At approximately 28 seconds after fault inception, the three PVNGS
generators were isolated from the switchyard and, by approximately 38 seconds, all remaining
lines feeding the fault had tripped and the fault was isolated.
The trips resulted in a total loss of nearly 5,500 megawatts electric of local electric generation.
Because of the loss of offsite power (LOOP), a Notice of Unusual Event was declared for all
three Palo Verde units at approximately 7:50 a.m. MST. The Unit 2 train A emergency diesel
generator started but failed early in the load sequence process due to a diode which short- circuited. The subject diode had less than 70 hours8.101852e-4 days <br />0.0194 hours <br />1.157407e-4 weeks <br />2.6635e-5 months <br /> of run time in the exciter rectifier circuit. As
a result, the train A engineered safeguards features busses deenergized, limiting the availability
of certain safety equipment for operators. Because of this failure, the emergency declaration
for Unit 2 was elevated to an Alert at 7:54 a.m. MST. All three units were safely shut down and
stabilized under hot shutdown conditions. Units 1, 2, and 3 were without offsite power for
approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 9 minutes, 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 46 minutes, and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 15 minutes, respectively.
DISCUSSION
External fouling on a 230 kV insulator resulted in the deenergizing of a 500 kV switchyard, removing all sources of power to three nuclear units. The single-failure susceptibility of a
transmission line protective system was the primary cause of the cascading blackout. The insulator degradation was caused by external fouling and did not, by itself, represent a
concern about the reliability of the insulators on the 230 kV transmission system. Nevertheless, the failed AR relay and the lack of a robust tripping scheme raised concerns about the
maintenance, testing, and design of 230 kV system protective relaying. The 230 kV substation
where the relay failure occurred was subject to annual maintenance and testing. Following the
event, the failed AR relay was visually inspected. No apparent signs of contamination or
deterioration were found.
As noted earlier, the tripping scheme lacked redundancy that could have prevented the failure
of the protective scheme to clear the fault. The review of the design of the substations
connected to the PVNGS switchyard indicated that two transmission lines at the subject
substation featured a tripping scheme with only one AR relay. The newer lines had two AR
relays. However, the review found that the bus-sectioning breakers at the subject substation
contained only one trip coil instead of two trip coils.
To improve reliability, the tripping schemes for the two identified lines were modified to have
two AR relays energizing separate trip coils for each breaker. The utility is considering
installation of two trip coils in all single-trip-coil breakers. The tielines that connected 500 kV
and 230 kV switchyards did not have overcurrent or ground fault protection. The installation of
overcurrent protection for these tielines were completed in a later modification.
The apparent failure of the Unit 2 train A EDG was a failed diode in phase B of the voltage
regulator exciter circuit. The diode failure resulted in a reduced excitation current and the
current was unable to maintain the voltage output with the applied loads. The failed EDG did
not have a significant impact on plant stabilization and recovery, but it did result in limited
availability of certain safety equipment during a design basis event.
Refer to Attachment 1 for additional discussion.
CONTACT
S
This information notice requires no specific action or written response. Please direct any
questions about this matter to the technical contact(s) listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/RA/
Patrick L. Hiland, Chief
Reactor Operations Branch
Division of Inspection Program Management
Office of Nuclear Reactor Regulation
Technical Contacts: Amar N. Pal, NRR Thomas Koshy, NRR
301-415-2760 301-415-1176 E-mail: anp@nrc.gov E-mail: txk@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collections.
