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	Discovered date	Reporting criterion	Title	Event description
ENS 57128	15 May 2024 08:27:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Unit 2 Manual Reactor Trip	The following information was provided by the licensee via email: On May 15, 2024 at 0427 EDT, DC Cooks Unit 2 reactor was manually tripped due to difficulty maintaining steam generator water levels. DC Cook Unit 2 had removed the main turbine from service at approximately 0354 EDT during a planned down-power to repair a steam leak on the high pressure turbine right outer steam/stop control valve upstream drip pot. Stable steam generator water levels were unable to be maintained. As a result, DC Cook Unit 2 was manually tripped with reactor power stabilizing at approximately 20 percent. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System actuation as a four hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight hour report. The reactor trip was not complicated and all plant systems functioned normally. The DC Cook NRC Resident Inspector was notified.
ENS 57124	12 May 2024 21:41:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Trip	The following information was provided by the licensee via email and phone: At 1641 CDT on May 12, 2024, with Unit 2 in Mode 1 at 15 percent power, the reactor automatically tripped due to a unit auxiliary transformer lockout. During the trip, all control rods fully inserted. The cause of the transformer lockout is currently unknown. Emergency diesel generator (EDG) 21 and 23 actuated and all three engineered safety feature (ESF) busses were energized. All equipment responded as expected except for steam generator power operated relief valve (PORV) 2C which failed to open when required in automatic, and the load center (LC) E2A output breaker which failed to close automatically but was closed manually. Steam generator PORV 2C did open when placed in manual, although it subsequently failed to full open and was then closed. Primary system temperature and pressure are currently being maintained at 567 degrees/2235 psig following start of reactor coolant pumps 2A and 2D. Due to the reactor protection system actuation (RPS) while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the emergency diesel generators. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: South Texas Project Unit 2 was in Mode 1 at 15 percent power due to performance of testing and analysis on the main turbine prior to the RPS actuation. * * UPDATE FROM ROBERT DEWOODY TO BRIAN P. SMITH ON MAY 22, 2024 AT 1805 EDT * * * The following information was provided by the licensee via email and phone: South Texas Project is submitting the following correction to the event notification: The steam generator (SG) power operated relief valve (PORV) 2C did not fail to open automatically. System pressure during this event did not reach the automatic setpoint for the PORV (1225 psi), and there was no demand for it to open automatically. During the event, SG PORV 2C was taken to manual and it went full open when the up button was pushed slightly. It went closed when the down button was pressed to close it manually. In addition, the load center E2A output breaker initially failed to close automatically, however, after operations placed it in pull-to-lock and returned the hand switch to automatic, it closed automatically. Notified R4DO (Dixon).
ENS 56645	30 July 2023 19:26:00	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 LOW Main Turbine ELECTRO-HYDRAULIC Control (EHC) Oil Level	The following information was provided by the licensee via email: On July 30, 2023 at 1526 EDT, with unit 1 in mode 1 at 100 percent power, the reactor was manually tripped due to low main turbine electro-hydraulic control oil level. The trip was uncomplicated with all systems responding normally post-trip. Operations stabilized the plant in mode 3. Decay heat removal is being accomplished using the steam dumps in steam pressure mode to the main condenser. Emergency Feedwater actuated due to low-low steam generator level as expected. This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified.
ENS 56459	9 April 2023 04:44:00	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 Loss of Reactor Coolant Pumps	The following information was provided by the licensee via email: The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to this event or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10 CFR 50.73. At 2144 MST on April 8, 2023, the Unit 1 reactor automatically tripped due to the loss of reactor coolant pumps stemming from the loss of 13.8 kV power to the pumps. Prior to the reactor trip, the main turbine tripped due to a loss of hydraulic pressure. The main generator output breakers did not automatically open on the turbine trip as expected so the control room operators opened the breakers per procedural guidance. Once the breakers were opened, the two 13.8 kV electrical distribution buses failed to complete a fast bus transfer, which resulted in the loss of power to the reactor coolant pumps, initiating the reactor trip. The control room operators manually actuated a main steam isolation signal per procedure, requiring use of the atmospheric dump valves. Following the reactor trip, all control element assemblies inserted fully into the core. No automatic specified system actuation was required or occurred. No emergency plan classification was required per the Emergency Plan. Safety related buses remained powered from offsite power during the event and the offsite power grid is stable. Unit 1 is stable and in Mode 3. Decay heat is being removed by the atmospheric dump valves and the class 1E powered motor driven auxiliary feedwater pump. The loss of hydraulic pressure, the main generator output breakers failing to automatically open and the fast bus transfer not actuating are being investigated. This event is being reported as a reactor protection system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B). The NRC Senior Resident Inspector has been informed. Unit 2 is in a refueling outage in Mode 5 and Unit 3 is in Mode 1 at 100 percent power. * * UPDATE ON 4/9/23 AT 0835 EDT FROM TANNER GOODMAN TO ADAM KOZIOL * * * This update is being made to report the manual actuation of the B-train auxiliary feedwater pump and manual main steam isolation signal (MSIS) actuation affecting multiple main steam isolation valves (MSIVs) following the reactor trip. This event is being reported as a reactor protection system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) and a specified system actuation in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector has been informed of the update. Notified R4DO (Warnick) * * UPDATE ON 5/3/23 AT 1945 EDT FROM LORRAINE WEAVER TO JOHN RUSSELL * * * This update is intended to clarify the initial description of the event that occurred on 4/8/2023. Prior to the reactor trip, the main turbine tripped due to a loss of hydraulic pressure. The main generator output breakers did not automatically open on the turbine trip. The control room operators manually opened the breakers per procedural guidance. Once the breakers were opened, the two 13.8 kV electrical distribution buses de-energized. A fast bus transfer did not occur per design, which resulted in the loss of power to the reactor coolant pumps, initiating the reactor trip. The control room operators manually actuated a main steam isolation signal per procedure, requiring use of the atmospheric dump valves. The NRC Senior Resident Inspector has been informed of the update. Notified R4DO (Gaddy)
ENS 55910	24 May 2022 08:14:00	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 Manual Turbine Trip from High Vibrations on Main Turbine	The following information was provided by the licensee via email: On May 24, 2022, at 0414 EDT, while rolling the Unit 1 main turbine during the Unit 1 Cycle 31 refueling outage, the Unit 1 main turbine experienced high vibrations and the main turbine was manually tripped with reactor power at 12 percent. Main turbine vibrations persisted and the reactor was manually tripped, Main Steam Stop Valves were closed, and main condenser vacuum was broken. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. The DC Cook Resident NRC Inspector has been notified. Unit 1 is being supplied by offsite power. All control rods fully inserted. Both Motor Driven Auxiliary Feedwater Pumps started properly. Decay heat is being removed via Steam Generator Power Operated Relief Valves. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 1 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event.
ENS 55616	30 November 2021 17:54:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Unit 1 Automatic Scram	At 1254 EST on November 30, 2021, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed during Turbine Valve Cycling surveillance activities. Unit 1 reactor was being operated at approximately 80 percent rated thermal power with turbine valve cycling surveillance activities in progress. The Control Room received indication that both divisions of RPS (reactor protection system) actuated from turbine valve closure signals and all control rods fully inserted. The Main Turbine was manually tripped, and turbine bypass valves opened automatically to control reactor pressure. Reactor water level lowered to -35 inches causing Level 3 and Level 2 isolations. No ECCS (emergency core cooling systems) actuations occurred. RCIC (reactor core isolation cooling) automatically initiated as designed at -30 inches. The Operations crew subsequently maintained reactor water level at the normal operating band using Feedwater pumps and RCIC was placed in a standby lineup. The reactor is currently stable in Mode 3. An investigation is in progress into the cause of the turbine valve closure signals. The NRC Senior Resident Inspector was notified. A voluntary notification to PEMA (Pennsylvania Emergency Management Agency) will be made. This event requires a 4-hour ENS notification in accordance with 10CFR50.72(b)(2)(iv)(B) and an 8-hour ENS notification in accordance with 10CFR50.72(b)(3)(iv)(A). Unit 2 was not affected and remains at 100 percent power, Mode 1.
