On November 1, 2017, at approximately 1425 Central Daylight Time, during an extent of condition review, a 4kV Shutdown Boards ( SD BD) do not selectively coordinate with upstream 0.5 amp primary fuses for fault currents greater than 30 amps on the 120 V secondary. Cable fire damage could cause an affected SD BD to spuriously disconnect from off-site power, and could cause a spurious, maintained under-voltage trip signal. The under-voltage trip signal would prevent motor load operation on the board whether on off-site 4kV SD BDs could be affected. In fire area 21, 4kV SD BDs 3EA and 3EB could be affected.
This condition was determined to be a legacy issue dating to the original design of the plant. The most likely cause is lack of rigorous oversight of the vendor during the preparation and subsequent issuance of the fuse evaluation for the four Unit 3 4kV SD BDs. The required coordination studies have since been performed and a vendor oversight process has been added to TVA procedures. Compensatory measures (hourly fire watches) have been put in place for affected fire areas. Additional corrective actions include issuing an Engineering Change Package to replace the Unit 3 4kV SD BDs primary 0.5 amp PT fuses with 1 amp fuses of the same type. |
|
---|
Category:Letter
MONTHYEARML24032A4762024-02-0101 February 2024 Final Report of a Part 21 Evaluation Associated with Starter Contactors for the BFN Unit 1 High Pressure Coolant Injection Suppression Pool Inboard Suction Valve ML24023A2802024-01-23023 January 2024 Final Report of a Deviation or Failure to Comply Associated with a Relay in the Reactor Core Isolation Cooling Condensate Pump CNL-24-017, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions2024-01-17017 January 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions ML24016A3042024-01-16016 January 2024 Final Report of a Part 21 Evaluation Associated with Check Valve 0-CKV-023-0565 for D1 Residual Heat Removal Service Water Pump CNL-23-071, Response to Request for Additional Information Regarding Browns Ferry Nuclear Plant, Units 1, 2, and 3, Inservice Inspection and Augmented Program Interval Revised Request for Alternative 0-ISI-472024-01-11011 January 2024 Response to Request for Additional Information Regarding Browns Ferry Nuclear Plant, Units 1, 2, and 3, Inservice Inspection and Augmented Program Interval Revised Request for Alternative 0-ISI-47 ML24022A1732024-01-0303 January 2024 Receipt and Availability of the Subsequent License Renewal Application ML23319A1992024-01-0303 January 2024 Issuance of Amendment Nos. 333, 356, and 316 Regarding the Technical Specification Surveillance Requirements 3.4.3.2 and 3.5.1.11 Regarding Safety Relief Valves ML23355A2062023-12-21021 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23348A3942023-12-14014 December 2023 Interim Part 21 Report of a Potential Deviation or Failure to Comply Associated with Starter Contactors for the High Pressure Coolant Injection Suppression Pool Inboard Suction Valve IR 05000259/20230102023-12-11011 December 2023 Commercial Grade Dedication Inspection Report 05000259/2023010 and 05000260/2023010 and 05000296/2023010 ML23335A0722023-12-0101 December 2023 Interim Report of a Deviation or Failure to Comply Associated with a Relay in the Unit 2 Reactor Core Isolation Cooling Condensate Pump ML23334A2492023-11-30030 November 2023 Site Emergency Plan Implementing Procedure Revision CNL-23-070, Submittal of Fifth 10-Year Interval Inservice Testing Program Plan2023-11-29029 November 2023 Submittal of Fifth 10-Year Interval Inservice Testing Program Plan ML23331A2532023-11-27027 November 2023 Summary Report for 10 CFR 50.9 Evaluations, Technical Specifications Bases Changes, Technical Requirement Manual Changes, and NRC Commitment Revisions CNL-23-067, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2023-11-27027 November 2023 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML23325A1102023-11-21021 November 2023 Anchor Darling Double Disc Gate Valve Commitment Revision ML23320A2542023-11-16016 November 