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 Discovered dateReporting criterionTitleEvent description
ENS 5409529 May 2019 04:00:0010 CFR 21.21(d)(3)(i), Failure to Comply or DefectEn Revision Imported Date 6/10/2019

EN Revision Text: PART 21 NOTIFICATION - INTROL POSITIONERS POTENTIAL LATENT DEFECT The following is an excerpt of the Part 21 information received via email: Introl Positioners used by stations in G32 Terry Turbine control applicators have the potential to contain a latent defect. The defect is the result of internal corrosion which has been identified in Tl Operational Amplifiers Part No.TL084CN on the SL3EX Controller Boards of the turbine throttle valve positioner. It is believed the likely cause is associated with the ingress of solder flux into the IC Chip package on the controller board due to delamination caused by the soldering process during fabrication. The corrosion over time can result in intermittent open circuiting and high resistance in the aluminum metallization. Chlorine ionic contamination can also result in high leakage currents within the component circuitry. Failures may be manifested by a reduced valve position signal disproportional to the expected demand condition, no actuation signal (i.e. throttle valve remaining full open), or other anomalous unexpected behavior. There are three TL084CN chips on each SL3EX Controller Board within the positioner assembly. There have been two documented failures to date occurring in 2015 and 2019 in installed systems. Date determination was made: May 29, 2019 Affected sites: Farley, SONGS, Cooper, Almaraz Trillo Nuclear Power Plant (Spain), Clinton, Harris, Wolf Creek, Point Beach, Hatch, Watts Bar, Sequoyah. Stations are advised to work directly with Curtiss-Wright SAS via the technical contacts below. Randy F. Iantorno Project Manager, T: 585.596.3831, M: 585.596.9248, email riantorno@curtisswright.com or Justin Pierce 585.596.3866.

  • * * UPDATE FROM RANDY IANTORNO (CURTISS-WRIGHT) TO DONALD NORWOOD AT 1537 EDT ON 6/7/2019 * * *

The following is a synopsis of information received via E-mail: Shearon Harris Nuclear Plant experienced an overspeed trip of the Turbine Driven Auxiliary Feedwater Pump (TDAFW) on January 18, 2019 during routine system testing. Upon receipt of the initial start signal, the valve remained in the fully open position causing the TDAFW to trip on overspeed. Investigation into the overspeed trip revealed the positioner was not controlling the actuator properly in response to the governor command signal. This situation and subsequent troubleshooting led to replacement with the site spare positioner. Once installed, the system responded as expected and the suspect positioner was sent to Curtiss-Wright SAS (CW SAS) for evaluation. In a joint effort between CW SAS and Paragon Energy Solutions (PES), the positioner was tested and evaluated to determine the cause of the failure. Corrective action which has been, is being, or will be taken: - The three TI chips on the affected board have been successfully replaced at PES. The repaired positioner will be configured and returned to Shearon Harris. - The evaluation of suspect chips has been limited to those removed from the failed positioner, along with some supplied to PES by CW SAS. Work is ongoing in this area. - A complete list of potentially affected installations is listed in the PES Part 21 Report dated May 31, 2019. - Although this defect has the potential of preventing the Electronic Governor Speed Control System (EGSCS) from performing its intended safety function, it does not prevent the Terry Steam Turbine from operating. If the EGSCS fails, the turbine can be operated manually using the Trip and Throttle Valve (TTV) to control speed by regulating steam flow to the turbine. - Steps are being taken to develop a plan to replace chips on affected positioner boards. This is still in the preliminary stages and specific recommendations will follow. Notified R1DO (Carfang), R2DO (Rose), R3DO (Kozak), R4DO (Kellar), Part 21 Reactors E-mail group, and Part 21 Materials E-mail group.

ENS 5408724 May 2019 18:10:0010 CFR 50.72(b)(3)(iv)(A), System ActuationLoss of Offsite Power Due to Fire on Startup TransformerAt 1310 CDT on 5/24/2019, Wolf Creek experienced a loss of offsite power to the safety-related NB02 bus, due to an external fire on a bushing on the startup transformer. The NB02 bus was reenergized when the 'B' Emergency Diesel Generator started and the output breaker automatically closed. The shutdown sequencer automatically started equipment as expected. Due to the undervoltage condition on the NB02 bus, an AFAS-T (Auxiliary Feedwater Actuation Signal) signal was generated which started the turbine driven auxiliary feedwater pump. Turbine load was reduced to maintain reactor power less than 100% in response to the start of turbine driven and 'B' motor driven auxiliary feedwater pumps. The fire was extinguished using a fire extinguisher at 1320 CDT. The unit is stable at 97% power. The NB02 bus remains on the 'B' Emergency Diesel Generator (EDG). The other EDG is operable in standby. The NRC Resident Inspector was notified.
ENS 5407722 May 2019 06:33:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Due to Failure of Main Feedwater Regulating ValveOn 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 5407218 May 2019 15:08:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Due Grid DisturbanceThis is a non-emergency notification to the NRC Operations Center in accordance with 10 CFR 50.72(b)(2)(iv)(B) for a valid actuation of the Reactor Protection System (RPS) (four hour notification) and 10 CFR 50.72(b)(3)(iv)(A) for a valid Engineered Safeguards (ESF) actuation (eight hour notification) due to Auxiliary Feedwater (AFW) initiation. Unit 3 manual reactor trip following grid disturbance. Following the grid disturbance, a manual reactor trip was initiated due to lowering steam generator water levels. All control rods fully inserted. AFW started as expected. All other systems responded as expected. Current reactor temperature is 547 degrees F. Current reactor pressure is 2235 psig. Decay heat is being removed through the Atmospheric Steam Dumps (no known primary to secondary Reactor Coolant System leakage exists). The unit is in a normal post-trip electrical lineup. There was no affect on Unit 4. The cause of the grid disturbance is under investigation. The licensee notified the NRC Resident Inspector.
ENS 5406917 May 2019 04:03:0010 CFR 50.72(b)(3)(iv)(A), System ActuationEn Revision Imported Date 6/6/2019

EN Revision Text: REACTOR TRIP DUE TO SOURCE RANGE HI FLUX SIGNAL This is an 8-hour, non-emergency notification for a valid reactor trip signal with the reactor not critical, and a valid auxiliary feedwater system actuation in accordance with 10 CFR 50.72(b)(3)(iv)(A) - Valid System Actuation.