ENS 55514	11 October 2021 17:21:00	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)(iv)(A), System Actuation - ECCS Discharge	Automatic Reactor Scram After Main Turbine Trip	At 1321 EDT on October 11, 2021, Susquehanna Steam Electric Station Unit 2 reactor automatically scrammed due to a trip of the Main Turbine. Unit 2 reactor was being operated at approximately 95 percent RTP (rated thermal power) with no evolutions in progress. The Control Room received indication of a Main Turbine trip with both divisions of RPS (Reactor Protection System) actuated and all control rods inserted. Turbine bypass valves opened automatically to control reactor pressure and subsequently failed open causing the reactor to depressurize. When reactor pressure reached approximately 560 psig, the operations crew manually closed the Main Steam Isolation Valves (MISVs) to stop the depressurization. Reactor water level lowered to -31 inches causing Level 3 (+13 inches) isolations. No (automatic) ECCS (Emergency Core Cooling System) actuations occurred. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) were manually initiated to control reactor water level. The Operations crew subsequently maintained reactor water level at the normal operating band using RCIC and reactor pressure was controlled with HPCI in pressure control mode and main steam line drains. The Reactor Recirculation Pumps tripped as designed on EOC-RPT (end of cycle recirculation pump trip). The reactor is currently stable in Mode 3. An investigation into the cause of the turbine trip is underway. The NRC Resident Inspector was notified. A voluntary notification to PEMA will be made. This event requires a 4 hour ENS notification in accordance with 10 CFR 50.72(b)(2)(iv)(A), 10 CFR 50.72(b)(2)(iv)(B) and an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(iv)(A).
ENS 55370	21 July 2021 22:26:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor SCRAM	At 1826 EDT on July 21, 2021, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a trip of the Main Turbine. Unit 1 reactor was operating at 100 percent reactor power with no evolutions in progress. The Control Room received indication of a Main Turbine trip with both divisions of RPS (Reactor Protection System) actuated and all control rods inserted. The Reactor Recirculation Pumps tripped on EOC-RPT (end of cycle recirculation pump trip). Reactor water level lowered to +8 inches causing Level 3 (+13 inches) isolations. No ECCS (Emergency Core Cooling Systems) or RCIC (Reactor Core Isolation Cooling system) actuations occurred. The Operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. The reactor is currently stable in Mode 3 with main condenser available. Investigation into the trip of the Main Turbine is in progress. The NRC Resident Inspector was notified. A voluntary notification to PEMA will be made. This event requires a 4 hour ENS notification in accordance with 10CFR50.72(b)(2)(iv)(B) and an 8 hour ENS notification in accordance with 10CFR50.72(b)(3)(iv)(A) and 10CFR50.72(b)(3)(iv)(B).
ENS 55346	9 July 2021 01:54:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Trip Due to Main Turbine Trip	At 2154 EDT on 7/8/2021, with the Unit in Mode 1 at 100% power, the reactor automatically tripped due to trip of the main turbine, caused by failure of a non-safety related breaker during functional testing. Following the reactor trip the Steam Feed Rupture Control System automatically initiated on low Steam Generator 1 level, actuating both turbine-driven Auxiliary Feedwater Pumps. The operators subsequently started the high pressure injection pumps manually per procedure in response to overcooling indications. Operations responded and stabilized the plant. Decay heat was initially being removed via the Main Condenser. During post-trip response actions, while attempting to shut down the Auxiliary Feedwater Pumps, a low pressure condition was experienced in Steam Generator 2, resulting in isolation of the Main Condenser and steam being discharged through the Atmospheric Vent Valves for decay heat removal. There is no known primary to secondary leakage. 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). This event is also being reported in accordance with 10 CFR 50.72(b)(2)(iv)(A) as a four-hour, non-emergency notification of emergency core cooling system (ECCS) discharge into the reactor coolant system, and in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an eight-hour, non-emergency notification of an event that results in a valid actuation of the Auxiliary Feedwater System. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55030	11 December 2020 18:04:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Scram Due to Main Turbine / Generator Trip	On December 11, 2020 at 1204 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 100 percent Reactor Power after a Main Turbine and Generator Trip. All Control Rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Branch Chief has been notified.
ENS 54986	6 November 2020 08:39:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Scram Due to Turbine/Generator Trip	On November 6, 2020, at 0239 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 84 percent Reactor Power after a Main Turbine and Generator Trip. All control rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Resident has been notified.
ENS 54691	3 May 2020 12:21:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Scram Due to Main Turbine Trip	At 0821 EDT on May 3, 2020, the Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a trip of the Main Turbine. The Unit 1 reactor was operating at 76 percent reactor power following a ramp schedule to full power subsequent to a maintenance outage. The Control Room received indication of a Main Turbine trip with both divisions of the Reactor Protection System actuated and all control rods inserted. The Reactor Recirculation Pumps tripped on End of Cycle - Recirculation Pump Trip. Reactor water level lowered to -1 inch causing Level 3 (+13 inches) isolations. No Emergency Core Cooling System or Reactor Core Isolation Cooling actuations occurred. The operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. No Steam Relief Valves opened. The reactor is currently stable in Mode 3. Investigation into the trip of the Main Turbine is in progress. The NRC Resident Inspector was notified. A voluntary notification to the Pennsylvania Emergency Management Agency and press release will occur. This event requires a 4-hour Emergency Notification System (ENS) notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) and an 8-hour ENS notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(3)(iv)(B).
ENS 54263	7 September 2019 17:09:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Trip	At 1309 EDT on September 7, 2019, with the unit in Mode 1 at approximately 95 percent power, the reactor automatically tripped during main turbine valve testing. 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 turbine bypass valves discharging steam to 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). The cause of the reactor protection system actuation is under evaluation. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 54176	21 July 2019 12:26:00	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 Non-Essential Service Water System Degraded Condition	On July 19, 2019, DC Cook Unit 2 started experiencing degraded performance on the Unit 2 Non-Essential Service Water System (NESW) which affected one (1) NESW pump. On July 21, 2019, a second NESW pump on Unit 2 experienced degradation. On July 21, 2019, DC Cook Unit 2 elected to do a rapid downpower over approximately 40 minutes and perform a Manual Reactor Trip from 17 percent (rated thermal power) to repair the condition before any threshold was exceeded. The manual reactor trip was completed at 0826 EDT on July 21, 2019. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), Reactor Protection System (RPS), as an eight (8) hour report. The DC Cook NRC Resident Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. Aux Feedwater pumps were started as required and are operating properly. Decay heat is being removed via the Steam Generator Power Operated Relief Valves following breaking Main Condenser Vacuum for expedited cooldown of the Main Turbine. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip. DC Cook Unit 2 remains stable in Mode 3. No radioactive release is in progress as a result of this event. Unit 1 was not affected.
ENS 53966	30 March 2019 21:47:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Manual Reactor Scram and Specified System Actuation	At 17:47 Eastern Daylight Time (EDT) on March 30, 2019, with Unit 2 in Mode 1 at approximately 23 percent reactor power and main turbine startup in progress coming out of a refuel outage, a high temperature was sensed at main turbine bearing #9. As a result of and to arrest the high temperature condition, the main control room inserted a manual reactor scram. All control rods inserted as expected during the scram. When the scram was inserted, reactor water level dropped below the Low Level 1 actuation setpoint. Per design, the Low Level 1 signal resulted in Group 2 (i.e., floor and equipment drain isolation valves), Group 6 (i.e., monitoring and sampling isolation valves) and Group 8 (i.e., shutdown cooling isolation valves) isolations. The main control room manually closed all Main Steam Isolation Valves (MSIVs), in anticipation of a low vacuum prior to the Group 1 automatic closure signal being received. High Pressure Coolant Injection (HPCI) was aligned for pressure control and Reactor Coolant Isolation System (RCIC) was aligned for level control. The Reactor Coolant Sample Line Isolation valves closed as expected on low main condenser vacuum. All systems responded as designed. This event is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) for RPS actuation and 10 CFR 50.72(b)(3)(iv)(A) as an event that results in valid actuations of the Primary Containment Isolation System. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. At the time of notification, decay heat was being removed by the condenser through one open MSIV and a feedwater pump running.
ENS 53894	23 February 2019 20:58:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Scram After Turbine Control Valve Fast Closure	Actuation of RPS (Reactor Protection System) with the reactor critical. Reactor scram occurred at 1458 (CST) on 2/23/2019 from 100% power. The cause of the scram was due to Turbine Control Valve Fast Closure. All control rods are fully inserted. Currently reactor water level is being maintained by the Condensate Feedwater System in normal band and reactor pressure is being controlled via Main Turbine Bypass valves to the main condenser. No ECCS (Emergency Core Cooling System) initiation signals were reached and no ECCS or Diesel Generator initiation occurred. The Low-Low Set function of the Safety Relief Valves actuated upon turbine trip. This was reset when pressure was established on main turbine bypass valves. The cause of the turbine trip is still under investigation. There were no complications with scram response. The licensee notified the NRC Resident Inspector. There was no maintenance occurring on the main turbine at the time of the scram.
