12-22-2017 | At 1957 on November 07, 2017, VCSNS Unit 1 was operating. in Mode 1 at 100% reactor power when a turb'ne trip caused an automatic reactor trip. All systems responded as expected, with the exception of 'B' Steani Generator Feedwater Isolation Valve (FW1V) XVG1611B-FW. This valve did not appear to automatically close and was slow to indicate closed from the Main Control Board, however this did not complicate the response. All Control Rods fully inserted and all Emergency Feedwater (Mk') pumps started as required. The Operating crew stabilized the plant, which remained in Mode 3 with decay heat removal via the Steam Dump system to the Main Condenser.
The cause of the turbine trip has been determined to be a loss of Digital Control System ( DCS) power to all three Main Feedwater Pumps (FWP), which was caused by the failure of Non-Safety Related Inverter XIT5905. |
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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
[Table view] Category:Licensee Event Report (LER)
MONTHYEARRC-18-0049, LER 2018-001-01 Tor Virgil C. Summer, Unit 1, Valid Actuation of Emergency Diesel Generator2018-05-0707 May 2018 LER 2018-001-01 Tor Virgil C. Summer, Unit 1, Valid Actuation of Emergency Diesel Generator RC-18-0056, (Vcsns), Unit 1 - Licensee Event Reports (2016-001-02, 2016-002-01, 2016-003-02) - Revision to Correct Typographical Errors2018-04-25025 April 2018 (Vcsns), Unit 1 - Licensee Event Reports (2016-001-02, 2016-002-01, 2016-003-02) - Revision to Correct Typographical Errors 05000395/LER-2017-0052017-12-22022 December 2017 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 05000395/LER-2017-0062017-12-15015 December 2017 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 05000395/LER-2017-0032017-10-26026 October 2017 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 05000395/LER-2017-0022017-08-25025 August 2017 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 05000395/LER-2017-0012017-07-24024 July 2017 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 RC-15-0190, Special Report (Spr) 2014-005-01, Loss or Theft of License Material2015-12-16016 December 2015 Special Report (Spr) 2014-005-01, Loss or Theft of License Material RC-15-0179, Special Report (Spr) 2015-002 Regarding One or More Required Meteorological Monitoring Channels Being Inoperable for More than Seven (7) Days2015-11-0303 November 2015 Special Report (Spr) 2015-002 Regarding One or More Required Meteorological Monitoring Channels Being Inoperable for More than Seven (7) Days RC-15-0139, Submittal of Special Report (Spr) 2015-001 Regarding the Loose-Part Monitoring System (Lpms) Channel Number 8 Being Inoperable in Excess of 30 Days2015-08-20020 August 2015 Submittal of Special Report (Spr) 2015-001 Regarding the Loose-Part Monitoring System (Lpms) Channel Number 8 Being Inoperable in Excess of 30 Days RC-14-0084, Special Report 2014-003 for V.C. Summer, One or More Required Meteorological Monitoring Channels Being Inoperable for More than Seven (7) Days2014-05-14014 May 2014 Special Report 2014-003 for V.C. Summer, One or More Required Meteorological Monitoring Channels Being Inoperable for More than Seven (7) Days RC-14-0085, Special Report 2014-002 for V.C. Summer, Degraded Conditions Lasting Longer than Seven Days2014-05-14014 May 2014 Special Report 2014-002 for V.C. Summer, Degraded Conditions Lasting Longer than Seven Days ML12334A4432012-11-27027 November 2012 SR 12-002-00 for Virgil C. Summer, Unit 1 Regarding Meteorological Monitoring Channels Being Inoperable for More than Seven Days ML12188A5422012-07-0303 July 2012 Special Report 2012-001 ML12079A2862012-03-16016 March 2012 LER 12-01-00 for Virgil C. Summer, Unit 1 Regarding Core Exit Thermocouples Inoperable Due to an Inadequate Maintenance Procedure ML11186A9742011-06-30030 June 2011 Regarding Depressurization of the 'C' Steam Line Creating a Differential Pressure Greater than 97 PSIG Between the Steam Lines, Initiating a Safety Injection ML11117A3042011-04-25025 April 2011 V. C. Summer, Unit 1, Submittal of Special Report (Spr) 2011-001 Re Control Building Fire/Pressure Door (DRCB/102) Being Inoperable for Greater than Seven Days Prior to Completing Repair of the Door ML0614201452006-05-17017 May 2006 LER 99-014-03 for Virgil C. Summer Nuclear Station, Re Kaowool Fire Barriers Outside 10 CFR 50 Appendix R Design Basis RC-06-0051, Special Report (Spr) 2006-002 - Inoperability of the Main Steam Line Radiation Monitors (RMG-1 9A(B)(C)) for Greater than 72 Hours2006-03-13013 March 2006 Special Report (Spr) 2006-002 - Inoperability of the Main Steam Line Radiation Monitors (RMG-1 9A(B)(C)) for Greater than 72 Hours ML0527803362005-09-28028 September 2005 LER 05-S01-01 for Virgil C. Summer Nuclear Station Regarding Entry of Unauthorized Employee Into the Protected Area RC-05-0095, LER 05-S01-00 for Virgil C. Summer Nuclear Station Entry of Unauthorized Employee Into the Protected Area2005-06-22022 June 2005 LER 05-S01-00 for Virgil C. Summer Nuclear Station Entry of Unauthorized Employee Into the Protected Area ML0335001292003-12-11011 December 2003 LER 03-S03-00 for Virgil C. Summer Regarding Access to Protected Area by an Individual Without Proper Authorization ML0326605072003-09-16016 September 2003 LER 03-S02-00 for Virgil C. Summer Regarding Access to Protected Area by an Individual with Expired Training ML0318404692003-07-0101 July 2003 LER 99-014-02, Virgil C. Summer Re Kaowool Fire Barriers Outside 10CFR50 Appendix R Design Basis ML0308605122003-03-20020 March 2003 LER 03-S01-00 from Summer Regarding Access to Protected Area by an Individual with an Expired Badge 2018-05-07
[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- V.C. Summer Nuclear Station, Unit 1 395 1.0 EVENT DESCRIPTION At 1957 on November 07, 2017, VCSNS Unit 1 was operating in Mode 1 at 100% power and experienced an automatic reactor trip. All systems responded as expected, with the exception of 'B' Steam Generator Feedwater Isolation Valve (FWIV) XVG1611B-FW. This valve did not indicate closed from the Main Control Board despite the FWIV signal being automatically provided. The operator attempted to close the valve using manual switch manipulation however this was not immediately successful. The valve indicated closed approximately 30 seconds after the manual manipulation. There was no impact to plant operation as a result of the 'B' FWIV failing to close.
