|
---|
Category:Letter
MONTHYEARCNL-24-074, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-10-23023 October 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML24282B0412024-10-15015 October 2024 Request for Withholding Information from Public Disclosure for Sequoyah Nuclear Plant, Units 1 and 2 and Watts Bar Nuclear Plant, Units 1 and 2 ML24260A1682024-10-0404 October 2024 Regulatory Audit Summary Related to Request to Add and Revise Notes Related to Technical Specification Table 3.3.2-1, Function 5 ML24284A1072024-09-26026 September 2024 Affidavit for Request for Withholding Information from Public Disclosure for Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2 05000328/LER-2024-001, Reactor Trip Due to an Electrical Trouble Turbine Trip2024-09-25025 September 2024 Reactor Trip Due to an Electrical Trouble Turbine Trip CNL-24-060, Supplement to Request for Approval of the Tennessee Valley Authority Nuclear Quality Assurance Program Description2024-09-24024 September 2024 Supplement to Request for Approval of the Tennessee Valley Authority Nuclear Quality Assurance Program Description CNL-24-047, Decommitment of Flood Mode Mitigation Improvement Systems2024-09-24024 September 2024 Decommitment of Flood Mode Mitigation Improvement Systems ML24262A0602024-09-23023 September 2024 Summary of August 19, 2024, Meeting with Tennessee Valley Authority Regarding a Proposed Supplement to the Tennessee Valley Authority Nuclear Quality Assurance Plan ML24267A0402024-09-19019 September 2024 Cycle 27 Core Operating Limits Report Revision 0 CNL-24-065, Tennessee Valley Authority – Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-09-18018 September 2024 Tennessee Valley Authority – Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML24185A1742024-09-18018 September 2024 Cover Letter - Issuance of Exemption Related to Non-Destructive Examination Compliance Regarding Sequoyah Nuclear Plant Independent Spent Fuel Storage Installation ML24253A0152024-09-0808 September 2024 Emergency Plan Implementing Procedure Revisions ML24247A2212024-08-29029 August 2024 Notification of Deviation from Pressurized Water Reactor Owners Group (PWROG) Letter OG-21-160, NEI 03-08 Needed Guidance: PWR Lower Radial Support Clevis Insert X-750 Bolt Inspection Requirements, September 1, 2021 ML24247A1802024-08-28028 August 2024 Application to Revise the Fuel Handling Accident Analysis, to Delete Technical Specification 3.9.4, Containment Penetrations, and to Modify Technical Specification 3.3.6, Containment Ventilation Isolation Instrumentation for Sequoyah Nuclea IR 05000327/20240052024-08-26026 August 2024 Updated Inspection Plan for Sequoyah Nuclear Plant, Units 1 and 2 - Report 05000327/2024005 and 05000328/2024005 ML24239A3972024-08-23023 August 2024 Rssc Wire & Cable LLC Dba Marmon - Part 21 Final Notification - 57243-EN 57243 CNL-24-061, Supplement to Application to Revise Function 5 of Technical Specification Table 3.3.2-1, ‘Engineered Safety Feature Actuation System Instrumentation,’ for the Sequoyah and Watts Bar (SQN-TS-23-02 and WBN-TS-23-08),2024-08-19019 August 2024 Supplement to Application to Revise Function 5 of Technical Specification Table 3.3.2-1, ‘Engineered Safety Feature Actuation System Instrumentation,’ for the Sequoyah and Watts Bar (SQN-TS-23-02 and WBN-TS-23-08), IR 05000327/20240022024-07-31031 July 2024 Integrated Inspection Report 05000327/2024002 and 05000328/2024002 ML24211A0542024-07-29029 July 2024 Operator License Examination Report ML24211A0572024-07-29029 July 2024 Submittal of Emergency Plan Implementing Procedure Revision ML24211A0412024-07-26026 July 2024 Unit 1 Cycle 26 Refueling Outage - 90-Day Inservice Inspection Summary Report ML24199A0012024-07-22022 July 2024 Clarification and Correction to Exemption from Requirement of 10 CFR 37.11(c)(2) ML24172A1342024-07-15015 July 2024 Exemptions from 10 CFR 37.11(C)(2) (EPID L-2023-LLE-0024) - Letter ML24191A4652024-07-0909 July 2024 Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations ML24177A0282024-06-25025 June 2024 Emergency Plan Implementing Procedure Revisions ML24176A0222024-06-24024 June 2024 Retraction of Interim Report of a Deviation or Failure to Comply – Transducer Model 8005N ML24089A1152024-06-21021 June 2024 Transmittal Letter, Environmental Assessments and Findings of No Significant Impact Related to Exemption Requests from 10 CFR 37.11(c)(2) ML24145A0852024-05-30030 May 2024 1B-B Diesel Generator Failure - Final Significance Determination Letter ML24145A1052024-05-29029 May 2024 301 Exam Approval Letter ML24134A1762024-05-13013 May 2024 Submittal of 2023 Annual Radiological Environmental Operating Report CNL-24-040, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-05-0808 May 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML24128A0352024-05-0707 May 2024 Providing Supplemental Information to Apparent Violation ML24120A0582024-04-26026 April 2024 10 CFR 50.46 Annual Report for Sequoyah Nuclear Plant Units 1 and 2 ML24116A2612024-04-25025 April 2024 Interim Report of a Deviation or Failure to Comply - Transducer Model 8005N ML24114A0482024-04-23023 April 2024 Annual Radioactive Effluent Release Report for 2023 Monitoring Period CNL-24-037, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 422024-04-22022 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 42 ML24144A2322024-04-20020 