ENS 53677	19 October 2018 04:00:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Turbine Steam Seal Header Pressure Malfunction	On 10/19/18 at 2202 EDT, at 19 (percent) Reactor power, a malfunction of (the) Turbine Steam Seal Header pressure control caused a loss of Condenser vacuum, resulting in an automatic trip of the Main Turbine and a manual reactor trip (RPS Actuation). Just prior to the reactor trip, Emergency Feedwater was manually initiated to mitigate the potential loss of Main Feedwater. Condenser vacuum was recovered after the reactor trip and Main Feedwater remained in operation. Due to the RPS actuation while critical, this event is being reported as a 4-hour non-emergency per 10CFR50.72(b)(2). Also, due to the manual initiation of Emergency Feedwater, this event is also being reported as an 8-hour non-emergency per 10CFR50.72(b)(3). Following the reactor trip, all systems responded as expected with no complications. Emergency feedwater was secured at 2300. Unit 1 is in Mode 3 and stable, continuing to cooldown for a refueling outage. The NRC Resident Inspector has been notified.
ENS 53459	16 June 2018 05:00:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Manual Reactor Trip During Startup	At 1121 CDT on June 16, 2018, Arkansas Nuclear One, Unit 1 (ANO-1) performed a manual reactor trip due to a Turbine Bypass valve failing open on reactor startup. At the time, ANO-1 was in Mode 2 at approximately 2 percent power. The failed Turbine Bypass valve resulted in an overcooling event and the Overcooling Emergency Operating Procedure (EOP) was entered. Main Steam Line Isolation (MSLI) automatic actuation occurred on 2 of the 4 channels of Emergency Feedwater Initiation and Control during the overcooling event in the 'B' Steam Generator. The remaining channels of MSLI were manually actuated by the control room staff from the control room. Overcooling was terminated after the closure of the Main Steam Isolation Valve (MSIV) and reactor coolant parameters were stabilized as directed by the Overcooling EOP. Additionally, Gland Sealing Steam was lost to the main turbine due to the closure of the 'B' Steam Generator MSIV and Loss of Condenser Vacuum Abnormal Operating Procedure was entered. This is a 4-hour non-emergency 10 CFR 50.72 (b)(2)(iv)(B) notification due to a Reactor Protection System actuation (scram) and an 8-hour non-emergency 10 CFR 50.72 (b)(3)(iv)(A) notification for safety system actuation." All control rods fully inserted into the core during the trip. Heat removal is via the Atmospheric Dump Control valves to atmosphere. The NRC Resident Inspector has been notified. The licensee also notified the State of Arkansas.
ENS 53188	31 January 2018 00:22:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Manual Reactor Scram Due to Main Turbine Load Oscillations	On 1/30/2018 at 1750 (CST), the Reactor Pressure Control Malfunctions ONEP (Off Normal Event Procedure) was entered due to main turbine load oscillations of approximately 30 MWe peak to peak. At 1822 (CST), a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown due to continued main turbine load oscillations. Reactor SCRAM ONEP, Turbine Trip ONEP, and EP-2 were entered. Reactor water level was stabilized at 36 inches narrow range on startup level and reactor pressure stabilized at 933 psig using main turbine bypass valves. Reactor Water Level 3 (11.4 inches) was reached which is the setpoint for Group 2 (RHR to Radwaste Isolation) and Group 3 (Shutdown Cooling Isolation). No valve isolated in these systems due to all isolation valves in these groups being in their normally closed position. The lowest Reactor Water level reached was -36 inches wide range. No other safety system actuations occurred and all systems performed as designed. That event is being reported under 10CFR 50.72(b)(2)(iv)(B) as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical and also reported under 10CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of RPS. The MSIVs are open with decay heat being removed via steam to the main condenser using the bypass valves. Off site power is stable, and the plant is in a normal shutdown electrical lineup. RCIC (Reactor Core Isolation Cooling) was out of service for maintenance, and the reactor water level did not reach the system activation level. The cause of the main turbine load oscillations being investigated. The licensee notified the NRC Resident Inspector.
ENS 52863	17 July 2017 21:17:00	10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Unusual Event Declared Due to Loss of Offsite Power	During a rain and lightning storm, plant operators observed arcing from the main transformer bus duct and notified the control room. The decision was made to trip the main generator which resulted in an automatic reactor trip. The plant entered EAL SU.1 as a result of the loss of offsite power for greater than fifteen minutes. Plant safety busses are being supplied by both emergency diesel generators while the licensee inspects the electrical system to determine any damage prior to bringing offsite power back into the facility. Offsite power is available to the facility. No offsite assistance was requested by the licensee. During the trip, all rods inserted into the core. Decay heat is being removed via the atmospheric dump valves with emergency feedwater supplying the steam generators. The main steam isolation valves were manually closed to protect the main condenser. There were no safeties or relief valves that actuated during the plant transient. There is no known primary-to-secondary leakage. Reactor cooling is via natural circulation. All safety equipment is available for the safe shutdown of the plant. The licensee has notified the NRC Resident Inspector, Louisiana Department of Environmental Quality and the local Parish emergency management agencies. Notified DHS SWO, FEMA, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email). * * UPDATE ON 7/17/17 AT 2007 EDT FROM MARIA ZAMBER TO DONG PARK * * * This notification is also made under 10 CFR 50.72(b)(3)(v)(D). This is a non-emergency notification from Waterford 3. On July 17, 2017 at 1606 CDT, the reactor automatically tripped due to a loss of Forced Circulation, which was the result of Loss of Offsite Power (LOOP) to the electrical (safety and non-safety) buses. Both 'A' and 'B' trains of Emergency Diesel Generators (EDGs) started as designed to reenergize the 'A' and 'B' safety buses. The LOOP caused a loss of feedwater pumps, resulting in an automatic actuation of the Emergency Feedwater (EFW) system. Prior to the reactor trip, at 1600 CDT, personnel noticed the isophase bus duct to main transformer 'B' glowing orange due to an unknown reason. Due to this, the main turbine was manually tripped at 1606 CDT. Following the turbine trip, the electrical (safety and non-safety) buses did not transfer to the startup transformers as expected due to an unknown reason. The plant entered the Emergency Operating Procedure for LOOP/Loss of Forced Circulation Recovery. At 1617 CDT, an Unusual Event was declared due to Initiating Condition (IC) SU1 - Loss of all offsite AC power to safety buses (greater than) 15 minutes. All safety systems responded as expected. The plant is currently in mode 3 and stable with the EDGs supplying both safety buses and with EFW feeding and maintaining both steam generators. Offsite power is in the process of being restored. The licensee has notified the NRC Resident Inspector, Louisiana Department of Environmental Quality and the local Parish emergency management agencies. * * UPDATE FROM ADAM TAMPLAIN TO HOWIE CROUCH AT 2203 EDT ON 7/17/17 * * * The licensee terminated the Notification of Unusual Event at 2056 CDT. The basis for terminating was that offsite power was restored to the safety busses. The licensee has notified Louisiana Department of Environmental Quality, St. John and St. Charles Parishes, Louisiana Homeland Security Emergency Preparedness, and will be notifying the NRC Resident Inspector. Notified IRD (Stapleton), NRR (King), R4DO (Hipschman), DHS SWO, FEMA, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email). * * UPDATE FROM SCOTT MEIKLEJOHN TO HOWIE CROUCH AT 1724 EDT ON 7/19/17 * * * This update is being reported under 10 CFR 50.72(b)(3)(v)(B). During the event discussed in EN# 52863, at 1642 CDT (on July 17, 2017), Condensate Storage Pool (CSP) level lowered to less than 92% resulting in entry to Technical Specification (TS) 3.7.1.3. Level in the CSP was lowered due to feeding from both Steam Generators with EFW. Normal makeup to the CSP was temporarily unavailable due to the LOOP. Filling the CSP commenced at 1815 CDT (on July 17, 2017), and TS 3.7.1.3 was exited on July 18, 2017 at 0039 CDT. The licensee notified the NRC Resident Inspector. Notified R4DO (Hipschman). * * UPDATE FROM SCOTT MEIKLEJOHN TO HOWIE CROUCH AT 1233 EDT ON 9/14/17 * * * Waterford 3 is retracting a follow up notification made on July 19, 2017 for EN# 52863, concerning the loss of safety function associated with the Condensate Storage Pool (CSP) per 10 CFR 50.72(b)(3)(v)(B). The Condensate Storage Pool was performing its required safety function by providing inventory to the Emergency Feed Water pumps when the required Tech Spec level (T.S. 3.7.1.3) dropped below 92%. The Technical Specification was entered at 1624 (CDT) on July 17, 2017 and exited after filling at 0039 on July 18, 2017. The total allowed outage time allowed by Tech Spec 3.7.1.3 is 10 hours to be in Hot Shutdown if not restored. The Condensate Storage Pool level was restored to greater than 92% prior to exceeding the allowed outage time. Based on level being restored and the Condensate Storage Pool performing its required safety function, 10 CFR 50.72(b)(3)(v)(B) does not apply. Prior to the automatic reactor trip, Condensate Storage Pool level was greater than 92%. The NRC Resident Inspector has been notified of the retraction. Notified R4DO (Groom).