At 2303 (CDT) on May 16, 2019, the plant was administratively in mode 2 due to withdrawing control rods for startup following refuel. The reactor had not been declared critical. The P-6 permissive at 10E-10 Amps was met for one of two Intermediate Range detectors allowing for block of the Source Range high flux trip (1E5CPS). Prior to performing the block, the Source Range high flux trip setpoint was exceeded and a reactor trip received. All systems responded as expected. A feedwater isolation signal was received due to the reactor trip with feedwater temperature less than 564 degrees Fahrenheit. Auxiliary feedwater was started to maintain steam generator levels. The plant is being maintained stable in mode 3 with no complications. The NRC Resident Inspector was present during the startup and was notified of the reactor trip.

  • * * UPDATE FROM JONATHAN LAUF TO HOWIE CROUCH AT 1454 EDT ON 6/5/19 * * *

A correction is being made for the sixth sentence in the second paragraph above, which states, 'A Feedwater Isolation signal was received due to the reactor trip with feedwater temperature less than 564 degrees Fahrenheit.' Within this sentence, 'feedwater temperature' is to be replaced with 'reactor coolant system temperature.' The licensee has notified the NRC Senior Resident Inspector.

ENS 5406415 May 2019 02:51:0010 CFR 50.72(b)(3)(iv)(A), System ActuationVoltage Transient Due to Loss of Offsite SwitchyardAt 2151 CDT, on 14 May 2019, Comanche Peak Nuclear Power Plant (CPNPP) experienced a voltage transient within the onsite 138kV switchyard due to the loss of one of the offsite switchyards supplying power to the CPNPP 138kV switchyard. The reduction in safeguards bus voltage due to the transient caused the Unit 2 safeguard busses to load shed and perform a slow transfer to power supplied from 345kV transformer XST2A. Unit 2 was subjected to actuation of both blackout sequencers causing an automatic start of both motor driven Auxiliary Feedwater (AFW) pumps as well as the turbine-driven AFW pump. No emergency diesel generators started by design. All AFW pumps have been returned to standby status. All other safety systems functioned as designed. Unit 1 is currently defueled, and was unaffected by this event. The licensee has notified the NRC resident inspector."
ENS 540473 May 2019 19:54:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip on Over Temperature Delta TemperatureAt 1554 EDT on 5/3/19, with Unit 1 in Mode 1 at approximately 100 percent power, the reactor automatically tripped on Over Temperature Delta Temperature following a pressure transient in the Reactor Coolant System. The trip was uncomplicated with all systems responding normally post trip. Operations manually started the motor driven auxiliary feedwater pumps and has stabilized the plant. Decay heat is being removed by the condenser. Unit 2 is not affected. Due to Reactor Protection System actuation while critical and actuation of the motor driven auxiliary feedwater pumps, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an 8-hour non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Unit 1 is in a normal electrical lineup. Prior to the automatic trip, the backup pressurizer heaters were in service as is normal during power ascension. The pressure transient started when the backup heaters were in the process of being removed from service. The licensee notified the NRC Resident Inspector.
ENS 5402022 April 2019 18:24:0010 CFR 50.72(b)(3)(iv)(A), System ActuationManual Initiation of the Auxiliary Feedwater System in Response to a Loss of FeedwaterAt 1324 CDT, on 4/22/2019, with unit 2 in Mode 3 at 0 percent power, an intentional manual initiation of the Auxiliary Feedwater System occurred in response to a loss of feedwater condition. The loss of feedwater condition occurred after the non-safety related Startup Feedwater Pump was secured due to high bearing temperatures. The A Train Auxiliary Feedwater Pump was started per procedure. The Auxiliary Feedwater System started and operated as designed following intentional manual initiation. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as 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 5399914 April 2019 07:20:0010 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 Main Feedwater Pump TripAt 0320 EDT, April 14, 2019, Sequoyah Unit 1 experienced an automatic reactor trip. The event was initiated by the trip of the 1A main feedwater pump. During the automatic unit runback, an automatic reactor trip was initiated due to low-low level in Steam Generator number 3. The Auxiliary Feedwater System (AFWS) automatically actuated as required when the expected post-trip feedwater isolation actuated. Reactor Coolant System temperature is being maintained by the AFWS and the steam dump system. During this operational cycle, one control Rod Position Indicator (RPI) for core position E-5 in shutdown bank 'A' has been inoperable, and the appropriate Condition and Required Actions of (Technical Specification Limiting Condition of Operation) 3.1.7 were complied with. Due to this inoperable RPI, the associated shutdown rod is conservatively assumed to be full out and untrippable. Consequently, boration was required to establish adequate shutdown margin. All other Control and Shutdown rods fully inserted. All safety systems responded as designed. No primary or secondary safety valves actuated during or after the reactor trip. The unit is currently stable in Mode 3. Unit 1 is in a normal shutdown electrical alignment. There was no impact on Unit 2. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the AFW system. There was no impact on the health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified."
ENS 5396731 March 2019 01:30:0010 CFR 50.72(b)(3)(iv)(A), System Actuation
10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
Manual Reactor Trip Due to Msiv Failing ClosedAt 2130 (EDT) on March 30, 2019, with Unit 2 in Mode 1 at 30 percent reactor power, the reactor was manually tripped due to a main steam isolation valve failing closed. The trip was not complex, with all systems responding normally. Operations stabilized the plant in Mode 3. Decay heat is being removed through the main steam lines through the steam dumps and into the condenser. 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). Unit 1 was not affected. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspectors have been notified."
ENS 5395424 March 2019 18:45:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Automatic Trip on Turbine TripOn March 24, 2019, at 1445 EDT, Indian Point Unit 2 automatically tripped on a turbine trip due to a loss of excitation. All control rods fully inserted and plant equipment responded normally to the unit trip. This RPS (reactor protection system) actuation is reportable under 10 CFR 50.72(b)(2)(iv)(B). The auxiliary feedwater system actuated following the automatic trip as expected. This specified system actuation is reportable under 10 CFR 50.72(b)(3)(iv)(A). During the event offsite power remained available and stable. No primary or secondary reliefs lifted. Unit 2 is in Mode 3 at normal operating temperature and pressure. Decay heat removal is via the steam generators to the atmospheric steam dumps. No radiation was released. Indian Point Unit 3 was unaffected by this event and remains defueled in a scheduled refueling outage. A post trip investigation is in progress. The licensee has notified the NRC Resident Inspector The New York State Public Service Commission, Consolidated Edison System Operator, and New York State Independent System Operator were also notified.
ENS 5393715 March 2019 17:00:0010 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 Turbine Generator TripOn March 15, 2019 at 1300 EDT, Indian Point Unit 2 automatically tripped offline from mode 1 - 100% power operations. Reactor Operators verified the reactor trip and the plant is currently stable in mode 3. All automatic systems functioned as required. The auxiliary feedwater system actuated following the trip, as expected. All control rods fully inserted upon the trip, as expected. This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(2)(iv)(B). The unit remains on offsite power in hot standby at normal operating temperature and pressure. Decay heat is being removed from the steam generators via the auxiliary feedwater system and the condensate steam dump valves. Unit 3 remains in mode 6 for a scheduled refueling outage. The licensee notified the NRC Resident Inspector, the local transmission company, and New York State Independent System Operator. The Indian Point Unit 2 automatic trip was caused by the trip of the main generator. The cause of the generator trip is unknown at this time.
ENS 539062 March 2019 09:17:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Trip Due to Feedwater Isolation Valve ClosureAt 0317 CST, the Unit 2 Reactor tripped due to Feedwater Isolation Valve (FWIV) 2-04 going closed. All Auxiliary Feedwater Pumps started due to steam generator Lo-Lo levels. Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IPO-007B. The Emergency Response Guideline Procedure Network has been exited. Decay heat is being rejected to the Main Condenser via the Steam Dump Valves. The cause of the FWIV going closed is currently under investigation. All control rods fully inserted and the reactor trip was uncomplicated. Unit 2 is in a normal post-trip electrical line-up. There was no impact on Unit 1 due to the Unit 2 reactor trip. The licensee notified the NRC Resident Inspector.
ENS 5385231 January 2019 08:01:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip - Circulating Water Icing ConditionsAt 0301 (EST) on 1/31/19, with Unit 2 in Mode 1 at 100% power, the reactor was manually tripped due to icing conditions requiring the removal of 4 Circulating Water Pumps from service. The trip was not complex, with all systems responding normally post-trip. 21 CFCU (Containment Fan Cooler Unit) was inoperable prior to the event for a planned maintenance window and did not contribute to the cause of the event and did not adversely impact the plant response to the trip. An actuation of the Auxiliary Feedwater System occurred following the manual reactor trip. The reason for the Auxiliary Feed Water System auto-start was due to low level in a steam generator. Operations responded and stabilized the plant. Decay heat is being removed by the Main Steam Dumps and Auxiliary Feedwater System. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported as an eight hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Auxiliary Feed Water System. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The icing condition was described as frazil ice. Unit-1 reduced power to 88% because one circulating water pump was shutdown.
