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On September 11, 2017 at 1648. the VCSNS Unit I 'A' emergency diesel generator ( EDG) was actuated. VCSNS Unit I was and continued to operate in Mode 1 at 100% reactor power. The EDG actuation was caused by a storm induced perturbation on the off-site power system. The duration of the fault was longer than it should have been due to a malfunction of a transmission system relay. The perturbation cleared and off-site voltage was returned to normal within the designed recovery time limit. The bus continued to be carried by the off-site source and the EDG output breaker remained open.
The station review of this event has shown that plant response was as designed and that no safety consequences occurred.
NRC FORM 365 (04-2017) |
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Category:Letter
MONTHYEARML24038A0322024-02-0707 February 2024 (Vcsns), Unit 1, 10 CFR 21 Report - Emergency Diesel Generator Flash Contactor Relay IR 05000395/20230042024-01-31031 January 2024 Integrated Inspection Report 05000395/2023004 ML24022A1582024-01-22022 January 2024 (Vcsns), Unit 1 - Reply to a Notice of Violation: EA-23-093 ML24022A1202024-01-22022 January 2024 Notification of Target Set Inspection and Request for Information (NRC Inspection Report 05000395/2024403) ML24018A0112024-01-18018 January 2024 CFR 21 Report Emergency Diesel Generator Fuel Oil Piping IR 05000395/20240112024-01-17017 January 2024 Notification of VC Summer Station Comprehensive Engineering Team Inspection - U.S. Nuclear Regulatory Commission Inspection Report 05000395/2024011 ML23361A1042023-12-21021 December 2023 Inservice Testing Program for Pumps and Valves Fifth Interval Update and Associated Relief and Alternative Requests IR 05000395/20230912023-12-21021 December 2023 Final Significance Determination of a White Finding and Notice of Violation and Assessment Followup Letternrc Inspection Report 05000395/2023091 ML23354A1802023-12-20020 December 2023 301 Examination Report with Cover Letter ML23347A0492023-12-12012 December 2023 Technical Specification Bases Changes Updated Through November 2023 ML23334A2462023-11-30030 November 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23334A2372023-11-30030 November 2023 (Vvsns), Unit 1 - Annual Commitment Change Summary Report ML23332A1942023-11-28028 November 2023 (Vcsns), Unit 1, Correction of Typographical Error in License Amendment Request - Inverter Allowed Outage Time (AOT) Extension ML23317A2242023-11-0909 November 2023 (Vcsns), Unit 1 - License Amendment Request - Inverter Allowed Outage Time (AOT) Extension ML23289A1172023-11-0303 November 2023 Tribal Request for Scoping Comments Concerning the Environmental Review of the V.C. Summer SLRA ML23289A1152023-11-0303 November 2023 Ltr to R. Nelson - Request for Scoping Comments Concerning the Environmental Review of the V.C. Summer SLRA ML23289A1162023-11-0303 November 2023 Ltr to W. Emerson - Request for Scoping Comments Concerning the Environmental Review of the V.C. Summer SLRA IR 05000395/20234032023-11-0101 November 2023 Material Control and Accounting Program Inspection Report 05000395/2023403 Cover IR 05000395/20230032023-11-0101 November 2023 Integrated Inspection Report 05000395/2023003 ML23284A1792023-10-16016 October 2023 Subsequent License Renewal Application Online Reference Portal ML23275A0142023-10-11011 October 2023 SLRA - Acceptance and Opportunity for Hearing - Letter ML23284A1662023-10-10010 October 2023 (Vcsns), Unit 1 - Request for Regulatory Conference; (EA-23-093) IR 05000395/20230902023-10-0404 October 2023 NRC Inspection Report 05000395/2023090 and Preliminary Yellow Finding and Apparent Violation IR 05000395/20230112023-09-27027 September 2023 Focused Engineering Inspection Report 05000395/2023011 ML23250A3112023-09-20020 September 2023 Request to Revise Reactor