ENS 52795	8 June 2017 19:27:00	10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 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)(iv)(A), System Actuation - ECCS Discharge	Automatic Reactor Scram After Main Turbine Control Logic Loss of Power	At 1527 hrs (EDT) on June 8, 2017, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a loss of Main Turbine Electro-Hydraulic Control (EHC) logic power causing a High Flux Reactor Power RPS (Reactor Protection System) trip. All control rods (fully) inserted and both reactor recirculation pumps tripped due to reaching reactor water level 2. Reactor water level lowered to -49 inches causing Level 3 (+13 inches) and Level 2 (-38 inches) isolations. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) automatically initiated and were overridden by control room operators after RPV (Reactor Pressure Vessel) water level was restored to the normal band with feedwater. HPCI and RCIC injected to the Reactor Coolant System during reactor level stabilization. All isolations and initiations occurred as expected. No main steam relief valves opened. Pressure was controlled via main turbine bypass valve operation. All safety systems operated as expected. Secondary Containment Zone 1, 2, and 3 differential pressure lowered to 0 inch WG (Water Gauge) due to a trip of the Reactor Building Ventilation system that resulted from Unit 1 Level 2 isolation. Differential pressure was restored to Zones 1, 2, and 3 by the initiation of Standby Gas Treatment System on the Unit 1 Level 2 initiation. Unit 1 reactor is currently stable in Mode 3. Investigation into the loss of Main Turbine EHC logic power is underway. The NRC Resident Inspector has been notified. A voluntary notification to PEMA and press release will occur. The suspected cause of the loss of power to the EHC logic circuit is ongoing maintenance on the system.
ENS 52747	20 March 2017 06:16:00	10 CFR 50.73(a)(1), Submit an LER	60-Day Optional Telephone Notification for an Invalid High Pressure Coolant Injection System Actuation	Pursuant to 50.73(a)(1) the following information is provided as a sixty (60) day telephone notification to the NRC. This notification, reported under 50.73(a)(2)(iv), is being provided in lieu of the submittal of a written LER to report a condition that resulted in an invalid actuation of the high pressure coolant injection (HPCI). At Nine Mile Point Unit 1, HPCI is a flow control mode of the normal feedwater system and is not an emergency core cooling system. On March 20, 2017 at 0216 EDT, Nine Mile Point Unit 1 reactor shutdown was in progress. The Unit 1 generator was off line, the 100 percent capacity 13 feedwater pump (13 FW) was removed from service, and the Unit 1 main turbine had been tripped appropriately per procedure while entering a planned refueling outage. At approximately 4 percent reactor power, a clearance tagging evolution was in progress to support shutdown activities. During this evolution a tag was applied that caused an unanticipated activation of a lock out (86) relay due to the failure to bypass this relay prior to the tag application. This 86 relay activation in turn resulted in a generator trip signal followed by a turbine trip signal. With the generator off line and the turbine already tripped there was no actual change in any plant parameter or condition that would have created a valid turbine trip signal and the associated HPCI initiation. The plant configuration at the time of the main turbine trip signal had one motor operated feedwater pump, 12 Feedwater Pump (12 FW), in service and providing normal reactor level control. HPCI did initiate as designed upon receiving the generator and main turbine trip signals caused by the activation of the 86 relay. The 12 FW pump, which was providing normal reactor level control, transitioned the level control from automatic mode into HPCI mode of operation. Per design, the 11 FW pump automatically started but was not required to and did not flow water since 12 FW pump was in operation. The 11 FW pump was subsequently secured by operations. At no point in time did the HPCI system receive a valid initiation signal (due to high DW pressure, low reactor water level, or a valid turbine trip with loss of the turbine driven 13 FW pump). Operators reset HPCI and returned water level to Automatic Control at 0218. The Licensee has notified the NRC Resident Inspector.
ENS 52727	30 April 2017 22:18:00	10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident	Open Bypass Valve Causes Loss of Safety Function	On April 30, 2017, at 1818 (EDT), the main turbine steam bypass valve #1 partially opened. Power was incrementally lowered. While lowering power the bypass valve would shut and then reopen and power would again be lowered. When power was lowered to approximately 74 percent the bypass valve remained closed. During the transient the reactor protection system (RPS) Turbine Stop Valve Closure and Control Valve Fast Closure trip functions were declared inoperable due to the opening of the bypass valve which affects the bypass setpoint for those RPS trip functions. With the loss of these RPS trip functions a loss of safety function existed intermittently for approximately 37 minutes. The manual reactor trip function and other RPS functions remained operable. Both channels of the rod withdrawal limiter (RWL) and the end of cycle reactor recirculation pump trip (EOC-RPT) function were also declared inoperable. These functions are credited in accident analysis, this also resulted in a loss of safety function. Currently the bypass valve is closed and the RWL, EOC-RPT and RPS function are operable. Troubleshooting continues to determine the issue with the main turbine that caused the bypass valve to open. NRC Resident Inspector has been notified.
ENS 52683	17 April 2017 04:04:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Actuation of Emergency Diesel Generators	On April 17, 2017, at 0004 Eastern Daylight Time (EDT), an automatic actuation of the four Emergency Diesel Generators (EDGs) was received. At the time of the event, Unit 2 was in the process of starting the main turbine following a refueling outage. Operations personnel tripped the main turbine due to elevated bearing vibrations. When the main turbine was tripped, Power Circuit Breakers (PCBs) 29A and 29B failed to open. This caused a main generator primary lockout due to generator reverse power and the subsequent automatic actuation of all four EDGs. All emergency buses remained energized from offsite power and therefore, the EDGs did not tie to their respective buses. The protective relaying and EDGs responded per design to this event. This event is being reported in accordance with 10 CFR 50.73(b)(3)(iv)(A) as an event that results in a valid actuation of the EDGs. Due to the shared configuration of the Brunswick electrical system, both Unit 1 and Unit 2 are affected. This event did not impact public health and safety. The NRC Resident lnspector has been notified.
ENS 52425	10 December 2016 13:48:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Manual Reactor Scram Due to High Main Turbine Vibrations	On December 10, 2016 at 0848 EST, (operators at) Nine Mile Point Unit 1 manually scrammed the reactor due to high vibrations on the Main Turbine. Cause of the high vibrations is being investigated. Following the scram, the High Pressure Coolant Injection (HPCI) system automatically initiated as expected. At Nine Mile Point Unit 1, a HPCI system actuation signal on low reactor pressure vessel (RPV) level is normally received following a reactor scram, due to level shrink. HPCI is a flow control mode of the normal feedwater system and is not an emergency core cooling system. At 0849, RPV level was restored above the HPCI system low level actuation set point and the HPCI system initiation signal was reset. Pressure control was established on the turbine bypass valves, the preferred system. No Electromatic relief valves actuated due to this scram. Nine Mile Point Unit 1 is currently in Hot Shutdown, with reactor water level and pressure maintained within normal bands. Decay heat is being removed via steam to the main condenser using the bypass valves. The offsite grid is stable with no grid restrictions or warnings in effect. The unit is currently implementing post scram recovery procedures. The licensee has notified the state of New York Public Service Commission and the NRC Resident Inspector.