2023 Interim Part 21 Report of a Deviation or Failure to Comply Associated with Check Valve 0-CKV-023-0565 for D1 Residual Heat Removal Service Water Pump IR 05000259/20230032023-11-13013 November 2023 Integrated Inspection Report 05000259/2023003, 05000260/2023003 and 05000296/2023003 IR 05000259/20230402023-11-0202 November 2023 Supplemental Inspection Supplemental Report 05000259 2023040 and Follow-Up Assessment Letter ML23292A2532023-10-18018 October 2023 BFN 2024-301, Corporate Notification Letter (210-day Ltr) ML23282A0022023-10-0606 October 2023 Interim Part 21 Report of a Deviation or Failure to Comply Associated with Check Valve 0-CKV-023-0565 for D1 Residual Heat Removal Service Water Pump ML23278A0122023-10-0505 October 2023 Updated Final Safety Analysis Report, Amendment 30 ML23271A1702023-09-28028 September 2023 Site Emergency Plan Implementing Procedure Revision ML23270A0702023-09-26026 September 2023 SLRA Pre-Application Meeting Summary 09-13-2023 ML23257A1232023-09-22022 September 2023 Administrative Changes to Technical Specification Pages Issued for License Amendment Nos. 332, 355, and 315 CNL-23-061, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revision2023-09-20020 September 2023 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revision ML23263B1042023-09-20020 September 2023 Special Report 260/2023-001 for Inoperable Post Accident Monitoring (PAM) Instrumentation ML23205A2132023-09-0808 September 2023 Issuance of Amendment Nos. 332, 355, and 315 Regarding the Revision of Technical Specifications to Adopt TSTF-566-A and TSTF-580-A, Rev. 1 CNL-23-057, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions. Includes CECC-EPIP-1, Revision 76 and CECC-EPIP-9, Revision 642023-09-0505 September 2023 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions. Includes CECC-EPIP-1, Revision 76 and CECC-EPIP-9, Revision 64 IR 05000259/20230052023-08-29029 August 2023 Updated Inspection Plan for Browns Ferry Nuclear Plant, Units 1, 2 and 3 - Report 05000259/2023005, 05000260/2023005 and 05000296/2023005 ML23233A0432023-08-18018 August 2023 Enforcement Action EA-22-122 Inspection Readiness Notification ML23219A1542023-08-17017 August 2023 Request to Use Later Edition of ASME Code for Operation and Maintenance and Alternative Requests BFN-IST-01 Through 05 for the Fifth 10-Year Interval Inservice Testing Program ML23228A1642023-08-16016 August 2023 Site Emergency Plan Implementing Procedure Revision ML23228A0202023-08-15015 August 2023 (BFN) Unit 1 - Special Report 259/2023-001 for Inoperable Post Accident Monitoring (PAM) Instrumentation IR 05000259/20230022023-08-10010 August 2023 Integrated Inspection Report 05000259/2023002, 05000260/2023002, 05000296/2023002 and 07200052/2023001 ML23192A4472023-07-31031 July 2023 Staff Assessment of Updated Seismic Hazards at TVA Sites Following the NRC Process for the Ongoing Assessment of Natural Hazards Information CNL-23-055, Tennessee Valley Authority - Emergency Preparedness Department Procedure Revision. Includes EPDP-3, Revision 3, Emergency Plan Exercises and Preparedness Drills2023-07-25025 July 2023 Tennessee Valley Authority - Emergency Preparedness Department Procedure Revision. Includes EPDP-3, Revision 3, Emergency Plan Exercises and Preparedness Drills ML23171A8862023-07-24024 July 2023 Issuance of Amend. Nos. 331, 354, and 314; 365 and 359 Regarding Adoption of TSTF-541-A, Add Exceptions to Surveillance Requirements for Valves and Dampers Locked in the Actuated Position ML23201A2182023-07-20020 July 2023 Registration of Use of Cask to Store Spent Fuel (MPC-298 and -299) ML23159A2552023-07-20020 July 2023 Proposed Alternative to the Requirements of the ASME Code Regarding Volumetric Inspection of Standby Liquid Control Nozzles ML23199A3072023-07-18018 July 2023 Site Emergency Plan Implementing Procedure Revision CNL-23-053, Tennessee Valley Authority - Radiological Emergency Plan Revisions2023-07-18018 July 2023 Tennessee Valley Authority - Radiological Emergency Plan Revisions IR 05000259/20233012023-07-18018 July 2023 NRC Operator License Examination Report Nos. 05000259/2023301, 05000260/2023301, and 05000296/2023301 2024-02-01