ENS 538199 January 2019 05:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Trip from Full Power Due to Rps TestingAt 1034 EST on January 9, 2019, with the reactor at 100% power, an automatic reactor trip was initiated. The trip occurred while Reactor Protection System testing was in progress. The trip was uncomplicated with all systems responding normally following the rip. Troubleshooting and investigation of the cause is ongoing. All full-length control rods inserted fully. Auxiliary Feedwater System actuated as designed in response to low steam generator water levels. Operations stabilized the plant in Mode 3 (hot standby). Decay heat is being removed by the turbine bypass valve. This condition has no impact to the health and safety of the public. The licensee notified the NRC Resident Inspector.
ENS 538133 January 2019 05:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Trip Due to Cycling of Turbine Governor ValveAt 2028 (EST) on January 3, 2019, with the reactor at 85% power, the reactor was manually tripped due to cycling of Turbine Governor Valve #4. The trip was uncomplicated with all systems responding normally following the trip. Investigation of the cause of the valve cycling is ongoing. All full-length control rods inserted fully. Auxiliary Feedwater System actuated as designed in response to low steam generator water levels. Operations stabilized the plant in Mode 3 (hot standby). Decay heat is being removed by atmospheric dump valves. This condition has no impact to the health and safety of the public. The licensee notified the NRC Senior Resident Inspector. This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A)."
ENS 5378615 October 2018 04:00:0010 CFR 50.73(a)(1), Submit an LERInvalid Auxiliary Feedwater Pump ActuationThis 60-day telephone notification is being made in accordance with the reporting requirements of 10 CFR 50.73(a)(2)(iv)(A). The successful, complete train actuation of the 22 Auxiliary Feedwater Pump was initiated by an invalid signal during testing. The Auxiliary Feedwater System was not impacted in its ability to perform its function. There were no safety consequences or impacts to the health and safety of the public as a result of this event. The NRC Resident Inspector has been notified."
ENS 537795 December 2018 06:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip on Loss of Main Condenser VacuumAt 1539 (CST) December 5, 2018, with Unit 1 at 100 percent power, the reactor was manually tripped due to degrading condenser vacuum. The trip was uncomplicated with all systems responding normally, post-trip. An actuation of the auxiliary feedwater system occurred during the manual trip. The auxiliary feedwater system automatically started as designed when the valid actuation signal was received. Operations stabilized the plant in mode 3 (hot standby). Decay heat is being removed by atmospheric dump valves. Unit 2 is not affected. 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 loss of condenser vacuum resulted because one of two circulating water pumps was running and its discharge valve shut. The cause for the valve shutting is under investigation. There is no primary to secondary leakage. The licensee notified the NRC Resident Inspector
ENS 537673 December 2018 06:00:0010 CFR 50.72(b)(3)(iv)(A), System ActuationActuation of Blackout Sequencers Due to Loss of One Offsite Power SourceAt 0315 (CST) on 12/3/18, the Comanche Peak Nuclear Power Plant experienced a loss of 138 KV transformer XST1. Unit 1 is currently at 100% power. Unit 2 was subjected to actuation of both blackout sequencers causing an automatic start of both motor driven Auxiliary Feedwater (AFW) pumps as well as the turbine driven AFW pump. No emergency diesel generators started as per design. Train A and B motor driven and the turbine driven AFW pumps have been returned to automatic. All other safety systems functioned per design. The loss of power to 138 KV transformer XST1 resulted in loss of power to both safeguards busses on Unit 2. The busses performed a load-shed and slow transfer to power supplied from 345 KV transformer XST2A as designed and were re-energized and loads sequenced back onto the busses. The emergency diesel generators are not required to start unless the busses are not re-energized by the alternate offsite transformer. All electrical power related actuations functioned as designed. There was no impact on Unit 1. The licensee has notified the NRC Resident Inspector."
ENS 537641 December 2018 08:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip of Unit 2 Due to a Load RejectionAt 1006 (PST), on December 1, 2018, with Unit 2 at 100 percent power, the reactor automatically tripped due to a load rejection from the 500 kV offsite electrical system. Operations responded and stabilized the plant. Decay heat is being removed by the Main Steam system to the main condenser using the steam dump valves. The cause of the load rejection is currently under investigation. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Additionally, due to the actuation of the Auxiliary Feedwater System, as expected, this event is being reported per 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Senior Resident Inspector was notified. A press release is planned for this event. All control rods fully inserted and the trip was uncomplicated. There was no effect on Unit 1.
ENS 5374519 November 2018 05:00:0010 CFR 50.72(b)(3)(iv)(A), System ActuationEmergency Diesel Generator Actuation Due to Low Voltage SignalOn 11/19/2018, at 1916 EST, with unit 2 in Mode 5 at 0 percent power, an actuation of the 'B' (Emergency Diesel Generator) EDG occurred during troubleshooting activities with the opposite train protected. The reason for the 'B' EDG auto-start was low voltage on the E-2 bus due to its supply breaker opening. The 'B' EDG automatically started as designed when the low voltage signal was received. Following the EDG start, required loads sequenced on as designed including the 'B' (Motor Driven Auxiliary Feedwater Pump) MDAFW Pump. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System (Emergency Diesel Generator) and Auxiliary Feedwater System (Motor Driven Auxiliary Feedwater Pump). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
ENS 5369727 October 2018 04:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Following StartupOn 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 5361118 September 2018 04:00:0010 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 a Steam Leak on a High Pressure Feedwater HeaterDue to a steam leak on the reheater line to 36C Feedwater Heater, operators initiated a manual trip of the reactor, verified the reactor trip, and closed all Main Steam Isolation Valves. The plant is currently stable in Mode 3 with the steam leak isolated. The Auxiliary Feedwater System actuated following the trip as expected. This is reportable under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(2)(iv)(B). The unit remains on offsite power in Hot Standby at normal operating temperature and pressure. Decay heat is being removed from the steam generators via the Auxiliary Feedwater System and atmospheric steam dumps. Unit 2 was unaffected and remains at 100 percent power. The licensee notified the NRC Resident Inspector, the State of New York, and the local transmission company.
ENS 5360614 September 2018 04:00:0010 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 a Failure of the Steam Generator Feed Regulating ValveAt 1323 (EDT) on 9/14/18, with Unit 2 in Mode 1 at 90% power, the reactor automatically tripped due to a failure of 23BF19, 23 Steam Generator (SG) Feed Regulating Valve. The trip was not complex, with all systems responding normally post-trip. No equipment was inoperable prior to the event. An actuation of the auxiliary feedwater system occurred following the automatic reactor trip. The reason for the auxiliary feed water system auto-start was due to low level in the steam generator. Operations responded and stabilized the plant. Decay heat is being removed by the main steam dumps and auxiliary feedwater system. Unit 1 is not affected. 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 being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the auxiliary feed water system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The Lower Alloways Creek Township will be notified."
ENS 5355722 August 2018 04:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor TripAt 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 5355013 August 2018 05:00:0010 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 Generator LockoutAt 23:58 (Central Daylight Time) Unit 2 Reactor Tripped (automatic reactor trip) due to a Turbine Trip/ Generator Lock Out. All Auxiliary Feedwater Pumps started due to steam generator Lo Lo levels. Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IP0-007B. The Emergency Response Guideline Procedure Network has been exited. Decay heat is being rejected to the Main Condenser via Steam Dump Valves. The cause of the Generator Lockout is currently under investigation. All control rods fully inserted in response to the automatic reactor trip. The licensee notified the NRC resident.
ENS 534916 July 2018 05:00:0010 CFR 50.72(b)(3)(iv)(A), System ActuationTransformer Failure Causes Loss of Offsite Power to Unit 2At 1201 (CDT), Station Auxiliary Transformer 242-2 experienced a bushing failure, resulting in a loss of offsite power to Unit 2. The 2A and 2B Diesel Generators started and sequenced loads onto the Unit 2 ESF buses appropriately. All other buses normally powered from the Station Auxiliary Transformers automatically transferred to the Unit Auxiliary Transformers. ESF Bus 241 and 242 Undervoltage Relays actuated to start the Diesel Generators and the 2A Auxiliary Feedwater Pump started on the 2A Diesel Generator sequencer. ESF Battery Charger 212 tripped at the same time, which was an unexpected condition. DC Bus 212 was cross-tied with DC Bus 112. This notification is being made under 10 CFR 50.72(b)3(iv)(A) due to the actuation of both Unit 2 Diesel Generators and the 2A Auxiliary Feedwater Pump. The NRC Senior Resident Inspector has been notified. Currently, offsite power was restored via the Unit 1 Unit Auxiliary Transformer. Both Unit 2 Emergency Diesel Generators have been secured. DC Busses are still cross-tied. The licensee is currently in a 72-hour shutdown action statement for the loss of offsite power and a 7-day action statement for having the Unit 2 DC Bus cross-tied to Unit 1.
ENS 534853 July 2018 05:00:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed ConditionEn Revision Imported Date 8/1/2018