ENS 52406	4 December 2016 03:24:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Trip Caused by Main Turbine Trip	On 12/3/16 at 2224 EST, Calvert Cliffs Unit-2 experienced an automatic reactor trip from full power due to a leak in the Unit-2 Main Turbine Electro-Hydraulic Control (EHC) system. The EHC leak caused the Unit-2 Main Turbine governor valves to close, resulting in a turbine trip and automatic reactor trip. The site Outage Control Center is manned, and investigation into the cause of the leak is underway. Unit-2 remains stable in Mode 3 with normal heat removal. Unit-1 remains at full power and was not affected by the trip. The plant is in a normal shutdown electrical lineup. All Control rods fully inserted and no primary or secondary safety relief valves lifted during the trip. The licensee has notified the NRC Resident Inspector. The licensee will be notifying Calvert County.
ENS 52381	20 November 2016 08:42:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Scram During Main Turbine Testing	At 0342 EST, an automatic reactor scram was processed during turbine valve testing. All rods inserted into the core as expected and all systems functioned as expected during the scram. The event is reportable within 4 hours per 10 CFR 50.72(b)(2)(iv)(B) - any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical except when the actuation results from and is part of a preplanned sequence during testing or reactor operation. The plant response to the reactor scram was uncomplicated. The main feedwater system is maintaining reactor water level and decay heat is being removed by the main turbine bypass valves to the main condenser. The unit is in a normal shutdown electrical lineup. No SRVs lifted during the scram. The licensee was testing the main turbine trip function just prior to the scram. The cause is under investigation. The licensee notified the NRC Resident Inspector.
ENS 52289	8 October 2016 05:50:00	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)(iv)(A), System Actuation - ECCS Discharge	Unplanned Reactor Trip and Safety Injection Due to Turbine Control Valve Transient	On October 8, 2016, while reducing power for a planned refueling outage, the unit was taken offline by opening the main generator output breakers. With the reactor at approximately 7 percent power in MODE 1, an unplanned actuation of the reactor protection system occurred. At 0150 (EDT), an unexpected steam valve transient occurred while main turbine valve control was being transferred from throttle valve to governor valves during main turbine overspeed testing. This resulted in an automatic low steamline pressure Safety Injection and Reactor Trip. All safety systems functioned as expected. The operations staff responded to the event in accordance with applicable plant procedures. The plant stabilized at normal operating no-load reactor coolant system (RCS) temperature and pressure following the reactor trip, with decay heat being removed using steam generator power operated relief valves. Steam generator water levels are being maintained using auxiliary feedwater. All emergency core cooling system (ECCS) equipment is available. The cause of the steam valve transient is under investigation. This condition is being reported as an ECCS discharge to RCS, an unplanned reactor protection system actuation, and a specified system actuation in accordance with 10 CFR 50.72(b)(2)(iv)(A), 10 CFR 50.72(b)(2)(iv)(B). and 10 CFR 50.72(b)(3)(iv)(A). This condition does not affect the health and safety of the public or station employees. The NRC Resident Inspector has been notified. The Safety Injection occurred for approximately 6 minutes and Pressurizer level increased to approximately 71%. The Main Steam Isolation Valves closed as a result of the Safety Injection and Decay Heat is being removed using the Steam Generator Atmospheric Relief Valves. There is no known primary to secondary leakage.
ENS 52210	31 August 2016 01:20:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Notice of Unusual Event - Fire in a Main Bank Transformer	A fault occurred on the unit 2 "B" main bank transformer resulting in an oil fire. The main turbine tripped resulting in a reactor trip. All control rods fully inserted and no safety or relief valves lifted. Decay heat is being removed via steam dumps to the main condenser and feeding steam generators with auxiliary feedwater. Electrical power is through the normal shutdown electrical lineup. Offsite assistance was requested from the county and off duty fire brigade members. At 2228, the fire was reported as out. Spray is continuing and a reflash watch is being set. Unit 1 continued to operate at 100% power throughout the event. Notified the DHS SWO, FEMA Ops Center, DHS NICC, FEMA National Watch Center (E-mail) and Nuclear SSA (E-mail). * * UPDATE AT 2352 EDT ON 08/30/2016 FROM MICHAEL BOTTORFF TO JEFF HERRERA * * * On August 30, 2016, at 2110 EDT, Watts Bar Nuclear Plant Unit 2 reactor tripped due to an electrical fault affecting the 2B Main Bank Transformer, resulting in a fire in the transformer. Concurrent with the reactor trip, the Auxiliary Feedwater system actuated as designed. All Control and Shutdown rods fully inserted. All safety systems responded as designed. The unit is currently stable in Mode 3, with decay heat removal via Auxiliary Feedwater and main steam dump systems. Unit 2 is in a normal shutdown electrical alignment. The fire was out at 2230 EDT. The cause of the fire is currently under investigation. The fire was reported at 2149 EDT. Local Fire Departments responded to the site as requested. The reactor trip and system actuation is being reported under 10CFR50.72(b)(3)(iv)(A) and 10CFR50.72 (b)(2)(iv)(B). There was no effect on WBN Unit 1. The NOUE was exited at 2342. The NRC Senior Resident Inspector has been notified. The Licensee notified the State of Tennessee. Notified the R2DO (Bartley), IRD MOC (Stapleton), NRR EO (Miller), DHS SWO, FEMA Ops Center, DHS NICC, FEMA National Watch Center (E-mail) and Nuclear SSA (E-mail).
ENS 52045	27 June 2016 01:15:00	10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release	Offsite Notification Due to an Oil Spill	The United States Coast Guard reported an oil sheen in the vicinity of the station's circulating water system effluent. Investigation by station personnel has not determined the source. The circulating water pumps were secured to mitigate the potential source. The United States Coast Guard response Center, and New York State Department of Environmental Conservation have been notified. The licensee notified the NRC Resident Inspector. Notified DOE, EPA, USDA, HHS, FEMA. * * UPDATE ON 06/27/2016 AT 02:52 FROM DUSTIN SCURLOCK TO DAN LIVERMORE * * * The source of the oil sheen has been identified. The source, main turbine lubricating oil, has been stopped and cleanup efforts are underway. Notified R1DO (Gray), DOE, EPA, USDA, HHS, and FEMA.
ENS 52012	17 June 2016 07:57:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Scram During Testing	During planned stop and control valve testing, two main turbine high pressure stop valves closed instead of the expected one (stop valve 'B'). This caused the main turbine control valves, power, reactor pressure to swing and a division 2 half SCRAM. Control rods were inserted to reduce power and the power swings. At 0257 (CDT) the reactor automatically SCRAMMED. Reactor SCRAM, Turbine Trip (procedures) ONEPs and EP-2 were entered. Reactor water level was stabilized at 34 inches narrow range on startup level control and reactor pressure stabilized at 884 psig using main turbine bypass valves. No other safety related systems actuated and all systems performed as expected. The plant is in its normal shutdown electrical lineup using normal feedwater and turbine bypass valves for decay heat removal. Reactor pressure is slowly trending down. The licensee is investigating the cause of the second stop valve shutting. The licensee notified the NRC Resident Inspector.
ENS 51983	6 June 2016 09:56:00	10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded	Isolable Leakage Identified from Seal Water Line Weld Inside Rcs Pressure Boundary	Susquehanna Unit 1 commenced a manual shutdown on 06/05/2016 for a maintenance outage. At 2202 hours (EDT) on 06/05/2016, operators began reducing power in accordance with plant procedures. At 0352 hours on 06/06/2016, the Main Turbine was tripped with reactor power at approximately 15%. The Mode switch was taken to 'STARTUP/HOT STANDBY' (Mode 2) at 0515 hours on 06/06/2016. Manual insertion of control rods was paused as scheduled for entry into the drywell for inspections. There were no ESF actuations. At 0556, the licensee identified leakage from a weld on seal water line piping connected to the 1B reactor recirculation pump seal area. The location is within the reactor recirculation loop isolation valves, therefore is isolable from the reactor vessel. The piping is ASME Class 2 and is reactor coolant pressure boundary. The reactor was in Mode 2 at the time of discovery. This event is being reported as a plant shutdown required by technical specifications pursuant to 10CFR50.72(b)(2)(i) and degraded condition pursuant to 10CFR50.72(b)(3)(ii)(A). Activities are continuing to achieve cold shutdown. The licensee informed the Commonwealth of Pennsylvania and the NRC Resident Inspector.
