01-31-2018 | 1.0 ABSTRACT On June 29, 2017 at 0857. VCSNS Unit 1 automatically tripped due to low Feedwater ( FW) flow to the 'B' Steam Generator ( SG). The trip was the result of a spurious closure of the Main FW to 'B' Steam Generator Flow Control Valve, IFV00488-FW. The Flow Control Valve's closure resulted in low SG level coincident with the low FW now, which caused an automatic reactor trip. The plant trip response was normal.
The cause of this event was determined to be the inadvertent closure of IFV00488-1'W due to solenoid valve failure. The solenoid valve failure appears to be a result of an inadequate solder applied to the solenoid coil during the manufacturing process.
NIRO FORM 366 (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
[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 Irfocollects.Resource@nrc.gov: and to the Desk Officer, Office of Information and Regulator/ Affairs, NEOB-10202, (3150-0104), Office of Management arid Budget. Washington, DC 20503. if a means used to impose an information collection doos not display a current!), 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 - 2.0 EVENT DESCRIPTION On June 29, 2017 at 0857, VCSNS Unit 1 automatically tripped due to low FW flow to the B' Steam Generator (SG). The trip was the result of a spurious closure of the Main FW to 'B' Steam Generator Flow Control Valve, IFV00488-FW. The Flow Control Valve's closure resulted in low SG level coincident with the low FW flow which caused an automatic reactor trip. The plant trip response was normal. Both Motor Driven (MD) Emergency Feed (EF) pumps and the Turbine Driven EF pump started on SG level LO/LO, as designed. Some secondary atmospheric steam dumps did lift and reseat due to the pressure excursion per design. No other automatic actuations occurred.
The apparent cause of this failure appears to be a manufacturing deficiency due to the lead wire to solenoid coil wire having inadequate solder applied to prevent intermittent failure of the solenoid coil. The faulty solenoid coil failure resulted in the closure of IFV00488-FW, which caused the plant trip.
The air supply solenoid was sent off for testing to Exelon PowerLabs for inspection, disassembly, and testing. During the testing, Exelon PowerLabs found the lead wire easily unwound from the solenoid coil wire with no indication of a wetted solder bond. The evidence found during the cause investigation suggests the lack of wetted solder bond was due to a manufacturing deficiency (Cause Code — N1) that has a low probability of recurrence from the manufacturer.
During the June, 2017 plant downpower, the 'A' and 'B' air supply solenoids were replaced on the 'B' Feedwater Regulator Valve (FRV). These 2 valves were sent to Exelon PowerLabs for testing. Disassembly results showed the 'A' solenoid with a properly soldered connection while the 'B' solenoid showed no indications of a wetted solder bond.
Following a subsequent downpower on August 28, 2017, in service 'B' air supply solenoids were removed from the 'A', 'B', and 'C' FRVs, as a preventative measure. The 2 solenoids removed on June 30, 2017, the 3 solenoids removed on August 28, 2017, and a spare solenoid from the warehouse were sent to be tested by DfR Solutions at the request of ASCO. During this investigation, all other solenoids were found to have properly soldered connections between the lead wire and the solenoid coil wire.
During disassembly testing at DfR Solutions (contracted by ASCO), it was found that Exelon PowerLabs did not include the lead wire to solenoid coil wire connections from the failed 'B' FRV solenoid in the return shipment. Follow-up with Exelon PowerLabs concluded that these parts were unintentionally disposed of and therefore could not be independently investigated by DfR solutions. As detailed in the Exelon PowerLabs report, one lead to solenoid coil wire connection exhibited no indication of a wetted solder bond, while the other exhibited some localized indications.
ASCO previously issued an information notice, dated March 6, 2017, informing consumers that RTV 108C off-gases acetic acid during the curing process. The acetic acid then attacks the solder that is applied to the connection between the lead wire and the solenoid coil wire, causing an intermittent loss of electrical power. The lack of evidence for testing led ASCO to attribute the failure of the 'B' solenoid to the use of acetic acid off-gassing sealant. Additional analysis requested of Exelon exhibited no presence of acetic acid or the associated corrosion products on the areas where the solder should be applied.
comments regarding burden estimate to the Information Services Brarch (T-2 F43). U.S. Nuclear Regulatory Commission, Wasftrigton, DC 20555-0001, or by e-mail to Infocollects.Reseurce©nrc.gov, and to the Desk Officer, Office of Information and Regula;ory Affairs, NEOB-10202, (3150 0104), Office of Management and Ddriget, Washington. DC 20503. If a means used to impose an information collection does riot 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 3.0 EVENT ANALYSIS The FW System continuously supplies FW from the Condensate System to the steam generators at the same rate as the steam leaves the steam generators, thus maintaining steam generator water level.
