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The query [[Category:ENS Notification]] [[Site::Watts Bar]] [[Scram::+]] was answered by the SMWSQLStore3 in 0.6670 seconds.


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 Entered dateSiteRegionScramReactor typeEvent description
ENS 542521 September 2019 00:09:00Watts BarNRC Region 2Manual ScramWhile operating at 100 percent power, the Watts Bar Unit 1 reactor was manually tripped at 2055 EDT on August 31, 2019 due to loss of steam generator #2 level control. The trip was not complex. All control and shutdown bank rods inserted properly in response to the manual reactor trip. All safety systems, including Auxiliary Feedwater, actuated as designed. Operations responded and stabilized the plant. Decay heat is being removed by the Auxiliary Feedwater and the Steam Dump System. Unit 2 is not affected. The cause of the loss of steam generator water level control is being investigated. The manual actuation of the Reactor Protection System (RPS) is being reported as a four hour report under 10 CFR 50.72 (b)(2)(iv)(B). The automatic actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 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 Resident Inspector was notified."
ENS 5407722 May 2019 05:45:00Watts BarNRC Region 2Manual ScramOn May 22, 2019, at 0233 EDT, Watts Bar Nuclear Plant (WBN) Unit 2 reactor was manually tripped due to a failure of the #2 Main Feedwater Regulating Valve during power ascension following a refueling outage. 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 Steam Dumps. Unit 2 is in a normal shutdown electrical alignment. This reactor trip and system actuation is being reported under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(2)(iv)(B). There was no impact to WBN Unit 1. The NRC Senior Resident has been notified."
ENS 5369727 October 2018 16:52:00Watts BarNRC Region 2Manual ScramOn October 27, 2018, at 1533 EDT, Watts Bar Nuclear (WBN) Plant Unit 1 reactor was manually tripped due to a failure of the #3 Reactor Coolant Pump normal feeder breaker to close during the planned power transfer to unit power following startup. Concurrent with the reactor trip, the Auxiliary Feedwater system actuated as designed. All Control and Shutdown rods fully inserted. (Main Steam Isolation Valves) MSIVs were required to be isolated due to cooldown. All safety systems responded as designed. The unit is currently stable in Mode 3, with decay heat removal via Auxiliary Feedwater and Steam Generator Atmospheric Dump Valves. Unit 1 is in a normal shutdown electrical alignment. This reactor trip and system actuation is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72 (b)(2)(iv)(B). There was no effect on WBN Unit 2. The NRC Senior Resident has been notified."
ENS 5355722 August 2018 11:23:00Watts BarNRC Region 2Automatic ScramAt 0943 EDT on August 22, 2018, the Watts Bar Unit 2 reactor automatically tripped while operating at 100 percent power. All control and shutdown bank rods inserted properly in response to the automatic reactor trip. All safety systems including Auxiliary Feedwater actuated as designed. The plant is stable with decay heat removal through Auxiliary Feedwater and Steam Dump Systems. The reactor automatically tripped due to a main turbine trip signal. An investigation is in progress. The automatic actuation of the Reactor Protection System (RPS) is being reported as a four-hour report under 10 CFR 50.72 (b)(2)(iv)(B). The expected actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight-hour report under 10 CFR 50.72 (b)(3)(iv)(A). The NRC Senior Resident Inspector has been notified for this event."
ENS 5346722 June 2018 12:14:00Watts BarNRC Region 2Automatic ScramAt 0841 EDT on June 22, 2018, the Watts Bar Unit 2 reactor automatically tripped while operating at 95% power. All control and shutdown bank rods inserted properly in response to the automatic reactor trip. All safety systems including Auxiliary Feedwater actuated as designed. The plant is stable with decay heat removal through Auxiliary Feedwater and Steam Dump Systems. The reactor automatically tripped due to a main turbine trip. The turbine trip was caused by main generator electrical trip. An investigation is in progress. The automatic actuation of the Reactor Protection System (RPS) is being reported as a four hour report under 10 CFR 50.72 (b)(2)(iv)(B). The expected actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv)(A). The NRC Senior Resident Inspector has been notified for this event. The plant is currently stable at normal operating temperature and pressure. The grid is stable and the plant is in its normal shutdown electrical lineup. Unit 1 was unaffected by the Unit 2 trip.