[Table view] Category:Licensee Event Report (LER)
MONTHYEARML20160A0232020-06-0404 June 2020 SR 2020-001-00 for Browns Ferry Nuclear Plant (Bfn),Inoperable Oscillating Power Range Monitor (OPRM) Instrumentation 05000296/LER-2017-0022017-12-29029 December 2017 4kV Shutdown Board Potential Transformer Primary Fuses Do Not Coordinate with Secondary Fuses, LER 17-002-00 for Browns Ferry Nuclear Plant, Unit 3 Regarding 4kV Shutdown Board Potential Transformer Primary Fuses Do Not Coordinate with Secondary Fuses 05000296/LER-2017-0012017-10-31031 October 2017 Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications, LER 17-001-00 for Browns Ferry Nuclear Plant, Unit 3, Regarding Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications 05000260/LER-2017-0042017-07-0707 July 2017 Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints, LER 17-004-00 for Browns Ferry, Unit 2, Regarding Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints 05000260/LER-2017-0032017-05-30030 May 2017 Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting, LER 17-003-00 for Browns Ferry Nuclear Plant, Unit 2 Regarding Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting 05000259/LER-2017-0022017-04-27027 April 2017 Unauthorized Firearm Introduced into the Protected Area, LER 17-002-00 for Browns Ferry, Unit 1, Regarding Unauthorized Firearm Introduced into the Protected Area 05000260/LER-2017-0022017-04-24024 April 2017 Inoperable Primary Containment Isolation Valve Resulting in Condition Prohibited by Technical Specifications, LER 17-002-00 for Browns Ferry, Unit 2, Regarding Inoperable Primary Containment Isolation Valve Resulting in Condition Prohibited by Technical Specifications 05000260/LER-2017-0012017-04-14014 April 2017 High Pressure Coolant Injection Safety System Functional Failure Due to a Blown Fuse, LER 17-001-00 for Browns Ferry, Unit 2, Regarding High Pressure Coolant Injection Safety System Functional Failure Due to a Blown Fuse 05000259/LER-2016-0022016-09-19019 September 2016 High Pressure Coolant Injection Safety System Functional Failure due to Inoperability of Primary Containment Isolation Valve, LER 16-002-00 for Browns Ferry, Unit 1, Regarding High Pressure Coolant Injection Safety System Functional Failure Due to Inoperability of Primary Containment Isolation Valve 05000260/LER-2016-0022016-09-13013 September 2016 High Pressure Coolant Injection System Failure Due To Stuck Contactor, LER 16-002-00 for Browns Ferry Nuclear Plant, Unit 2, Regarding High Pressure Coolant Injection System Failure Due To Stuck Contactor 05000260/LER-2016-0012016-08-16016 August 2016 High Pressure Coolant Injection Safety System Functional Failure due to a Blown Fuse and a Failed Relay, LER 16-001-00 for Browns Ferry, Unit 2, Regarding High Pressure Coolant Injection Safety System Functional Failure Due to a Blown Fuse and a Failed Relay 05000296/LER-2016-0062016-08-0505 August 2016 1 OF 8, LER 16-006-00 for Browns Ferry Nuclear Plant, Unit 3, Regarding High Pressure Coolant Injection System Found to be Inoperable During Testing 05000259/LER-2016-0012016-06-21021 June 2016 Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves, LER 16-001-00 for Browns Ferry, Unit 1, Regarding Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves 05000296/LER-2016-0052016-06-17017 June 2016 Automatic Depressurization System Valve Inoperability Exceeded Technical Specification Limits, LER 16-005-00 for Browns Ferry, Unit 3, Regarding Automatic Depressurization System Valve Inoperability Exceeded Technical Specification Limits 05000296/LER-2016-0042016-06-0606 June 2016 Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints, LER 16-004-00 for Browns Ferry, Unit 3, Regarding Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints 05000296/LER-2016-0032016-04-25025 April 2016 Main Steam Isolation Valve Leaking in Excess of Technical Specification Requirements, LER 16-003-00 for Browns Ferry Nuclear