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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56453 | 5 April 2023 10:51:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip | The following information was provided by the licensee via email: At 0651 EDT on April 5, 2023, with Unit 1 in mode 1 at 85 percent power, the reactor was manually tripped due to loss of main feedwater pump 'C'. The trip was not complex, with all systems responding normally post-trip. Main feedwater pump 'B' had previously been removed from service in preparation for a planned shutdown as a part of refueling outage RF27. Operations responded and stabilized the plant. Decay heat is being removed by the emergency feedwater system. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) resulting from valid actuation of the reactor protection and emergency feedwater systems. There was no impact on the health and safety of the public or plant personnel. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee continues to investigate the loss of main feedwater pump 'C'. The licensee notified the NRC Resident Inspector. | Feedwater Reactor Protection System | |
| ENS 55580 | 15 November 2021 22:28:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip Due to Main Transformer Fault | At 1728 EST on 11/15/2021, with Unit 1 in Mode 1 at 47 percent power, the reactor was manually tripped due to a main transformer fault. The trip was not complex, with all systems responding normally post-trip. Operations responded and stabilized the plant. Decay heat is being removed by the emergency feedwater system through the main condenser. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Additionally, due to the valid actuation of the emergency feedwater system, this event is being reported as a non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified."
At approximately 0900 (EST) on 11/16/2021, it was identified that mineral oil from the faulted main transformer had surpassed the capability of the oil containment system and discharged into Lake Monticello. It is estimated that less than 50 gallons of mineral oil entered the Lake. The oil is contained with booms and cleanup is ongoing. The EPA National Response Center and the South Carolina Department of Health and Environmental Control have been notified. This is considered a news release or notification to other government agencies; therefore, this event is reportable under 10 CFR 50.72(b)(2)(xi). The NRC Senior Resident Inspector has been notified. Notified R2DO (Miller). | Feedwater Reactor Protection System Main Transformer Main Condenser | |
| ENS 53060 | 8 November 2017 00:57:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip on Turbine Trip | On 11/7/2017 at 1957 (EST), VC Summer Nuclear Station automatically tripped due to a turbine trip. The cause of the turbine trip is under investigation at this time. All systems responded as expected. All Control Rods fully inserted and all Emergency Feedwater pumps started as required. The plant is stable in Mode 3. This event is reportable per 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). The unit is currently stable in Mode 3 with decay heat removal via the Main Steam to the Main Condenser. The NRC Resident Inspector has been notified. The licensee will notify the South Carolina State Emergency Management Division, the Fairfield, Richland, Lexington and Newberry Counties.
All systems responded as expected, with the exception of 'B' Steam Generator Feedwater Isolation Valve XVG1611 B-FW. This valve did not appear to automatically close and was slow to indicate closed from the Main Control Board. All Control Rods fully inserted and all Emergency Feedwater pumps started as required. The plant is stable in Mode 3. Notified the R2DO (Musser). | Steam Generator Feedwater Decay Heat Removal Main Condenser Control Rod Main Steam | |
| ENS 52932 | 28 August 2017 12:37:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip on Turbine Trip | On 8/28/2017 at 0837 (EDT), VC Summer Nuclear Station automatically tripped due to a turbine trip. The turbine trip was caused by the Main Generator Differential Lockout due to a fault on the center phase lightning arrester on the Main Transformer (XTF-001). There were no complications with the trip. All control rods fully inserted. Balance of Plant (BOP) buses automatically transferred to their alternate power source XTF 31/32. All Emergency Feedwater pumps started as required. All systems responded as required. The plant is stable in Mode 3. Station personnel are investigating the cause of the fault on the main transformer lightning arrester. This event is reportable per 10 CFR 50. 72(b)(2)(iv)(B) and 10 CFR 50. 72(b)(3)(iv)(A). The NRC Resident Inspector has been notified. The unit is currently stable in Mode 3 with decay heat removal via the Main Steam to the Main Condenser. The licensee will inform both State and local authorities. | Feedwater Main Transformer Decay Heat Removal Main Condenser Control Rod Main Steam | |