ENS 5332712 April 2018 12:14:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopAt 0920 EDT on April 12, 2018, the Watts Bar Unit 2 reactor automatically tripped while operating at 100 percent power. All control and shutdown bank rods inserted properly in response to the automatic reactor trip. All safety systems including Auxiliary Feedwater actuated as designed. The plant is stable with decay heat removal through Auxiliary Feedwater and Steam Dump Systems. The cause of the automatic reactor trip is being investigated. The automatic actuation of the Reactor Protection System (RPS) is being reported as a four-hour report under 10 CFR 50.72 (b)(2)(iv)(B). The expected actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight-hour report under 10 CFR 50.72 (b)(3)(iv)(A). The NRC Senior Resident Inspector has been notified for this event. The plant is currently stable at normal operating temperature and pressure. The grid is stable and the plant is in its normal shutdown electrical lineup. Unit 1 was unaffected by the Unit 2 trip.
ENS 5311211 December 2017 11:06:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopWhile operating at 97% power, the Watts Bar Unit 2 reactor was manually tripped at 0857 EST on December 11, 2017 due to multiple dropped control rods. All control and shutdown bank rods inserted properly in response to the manual reactor trip. All safety systems including Auxiliary Feedwater actuated as designed. The plant is stable with decay heat removal through Auxiliary Feedwater and the Steam Dump System. The cause of the dropped rods is being investigated. The manual actuation of the Reactor Protection System (RPS) is being reported as a four hour report under 10 CFR 50.72 (b)(2)(iv)(B). The actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv)(A). The NRC Senior Resident Inspector has been notified for this event. No safety or relief valves lifted during this event.
ENS 5287225 July 2017 11:07:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn July 25, 2017, at 0428 Eastern Daylight Time (EDT) Watts Bar Nuclear Plant (WBN) Unit 2 was in Mode 3, beginning a Reactor Startup. While in the initial phase of withdrawing the first of four Control Rod banks, the two associated group demand position indicators deviated greater than 2 steps from each other. In accordance with Technical Requirement 3.1.7, Position Indication System, Shutdown, with one or more group demand position indicators inoperable, the reactor trip breakers are to be opened immediately. Operations personnel opened the reactor trip breakers immediately by initiating a manual trip of the Reactor Protection System (RPS). The Auxiliary Feedwater system was in service and controlling Steam Generator water levels at the time of the event and did not receive any valid actuation signals. No other system actuations occurred as a result of this reactor trip and all systems operated as designed. The cause of the position indication system inoperability is currently under investigation. NRC Resident Inspector has been notified.
ENS 527324 May 2017 19:53:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn May 4th, 2017, at 1709 EDT, Watts Bar Nuclear Plant Unit 1 reactor was manually tripped due to a failure of the #3 Reactor Coolant Pump normal feeder breaker to close during the planned power transfer to unit power following startup. 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 Steam Generator Atmospheric Dump Valves. Unit 1 is in a normal shutdown electrical alignment. This reactor trip and system actuation is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72(b)(2)(iv)(B). There was no effect on WBN Unit 2. The NRC Senior Resident (Inspector) has been notified.
ENS 527252 May 2017 22:33:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn May 2nd, 2017, at 1945 EDT, Watts Bar Nuclear (WBN) Plant Unit 1 reactor was manually tripped due to a failure of the #3 Reactor Coolant Pump normal feeder breaker to close during the planned power transfer to unit power following startup. 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 1 is in a normal shutdown electrical alignment. This reactor trip and system actuation is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72 (b)(2)(iv)(B). There was no effect on WBN Unit 2. The NRC Senior Resident (Inspector) has been notified.