EN Revision Text: DISCOVERY OF AN UNANALYZED CONDITION THAT SIGNIFICANTLY DEGRADES PLANT SAFETY On July 3, 2018, while performing a review of Emergency Operating Procedures, a concern was identified regarding the potential for excessive loss of ultimate heat sink inventory (UHS) through the auxiliary feedwater (AFW) system mini-flow recirculation pathway. This condition would have the potential to prevent the ultimate heat sink from providing an adequate inventory of water for a 30-day mission time.

The normal water supply for the Callaway AFW system is the condensate storage tank (CST). The CST is a non-safety grade component. The safety-grade supply for AFW is the essential service water (ESW) system. The ESW system is supplied by the UHS. The UHS thermal performance analysis accounts for a loss of UHS inventory to the AFW system up until the point of the accident sequence that the AFW pumps would be secured. The analysis did not include an allowance for loss of UHS inventory through the AFW mini-flow recirculation pathway following the AFW pumps being secured. The EOP guidance that secures the AFW pumps does not isolate the mini-flow recirculation pathway.

Initial estimates indicate that loss of UHS inventory through the mini-flow recirculation pathway, if not isolated, would preclude the UHS from completing its 30-day mission time. This potential for depletion of the UHS placed the plant in an unanalyzed condition that significantly degraded safety.

Callaway has issued interim guidance to the on-shift personnel regarding this concern to ensure that the ultimate heat sink water level is maintained at a level that will be adequate to mitigate the potential loss of inventory.

This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades safety. The NRC Resident Inspectors have been notified of this condition.