| ENS 52833 | 29 June 2017 12:57:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Trip Due to a Loss of Normal Feedwater Flow to B Steam Generator | On 6/29/2017 at 0857 (EDT), VC Summer Nuclear Station automatically tripped due to a loss of normal feed water flow to the B Steam Generator. There were no complications with the trip. All control rods fully inserted. All emergency feedwater pumps automatically started and recovered steam generator levels. The plant is stable in Mode 3. Station personnel are investigating the cause of the loss of normal feedwater to the B Steam Generator. This is reportable per 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified. The licensee notified the State of South Carolina as well as Fairfield, Lexington, Richland and Newberry Counties regarding the event. | Steam Generator Feedwater Control Rod | |
| ENS 50293 | 22 July 2014 08:14:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip Due to Low Steam Generator Level | At 0414 (EDT on 7/22/2014), VC Summer Nuclear Station automatically tripped due to decreasing water level in the 'C' Steam Generator. The trip occurred when valve XVB-09210 WI System Condensate Bypass Valve failed to open as required while the station was removing the Condensate Polishing System during startup. The Condensate Polishing System is used to purify and filter the condensate from the non-nuclear, secondary side of the plant. This valve failure caused low level in the Deaerator Storage Tank, which consequently tripped all feedwater pumps. This loss of feedwater led to Lo-Lo Steam Generator level in the 'C' Steam Generator. All Emergency Feedwater pumps automatically started on Lo-Lo Steam Generator level and all control rods inserted fully. The Steam Generator levels recovered quickly. Presently the plant is in Mode 3. Decay heat is being removed by dumping steam to the condenser. A station response team is actively investigating the cause of the event. The NRC Resident Inspector has been notified." The licensee will notify the State and local governments. | Steam Generator Feedwater Control Rod | |
| ENS 45577 | 16 December 2009 19:15:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip Following a Failure of the Steam Dump System | VC Summer Nuclear Station (VCSNS) was performing a preplanned turbine shutdown in order to perform maintenance on a faulty turbine control valve. After the manual turbine trip, the steam dump system failed to operate and the crew manually tripped the reactor. The cause of the failure of the steam dump system is unknown, and is currently being investigated. Both motor driven Emergency Feedwater pumps were manually started at 40% Steam Generator Level. Preliminary review indicates all other primary and secondary systems responded as required. The plant is in mode 3 at normal RCS (Reactor Coolant System) pressure and temperature. Decay heat is being removed by dumping steam via the secondary (steam generator) power operated relief valves. The station will remain in mode 3 until repairs are complete. Estimated restart date has not been determined. All rods fully inserted. There is no known primary to secondary leakage. Off site power supply configuration is normal. The turbine trip was performed at 45% power due to a stuck open turbine control valve. The licensee has notified the NRC Resident Inspector and will notify state and local contacts. | Steam Generator Feedwater | |
| ENS 45404 | 2 October 2009 10:49:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip on Turbine Trip Possibly Caused by a Faulted Main Generator Breaker | At 0649 (EDT) The VC Summer Nuclear Station automatically tripped due to a turbine trip. The cause of turbine trip is under investigation. Preliminary review indicates a possible failure of one phase of the main generator breaker. The three emergency feedwater pumps automatically started on Lo-Lo steam generator level. Preliminary review indicates all primary and secondary systems responded as required. The plant is in mode 3 with normal RCS pressure and temperature. Decay heat is being removed by dumping steam to the condenser. The station will remain in mode 3 until repairs are complete. Estimated restart date has not been determined. All control rods fully inserted. The plant is in a normal post-trip electrical lineup with the exception of the balance of plant buses which are on the alternate electrical source. The licensee will inform State and local agencies and has informed the NRC Resident Inspector. | Steam Generator Feedwater Control Rod | |