The FW System transports the condensate collected in the deaerator storage tank to the steam generators via a series of pumps, FW heaters, and flow control valves. Four FW booster pumps take suction on the deaerator storage tank. These pumps discharge to the suctions of three FW pumps.
The FW pumps discharge through two parallel strings of FW heaters, which preheat the FW before it enters the steam generators. From the outlet of the FW heaters, the water flows through three separate flow paths, one to each steam generator. Each of these three flow paths contains a FW regulating valve and a FW isolation valve for FW flow control and FW isolation.
The main feed regulating valves (IFV-478, 488, 498) are 16-inch, angled, plug valves. They are direct-acting and pneumatically-controlled. The actuator's air diaphragm is connected to the valve stem and receives its air signal from one of two redundant Digital Valve Controllers.
Air to the Feed Water Regulator Valve (FRV) must pass through 2 solenoid valves, 20A & 20B. These solenoid valves port plant supplied air to the Digital Valve Controllers that control the FRVs and also provide control air to the quick exhaust valves. The quick exhaust valve vents actuator air from the valve to provide quick closure of the FRVs to meet stroke time requirements. In this event, the 20B solenoid valve intermittently deenergized and allowed the quick exhaust valve to open, venting the FRV actuator. The 'B' FRV quickly closed, isolating FW flow to the 'B' SG. The low SG level coincident with low FW flow caused the automatic reactor trip.
4.0 SAFETY SIGNIFICANCE A PRA sensitivity study was performed as a result of this reactor trip. This trip was modeled as a partial loss of main FW.
VCSNS uses a frequency for partial loss of main FW of 0.206/yr. based on a generic frequency of 0.1615/yr. updated with plant specific experience of 3 events in 10.8 years.
For the sensitivity study, the partial loss of main FW initiating event frequency was set to 1.0/yr. The resulting change in CDF is 2.70E-07/yr. and the resulting change in LERF is 1.17E-08/yr. The baseline CDF and LERF for the model (version 8a2) used for this study are 3.28E-06/yr. and 1.01E-07/yr. respectively, so the changes constitute an 8% increase in CDF and an 11% increase in LERF.
The changes in CDF and LERF described above are not considered significant.
5.0 PREVIOUS OCCURRENCE No previous occurrence within the last three years.
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 Infoc,ollects.ResoJrce@nrc.goy, and to the Desk Officer, Office of Information and Regulatory Affairs, used to impose an information collection does not display a currerty 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 20171 002 6.0 CORRECTIVE ACTIONS A troubleshooting plan was performed to provide backup monitoring to IPCS for FRV and Feedwater Isolation Valve limit switch position indication.
The potential failed components were replaced per the Failure Modes Analysis and post maintenance testing was successful.
The following components associated with the `B' FW Regulating Valve IFV00488-FW were replaced under Work Order 1708087:
- Primary XACT Feedback Transducer IFY00488A-ZT - Solenoid Valve IFV00488-20A-FW - Solenoid Valve IFV00488-20B-FW - Quick Exhaust Valves IFV00488-EV2 and IFV00488-EV3 - Contacts 7 and 8 on relay K636 - Solenoid Valve IFV00478-20B-FW was replaced under Work Order 1712469 - Solenoid Valve IFV00488-20B-FW was replaced under Work Order 1712471 - Solenoid Valve IFV00498-20B-FW was replaced under Work Order 1712472 The following components were sent off for testing:
- K636 Contacts 7/8 Cartridge: No issues identified by Applied Technical Services - IFV00488-20A-FW and IFV00488-20B-FW ASCO Solenoid Valves: Inadequate solder connection identified at magnet wire on IFV00488-20B-FW.
- Solenoid Valve IFV00478-20B-FW - Solenoid Valve IFV00488-20B-FW - Solenoid Valve IFV00498-20B-FW - Spare Solenoid Valve S/S A612152-015, Date Code 1038 — never placed in service
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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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