  • * * RETRACTION ON 07/31/2018 AT 1430 EDT FROM LEE YOUNG TO ANDREW WAUGH * * *

Event Notification (EN) 53485, made on July 3, 2018, is being retracted because re-evaluation performed subsequent to the notification has demonstrated, based on actual plant equipment and environmental conditions, that the unanalyzed inventory losses previously reported by EN 53485 would not have depleted the UHS inventory to an unacceptable level during its 30-day mission time. The re-evaluation has led to the conclusion that the previously unanalyzed losses of UHS inventory would not have prevented the UHS from performing its specified safety functions and meeting its 30-day mission time requirements. With the UHS capable of performing its specified safety functions and meeting its 30-day mission time requirements, the systems supported by the UHS would have remained capable of performing their specified safety functions. Based on these considerations, it has been determined that the condition reported in EN 53485 did not result in the plant being in an unanalyzed condition that significantly degraded safety. Consequently, the condition did not meet the criteria for an 8-hour notification per 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades safety. The NRC Resident Inspector has been notified of the Event Notification retraction. Notified R4DO (Gaddy).

ENS 534843 July 2018 04:00:0010 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 High Steam Generator Water LevelAt 0954 (EDT) on July 3, 2018, with Unit 1 in Mode 1 at 100 percent power, the reactor was manually tripped due to high steam generator water level. The trip was not complex, with all systems responding normally. Operations stabilized the plant in Mode 3. Decay heat is being removed through the main steam lines through the steam dumps and into the condenser. 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). Unit 2 was not affected. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspectors have been notified. All control rods inserted and Unit 1 is in an electrical shutdown lineup. The cause of the high steam generator water level transient is being investigated.
ENS 5346722 June 2018 04:00:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor TripAt 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 534434 June 2018 14:20:0010 CFR 50.72(b)(2)(iv)(B), RPS System ActuationManual Reactor Trip on Lowering Steam Generator Water LevelAt 0920 CDT, Braidwood Unit 1 reactor was manually tripped due to lowering steam generator water levels following a trip of the 1C main feedwater pump. The cause of the 1C main feedwater pump trip is unknown at this time and is under investigation. Both trains of Braidwood Unit 1 auxiliary feedwater started automatically following the reactor trip to maintain steam generator water levels. All systems responded as expected. Steam generator power operated relief valves lifted momentarily and reseated as designed in response to the secondary transient due to the reactor trip. The main steam dump valves are in service to the main condenser to provide heat sink cooling. The plant is being maintained at normal operating pressure and temperature. AC power is being provided by offsite power with the diesel generators in standby and all safety systems available. There is no impact to Unit 2. This report is being made per 10CFR50.72(b)(2)(iv)(B) for a RPS actuation, 4-hr. notification, and per 10CFR50.72(b)(3)(iv)(A) for an automatic actuation of the auxiliary feedwater system, 8-hr. notification. All rods inserted into the core during the trip. Concerning the relief valves momentarily lifting and reseating, there is no known primary-to-secondary leakage. The licensee has notified the NRC Resident Inspector.
ENS 534381 June 2018 04:00:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
Tornado Missile Vulnerabilities

During the period of evaluation of tornado missile vulnerabilities and the potential impacts to technical specification (TS) plant equipment, it was determined that the power cables to a safety related motor control center (MCC) in the service water (SW) intake structure are not adequately protected from tornado generated missiles. During walk downs, it was identified that the installed SW pipe tunnel barrier is not adequate. A tornado could generate missiles capable of striking the power cables and rendering a SW MCC inoperable. These conditions are reportable per 10 CFR 50.72(b)(3)(ii)(B) and per 10 CFR 50.72(b)(3)(v)(D). This condition is being addressed in accordance with NRC enforcement guidance provided in Enforcement Guidance Memorandum (EGM) 15-002, 'Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,' Revision 1, and DSS-ISG-2016-01, 'Clarification of Licensee Actions in Receipt of Enforcement Discretion per Enforcement Guidance Memorandum EGM 15-002, Enforcement Discretion for Tornado- Generated Missile Protection Noncompliance,' Revision 1. Compensatory measures have been implemented in accordance with these documents. The NRC Resident Inspector has been notified. The licensee will be notifying the Lower Alloways Creek Township.

  • * * UPDATE ON 6/18/2018 AT 1604 EDT FROM JUSTIN HARGRAVE TO RICHARD SMITH * * *

During subsequent walk downs, PSEG (Public Service Enterprise Group) identified that both the Unit 1 and Unit 2 turbine driven auxiliary feedwater pumps are also not adequately protected from tornado generated missiles. The steam exhaust pipe could be potentially impacted and cause crimping that could reduce steam exhaust flow and pump capacity. EN 53438 is updated to include both Salem units and these additional components. This condition is being addressed in accordance with NRC enforcement guidance provided in enforcement Guidance Memorandum (EGM) 15-002, 'Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,' Revision 1, and DSS-ISG-2016-01, 'Clarification of Licensee Actions in Receipt of Enforcement Discretion per Enforcement Guidance Memorandum EGM 15-002, Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,' Revision 1. Compensatory measures have been implemented in accordance with these documents." The NRC Resident Inspector has been notified. The licensee will be notifying the Lower Alloways Creek Township. Notified R1DO (Burritt).