ENS 51854	7 April 2016 19:07:00	10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition	Unanalyzed Condition - High Pressure Fire Suppression Isolated from Containment	This notification is being made as the result of the review of an occurrence on March 30, 2016 at 2220 (EDT) that resulted when a major portion of the site high pressure fire protection (HPFP) system, including fire suppression capabilities for the Main Turbine Building, Auxiliary Building, Control Building, Diesel Generator Buildings, and both Unit 1 and Unit 2 Containments were isolated without having the required compensatory suppression systems established. Upon discovery of the non-functional HPFP system, compensatory fire watches were established and an alternate means to provide water to the HPFP system was aligned. A review of the Sequoyah Nuclear Plant (SQN) Safe Shutdown Analysis identified this loss of fire suppression may not have ensured the required equipment remained available under certain postulated fire scenarios. The analysis determined that the effects of a postulated fire in specific fire areas could have prevented critical systems or components from performing their intended functions, potentially resulting in the inability to achieve and maintain safe shutdown. Analysis identified areas which credit the availability of fire suppression to assure that the safe shutdown capability could have been achieved, the site did not have fire suppression for approximately 45 hours. No actual fire occurred or existed during the time the fire suppression system was not functional. Installed fire detection equipment and communication to the Main Control Room remained available. The condition has been corrected and the HPFP system is functional. At the time of the non-functional HPFP system, it was not recognized that an unanalyzed condition that could have significantly degraded plant safety existed. The condition placed both Unit 1 and Unit 2 in an unanalyzed condition that significantly degraded plant safety and is reportable under 10 CFR 50.72(b)(3)(ii)(B). This 8-hour non emergency notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(B). The condition has been entered into the licensee's corrective action program (CR 1155763) and a License Event Report will be submitted. The NRC Resident Inspector has been notified of this condition. The original clearance that created this event was satisfactory as written, however, one of the valves was leaking and the clearance boundaries were expanded. The clearance was issued at 1411 EDT on 3/29/2016.
ENS 51846	3 April 2016 04:02:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Reactor Protection System Actuation While Reactor Shutdown	At 2302 (CDT) on April 2, 2016, with the plant shutdown, (with) all control rods inserted in the reactor and while attempting to reset the reactor trip breakers to support outage activities (reset of the main turbine), the reactor trip breakers reopened. This was identified to be due to having both trains of Solid State Protection System (SSPS) out of service while in Mode 5. With both trains of SSPS out of service, a condition was met that would cause a reactor trip signal due to having a general warning condition on both trains. Per procedure, the control rods were incapable of withdrawal and fully inserted. Reactor Coolant System boron was 2280 ppm. There were no actuations as a result of the reactor trip breakers opening due to SSPS being removed from service. The licensee will be notifying the NRC Resident Inspector. * * RETRACTION AT 1635 EDT ON 4/4/16 FROM TIM HOLLAND TO JEFF HERRERA * * * At 0713 EDT on April 3, 2016, EN #51846 provided notification of a Reactor Protection System actuation as revealed by the reactor trip breakers opening. Upon further investigation, it has been determined that the system actuated during maintenance activities due to a reactor trip signal caused by both trains of the Solid State Protection System (SSPS) being in test. This signal was not in response to actual plant conditions or parameters satisfying the requirements for initiation of the system and was therefore invalid. As such, the notification made by EN #51846 for a valid actuation of a specified system is hereby retracted. In addition, an editorial change to the first sentence of the original notification description is hereby made. The first sentence is revised to read as follows: At 2303 EDT on April 2, 2016, with the plant shut down and all control rods inserted into the reactor, while attempting to reset the reactor trip breakers to support outage activities (reset of the main turbine), the reactor trip breakers reopened. The NRC Resident Inspector will be notified. Notified the R4DO (Kellar).
ENS 51615	21 December 2015 21:33:00	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 Feedwater Isolation	At 1519 (CST), the Main Turbine was tripped due to an Oscillating Governor Valve 2 (cause not known). At 1533, Unit 1 was manually tripped due to a feedwater isolation P-14 (caused by steam generator swell induced high steam generator level, resulting in) steam generator low level (after the isolation). Aux feedwater actuated as designed. All Control and Shutdown Rods fully inserted. Intermediate Range NI 36 failed above P-10 so SR-Nis (source range nuclear instruments) were manually energized. No primary relief valves lifted. All Steam Generator PORVs (power operated relief valves) opened. There were no electrical bus problems. Normal operating temperature and pressure (NOT/NOP) is 567F and 2235 psig. There were no significant TS LCOs (Technical Specification limiting conditions for operations) entered. This event was not significant to the health and safety of the public based on all safety systems performed as designed. Unit 2 was not affected and continues to operate at 100% power. The licensee has notified the NRC Resident Inspector.
ENS 51474	7 October 2015 10:55:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Unplanned Afw Actuation During Refueling Outage Testing	On October 7, 2015, with McGuire Nuclear Station Unit 2 in Mode 4, operators were testing the main turbine and main feedwater pump turbines, 2A safety injection (SI) train trip functions. At the time of the test, the 2A and 2B Auxiliary Feedwater (AFW) pumps were in operation to provide make-up to the steam generators. The main feedwater system was not in service. During realignment activities from the 2A Sl test, the 2A AFW train actuation signal was unblocked when the '2A AFW auto start defeat' switch was returned to 'reset.' This caused the 2A AFW train control valves to fully open, and the associated steam generator sampling and blowdown valves to close. The actuation occurred as designed and there was no adverse impact to the Unit. Public health and safety were not impacted by this event. Based on a review of the Event Reporting Guidelines and the plant licensing basis, this event was initially determined to be an invalid actuation. However, after further review and discussions with the NRC, Duke Energy concluded the event should be reported as an 8-hour non-emergency in accordance with 10 CFR 50.72 (b)(3)(iv)(A) as a valid actuation of the Auxiliary Feedwater System. A Nuclear Condition Report was initiated for the late notification. The NRC Resident Inspector has been notified.
ENS 51391	14 September 2015 03:05:00	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)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material	Manual Scram Due to Loss of Turbine Building Closed Cooling Water	At 2305 EDT on September 13, 2015, a manual scram was initiated in response to a loss of all Turbine Building Closed Cooling Water (TBCCW). All control rods fully inserted. The lowest Reactor Water Level (RWL) reached was 137 inches. All isolations and actuations for RWL 3 occurred as expected. Decay heat was initially being removed through the Main Turbine Bypass System to the Main Condenser, however, as a result of the loss of TBCCW, the Main Feed Pumps lost cooling and had to be secured. At 2310, Standby Feedwater was initiated and Main Feedwater was secured. The loss of TBCCW also caused all Station Air Compressors (SACs) to trip on loss of cooling. The loss of SACs caused the Instrument Air header pressure to degrade to the point at which the Secondary Containment isolation dampers drifted closed. This resulted in the Reactor Building vacuum exceeding the Technical Specification limit. At 2325, operators started the Standby Gas Treatment system and manually initiated a Secondary Containment isolation signal. Secondary Containment vacuum was promptly restored to within Technical Specification limits. Additionally, Operators were monitoring for expected MSIV drift due to the degraded Instrument Air header pressure. When outboard MSIVs were observed to be drifting, Operators closed the outboard and inboard MSIVs at 2345. At 2352, Safety Relief Valves (SRVs) reached the Low-Low Setpoint and began cycling to control reactor pressure. RWL is currently being maintained in the normal level band with the Standby Feedwater and Control Rod Drive systems. Reactor Pressure is being controlled with Safety Relief Valves. Operators are currently in the Emergency Operating Procedure for Reactor Pressure Vessel control. Investigation into the loss of TBCCW continues. No safety-related equipment was out of service at the time of the event. All offsite power sources were adequate and available throughout the duration of the event. The NRC resident inspector has been notified. * * UPDATE AT 0555 EDT AT 09/14/15 FROM CHRIS ROBINSON TO JEFF HERRERA * * * At 0409 EDT the Reactor Core Isolation Cooling (RCIC) system was placed in service due to identification of an unisolable leak in the Standby Feedwater System. Reactor water level and pressure is now being controlled though the RCIC system and Safety Relief Valves. This event update is reportable as a valid manual initiation of a specified safety system under 10CFR50.72(b)(3)(iv)(A). The NRC resident inspector has been notified. The leak rate was reported as approximately 5-10 gallons per minute from a weld on the standby feedwater pump header drain valve F326. The licensee reported the leak stopped once RCIC was placed into service. The licensee is still investigating the issue. Notified the R3DO (Pelke), IRD Manager (Grant), NRR EO (Morris). * * UPDATE PROVIDED BY CHRIS ROBINSON TO JEFF ROTTON AT 2135 EDT ON 09/14/2015 * * * At 1847 EDT on September 14, 2015, a valid automatic Reactor Protection System (RPS) actuation occurred due to Reactor Water Level 3 while shutdown in MODE 3. Operators were manually controlling Reactor Pressure Vessel (RPV) level and pressure with Reactor Core Isolation Cooling (RCIC) and Safety Relief Valves (SRV). While operators were cycling SRVs, the RPV level went below the Level 3 setpoint. Operators promptly restored RPV level by manual operation of RCIC. The Level 3 actuation and associated isolations were verified to operate properly. The scram signal has been reset. Fermi 2 remains in MODE 3 controlling RPV Level and Pressure through manual operation of RCIC and SRVs. This is the second occurrence of a valid specified safety system actuation reportable under 10CFR50.72(b)(3)(iv)(A) for this ongoing event. The NRC Resident Inspector has been notified. Notified R3DO (Riemer), IRD Manager (Grant), and NRR EO (Morris) * * UPDATE FROM BRETT JEBBIA TO JOHN SHOEMAKER AT 1446 EST ON 2/27/16 * * * This update provides clarification of the applicable reporting criteria for this Event associated with primary containment isolation actuations. Upon the manual reactor scram at 2305 EDT on September 13, 2015, Reactor Protection System (RPS) Level 3 actuated and Primary Containment Isolation System (PCIS) Groups 4, 13 and 15 actuated as expected. The applicable reporting criterion for these actuations is 10 CFR 50.72(b)(3)(iv)(A). The applicable reporting criterion for the manual closure of the inboard and outboard main steam isolation valves at 2345 EDT on September 13, 2015, is also 10 CFR 50.72(b)(3)(iv)(A). In addition, the manual closures of all MSIV lead to a loss of condenser vacuum which resulted in the actuation of PCIS Group 1 at 0001 EDT on September 14, 2015, as expected. The applicable reporting criterion for this actuation is also 10 CFR 50.72(b)(3)(iv)(A). Upon reaching Level 3 at 1847 EDT on September 14, 2015, PCIS Groups 4, 13 and 15 actuated as expected. The applicable reporting criterion for this actuation is 10 CFR 50.72(b)(3)(iv)(A). The licensee informed the NRC Resident Inspector. Notified the R3DO (Stone).