ENS 5262520 March 2017 10:17:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn March 20, 2017 at 0813 EDT, Watts Bar Nuclear Plant (WBN) Unit 2 operations personnel manually tripped the plant from approximately 91 percent power based on lowering steam generator levels. Prior to the plant trip, the 2A Hotwell pump tripped at 0758 EDT and the 2C Condensate Booster Pump subsequently tripped at 0802 EDT. Operations personnel commenced to lower plant power after the 2A Hotwell pump trip in an attempt to maintain steam generator levels, but were unable to recover level and manually tripped the unit. All control rods fully inserted and all automatically actuated safety related equipment operated as designed. At 0905 EDT, operations personnel exited the emergency operating instructions after the plant was stabilized. The cause of the event is under investigation. This event is reportable to the NRC within four hours under 10 CFR 50.72(b)(2)(iv)(B) as a result of the actuation of the Reactor Protection System and in eight hours under 10 CFR 50.72(b)(3)(iv)(A) as a result of actuation of the Auxiliary Feedwater system. The licensee notified the NRC Resident Inspector.
ENS 5219423 August 2016 15:30:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn August 23, 2016, at 1356 EDT, Watts Bar Nuclear Plant (WBN) Unit 2 reactor was manually tripped due to a loss of main feedwater. 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 cause is currently under investigation. This is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72(b)(2)(iv)(B). There was no effect on WBN Unit 1. The NRC Senior Resident Inspector has been notified.
ENS 5083921 February 2015 12:46:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn February 21, 2015 at 10:32 EST, Watts Bar Nuclear Plant Unit 1 reactor was manually tripped due to rapidly dropping main condenser vacuum. 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 S/G PORVs. Main Steam Isolation Valves are closed. The Station is in a normal shutdown electrical alignment. The cause is currently under investigation. This is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72 (b)(2)(iv)(B). The NRC Senior Resident has been notified. This event had no affect on Unit 2 (Under Construction)
ENS 5027813 July 2014 23:13:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn July 13, 2014 at 1937 (EDT), Watts Bar Nuclear Plant Unit 1 reactor was manually tripped due to automatic isolation of all low pressure feedwater heaters. 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, steam dumps and the main condenser. The station is in a normal shutdown electrical alignment. The cause is currently under investigation. This is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72 (b)(2)(iv)(B). The NRC Senior Resident (Inspector) has been notified. Initial indications are that a level switch failed on the #7 heater drain tank which caused the heater drain tank pumps to trip. When the high level tank setpoint was reached, the feedwater system isolated.
ENS 4915428 June 2013 16:34:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopOn June 28, 2013 at 1330 (EDT), Watts Bar Nuclear Plant Unit 1 reactor automatically tripped due to an electrical fault causing a main generator lockout and subsequent turbine trip. The electrical fault generated an 'A' Main Bank Transformer Differential Relay actuation. Suspected cause is due to an offsite fault. This is being reported under 10CFR50.72(b)(2)(iv)(B). Concurrent with the reactor trip the Auxiliary Feedwater system actuated as designed. This is being reported under 10CFR50.72(b)(3)(iv)(A). 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, steam dumps and the main condenser. The station is in a normal shutdown electrical alignment. The NRC Senior Resident has been notified. There were no primary or secondary relief valve actuations during the plant transient. The cause of the electrical fault is being investigated.
ENS 4823828 August 2012 06:13:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopOn August 28, 2012, Watts Bar Nuclear Plant Unit 1 reactor automatically tripped due to low level in steam generator (SG) #2. The low level resulted when the Main Feedwater Control Valve for SG#2 (1-FCV-3-48) failed closed. This is being reported under 10CFR 50.72 (b)(2) (iv) (B). Concurrent with the reactor trip the Auxiliary Feedwater system actuated as designed. This is being reported under 10CFR 50.72(b)(3) (iv)(A). All Control and Shutdown rods fully inserted. All safety systems responded as designed. The unit is currently stable in Mode 3. The NRC Senior Resident has been notified. Decay heat is being removed to the main condenser via condenser steam dumps. The plant is in its normal shutdown electrical lineup. No steam safety or relief valves lifted during the event.