Plant Unit 3 Regarding Main Steam Isolation Valve Leaking in Excess of Technical Specification Requirements 05000296/LER-2016-0022016-04-22022 April 2016 Improperly Installed Switch Results in Condition Prohibited by Technical Specifications, LER 16-002-00 for Browns Ferry Nuclear Plant, Unit 3, Regarding Improperly Installed Switch Results in Condition Prohibited by Technical Specifications 05000296/LER-2016-0012016-03-21021 March 2016 Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications and Safety System Functional Failure, LER 16-001-00 for Browns Ferry, Unit 3, Regarding Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications and Safety System Functional Failure 05000260/LER-2015-0022016-03-17017 March 2016 High Pressure Coolant Injection System Inoperable due to Manual Isolation of Steam Leak I, LER 15-002-01 for Browns Ferry, Unit 2, Regarding High Pressure Coolant Injection System Inoperable Due to Manual Isolation of Steam Leak ML1108400352011-03-22022 March 2011 Letter Re Licensee Event Report Which Occurred on December 22, 2010, Concerning Low Pressure Coolant Injection Operability, TVA Expects to Submit a Revised LER by April 15, 2011 ML1015505752010-04-0707 April 2010 Event Notification for Browns Ferry on Spill of Water Containing Tritium ML1015505632008-01-10010 January 2008 Event Notification for Browns Ferry on Offsite Notification - Spill of Water Containing Tritium ML18283B3261978-09-29029 September 1978 LER 1978-205-01 for Browns Ferry, Unit 3 Four Main Steam Isolation Valves Which Exceeded the Leakage Limits of Technical Specification 4.7.A.2.i While Performing Local Leak Rate Testing During Refueling ML18283B3391978-07-25025 July 1978 Licensee Event Report Concerning Excessive Drywell Floor Drain Leak Rate Observed During Normal Operation ML18283B3411978-07-18018 July 1978 Licensee Event Report Concerning an Abnormal Indication on a 4-kV Standby Power Circuit Breaker During Normal Operation ML18283B3401978-07-18018 July 1978 Licensee Event Report Concerning an Outboard Main Steam Isolation Valve, Which Closed Faster than Allowed by Technical Specifications ML18283B3421978-05-31031 May 1978 Licensee Event Report Concerning MSIV 1-38 Which Closed in 1 Second Exceeding Limiting Condition of Operation ML18283A9901978-05-30030 May 1978 LER 1978-010-00 for Browns Ferry Nuclear Plant, Unit 2, Relief Valve on Standby Liquid Control Pump B Opened at 900 Psig (Which Is Lower than Designed Setting of 1425 +/- 75 Psig as Designated by Tech Spec 4.4.A.2.A) During Surveillance Tes ML18283A9911978-05-0909 May 1978 LER 1978-008-00 for Browns Ferry Nuclear Plant, Unit 2, Reactor Building Ventilation Radiation Monitoring Channel Failed During Refueling Outage ML18283A9941978-05-0505 May 1978 LER 1978-009-00 for Browns Ferry Nuclear Plant, Unit 2, Local Leak Rate Tests of All Containment Isolation Valves Where Leak Rate Exceeded Allowable Leak Rate of 60 Percent of La Per 24 Hours or 707.1 Scfh ML18283A9921978-05-0505 May 1978 LER 1978-006-00 for Browns Ferry Nuclear Plant, Unit 2, Check Valve 2-73-603 in High-Pressure Coolant Injection System Was Found in Open Position During Maintenance Inspection After Failing Local Leak Rate Test ML18283B4001978-05-0101 May 1978 LER 1978-010-00 for Browns Ferry Nuclear Plant, Unit 3, Both RBM Channels Which Became Continuously Bypassed During Power Ascension ML18283B4011978-04-28028 April 1978 LER 1978-009-00 for Browns Ferry Nuclear Plant, Unit 3, Smoke Alarm Which Would Not Clear & Was Received for Preaction Sprinkler Zone in Reactor Building During Normal Operation ML18283B4021978-04-28028 April 1978 LER 1978-008-00 for Browns Ferry Nuclear Plant, Unit 3, Relief Valve 3-1-31 Which Failed to Reseat Until Reactor Pressure Reached 280 Psig During Reactor Scram ML18283B4041978-04-24024 April 1978 LER 1978-001-00 for Browns Ferry Nuclear Plant, Unit 3, Torus Oxygen Sensor O2M-76-42, Found to Be Erratic & Did Not Meet Requirements of Tech Spec 4.7.II During Normal Operation, Which Is Superseding Previous Letter of 2/8/1978 ML18283B4031978-04-24024 