April 2024 Tennessee Multi-Sector Permit (Tmsp), 2024 Annual Discharge Monitoring Report for Outfalls SW-3, SW-3, and SW-9 ML24144A2362024-04-20020 April 2024 Discharge Monitoring Report (Dmr), March 2024 ML24102A1212024-04-18018 April 2024 Summary of Conference Call with Tennessee Valley Authority Regarding Sequoyah Nuclear Plant, Unit 1 Spring 2024 Steam Generator Tube Inspections ML24089A0882024-04-18018 April 2024 – Exemption from Select Requirements of 10 CFR Part 73; Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting IR 05000327/20240012024-04-17017 April 2024 Integrated Inspection Report 05000327/2024001 and 05000328/2024001 CNL-24-033, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-04-17017 April 2024 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions CNL-24-024, Hydrologic Engineering Center River Analysis System Project Milestone Status Update2024-04-17017 April 2024 Hydrologic Engineering Center River Analysis System Project Milestone Status Update ML24109A0272024-04-16016 April 2024 Cycle 27 Core Operating Limits Report Revision 0 CNL-23-006, Application to Modify Technical Specifications 3.8.1, AC Sources – Operating, and 3.8.2, AC Sources – Shutdown, for Sequoyah Nuclear Plant (SQN-TSC-22-03)2024-04-15015 April 2024 Application to Modify Technical Specifications 3.8.1, AC Sources – Operating, and 3.8.2, AC Sources – Shutdown, for Sequoyah Nuclear Plant (SQN-TSC-22-03) ML24106A0502024-04-12012 April 2024 Discharge Monitoring Report (Dmr), February 2024 ML24100A0162024-04-11011 April 2024 Request for Regulatory Conference (Tennessee Valley Authority - Sequoyah Nuclear Plant) CNL-24-020, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements2024-04-0101 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements ML24088A0332024-03-28028 March 2024 Request for Regulatory Conference (Tennessee Valley Authority) CNL-24-007, Annual Insurance Status Report2024-03-27027 March 2024 Annual Insurance Status Report 2024-09-08
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000328/LER-2024-001, Reactor Trip Due to an Electrical Trouble Turbine Trip2024-09-25025 September 2024 Reactor Trip Due to an Electrical Trouble Turbine Trip 05000327/LER-2021-001, & LER 2021-001-00 for Sequoyah Nuclear Plant, Units 1 & 2, Ice Bed Inoperable Due to Exceeding Surveillance Requirement Frequency2021-09-22022 September 2021 & LER 2021-001-00 for Sequoyah Nuclear Plant, Units 1 & 2, Ice Bed Inoperable Due to Exceeding Surveillance Requirement Frequency 05000327/LER-2017-0022017-07-14014 July 2017 Automatic Actuation of Emergency Diesel Generators Due to Loss of Power to 6.9kV Shutdown Board, LER 17-002-00 for Sequoyah, Unit 1, Regarding Automatic Actuation of Emergency Diesel Generators Due to Loss of Power to 6.9kV Shutdown Board 05000327/LER-2017-0012017-04-26026 April 2017 Breached Door Renders Both Trains of the Auxiliary Building Gas Treatment System Inoperable, LER 17-001-00 for Sequoyah, Unit 1, Regarding Breached Door Renders Both Trains of the Auxiliary Building Gas Treatment System Inoperable 05000327/LER-2016-0012016-04-11011 April 2016 Automatic Safety Injection due to Low Steam Line Pressure on Loop 2 Main Steam, LER 16-001-00 for Sequoyah, Unit 1, Regarding Automatic Safety Injection due to Low Steam Line Pressure on Loop 2 Main Steam 05000327/LER-2015-0042016-01-22022 January 2016 Manual Reactor Trip due to Main Steam Isolation Valve Drifting in the Closed Direction, LER 15-004-00 for Sequoyah, Unit 1, Regarding Manual Reactor Trip Due to Main Steam Isolation Valve Drifting in the Closed Direction 05000328/LER-2015-0022016-01-0606 January 2016 Unanalyzed Condition Due To Inoperable Containment Recirculation Drains, LER 15-002-00 for Sequoyah, Unit 2, Regarding Unanalyzed Condition Due to Inoperable Containment Recirculation Drains ML11276A1492011-09-30030 September 2011 Revised Submittal Schedule for Supplemental Report for License Event Report 327/2011-003, Unit I Reactor Trip as a Result of Turbine Control Card Failure ML11256A0162011-09-0606 September 2011 Withdrawal of License Event Report 327/2011-002, Feedwater Regulator Valve Inoperable ML0516403152005-06-0707 June 2005 LER 50-001-00 for Sequoyah, Unit 1 Re Automatic Reactor Trip Following Loss of Turbine Auto Stop Oil (ASO) Pressure ML0325804392003-09-0202 September 2003 LER 03-S01-00, Sequoyah Units 1 & 2, 30-Day Report Re Uncontrolled Security Weapon in the Protected Area 2024-09-25
[Table view] |
LER-2024-001, Reactor Trip Due to an Electrical Trouble Turbine Trip |
Event date: |
|
---|
Report date: |
|
---|
3282024001R00 - NRC Website |
|
text
Sequoyah Nuclear Plant, Post Office Box 2000, Soddy Daisy, Tennessee 37384
September 25, 2024 10 CFR 50.73
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Sequoyah Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-79 NRC Docket No. 50-328
Subject: Licensee Event Report 50-328/2024-001-00, Reactor Trip due to an Electrical Trouble Turbine Trip
The enclosed licensee event report provides details concerning an automatic reactor trip due to an electrical trouble turbine trip. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(iv), as an event that resulted in an automatic actuation of the reactor protection system and the auxiliary feedwater system. A supplement to this LER will be submitted following completion of the associated root cause evaluation.