ENS 4690229 May 2011 04:25:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopAt 0155 EDT, the Watts Bar Unit 1 reactor tripped from 100% power due to a turbine trip above P-9 (reactor trip on turbine trip permissive). The cause of the turbine trip is under investigation at this time. All systems functioned as designed with the exception of Pressurizer Backup Heaters which failed to energize on lowering Pressurizer pressure. The unit is stable in Mode 3 with Auxiliary Feedwater supplying the Steam Generators. The electrical system is in normal shutdown alignment with all Emergency Diesel Generators available in standby. There are no abnormal radiological conditions at this time. The reason the Pressurizer Backup Heaters failed to energize is unknown at this time. All control rods fully inserted. No relief valves or safety valves lifted. The licensee notified the NRC Resident Inspector.
ENS 4641814 November 2010 09:05:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopAt 0617 (hrs. EST), Watts Bar experienced a failure of the cooling system to the 'A' phase Main Bank Transformer. Due to rising oil temperatures on the 'A' phase Main Bank Transformer, the reactor was manually tripped at 0652 hrs. All systems responded as designed with no issues. All rods inserted during the trip. There were no primary or secondary relief valves that lifted during the transient. The grid is stable and the plant is in a normal shutdown electrical line-up. The reactor is at normal pressure and temperature with decay heat being removed via the steam dumps to condenser with auxiliary feedwater providing steam generator make-up. The cause of the loss of cooling to the 'A' phase Main Bank Transformer was the failure of a control power transformer that supplies the Main Bank Transformer cooling system components. The licensee has notified the NRC Resident Inspector.
ENS 4594421 May 2010 22:57:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopAt 1937 Eastern Daylight Saving Time (EDT), Watts Bar Nuclear Power Plant Unit 1 experienced a reactor trip due to a turbine trip. This caused an automatic AFW Pump start from P-4 coincident with Lo Tave signal. The cause of the turbine trip has not yet been identified, and is under investigation. The plant is stable and is being maintained in Mode 3, at normal operating pressure and temperature, with steam generator and pressurizer levels normal. Plant systems responded to return the plant to a stable condition without complication, and all systems performed as expected with one exception: The 'B' Motor Driven Auxiliary Feedwater Backpressure Control Valve failed closed, but the Steam Driven Auxiliary Feedwater Pump provided sufficient feedwater so that all Steam Generators were provided sufficient feedwater to maintain cooling and normal steam generator level. Plans for plant restart are pending awaiting the cause investigation. All control rods inserted into the core. Plant decay heat removal is through the steam dumps to the main condenser. Offsite power is available and lined up to plant system loads. Watts Bar (NRC) Resident Inspector has been notified of this event.
ENS 443887 August 2008 04:12:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopOn August 7, 2008 at 0228 EDT, TVA was reducing reactor power in preparation for a planned reactor shut down. While at approximately 50% power, the feedwater system isolated due to high levels in the low pressure heater strings. Based on the condition stated, the reactor was manually scrammed. All systems functioned as designed in response to the scram. The plant is currently being maintained in Mode 3 Hot Standby condition. All control rods fully inserted on the manual trip. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the main condenser. Offsite power is supplying safety buses and emergency diesel generators are available if required. The licensee notified the NRC Resident Inspector.
ENS 4274431 July 2006 14:13:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopAt approximately 1213 hours on July 31, 2006, with Watts Bar Nuclear Plant Unit 1 operating normally at 100% power, the main generator tripped resulting in a reactor trip per design. All control rods inserted (fully) and the auxiliary feedwater system (AFW) automatically actuated per design and the reactor was stabilized in mode 3. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) for the reactor trip (4-hour report) and under 10 CFR 50.72(b)(3)(iv)(A ) for the RPS (reactor protection system) and AFW actuations (8-hour report). The cause of the generator trip is currently under investigation. Steam is being released via steam dump to the condenser and all systems functioned as required. The licensee notified the NRC Resident Inspector.