ENS 533887 May 2018 18:35:0010 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
Discovery of a Condition That Could Have Prevented Fulfillment of a Safety FunctionOn May 7, 2018, during an engineering review of mission time requirements for Technical Specification related equipment, a deficiency was discovered regarding the Emergency Operating Procedure (EOP) guidance for natural circulation cooldown with a stagnant loop. This condition could be the result of a postulated Main Steam Line Break with a loss of offsite power. During a natural circulation cooldown with a faulted steam generator, flow in the stagnant reactor coolant system (RCS) loop associated with the isolated faulted steam generator (SG) could stagnate and result in elevated temperatures in that loop. This becomes an issue when RCS depressurization to residual heat removal system (RHR) entry conditions is attempted. The liquid in the stagnant loop will flash to steam and prevent RCS depressurization. In this condition, the time required to complete the cooldown would be sufficiently long that the nitrogen accumulators associated with Callaway's atmospheric steam dumps and turbine driven auxiliary feedwater pump flow control valves would be exhausted. The atmospheric steam dumps and turbine driven auxiliary feedwater pump would not be capable of performing their specified safety functions of cooling the plant to entry conditions for RHR operation. This issue has been analyzed by Westinghouse in WCAP-16632-P. This WCAP determined that to prevent loop stagnation, the RCS cooldown rate in these conditions should be limited to a rate dependent on the temperature differential present in the active loops. The WCAP analysis was used to support a revision to the generic Emergency Response Guideline (ERG) for ES-0.2 "Natural Circulation Cooldown." Figure 1 in ES-0.2 provides a curve of the maximum allowable cooldown rate as a function of active loop temperature differential which is directly proportional to the level of core decay heat. At the time of discovery of this condition, Callaway's EOP structure did not ensure that the ES-0.2 guidance would be implemented for a natural circulation cooldown with a stagnant loop. Callaway has issued interim guidance to the on-shift personnel regarding this concern and is in the process of revising the applicable EOPs. This condition is reportable per 10 CFR 50.72(b)(3)(v) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (A) Shutdown the reactor and maintain it in a safe shutdown condition, (B) Remove residual heat, or (D) mitigate the consequences of an accident." The licensee notified the NRC Resident Inspector of this condition.
ENS 533877 May 2018 07:36:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Rx Trip Due to High-High Level in Moisture Separator Drain TankOn May 7, 2018 at 0336 (EDT), DC Cook Unit 2 Reactor was manually tripped due to a high-high level experienced in the East Moisture Separator Drain Tank (MSDT) of the Moisture Separator Reheater (MSR). 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 NRC Resident Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. All Aux Feedwater Pumps started properly. Decay heat is being removed via the Steam Generator Power Operated Relief Valves following Main Steam Stop Valve closure at 0431 due to a slow RCS (Reactor Coolant System) cooldown. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event.
ENS 533867 May 2018 07:25:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor TripThis 4 and 8 hour notification is being made to report that Salem Unit 2 initiated a manual reactor trip and subsequent automatic Auxiliary Feedwater system actuation. The trip was initiated due to a 21 Reactor Coolant Pump reaching its procedural limit for motor winding temperature of 302F. Salem Unit 2 is currently stable in Mode 3. Reactor Coolant system pressure is 2235 PSIG and Reactor Coolant System temperature is 547 F with decay heat removal via the Main Steam Dump and Auxiliary Feedwater Systems. Unit 2 has no active shutdown technical specification action statements in effect. All control rods inserted on the reactor trip. All ECCS (emergency core cooling systems) and ESF (emergency safety function) systems functioned as expected. No safety related equipment or major secondary equipment was tagged for maintenance prior to this event. No personnel were injured during this event. The NRC Resident Inspector was notified. The Lower Alloways Creek Township will be notified.
ENS 5337130 April 2018 16:24:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip Following Turbine TripAt 1124 CDT, Braidwood Unit 1 experienced an automatic Reactor Trip. The cause of the Reactor Trip was a Turbine Trip with reactor power greater than P-8. The turbine trip was actuated as a result of a Turbine Motoring Generator Trip. The cause of the generator trip is unknown at this time and is under investigation. After the Reactor Trip occurred, the 1A Auxiliary Feedwater pump was manually started to provide feedwater flow to all four steam generators. The 1A Auxiliary Feedwater pump was subsequently secured and placed in standby when the Startup Feedwater pump was placed in service. Train A Main Control Room Ventilation Filtration system shifted to Makeup Mode due to a spurious actuation signal. No secondary relief valves lifted and no secondary steam was released as a result of the Reactor Trip. The Main Steam dump valves are in service to the Main Condenser to provide heat sink cooling. The plant is being maintained at normal operating pressure and temperature. AC power is being provided by Offsite Power with the Diesel Generators in standby and all safety systems available. There is no impact to Unit 2. This report is being made per 10 CFR 50.72(b)(2)(iv)(B) for a RPS actuation, 4-hr notification, and per 10 CFR 50.72(b)(3)(iv)(A) for a manual actuation of the Auxiliary Feedwater system, 8-hr notification. The licensee notified the NRC Resident Inspector and Illinois Emergency Management Agency.
ENS 5332712 April 2018 13:20:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor TripAt 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 533187 April 2018 08:51:0010 CFR 50.72(b)(3)(iv)(A), System ActuationAutomatic Actuation of Auxiliary Feedwater System (Afw)On April 7, 2018 at 0451 EDT, with Unit 1 in Mode 3 at 0 percent power, an auto actuation of 'A' and 'B' Motor Driven Auxiliary Feedwater (MDAFW) pumps occurred during the shutdown of Unit 1 for Harris Nuclear Plant's refueling outage. Plant Operators successfully took control of the AFW flow and noted the 'B' Main Feed pump was still running with proper suction and discharge pressures of 430 lbs. and 1000 lbs. The 'A' and 'B' Motor Driven Auxiliary Feedwater (MDAFW) pumps automatically started as designed when the 'Loss of Both Main Feedwater Pumps' signal was received. The cause of the actuation is still being evaluated. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as 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 532391 March 2018 22:43:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
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
Potential Tornado Missile VulnerabilitiesDuring review of protection of equipment from damaging effects of tornados, Point Beach Nuclear Plant identified a potential vulnerability for the turbine driven auxiliary feedwater pumps due to steam supply piping that is not routed through a Class 1 structure. Immediate compensatory measures were taken to mitigate the potential consequences of a tornado generated missile impact. This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) and per 10 CFR 50.72(b)(3)(v)(A) and (D). The identified vulnerability is being addressed in accordance with EGM 15-002 and DSS-ISG-2016-01, enforcement discretion memorandum and interim guidance document for resolution of noncompliance with tornado-generated missile protection. The NRC Resident Inspector has been notified.
ENS 5322320 February 2018 18:25:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
All Three Auxiliary Feedwater Pumps Inoperable Due to Helb Door Being Open

At 1225 CST, all three Auxiliary Feedwater (AFW) pumps were declared inoperable at the Callaway Plant upon discovery that a door (DSK13311) credited for protection of equipment from the effects of a high-energy line break (HELB) hazard had come partially open due to vibration harmonics from the running turbine-driven Auxiliary Feedwater pump (TDAFP). Immediate investigation identified that play in the mechanism that holds the door closed had rendered it susceptible to movement from the vibration harmonics. The affected HELB door specifically protects safety-related instruments that provide a swap-over signal upon detection of a low suction pressure condition for the AFW pumps and thereby automatically effect a suction transfer for the AFW pumps from the condensate storage tank (normal/standby source) to the Essential Service Water (ESW) system (credited safety-related source). All of the AFW pump suction transfer instrument channels were declared inoperable. Per Technical Specifications (TS) 3.3.2, 'Engineered Safety Feature Actuation System (ESFAS) Instrumentation,' the applicable Condition(s) and Required Action(s) for inoperable AFW pump suction transfer instrumentation only addresses a single channel being inoperable. Thus, the condition of having all three instrument channels inoperable required entry into TS Limiting Condition for Operation (LCO) 3.0.3. At the same time, however, with the automatic suction transfer capability rendered inoperable, all three AFW pumps, i.e., the TDAFP and the 'A' and 'B' motor-driven AFW pumps, were declared inoperable. Although LCO 3.0.3 was applicable, entry into the Required Actions of LCO 3.0.3 was suspended per the Note attached to Required Action E.1 of TS 3.7.5, 'Auxiliary Feedwater (AFW) System,' which states, 'LCO 3.0.3 and all other LCO Required Actions requiring MODE changes are suspended until one AFW train is restored to OPERABLE status.' At 1336 CST, Operations took actions to prevent the TDAFP from running, so the remaining (AFW Pumps) could be returned to Operable status. Operations then declared the affected instrumentation and the 'A' and 'B' motor-driven AFW pumps Operable. This allowed LCO 3.0.3 and Conditions A, B, D, and E under TS 3.7.5 to be exited. With only the TDAFP inoperable, TS 3.7.5 Condition C and its Required Actions remain in effect. Due to the degraded HELB door rendering all three AFW pumps inoperable, the unidentified condition is being reported as an unanalyzed condition that significantly degraded plant safety (per 10 CFR 50.72(b)(3)(ii)(B)) as well as a condition that could have prevented the fulfillment of the safety functions of structures or systems that are needed to shut down the reactor and maintain it in a safe shutdown condition, remove residual heat, and mitigate the consequences of an accident (per 10 CFR 50.72(b)(3)(v)(A), (B), and (D), respectively). The NRC Senior Resident Inspector has been notified.