| ENS 43932 | 24 January 2008 21:04:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip Due to Failure of the "C" Feedwater Flow Control Valve | At 1604 (EST), VC Summer Nuclear Station was manually tripped due to rapidly decreasing level in 'C' Steam Generator. The decreasing Steam Generator level was due to a failure of the 'C' Feedwater Flow Control Valve. All systems responded as required. All Emergency Feedwater Pumps automatically started on Lo-Lo Steam Generator level. The Steam Generator levels recovered quickly. The Pressurizer Level Control System cycling resulted in lifting the Letdown System Relief Valve due to high temperature and pressure. The Letdown Relief Valve reseated with no further problems. One Moisture Separator Reheater Relief Valve lifted momentarily and reseated. Presently, the plant is in Mode 3 with normal RCS pressure and temperature. Decay heat is being removed by dumping steam to the condenser. The plant will remain in Mode 3 until repairs are completed on the 'C' Feedwater Flow Control Valve. During the trip, all control rods fully inserted into the core. The electrical grid is stable and emergency power is being supplied from offsite via the station start-up transformer. There is no known primary to secondary leakage. The licensee has notified the NRC Resident Inspector and will be notifying State and local agencies. | Steam Generator Feedwater Control Rod | |
| ENS 43141 | 5 February 2007 08:07:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip Due to Steam Leak During Main Feed Booster Pump Startup | While starting D Feedwater Booster pump, a steam leak developed in the Turbine building. The Reactor was manually tripped at 0307 on 02/05/07. Investigation revealed that an orifice (XPS0006D) in the D Feedwater Booster pump recirculation header was the source of the leak. The steam/water leak was isolated at 0500 on 02/05/07. All systems responded normally on the Reactor trip. Emergency Feedwater (AFW) system started on LoLo Steam Generator level. Steam Generator level recovered quickly. All control rods fully inserted on the manual Reactor trip signal. No relief valves or PORVs lifted as a result of the transient. Decay heat is being removed by the main condenser via the steam dump valves. The licensee notified the NRC Resident Inspector. | Steam Generator Feedwater Main Condenser Control Rod | |
| ENS 43004 | 22 November 2006 09:26:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Main Turbine Trip Due to High- High Steam Generator "B" Water Level During Feedwater Swap Over. | At 0426 hours on 11/22/06, with the reactor critical and attempting to bring the Main Turbine on-line and shifting from Emergency Feedwater to Main Feedwater, 'B' Steam Generator level increased to the Hi-Hi level (P14) trip set point, resulting in tripping all 3 Main Feed Water Pumps. The reactor did not trip. All systems functioned as designed and the plant was stabilized. The NRC Resident Inspector was notified of this event by the licensee. | Steam Generator Feedwater Main Turbine | |
| ENS 40628 | 30 March 2004 16:29:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Automatic Reactor Trip Due to Lo-Lo Steam Generator Level | On March 30, 2004, while at power, VCSNS (V.C. Summer Nuclear Station) personnel were performing a reactor building inspection to identify the source of reactor coolant system unidentified leakage that was within Technical Specification (TS) limits. At 1129 hours, a pressure boundary leak was identified at the seal injection line to reactor coolant pump 'C'. Pursuant to TS 3.4.6.2, Action a., VCSNS commenced a controlled reactor shutdown at 1410 on March 30, 2004. During the shutdown, the main turbine experienced higher than normal vibration. At 1516, the turbine was manually tripped at approximately 43% reactor power. Subsequent to the turbine trip, feedwater regulating valve IFV-498 failed in the closed position while in automatic with a full open demand signal. The cause of this failure is not known. The reactor automatically tripped at 1520 due to lo-lo level in the 'C' steam generator at 10% reactor power. All control rods fully inserted and all safety systems responded normally. Both motor driven emergency feedwater pumps started as required. The plant stabilized in mode 3. The licensee notified the NRC Resident Inspector. | Steam Generator Reactor Coolant System Feedwater Main Turbine Control Rod | 05000395/LER-2004-001 |