April 1978 LER 1978-006-00 for Browns Ferry Nuclear Plant, Unit 3, Electrical Connector Carrying Thermocouple Circuits Monitoring Primary Containment Atmospheric Temperature Not Included as Part of Modification Which Qualified Connector Assemblies for ML18283B4051978-04-0404 April 1978 LER 1978-005-00 for Browns Ferry Nuclear Plant, Unit 3, Six CRD Accumulator Level Switches Which Would Not Alarm with Level Increases During Plant Operation While Performing Electrical Maintenance Instruction 50 ML18283B4061978-03-30030 March 1978 LER 1977-012-00 for Browns Ferry Nuclear Plant, Unit 3, Temperature Transients Which Were Experienced with Six Charcoal Adsorber Beds in Offgas System During Normal Operation, Which Is Supplementing Previous Letter of 7/29/1977 ML18283A9951978-03-29029 March 1978 LER 1978-005-00 for Browns Ferry Nuclear Plant, Unit 2, Unidentified Coolant Leakage in Drywall Was Found to Be 9.5 Gpm & Exceeded 5 Gpm Limit of Technical Specification 3.6.C.1. During Normal Operation ML18283B4091978-03-28028 March 1978 LER 1978-004-00 for Browns Ferry Nuclear Plant, Unit 3, Three of Five Test Specimens Failed During Simulated LOCA Conditions & During Qualification Testing of Bendix Electrical Connectors Identical to Those Used in Primary Containment ML18283B4101978-03-22022 March 1978 LER 1977-005-00 for Browns Ferry Nuclear Plant, Unit 3, RPS MG Set a Which Continued Running & MG Set B Output Breaker Which Did Not Trip During Startup Test STI-31, Which Is Supplementing Previous Letter of 3/24/1977 ML18283B4111978-03-10010 March 1978 LER 1978-003-00 for Browns Ferry Nuclear Plant, Unit 3, Valve FCV 3-74-52 Was Found Inoperable During Performance of Surveillance Instruction 4.5.B.1.C ML18283A9961978-02-28028 February 1978 LER 1978-004-00 for Browns Ferry Nuclear Plant, Unit 2, Relief Valve 2-1-5 Opened and Failed to Reseat During Steady State Operation ML18283B4141978-02-28028 February 1978 LER 1978-002-00 for Browns Ferry Nuclear Plant, Unit 3, Bendix Connectors of Type Used Inside Primary Containment Have Failed a Post-Aging Environmental Test at Wyle Laboratory Testing Facility ML18283A9971978-02-15015 February 1978 LER 1978-003-00 for Browns Ferry Nuclear Plant, Unit 2, Relief Valve 2-1-41 Opened and Failed to Reseat During Steady State Operation ML18283B0001978-02-13013 February 1978 LER 1978-002-00 for Browns Ferry Nuclear Plant, Unit 2, Reactor Pressure Switch PS-68-95 Not Functioning as Required by Tech Spec Table 4.2.B During Normal Operation While Performing Surveillance Instruction ST 4.2.B-7 ML18283A9991978-02-0606 February 1978 LER 1978-001-00 for Browns Ferry Nuclear Plant, Unit 2, Surveillance Samples Were Taken from Charcoal in Unit 2 Primary Containment Purge System Following Maintenance Outage ML18283B4161978-02-0606 February 1978 LER 1978-001-00 for Browns Ferry Nuclear Plant, Unit 3, Torus Oxygen Sensor O2M-76-42 Found to Be Erratic & Did Not Meet Requirements of Technical Specification 4.7.H During Normal Operation ML18283B4071977-10-0505 October 1977 LER 1977-012-00 for Browns Ferry Nuclear Plant, Unit 3, Temperature Transients Were Experienced with Six Charcoal Adsorber Beds in Offgas System ML18283B4171977-09-26026 September 1977 LER 1977-017-00 for Browns Ferry Nuclear Plant, Unit 3, Primary Containment Isolation Valve 3-FCV-77-2A on Drywell Floor Drain Sump Pump Discharge Line Would Not Operate as Required by Tech Spec 3.7.D.L During Routine Operability Checks 2020-06-04
[Table view] |
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number. the NRC may not conduct or sponsor. and a person is not required to respond to, the information collection.
05000-296
3. LER NUMBER
NO
- 00 Browns I. Plant At A.
C.
D.
Plant (BFN), Unit 3, was in Central Daylight Time was discovered. Four Shutdown Boards (SD primary fuses for fault currents could cause an affected a spurious, maintained motor load operation on the [DG] power [EK]. If a fire be affected. In fire area CDT, Event Notification that were inoperable inoperable at the 2017 - 002 100 II. Description B.