Vessel Material Surveillance Capsule Withdrawal Schedules ML23244A2352023-09-18018 September 2023 Request to Use a Subsequent Edition of the ASME Code, Section XI ML23230A0012023-09-15015 September 2023 Request to Use a Provision of a Previous Edition of the ASME Boiler and Pressure Vessel Code, Section XI, for Non-Destructive Examinations ML23235A0432023-09-0505 September 2023 Receipt and Availability of the Subsequent License Renewal Application IR 05000395/20234012023-08-30030 August 2023 Security Baseline Inspection Report 05000395/2023401 ML23242A1192023-08-29029 August 2023 (Vcsns), Unit 1 - Inservice Inspection (ISI) Owner'S Activity Report (OAR) for Refueling Outage 27 ML23243B0362023-08-25025 August 2023 Request for FEMA Consultation on the Dominion Energy Proposal to Consolidate the Emergency Operations Facility for the Virgil C. Summer Nuclear Station Unit 1 IR 05000395/20230052023-08-23023 August 2023 Updated Inspection Plan for Virgil C. Summer Nuclear Station (Report 05000395 2023005) ML23233A1752023-08-17017 August 2023 Application for Subsequent Renewed Operating License IR 05000395/20230022023-08-14014 August 2023 Integrated Inspection Report - Integrated Inspection Report 05000395/2023002 and Apparent Violation IR 05000395/20230102023-08-12012 August 2023 Biennial Problem Identification and Resolution Inspection Report 05000395/2023010 ML23207A1102023-07-26026 July 2023 NRC Regulatory Issues Summary 2023-01 Preparation and Scheduling of Operator Licensing Examinations IR 05000395/20234412023-07-17017 July 2023 95001 Supplemental Inspection Report 05000395/2023441 and Follow Up Assessment Letter ML23190A0012023-07-0909 July 2023 Special Report 2023-003 Inoperable Radiation Monitoring Instrumentation Channel ML23187A5092023-07-0606 July 2023 Request for Federal Emergency Management Agency Consultation on the Dominion Energy Proposal to Consolidate the Emergency Operations Facility for the Virgil C. Summer Nuclear Station Unit 1 ML23178A1682023-06-26026 June 2023 2022 Annual Report of Emergency Core Cooling System (ECCS) Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML23173A1052023-06-22022 June 2023 Special Report 2023-002 Inoperable Loose-Part Monitoring System Channel ML23163A2352023-06-12012 June 2023 Request to Use a Later Edition of the ASME Boiler and Pressure Vessel Code, Section XI, for the SPS Sixth Inservice Inspection (Isi) Intervals and VCSNS Fifth ISI Interval ML23159A2332023-06-0808 June 2023 License Amendment Request - Emergency Response Organization Augmentation Time Change, Emergency Operations Facility Relocation and Other Emergency Plan Changes ML23156A3092023-06-0505 June 2023 Requalification Program Inspection Virgil C. Summer Nuclear Station Unit 1 - 05000395/2023003 2024-02-07
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05000- V.C. Summer Nuclear Station, Unit 1 395 1.0 EVENT DESCRIPTION At 1648 on September 11, 2017, VCSNS Unit 1 was operating in Mode 1 at 100% reactor power when a storm induced perturbation on the off-site power system occurred which resulted in reduced voltage on the 1DA vital bus. The 'A' emergency diesel generator (EDG) started on loss of voltage signal, but it did not load since the low voltage condition cleared within the designed recovery time limit.
A fault on the Killian-Pineland 115kV line occurred as a result of high winds from hurricane Irma. The fault resulted in depressed voltages on both the 115kV and 230kV systems. The duration of the fault was longer than it should have been due to a malfunction of a transmission system relay.
There were two reasons for the delayed clearing of the fault. First, the high speed relay communication scheme on the Killian-Pineland line failed. Second, the relay incorrectly interpreted the fault as a power swing condition and blocked the tripping function that would have cleared the fault.