There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. Rick Medina, Site Licensing Manager, at (423) 843-8129 or rmedina4@tva.gov.
Respectfully,
Thomas Marshall Site Vice President Sequoyah Nuclear Plant
Enclosure: Licensee Event Report 50-328/2024-001-00 cc: NRC Regional Administrator Region II NRC Senior Resident Inspector Sequoyah Nuclear Plant
Abstract
On July 30, 2024, at 1640 eastern daylight time (EDT), SQN Unit 2 experienced an automatic reactor trip due to an electrical trouble turbine trip. The turbine tripped as a result of a generator neutral resistor overvoltage relay actuation.
Operators performed the appropriate actions in response to the reactor trip. All plant safety systems responded as designed. This event did not adversely affect the health and safety of plant personnel or the general public.
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided with the identified cause and associated corrective action(s).
I. Plant Operating Conditions before the Event
At the time of the event, Sequoyah Nuclear Plant (SQN) Unit 2 was in Mode 1 at approximately 94 percent rated thermal power and increasing after a forced outage.
II. Description of Event
A. Event Summary
On July 30, 2024, at 1640 eastern daylight time (EDT), SQN Unit 2 experienced an automatic reactor [EIIS: RCT] trip due to an electrical trouble turbine [EIIS: TRB] trip. The turbine tripped as a result of a generator [EIIS: GEN] neutral resistor overvoltage relay [EIIS: 87] actuation.
Operators performed the appropriate actions in response to the reactor trip. All plant safety systems responded as designed.
The event is reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A), as an event that resulted in an automatic actuation of the Reactor Protection System [EIIS: JC] and the Auxiliary Feedwater (AFW) System [EIIS: BA].
B. Status of structures, components, or systems that were inoperable at the start of the event and that contributed to the event
No inoperable structures, components, or systems contributed to this event.
C. Dates and approximate times of occurrences
Date/Time (EDT) Description
07/30/24, 1640 SQN Unit 2 experienced an automatic reactor trip due to an electrical trouble turbine trip. The unit entered Mode 3.
D. Manufacturer and model number of each component that failed during the event
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided.
E. Other systems or secondary functions affected
No other systems or secondary functions were affected.
F. Method of discovery of each component or system failure or procedural error
Main control room (MCR) alarms and annunciators provided indication to the operators during the reactor trip.
G. The failure mode, mechanism, and effect of each failed component
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided.
H. Operator actions
MCR operators responded to the reactor trip, as required, and then transitioned to post-trip response procedures.
I. Automatically and manually initiated safety system responses
The reactor protection system, including feedwater isolation and AFW start, responded to the trip, as designed.
III. Cause of the event
A. Cause of each component or system failure or personnel error
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided.
B. Cause(s) and circumstances for each human performance related root cause
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided.
IV. Analysis of the event
The reactor trip was not complex with all plant safety systems responded as designed. This event did not adversely affect the health and safety of plant personnel or the general public.
V. Assessment of Safety Consequences
There were no actual safety consequences as a result of this event.
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event
None.
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
The 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
There was no failure that rendered a train of a safety system inoperable.
VI. Corrective Actions
This event was entered into the Tennessee Valley Authority Corrective Action Program under condition report number 1947208.
A. Immediate Corrective Actions
A work order for troubleshooting the cause of the event was created.
B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future
The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided.
VII. Previous Similar Events at the Same Site
There were no previous similar events at SQN occurring within the last three years.
VIII. Additional Information
There is no additional information.
IX. Commitments
There are no new commitments.