Operating Conditions Before the Event the time of discovery, Browns Ferry Nuclear percent rated thermal power.
of Event Event Summary On November 1, 2017, at approximately 1425 condition review, a fuse [FU] coordination issue [XPT] 10 amp secondary fuses on Unit 3 4kV selectively coordinate with upstream 0.5 amp on the 120 V secondary. Cable [CBL] fire damage disconnect from off-site power, and could cause The under-voltage trip signal would prevent power or Emergency Diesel Generator (EDG) 03-03 or 16, all four Unit 3 4kV SD BDs could 3EB could be affected.
On November 1, 2017, at approximately 2126 the NRC.
Status of structures, components, or systems and that contributed to the event.
There were no systems, structures, or components contributed to this condition.
Dates and approximate times of occurrences
Mode 1 at approximately (CDT), during an extent of Potential Transformer (PT) BD) [ECBD] do not greater than 30 amps SD BD to spuriously under-voltage trip signal.
board whether on off-site were to occur in fire areas 21, 4kV SD BDs 3EA and (EN) 53049 was made to at the start of the event time of discovery which November 1, 2017, 1425 CDT Unanalyzed condition discovered during an extent of condition review.
November 1, 2017, 2126 CDT Event Notification 53049 made to the NRC.
Manufacturer and model number of each component that failed during the event There were no failed components associated with this condition.
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov. and to the Desk Officer. Office of Information and Regulatory Affairs, NEOB-10202. (3150-0104). Office of Management and Budget. Washington. DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3. LER NUMBER
- 002 - 00 Browns Ferry Nuclear Plant, Unit 3 05000-296 2017
E. Other systems or secondary functions affected
There were no other systems or secondary functions affected.
F. Method of discovery of each component or system failure or procedural error There were no component failures, system failures, or procedural errors associated with this condition.
G. The failure mode, mechanism, and effect of each failed component There were no failed components associated with this condition.
H. Operator actions
There were no operator actions associated with this condition.
I. Automatically and manually initiated safety system responses
There were no automatic or manual safety system responses associated with this condition.
III. Cause of the event
The cause of this event was the failure to perform a PT fuse coordination study to confirm that the primary and secondary fuses could coordinate. This condition was determined to be a legacy issue dating to the original design of the plant. The most likely cause is lack of rigorous oversight of the vendor during the preparation and subsequent issuance of the fuse evaluation for 4kV SD BDs A, B, C, D, 3EA, 3EB, 3EC, and 3ED, which was first issued by EBASCO in 1988. This may have resulted in failure of the vendor to perform a coordination study for the primary and secondary PT fuses.
A. Cause of each component or system failure or personnel error There were no component failures, system failures, or known personnel errors associated with this condition as it was determined to be a legacy issue.
B. Cause(s) and circumstances for each human performance related root cause The most likely cause is lack of rigorous oversight of the vendor during the preparation and subsequent issuance of the fuse evaluation for 4kV SD BDs A, B, C, D, 3EA, 3EB, 3EC, and 3ED, first issued by the vendor in 1988. This may have resulted in failure of the vendor to perform a coordination study for the primary and secondary PT fuses.
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington. DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov. and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202. (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor. and a person is not required to respond to. the information collection.
IV. Analysis of the event
The Tennessee Valley Authority (TVA) is submitting this report in accordance with 10 CFR 50.73(a)(2)(ii)(B), as any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degraded plant safety.
The basic function of the normal auxiliary electrical power system is to provide power for plant auxiliaries during startup, operation, and shutdown, and to provide highly reliable power sources for plant loads which are important to its safety.
For 4kV SD BD 3EA, PT secondary fuses are 10 amp fuses and do not selectively coordinate with upstream primary fuses, which are 0.5 amp fuses, for fault currents greater than approximately 30 amps on the 120V secondary. Cables tapping off from the PT secondary fuse route external to the board to the Main Control Room. A fire induced fault on an affected cable could clear two of the PT primary fuses, resulting in de-energizing of the A-phase secondary leg. Clearing of the two PT primary fuses would result in de-energization of undervoltage and degraded voltage relays [RLY].