ENS 4261030 May 2006 20:02:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-Loop

At approximately 1700 hours on May 30, 2006, with Watts Bar Nuclear Plant Unit 1 operating normally at 100% power, main turbine vibration increased to a value above the procedure limit and reactor operators manually tripped the reactor in accordance with site procedure requirements. All control rods inserted and the auxiliary feedwater system automatically actuated per design. No other significant equipment issues were identified and the reactor was stabilized in mode 3. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) for the manual reactor trip (4-hour report) and under 10 CFR 50.72(b)(3)(iv)(A) for the RPS and AFW actuations (8-hour report). Watts Bar had been monitoring indications of slightly elevated turbine vibration on the main turbine, but the reason for the increase above the procedure limit of 14 mils is not known at this time. TVA will be investigating the cause of the increased vibration to make necessary repairs before turbine startup. Decay heat is being removed by dumping steam to the main condenser. No safety or relief valves lifted. The licensee notified the NRC Resident Inspector.

  • * * UPDATE FROM LICENSEE (R. CREWS) TO M. RIPLEY 0020 EDT 06/02/06 * * *

As a result of the initial assessment of the turbine vibration discussed above, TVA has identified damage to the turbine end of the 'C' low pressure turbine. This is consistent with the initial indications of high vibration on the number 7, 8 and 9 bearings and not thought to be associated with previous condition monitoring of the number 11 bearing. Assessment and repair of secondary plant components damaged in the transient are in progress. The licensee will notify the NRC Resident Inspector. Notified R2DO (C. Ogle)

ENS 4105419 September 2004 07:46:00Watts BarNRC Region 2Manual ScramWestinghouse PWR 4-LoopThe following was received from the licensee via facsimile: While operating at 100% power, the Watts Bar Unit 1 reactor was manually tripped at approximately 0456 EDT on September 19, 2004, in response to an apparent four dropped rods in control bank 'B'. The cause of the dropped rods is being investigated. Safety systems functioned as expected in response to the trip. All control rods inserted properly in response to the reactor trip. The Auxiliary Feedwater (AFW) System actuated as designed in response to the trip. One reactor coolant pump (RCP) did not transfer to its alternate power supply. The manual actuation of the Reactor Protection System (RPS) is being reported as a four hour report under 10 CFR 50.72 (b)(2)(iv). The actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv). Notification to NRC was made by Rick O'Rear at 0744 EDT. The NRC Senior Resident Inspector was notified of this event. The licensee also reported that the reactor is being maintained at the normal temperature and pressure for this condition. All station service electrical systems and the emergency diesel generators are available and in normal configuration. All emergency core cooling systems are available. Decay heat is being removed using steam dump to the main condenser and feedwater to the steam generators is being provided by the electric main feedwater pump.
ENS 4045416 January 2004 13:48:00Watts BarNRC Region 2Automatic ScramWestinghouse PWR 4-LoopAt 1137 hours EST on January 16, 2004, with Watts Bar Unit 1 in Mode 1 at 100 % power, a turbine trip and reactor trip occurred. This is reportable as a 4-hour notification under 10 CFR 50.72 (b)(2)(iv)(B) and an 8-hour notification under 10 CFR 50.72 (b)(3)(iv)(A). In addition, per design, there was auto start of the Auxiliary Feedwater system which is reportable as an 8-hour notification under 10 CFR 50.72 (b)(3)(iv)(A). Plant safety systems performed as designed and the reactor is currently stable in mode 3. At the time of the trip, plant personnel were performing scheduled Solid State Protection System (SSPS) surveillance testing on the B Train Reactor Trip Breaker. Plant personnel are currently investigating the cause of the event. The licensee also reported that all control rods inserted on the reactor trip, no primary or secondary system relief valves operated, and that reactor temperature is being maintained using steam dump to the condenser. Steam generator water levels are being maintained using auxiliary feedwater. The station electrical system is available and in a normal configuration. All ECCS equipment is available. The reactor is currently stable at 2230 psig, 559 degrees Fahrenheit. The licensee has notified the NRC Resident Inspector.