ENS 51268	27 July 2015 13:56:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Valid Actuation of Unit 2 Emergency Feedwater System During Startup	At approximately 0956 EDT on July 27, 2015, Oconee Nuclear Station Unit 2 experienced a valid actuation of the Emergency Feedwater System (EFW). At the time of the event, Unit 2 was in Mode 1 at approximately 17% power and increasing with preparations in progress for placing the main turbine on line during a unit startup. The (EFW) actuation was due to a low level on the 2B steam generator, which resulted from failure of 2B Main Feedwater Block Valve 2FDW-40 to automatically open upon demand. All systems operated as expected with no problems observed. Unit 2 is currently stable at approximately 16% power while troubleshooting valve 2FDW-40 (and the 2B Steam Generator level stable at the normal operating level). Units 1 and 3 were unaffected and remain on line and stable at 100% power. Public health and safety were not impacted by this event. This event is being reported as an 8 hour non-emergency in accordance with 10 CPR 50.72(b)(3)(iv) for a valid actuation of the Emergency Feedwater System. The NRC Resident Inspector has been notified. Corrective Action: Troubleshooting of valve 2FDW-40 is on-going.
ENS 51244	21 July 2015 09:04:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Surry Unit 2 Trip During Reactor Startup	Unit 2 Reactor automatically tripped during Unit start up following a maintenance outage. The first indication of the reactor trip was the annunciator Reactor Trip by Turbine Trip. There were no complications following the trip and Unit 2 is stable at Hot Shut Down. Decay Heat Removal is being maintained by dumping steam to the Main Condenser. Steam Generator water level is being maintained by the Main Feedwater system. At the time of the Reactor Trip, Overspeed Protection Circuitry (OPC) Test was being performed on the Unit 2 Main Turbine. The SOV Turbine Trip annunciator was received. The cause of the reactor trip is under investigation. This notification is being made pursuant to 10 CFR 50.72(b)(2)(iv)(B) for 4-hour notification of Reactor Protection System activation. The Plant responded as expected for the trip. The NRC resident has been notified of the event. There was no radiation release due to this event, nor were there any personnel injuries or contamination events. The licensee has notified the NRC Resident Inspector.
ENS 51087	22 May 2015 14:02:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Manual Reactor Scram Due to Loss of Condenser Vacuum	On Friday, May 22, 2015 at 1002 EDT, with the Reactor Mode Select Switch in the Start-Up position and the reactor at approximately 3 percent core thermal power, while returning to power from Refueling Outage Number 20, a manual reactor scram was inserted due to degrading main condenser vacuum. The cause of the degraded vacuum is currently under investigation. Following the reactor scram, all rods were verified to be fully inserted and no Emergency Operating Procedure entry conditions existed. All plant systems responded as designed. Currently reactor pressure is being maintained at 400 psig with the Mechanical Hydraulic Control System (turbine by-pass valves). Reactor water level is being maintained in normal bands with the Condensate and Feedwater System. Off-site power is being supplied to the station by the Startup Transformer (normal power supply for shutdown operations). This event had no impact on the health and/or safety of the public. The NRC Resident Inspector is on-site and has been notified. The licensee has notified the Massachusetts Emergency Management Agency. The licensee will be issuing a press release. * * UPDATE FROM EVERETT PERKINS TO DONALD NORWOOD AT 1110 EDT ON 5/24/2015 * * * The following was provided by the licensee as clarifying information to the first paragraph of the original event notification: As a conservative measure, the operating crew had previously started reducing power from 20 percent core thermal power when it was first noticed that main condenser vacuum was degrading. This was well before any low condenser vacuum alarms were received. During the shutdown, after already securing the main turbine, the operating crew established benchmark values for degrading condenser vacuum for a normal plant shutdown and for a manual reactor scram should vacuum continue to decline to preclude an automatic scram. The licensee notified the NRC Resident Inspector. Notified R1DO (Dwyer).
ENS 50769	27 January 2015 09:02:00	10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Scram on Turbine Trip Due to Loss of Offsite Power	On Tuesday January 27, 2015 at 0402 hours, with the Pilgrim Nuclear Power Station (PNPS) Reactor Mode Select Switch (RMSS) in Run and reactor power approximately 52% an automatic reactor scram signal was received due to the automatic trip of the main turbine that was initiated by the opening of the main generator breaker, ACB-104. The event occurred during winter storm 'Juno.' Prior to the event off-site transmission Line 355 was de-energized due (to) weather conditions and its associated PNPS switchyard breakers (ACB-105, a main generator breaker and ACB-102), were open. Per station procedures, reactor power was being lowered, a reactor protection system bus had been placed onto a back-up power supply, the Emergency Diesel Generators had been started and were powering the associated safety related 4 KV buses. The second off-site transmission Line 342 de-energized and the associated PNPS switchyard breakers (ACB-104 main generator breaker and ACB-103) opened. The Shutdown Transformer off-site power supply has remained available throughout this event. All control rods were verified to be fully inserted. Per plant design, Primary Containment Isolation System (PCIS) Group lI sampling systems, Group VI Reactor Water Clean-up (RWCU) system and Reactor Building Isolation System (RBIS) isolations occurred. Currently, the EDG's are powering the safety related 4KV buses, reactor water level is being maintained by the Reactor Core Isolation Cooling (RCIC) system and reactor pressure is being maintained by High Pressure Coolant Injection (HPCI) system. The station is conducting a plant cool down at this time. All systems responded as designed with the exception of a non-safety-related diesel air compressor, K-117 that failed to start. The licensee will notify the State and local governments and plans on issuing a press release. The NRC Resident Inspector has been informed.
ENS 50697	20 December 2014 17:12:00	10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release	Offsite Notification Due to Oil Leak from Main Turbine Lube Oil System	At 1212 EST on December 12, 2014, D.C. Cook notified the State of Michigan and local authorities of an oil leak from the Unit 2 Main Turbine Lube Oil Cooler to Lake Michigan. Approximately 2000 gallons have leaked into Lake Michigan since October 25, 2014. No visible oil or oil sheen is present on Lake Michigan or the shore line. The leak is currently isolated as of 1030 EST on December 20, 2014. Leak repairs will be made to the cooler prior to placing back in service. The NRC Resident Inspector was notified. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies. Notified DOE, EPA, USDA, HHS, and FEMA. * * UPDATE FROM PERRY GRAHAM TO HOWIE CROUCH AT 1432 EST ON 12/22/14 * * * The licensee issued a press release about this event this afternoon. Notified R3DO (Dickson).