  • * * RETRACTION ON 4/4/2018 at 1109 EDT FROM JONATHAN LAUF TO DAVID AIRD * * *

Event Notification (EN) # 53223, made on 2/20/2018, is being retracted because new information has been obtained that negates the original basis for reporting the unanalyzed condition. Specifically, an evaluation of the HELB that is postulated to occur in the TDAFP room has determined that without crediting door DSK13311 for protection, the affected safety-related instruments would not be exposed to environmental conditions beyond their analyzed capability. This resulted in a conclusion that the unanalyzed condition of door DSK13311 being open did not prevent the affected safety-related instruments or their supported AFW pumps from performing their required safety functions to shut down the reactor and maintain it in a safe shutdown condition, remove residual heat, and/or mitigate the consequences of an accident, nor did it significantly degrade plant safety. Consequently, the condition did not meet the criteria for an 8-hour notification per 10 CFR 50.72(b)(3)(ii)(B) and 10 CFR 50.72(b)(3)(v)(A), (B), or (D). The licensee notified the NRC Resident Inspector. Notified R4DO (Drake).

ENS 5321716 February 2018 15:14:0010 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 TestingAt 1014 (EST) hours on 2/16/18, with Unit 1 in Mode 1 at approximately 100 percent power, the reactor automatically tripped when the Reactor Trip Breakers opened during Train B Solid State Protection System (SSPS) testing. The trip was uncomplicated with all systems responding normally post-trip. Operations manually started the motor driven auxiliary feedwater pumps. The turbine driven auxiliary feedwater pump (TDCAP) auto-started on low steam generator level. A Feedwater Isolation occurred as designed due to the Reactor Trip and Lo Tave condition. Operations stabilized the plant. Decay heat is being removed by the condenser. Unit 2 is not affected. Due to the Reactor Protection System actuation while critical, actuation of the TDCAP and motor driven auxiliary feedwater pumps along with the Feedwater Isolation, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an 8 hour non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5321616 February 2018 07:01:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Trip Due to Loss of Excitation on Main GeneratorOn February 16, 2018 at 02:01 EST Indian Point Unit 3 automatically tripped on a turbine trip due to a loss of main generator excitation. All control rods fully inserted and all plant equipment responded normally to the unit trip. This is reportable under 10 CFR 50.72(b)(2)(iv)(B). The auxiliary feedwater system actuated following the automatic trip as expected. This is reportable under 10 CFR 50.72(b)(3)(iv)(A). During the event offsite power remained available and stable. No primary or secondary reliefs lifted. The plant is stable, in Mode 3, at no load operating temperature and pressure. Decay heat removal is via the steam generators to the main condenser via the condenser steam dumps. No radiation was released. Indian Point Unit 2 was unaffected by this event and remains at 100 percent power. A post trip investigation is in progress. The licensee has notified the NRC Resident Inspector.
ENS 5313220 December 2017 15:40:0010 CFR 50.72(b)(3)(iv)(A), System ActuationSystem Actuations Due to Opening of Feeder Breaker to Shutdown BoardOn December 20, 2017, at 1040 Eastern Standard Time (EST), the Watts Bar Nuclear Plant (WBN) 1B-B 6.9kV Shutdown Board (SDBD) normal feeder breaker opened. The loss of voltage to the 1B-B SDBD resulted in the start of the 1B-B Motor Driven Auxiliary Feedwater (MDAFW) pump, the Unit 1 Turbine Driven Auxiliary Feedwater (TDAFW) pump, and the start of all four Emergency Diesel Generators (EDGs). Power was restored to the 1B-B 6.9 kV SDBD when it loaded on to its associated EDG. Following initial investigation, the 1B-B 6.9 kV SDBD was transferred to its alternate offsite power source, Common Station Service Transformer (CSST) C at 1217 EST. At 1230 EST, the 1B-B 6.9 kV SDBD alternate feeder breaker opened. The loss of voltage to the 1B-B SDBD did not result in the restart of the 1B MDAFW pump, the Unit 1 TDAFW pump, or EDGs; this equipment remained running from the earlier event. Power was restored to the 1B-B 6.9 kV SDBD when it loaded on to its associated EDG. Restoration of normal offsite power to the 1B-B SDBD was completed at 1654. Other than several common Unit Technical Specifications having not been met, Unit 2 was not operationally impacted by the transfer of the 1B-B Shutdown Board to onsite power and remains in Mode 1 at 100% power. This report is made per 10 CFR 50.72(b)(3)(iv)(A). NRC Resident Inspector has been notified. The licensee investigation continues for the cause of the event.
ENS 5311211 December 2017 13:57:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip in Response to Indication of Multiple Dropped Control RodsWhile 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 5309126 November 2017 02:25:0010 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 Loss of Main Feed WaterAt time 2025 (CST) on 11/25/17, Unit 2 reactor was manually tripped due to a loss of all Main Feedwater. Operators observed both Main Feed Pumps tripped and SG (Steam Generator) levels decreasing, resulting in the direction for a manual reactor trip. The reactor trip actuated a turbine trip, both Motor Driven Auxiliary Feedwater Pumps started on the loss of both Main Feed Pumps, and Steam Generator Lo Lo levels started the Turbine Driven Auxiliary Feedwater Pump. All systems responded as expected. There was no work in progress at the time of the incident. Currently Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IP0-0078 and the Emergency Response Guideline Procedure Network has been exited. Decay Heat is being rejected to the Main Condenser via Steam Dump Valves. The licensee has notified the NRC Resident Inspector.
ENS 5308420 November 2017 05:00:0010 CFR 21.21(d)(3)(i), Failure to Comply or DefectPart-21 - Auxiliary Feedwater Pump Power Supply FailureThe following report is an excerpt from a fax from Engine Systems, Inc.: Engine Systems Inc. (ESI) began a 10CFR21 evaluation on October 17, 2017 upon notification of a potential issue with power supply P/N 2938604 supplied to Vogtle Nuclear Plant. The power supply is installed in a safety-related control panel for the Terry Turbine driven auxiliary feedwater pump. Analysis determined the power supply failure was due to an internal rectifier diode failure which resulted in a short circuit on the power supply output. The evaluation was concluded on November 20, 2017 and it was determined that this issue is a reportable defect as defined by 10CFR Part 21. The power supply failure will adversely affect speed control of the turbine driven auxiliary feedwater pump and therefore may prevent safe shutdown of the nuclear reactor. This issue applies to all customers that have power supply P/N 2938604 within the date code range 0648 through 0723. ESI has supplied power supplies within the suspect date code range to (Vogtle and Farley). Point of Contact: Tom Horner, Quality Manager, 252-977-2720
ENS 530567 November 2017 10:04:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Unit 1 Automatic Reactor Trip Due to Main Unit Generator Over CurrentOn November 7, at 0504 (EST), BVPS (Beaver Valley Power Station) Unit 1 experienced an automatic reactor trip due to Main Unit Generator over current. The Auxiliary Feedwater system activated and remains in service. Offsite power supply is available. Normal and Emergency busses are being supplied by Offsite power. One Source Range channel failed to energize due to its corresponding Intermediate Range instrument being under compensated. It was manually energized and is not indicating as expected. The second Source Range instrument energized but is reading erratically. Both Source Range instruments have been declared inoperable and the appropriate Technical Specification has been complied with by making the Control Rods not capable of withdrawal and isolating all dilution flow paths. Plant trip response was as expected without complications, and all control rods fully inserted in the core. The plant is currently stable in Mode 3. This event is being reported as an actuation of the Reactor Protection system 10 CFR 50.72(b)(2)(iv)(B) and a Specified System Actuation (Auxiliary Feedwater System) 10 CFR 50.72(b)(3)(iv)(A). BVPS Unit 2 is unaffected by this event and remains at 100% power in Mode 1. The NRC Resident Inspector has been notified.
ENS 530524 November 2017 00:22:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Indian Point Unit 3 Reactor Trip on Low Steam Generator Level