All Control Rods fully inserted and all Emergency Feedwater pumps started as required. Feedwater (FW) to the 'B' steam generator (S/G) was automatically isolated by the FW Flow Control Valve and the FW Bypass Valve. All EFW flow responded to provide feedwater to the S/Gs. The Operating crew stabilized the plant, which remained in Mode 3 with decay heat removal via the Steam Dump system to the Main Condenser.
The cause of the turbine trip was determined to be a loss of DCS power to all three Main Feedwater Pumps, which was caused by the failure of Non-Safety Related Inverter XIT5905. Inverter XIT5905 was subsequently placed in "Bypass" to provide power from the Alternate AC source.
The Reactor was returned to Mode 1 and the Breaker was closed on November 10, 2017 at 0720.
2.0 EVENT ANALYSIS Turbine Trip The loss of power to the DCS was a result of a failure of Non-Safety Related Inverter XIT5905. The loss of power to the DCS cabinets caused a trip of all three FWPs. When all three FWPs are lost this causes an automatic turbine trip. Since the station was operating at greater than 50% power the automatic turbine trip resulted in a reactor trip.
Maintenance was performed on the XIT5905 inverter earlier in the day prior to the trip. The touchscreen, microprocessor stack on the control board, and the inverter gate driver card were replaced. Troubleshooting performed after the trip found that the recently serviced inverter output waveform was abnormal when viewed on an oscilloscope. The abnormal wave shape lead to the unsuccessful static switch transfer to the alternate source of power. This condition was confirmed by reinstallation of the old card and observing that the inverter section output now exhibited proper symmetry. The observed waveform of the alternate source also had excellent symmetry.
Following the trip, Inverter XIT5905 was left in Bypass Mode, which closes a switch contact to directly supply the output of XIT5905 from the Alternate AC source. The replacement Inverter Gate Drive card will be installed during Refueling Outage 24 (RF-24). Inverter XIT5905 will be returned to normal service following the post maintenance testing.
Feedwater Isolation Valve When a reactor trip input is received, the P-4 interlock of the Engineered Safety Features Actuation System should close the main feedwater valves on T avg below "low T avg setpoint". This did not occur immediately after receiving a feedwater isolation signal.
Estima!ei ri.irqes our res;)crsE, to comply this mandatory collection. request: 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Reported essons learned are incorporated into the ficensMg process and fed back to industry. Send 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 Infocofiects.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 g NRC may not conduct or sponsor, and a person is not required to respond to, the information co:lection.
05000- V.C. Summer Nuclear Station. Unit 1 395 2017 1 005 -L 00 The FWIV. XVG1611B-FVV, indicated closed approximately 30 seconds after manual manipulation of the switch.
An investigation determined that the
- B' FWIV operator air valve assembly was found to have the pilot seat seal on the 'A' train solenoid valve dislodged and a poppet valve seal dislodged. When energized, the 'A' train solenoid valve removes the air supply to the poppet valves, allowing 560 psig air to 'B' FWIV operator thus holding the 'B' FWIV open. When the 'A' train solenoid is de-energized, air supply is provided to the poppet valves. shuttling the poppets to another position, and closing the B' FWIV. The poppet valves are located within the air valve assembly.
A work order was generated to repair the 'A' train solenoid valve (pilot seat seal) and the air valve assembly (poppet valve seal) for the 'B' FWIV. The pilot seat seal within the 'A' train solenoid valve was dislodged due to internal pressure built up in the plunger during pilot seat seal installation and normal heat cycling. A new plunger was used during the repair of the 'A' train solenoid. The air valve assembly and solenoid were reinstalled and the 'B' FWIV was retested with no leakage.
3.0 SAFETY SIGNIFICANCE An evaluation was performed to determine the core damage frequency and large early release frequency impact of a turbine trip and subsequent reactor trip caused by a failure of Inverter XIT5905. The 8b PRA model was used with nominal values for maintenance. A 6.18% increase in Core Damage Frequency and a 7.04% increase in Large Early Release Frequency was observed. A review of the cutsets show that these increases are from the increase in the percent turbine trip initiation event. The modeled failure to isolate XVG01611B-FVV does not show up in the results. The impact from this plant trip is not greater than green".
4.0 PREVIOUS OCCURRENCE No previous occurrence within the last three years.
5.0 CORRECTIVE ACTIONS Work Order 1705755 Step 005 was created to repair and test Inverter XIT5905 during the next refueling outage (RF-24).
A root cause evaluation is being performed under CR-17-05908. Corrective actions will be determined after this is finalized.
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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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