The 'A' EDG was returned to standby at approximately 1742.
2.0 EVENT ANALYSIS The EDGs automatically start upon receipt of an undervoltage signal from the associated bus from either the loss of voltage relays or degraded voltage relays, or upon receipt of a safety injection signal. The 7.2 kV ESF buses are each provided with 3 loss of voltage relays set at approximately 81% of the nominal bus voltage level and 3 degraded voltage relays set at approximately 91% of the nominal bus voltage level. Operation of a set of loss of voltage or degraded voltage relays will initiate a diesel generator start.
All three XSW1DA loss of voltage relays sensed a 3-phase fault on the Killian-Pineland 115kV line caused by high winds from hurricane Irma. The voltage remained less than 81% on all three phases for greater than 0.25 seconds resulting in the 'A' EDG starting. Following the diesel start signal, a time delay relay allows 2 seconds for the voltage to recover prior to initiating the load sequencer. Voltage recovered to greater than 81% 1.55 seconds after the 'A' EDG started. Because the sequencer did not initiate, XSW1DA offsite feeder breakers did not open, the diesel output breaker did not close, and loads did not sequence onto the bus.
3.0 SAFETY SIGNIFICANCE Since plant equipment responded as designed, there was no PRA risk impact from this event. This event had no effect on baseline Core Damage Frequency or Large Early Release Frequency.
4.0 PREVIOUS OCCURRENCE No previous occurrence within the last three years.
Infccollects.Resource@nrc.gov, and to the Desk Off:cer, Office of Informaton and Regulatory Affairs, used :3 impose an information collection does not display a currently valid OMB control number, the NRO may not conduct or sponsor, and a person is no: required to respond to, the information collection.
05000- V.C. Summer Nuclear Station, Unit 1 385 5.0 CORRECTIVE ACTIONS The high speed relay communication scheme on the Killian-Pineland line has been repaired. Corporate Power Delivery and the Relay Department is working with the relay manufacturer to make adjustments to the relay to ensure that future faults are cleared prior to propagating to the station.
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05000395/LER-2017-001 | C MAIN FFFDWATER PUMP FAILURE '1'0 TRIP RESUI,TS IN LOSS OF EMERGENCY FE,EDWATER AUTO START ACTUATION SIGNAL LER 17-001-00 for V.C. Summer, Unit 1, Regarding C Main Feedwater Failure to Trip Results in Loss of Emergency Feedwater Auto Start Actuation Signal | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000395/LER-2017-002 | Low Feedwater Flow to the 'B' Steam Generator Causes Automatic Reactor Trip LER 17-002-00 for V.C. Summer, Unit 1, Regarding Low Feedwater Flow to the 'B' Steam Generator Causes Automatic Reactor Trip | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000395/LER-2017-003 | FAILED LIGHTNING ARRESTER ON MAIN TRANSFORMER CAUSES REACTOR TRIP LER 17-003-00 For Virgil C. Summer Nuclear Station, Unit 1, Regarding Failed Lightning Arrester On Main Transformer Causes Reactor Trip | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000395/LER-2017-004 | ACTUATION OF 'A' EMERGENCY DIESEL GENERATOR LER 17-004-00 for V.C. Summer, Unit 1, Regarding Actuation of 'A' Emergency Diesel Generator | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000395/LER-2017-005 | AUTOMATIC REACTOR TRIP DUE TO MAIN TURBINE TRIP LER 17-005-00 for V.C Summer, Unit 1, Regarding Automatic Reactor Trip Due to Main Turbine Trip | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000395/LER-2017-006 | TECHNICAL SPECIFICATION ACTION NOT MET FOR INOPERABLE OXYGEN MONITOR LER 17-006-00 for Virgil C. Summer, Unit 1, Regarding Technical Specification Action not Met for Inoperable Oxygen Monitor | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
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