On November 3rd, 2017 at 2022 EDT, the Indian Point Unit 3 Reactor Protection system automatically actuated at 100 percent power. Annunciator first out indication was from 33 SG (Steam Generator) Low Level. This automatic reactor trip is reportable to the NRC under 10 CFR 50.72(b)(2)(iv)(B). All control rods fully inserted on the reactor trip. All safety systems responded as expected. The Auxiliary Feedwater System actuated as expected. Offsite power and plant electrical lineups are normal. All plant equipment responded normally to the unit trip. No primary or secondary code safeties lifted during the trip. The Auxiliary Feedwater System actuated following the automatic trip as expected. This is reportable under 10 CFR 50.72(b)(3)(iv)(A). The Emergency Diesel Generators did not start as offsite power remained available and stable. The Unit remains on offsite power and all electrical loads are stable. Unit 3 is in Hot Standby at normal operating temperature and pressure with decay heat removal using auxiliary feedwater to the steam generators and normal heat removal through the condenser via the high pressure steam dumps. Unit 2 was unaffected and remains at 100 percent power. A post trip investigation is in progress. The licensee indicated that Radiation Monitor number 14 spiked twice during the transient, however, is currently not indicating any signs of radiation. The licensee will notify the NRC Resident Inspector and the NY Public Service Commission.

  • * * UPDATE AT 1523 EST ON 11/06/17 FROM RAMIREZ OVIDIO TO JEFF HERRERA * * *

The initial notification stated that Indian Point Unit 3 Reactor Tripped on 33 SG (Steam Generator) Low Level, this is incorrect. Indian Point Unit 3 Reactor Tripped on a Turbine Trip. The Turbine Trip was caused by a Generator Back-up Lockout Relay. The Turbine Trip was the 'first' annunciator first-out but was acknowledged instead of silenced during initial operator actions. The Turbine Trip first-out being acknowledged allowed a Low Steam Generator first-out to later annunciate. A Low Steam Generator Level is an expected condition post trip. This update does not change any actions taken by the operating team or required notifications under 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). A post trip investigation remains in progress. The licensee will notify the NRC Resident Inspector and the NY Public Commission. Notified the R1DO(Cook)

ENS 5303626 October 2017 06:12:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip Following a Loss of LoadOn October 26, 2017 at 0212 EDT St. Lucie Unit 2 experienced a reactor trip due to a loss of load event resulting in an RPS (Reactor Protection System) actuation. The cause of the loss of load is currently under investigation. Following the reactor trip, an Auxiliary Feedwater Actuation Signal occurred due to low level in the 2A Steam Generator. One of the two Main Feed Isolation Valves to the 2A Steam Generator did not close on the Auxiliary Feedwater Actuation Signal. 2A Steam Generator level was restored by Auxiliary Feedwater. The 2B Steam Generator level is being maintained by Main Feedwater. All CEAs (Control Element Assemblies) fully inserted into the core. Decay heat removal is being accomplished through forced circulation with stable conditions from Auxiliary Feedwater/Main Feedwater and Steam Bypass Control System. Currently maintaining pressurizer pressure at 2250 psia and Reactor Coolant System temperature at 532 degrees F. St. Lucie Unit 1 was unaffected and remains in Mode 1 at 100 percent power. This report is submitted in accordance with 10 CFR 50.72(b)(2)(iv)(B) for the reactor trip and 10 CFR 50.72(b)(3)(iv)(A) for the Specified System Actuation. The licensee notified the NRC Resident Inspector.
ENS 529452 September 2017 02:40:0010 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 Two Dropped RodsAt time 2140 (CDT) on September 1, 2017, CPNPP (Comanche Peak Nuclear Power Plant) Unit 2 experienced two (2) dropped rods, one control, one shutdown. The reactor was then manually tripped. This event is being reported in accordance with 10CFR50.72(b)(2)(iv)(B) for reactor trip and 10CFR 50.72(b)(3)(iv)(A) for an actuation of auxiliary feedwater. Currently Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IP0-007B, 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 NRC Resident Inspector has been notified. All rods inserted into the core during the trip. No relief or safety valves actuated during the plant transient. The electrical grid is stable and supplying plant loads. Unit 1 was not affected by the transient.