The combination of de-energized undervoltage and degraded voltage relays would result in spurious energization of degraded voltage auxiliary relays. This would result in 4kV motor load sheds, tripping of normal and off-site power breakers [BKR], starting of the DG, and closing of the DG breaker (provided these functions did not have separate unrelated fire damage). If the DG successfully connected to the 4kV SD BD, due to the cleared PT fuse condition, the degraded voltage signal would not reset. This condition could result in a loss of power to plant loads which are important to plant safety. Similar conditions exist on 4kV SD BDs 3EB, 3EC, and 3ED.
Assessment of Safety Consequences
This condition, if left uncorrected, could result in a loss of power to plant loads which are important to plant safety during postulated fire damage. However, a probabilistic risk analysis performed by WA concluded that the risk significance of this condition is very low, with a maximum change in Core Damage Frequency and Large Early Release Frequency of less than 1E-06 for the affected unit.
Based on this analysis, there was no significant increase in risk to the health and safety of the public or to plant personnel resulting from this condition.
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event No components or systems failed due to this event.
2017 comments regarding burden estimate to the Information Services Branch (T-2 F43). U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. or by e-mail to used to impose an information collection does not display a currently valid OMB control number: the NRC may not conduct or sponsor. and a person is not required to respond to: the information collection.
05000-296 2017
3. LER NUMBER
- 002
NO
- 00 B. For events that occurred when the reactor was shut down, availability of systems or components needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident This event did not occur when the reactor was shut down.
C. For failure that rendered a train of a safety system inoperable, estimate of the elapsed time from discovery of the failure until the train was returned to service This condition did not result in the inoperability of any safety systems.
VI. Corrective Actions
Corrective Actions are being managed by TVA's Corrective Action Program under Condition Report 1354129. The required fuse coordination studies have since been performed, and a vendor oversight process has been added to TVA procedures since this legacy event.
A. Immediate Corrective Actions
- Hourly fire watches were put in place for the affected fire areas (FPIP# 17-332).
B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future
- Issue an Engineering Change Package to replace Unit 3 4KV SD BD primary 0.5 amp PT fuses with 1 amp fuses of the same type.
VII. Previous Similar Events at the Same Site A review of the BFN CAP and Licensee Event Reports (LERs) for Units 1, 2, and 3 found no instances within the past five years of degraded or unanalyzed conditions related to coordination of PT fuses.
VIII. Additional Information
There is no additional information.
IX. Commitments There are no new commitments.
|
---|
|
|
| | Reporting criterion |
---|
05000296/LER-2017-001 | Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications LER 17-001-00 for Browns Ferry Nuclear Plant, Unit 3, Regarding Inoperable Residual Heat Removal Pump Results in Condition Prohibited by Technical Specifications | | 05000260/LER-2017-001 | High Pressure Coolant Injection Safety System Functional Failure Due to a Blown Fuse LER 17-001-00 for Browns Ferry, Unit 2, Regarding High Pressure Coolant Injection Safety System Functional Failure Due to a Blown Fuse | | 05000259/LER-2017-001 | Signal Timer for 4kV Shutdown Board C Inoperable for Longer Than Allowed by Technical Specifications due to Detached Restraining Strap | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000296/LER-2017-002 | 4kV Shutdown Board Potential Transformer Primary Fuses Do Not Coordinate with Secondary Fuses LER 17-002-00 for Browns Ferry Nuclear Plant, Unit 3 Regarding 4kV Shutdown Board Potential Transformer Primary Fuses Do Not Coordinate with Secondary Fuses | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition | 05000260/LER-2017-002 | Inoperable Primary Containment Isolation Valve Resulting in Condition Prohibited by Technical Specifications LER 17-002-00 for Browns Ferry, Unit 2, Regarding Inoperable Primary Containment Isolation Valve Resulting in Condition Prohibited by Technical Specifications | | 05000259/LER-2017-002 | Unauthorized Firearm Introduced into the Protected Area LER 17-002-00 for Browns Ferry, Unit 1, Regarding Unauthorized Firearm Introduced into the Protected Area | | 05000260/LER-2017-003 | Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting LER 17-003-00 for Browns Ferry Nuclear Plant, Unit 2 Regarding Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting | | 05000260/LER-2017-004 | Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints LER 17-004-00 for Browns Ferry, Unit 2, Regarding Main Steam Relief Valves Lift Settings Outside of Technical Specifications Required Setpoints | |
|