ENS 50197	12 June 2014 16:47:00	10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition	Inadequate Dc Cable Protection Could Adversely Affect Safe Shutdown	Postulated event could adversely affect safe shutdown equipment. This is a non-emergency notification. While operating at 100 percent power in mode 1, Harris plant personnel determined that inadequate cable protection exists in control cables for a DC powered main turbine lube oil pump. A short circuit could cause excessive current through affected cables, potentially resulting in overheating. The affected cables pass through the Control Room and other areas and could adversely affect safe shutdown. Compensatory measures (hourly fire watches) have been implemented for affected areas of the plant which ensures continued public safety. This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. The NRC Resident Inspector has been notified.
ENS 49928	19 March 2014 03:52:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Reactor Scram Due to Failure to Control Main Turbine Moisture Separator Level	At 2252 on 03/18/2014, the Unit 3 reactor automatically scrammed due to a turbine trip from a high Main Turbine moisture separator level. Initial indications show the level controller for 3B2 Moisture Separator failed to adequately maintain level. Additionally local manual control attempts failed to restore moisture separator level. Main Steam Isolation Valves remained open with main turbine bypass valves controlling reactor pressure. Reactor feedwater pumps are in service to control reactor water level. Primary Containment Isolation System Groups 2, 3, 6 and 8 containment isolation and initiation signals were received. Upon receipt of these signals all required components actuated as required. Neither High Pressure Coolant Injection nor Reactor Core Isolation Cooling initiation signals were received. The reactor had been operating near 35% power during scheduled power ascension. This event is reportable within 4 hours per 10CFR 50.72(b)(2)(iv)(B) 'any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.' It is also reportable within 8 hours per 10CFR 50.72(b)(3)(iv)(A) and requires an LER within 60 days per 10CFR 50.73(a)(2)(iv)(A). NRC Resident Inspector has been notified.
ENS 49903	12 March 2014 18:00:00	10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition	Unanalyzed Condition Due to a Postulated Hot Short That Could Affect Safe Shutdown Equipment	A review of industry operating experience (NRC Event Number 49889) regarding the impact of unfused Direct Current (DC) circuits has determined the described condition to be applicable to Millstone Power Station Unit 3 (MPS3) resulting in an unanalyzed condition with respect to fire safe shutdown requirements. In the postulated event, a fire induced hot short could adversely impact safe shutdown equipment. The MPS3 Main Turbine Emergency Bearing Oil Pump and Main Generator Emergency Seal Oil Pump control and indication circuits route to the main control room. It is postulated that a fire in one fire area can damage the cable and cause short circuits without protection that would overheat the cable and possibly result in secondary fires in other fire areas where the cables are routed. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by the approved fire protection program. Interim compensatory measures (i.e., fire watches) have been implemented for affected areas of the plant. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. The licensee notified the State of Connecticut and the town of Waterford.
ENS 49902	12 March 2014 18:00:00	10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition	Unanalyzed Condition Due to a Postulated Hot Short That Could Affect Safe Shutdown Equipment	A review of industry operating experience (NRC Event Number 49889) regarding the impact of unfused Direct Current (DC) circuits has determined the described condition to be applicable to Millstone Power Station Unit 2 (MPS2) resulting in an unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements. In the postulated event, a fire induced hot short could adversely impact safe shutdown equipment. The MPS2 Main Turbine Emergency Lube Oil pump control and indication circuits route to the main control room. It is postulated that a fire in one fire area can damage this cable and cause short circuits without protection that would overheat the cable and possibly result in secondary fires in other fire areas where the cables are routed. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R. Interim compensatory measures (i.e., fire watches) have been implemented for affected areas of the plant. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. The licensee notified the State of Connecticut and the town of Waterford.
ENS 49608	5 December 2013 08:25:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Scram Following Turbine Trip on High Moisture Separator Level	While operating at 76% power on 12/5/13 at 0325 EST, the main turbine tripped on moisture separator hi level. The reactor scrammed along with the main turbine trip. All safety systems responded as designed and expected. There was no radiological release. There were no injuries. During the scram, all rods inserted into the core. Plant is stable in Mode 3 in its normal S/D (shutdown) electrical line up. Decay heat is being removed via the turbine bypass valves dumping steam to the main condenser. At 0505 EST while securing from cooldown in an attempt to start a recirc pump, BPVs (Bypass Valve) opened causing reactor level swell and subsequent shrink. During this time, RPV (Reactor Pressure Vessel) level lowered to below RPV level 3 and caused a RPS (Reactor Protection System) actuation. RPV level was recovered and is now stable in normal band. The licensee has notified the NRC Resident Inspector. * * UPDATE ON 12/5/13 AT 1000 EST FROM LINDSAY KOBERLEIN TO DONG PARK * * * This update to ENS #49608 adds reporting criterion 10CFR50.72(b)(3)(iv)(A) for the RPS actuation at 0505 EST during post-scram recovery. The licensee notified the NRC Resident Inspector and the Lower Alloways Creek township. The licensee will be making a press release. Notified R1DO (Cook).
ENS 49592	1 December 2013 11:13:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Scram Due to Main Turbine Trip	While operating at 100% power on 12/01/2013, at 0613 EST, the main turbine tripped on moisture separator hi level. The reactor scrammed along with the main turbine trip. All safety systems responded as designed and expected. There was no radiological release. There were no injuries. During the scram, all rods inserted into the core. The plant is stable in mode 3 in its normal shutdown electrical line up. Decay heat is being removed via the turbine bypass valves dumping steam to the main condenser. The licensee notified the NRC Resident Inspector and will be notifying Lower Alloways Creek township.
ENS 49497	2 November 2013 02:47:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Trip During Solid State Protection System Testing	At 2147 CDT on 11/1/2013, Unit 2 Reactor tripped during Solid State Protection System Slave Relay Testing. This test utilizes a blocking circuit to verify the operability of the slave relay which trips the Main Turbine and both Main Feedwater pump turbines, on a Hi-Hi Steam Generator level or Safety Injection. No valve actuation is expected to occur. While positioning the Slave Relay switch in a testing lineup, the relay actutated. The Unit 2 Turbine tripped as well as both Main Feedwater Pumps. The Turbine Trip actuated the Reactor Trip since power was above 50%. The trip of both Main Feedwater Pumps started both Motor Driven Auxiliary Feedwater Pumps. The Steam Generator Lo Lo Levels started the Turbine Driven Auxiliary Feed Water Pump. All systems responded as expected. Currently, Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IPO-007B and the Emergency Response Guideline Procedure Network has been exited. Decay Heat is being rejected to the Main Condenser via Steam Dump Valves (Turbine Bypass Valves). The licensee has notified the NRC Resident Inspector.
ENS 49168	8 May 2013 01:14:00	10 CFR 50.73(a)(1), Submit an LER	Invalid Actuation of Emergency Diesel Generators	This 60-day telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of the Emergency Diesel Generators (EDGs) reportable under 10 CFR 50.73(a)(2)(iv)(A). Due to the shared configuration of the onsite AC Electrical Distribution System, this event is applicable to both Units 1 and 2. On May 7, 2013, at approximately 2114 hours Eastern Daylight Time (EDT), while Operations personnel were making preparations for Unit 2 main turbine generator synchronization to the grid, a Main Generator Reverse Power Trip occurred. Main Generator Reverse Power Trip was actuated after adjusting the Manual Voltage Regulator on the Main Generator. The reverse power relay operates the Generator Primary Lockout which initiates a turbine trip and start of all four EDGs. These features functioned as designed. The main generator breaker was open at the time of the event; as such, electrical power was not lost to the emergency busses. All four EDGs started and operated as expected. Because electrical power was never lost to the emergency busses and none of the EDGs loaded to their respective emergency busses, the actuations were considered to be partial. The EDGs were returned to their standby line-up by 2229 hours on May 7, 2013. Since no actual bus under voltage condition existed which required the EDGs to start and the start was not in response to actual plant conditions satisfying the requirements for initiation, this event has been classified as an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The licensee has notified the NRC Resident Inspector.

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