Attachment (exempt from public disclosure in accordance with 10 CFR 2.390)
PACKAGE: ML051520154, IN (PUBLIC): ML050490364 ATTACHMENT (NON-PUBLIC) ML051520164 OFFICE OES:IROB:DIPM Tech Editor EEIB:DE EEIB:DE LPD4:DLPM
NAME CVHodge PKleene ANPal TKoshy MBFields
DATE 02/24/2005 02/16/2005 02/24/2005 02/24/2005 02/28/2005 OFFICE PDIV-1:DLPM EEIB:DE A:SC:OES:IROB:DIPM C:IROB:DIPM
NAME WDReckley JACalvo EJBenner PLHiland
DATE 03/01/2005 03/01/2005 05/16/2005 06/01/2005
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list | - Information Notice 2005-02, Pressure Boundary Leakage Identified on Steam Generator Bowl Drain Welds (4 February 2005, Topic: Boric Acid, Stress corrosion cracking, Pressure Boundary Leakage)
- Information Notice 2005-04, Single-Failure and Fire Vulnerability of Redundant Electrical Safety Buses (14 February 2005, Topic: Safe Shutdown)
- Information Notice 2005-05, Improving Material Control and Accountability Interface with Criticality Safety Activities at Fuel Cycle Facilities (10 March 2005)
- Information Notice 2005-07, Results of Hemyc Electrical Raceway Fire Barrier System Full Scale Fire Testing (1 April 2005, Topic: Fire Barrier, Hemyc)
- Information Notice 2005-08, Monitoring Vibration to Detect Circumferential Cracking of Reactor Coolant Pump and Reactor Recirculation Pump Shafts (5 April 2005)
- Information Notice 2005-09, Official Exhibit - ENT000527-00-BD01 - NRC Information Notice 2005-09, Indications in Thermally Treated Alloy 600 Steam Generator Tubes and Tube-to Tubesheet Welds (Apr. 7, 2005) (7 April 2005)
- Information Notice 2005-11, Internal Flooding/Spray-Down of Safety-Related Equipment Due to Unsealed Equipment Hatch Floor Plugs And/Or Blocked Floor Drains (6 May 2005)
- Information Notice 2005-11, Internal Flooding/Spray-Down of Safety-Related Equipment Due to Unsealed Equipment Hatch Floor Plugs and/or Blocked Floor Drains (6 May 2005, Topic: Internal Flooding)
- Information Notice 2005-12, Excessively Large Criticality Safety Limits Fail to Provide Double Contingency at Fuel Cycle Facility (17 May 2005, Topic: Hemyc)
- Information Notice 2005-13, Potential Non-Conservative Error in Modeling Geometric Regions in the Keno-V. a Criticality Code (17 May 2005, Topic: Hemyc)
- Information Notice 2005-14, Fire Protection Findings on Loss of Seal Cooling to Westinghouse Reactor Coolant Pumps (1 June 2005, Topic: Safe Shutdown, Probabilistic Risk Assessment, Significance Determination Process, Fire Protection Program)
- Information Notice 2005-15, Three-Unit Trip and Loss of Offsite Power at Palo Verde Nuclear Generating Station (1 June 2005)
- Information Notice 2005-16, Outage Planning and Scheduling - Impacts on Risk (20 June 2005, Topic: Time to boil)
- Information Notice 2005-17, Manual Brachytherapy Source Jamming (23 June 2005, Topic: Brachytherapy)
- Information Notice 2005-18, Summary of Fitness-For-Duty Program Performance Reports for Calendar Years 2001, 2002 and 2003 (15 July 2005, Topic: Fitness for Duty, Contraband, Stolen)
- Information Notice 2005-20, Electrical Distribution System Failures Affecting Security Equipment (19 July 2005)
- Information Notice 2005-21, Plant Trip and Loss of Preferred AC Power From Inadequate Switchyard Maintenance (21 July 2005)
- Information Notice 2005-21, Plant Trip and Loss of Preferred AC Power from Inadequate Switchyard Maintenance (21 July 2005)
- Information Notice 2005-22, Inadequate Criticality Safety Analysis of Ventilation Systems At Fuel Cycle Facilities (29 July 2005, Topic: Brachytherapy)
- Information Notice 2005-22, Inadequate Criticality Safety Analysis of Ventilation Systems at Fuel Cycle Facilities (29 July 2005, Topic: Brachytherapy)
- Information Notice 2005-24, Nonconservatism in Leakage Detection Sensitivity (3 August 2005, Topic: Pressure Boundary Leakage)
- Information Notice 2005-26, Results of Chemical Effects Head Loss Tests In a Simulated PWR Sump Pool Environment (16 September 2005)
- Information Notice 2005-26, Results of Chemical Effects Head Loss Tests in a Simulated PWR Sump Pool Environment (16 September 2005)
- Information Notice 2005-27, Low-Dose-Rate Manual Brachytherapy Equipment-Related Medical Events (7 October 2005, Topic: Fire Barrier, RAMQC, Hemyc, Brachytherapy)
- Information Notice 2005-28, Inadequate Test Procedure Fails to Detect Inoperable Criticality Accident Alarm Horns (31 October 2005, Topic: Fire Barrier, RAMQC, Hemyc, Brachytherapy)
- Information Notice 2005-29, Steam Generator Tube and Support Configuration (27 October 2005, Topic: Eddy Current Testing)
- Information Notice 2005-30, Safe Shutdown Potentially Challenged by Unanalyzed Internal Flooding Events and Inadequate Design (7 November 2005, Topic: Safe Shutdown, Internal Flooding)
- Information Notice 2005-30, Safe Shutdown Potentially Challenged By Unanalyzed Internal Flooding Events and Inadequate Design (7 November 2005, Topic: Safe Shutdown, Internal Flooding)
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