| Site | Start date | Title | Description |
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ENS 57233 | Calvert Cliffs | 18 July 2024 19:24:00 | Automatic Reactor Trip | The following information was provided by the licensee via phone and email:
At 1524 (EDT) on 07/18/2024, with Unit 2 in Mode 1 at 100 percent power, the reactor automatically tripped due to a turbine trip. The trip was not complex, with all systems responding normally post-trip.
Operations responded and stabilized the plant. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves.
Unit 1 implemented AOP-7K (abnormal operating procedure), overcooling event, due to a grid transient. Operations responded and stabilized Unit 1 in Mode 1 at 100 percent power.
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).
There was no impact on the health and safety of the public or plant personnel.
The NRC resident inspector has been notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
All rods fully inserted. There were no other specified system actuations. | ENS 57221 | Peach Bottom | 10 July 2024 11:28:00 | Automatic Reactor Scram Due to Manual Turbine Trip | The following information was provided by the licensee via phone and email:
At 0728 EDT on July 10, 2024, with Unit 2 in Mode 1 at 24 percent power, the reactor automatically scrammed due to a manual turbine trip. The (reactor) scram was not complex with all systems responding normally. Reactor vessel level reached the low-level set-point following the scram, resulting in valid Group 2 and Group 3 containment isolation signals. Due to the reactor protection system actuation while critical, this event is being reported as a four hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an eight hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) for the Group 2 and Group 3 isolations.
Operations responded using emergency operating procedures and stabilized the plant in Mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 3 was not affected.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | ENS 57214 | Watts Bar | 8 July 2024 19:21:00 | Automatic Reactor Trip | The following information was provided by the licensee via phone and email:
At 1521 EDT on July 8, 2024, with Unit 1 in Mode 1 at 100 percent power, the reactor automatically tripped due to a main turbine trip. The (reactor) trip was not complex with all systems responding normally post trip.
Operations responded and stabilized the plant. Decay heat is being removed by discharging steam to the main condenser using the steam dump system and the auxiliary feedwater (AFW) system. Unit 2 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). The expected actuation of the AFW 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 has been notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
The specific cause of the turbine trip is under investigation by the licensee. | ENS 57195 | Cook | 27 June 2024 12:04:00 | Automatic Start of Turbine Driven Auxiliary Feedwater Pump | The following information was provided by the licensee email:
On June 27, 2024, at 0804 (EDT), D.C. Cook Unit 2 had an automatic start of the turbine driven auxiliary feedwater pump (TDAFP) following a controlled down power and manual reactor trip at approximately 17 percent power. The automatic start of the TDAFP was due to a steam generator water level 'low low' signal following the reactor trip. The down power and trip were performed in accordance with normal shutdown procedures to comply with the required action C.1 of technical specification 3.4.13, 'reactor coolant system operational leakage.' Reference event notification number EN57194.
An automatic start of the TDAFP is an eight hour report per 10CFR 50.72(b)(3)(iv)(A).
Unit 2 is being supplied by offsite power. All control rods fully inserted. Steam generators are being fed by both motor driven auxiliary feedwater pumps. Decay heat is being removed via the steam dump system to the main condenser. Preliminary evaluation indicates plant systems functioned normally following the reactor trip. D.C. Cook Unit 2 remains in Mode 3 to repair the previously reported reactor coolant system leakage through valve 2-QRV-251, 'CVCS (chemical and volume control system) charging pumps discharge flow control' valve packing.
The NRC Resident Inspector has been notified. | ENS 57175 | Waterford | 16 June 2024 17:33:00 | Automatic Reactor Trip | The following information was provided by the licensee via email:
On June 16, 2024, at 1233 CDT, Waterford Steam Electric Station Unit 3 was operating at 93 percent power when an automatic reactor trip occurred. Immediately following the reactor trip, emergency feedwater (EFW) actuated automatically. The unit is currently in Mode 3. All control rods fully inserted. Decay heat removal is via the main condenser. Preliminary evaluation indicates that all plant systems functioned normally after the reactor trip, except steam generator (SG) feedwater pump 'A' tripped and SG '1' main feed regulatory controller went to manual. Steam generator water levels are being controlled with the SG feedwater pump 'B'. The cause of the trip is currently being investigated.
This event is being reported as a 4-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the reactor protection system when the reactor is critical and as an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as a valid actuation of the EFW system.
The NRC Resident Inspector has been notified. | ENS 57164 | Vogtle | 5 June 2024 20:48:00 | Manual Reactor Trip | The following information was provided by the licensee via email:
At 1648 EDT on 06/05/2024, with Unit 4 in Mode 1 at approximately 35 percent power, the reactor was manually tripped due to unexpected response of the turbine run back circuitry following a trip of main feedwater pump `C. The trip was not complex, with all safety systems responding normally post-trip.
Operations responded and stabilized the plant. Decay heat is being removed by discharging steam through the steam dumps to the main condenser and main feedwater is supplying the steam generators. Units 1, 2 and 3 are 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).
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | ENS 57161 | Saint Lucie | 4 June 2024 17:52:00 | Manual Reactor Trip | The following information was provided by the licensee via email:
At 1352 EDT, on June 4, 2024 with Unit 2 at 92 percent power, the reactor was manually tripped due to a loss of condenser vacuum resulting from a circulating water pump trip. The trip was uncomplicated with all systems responding normally post trip. Operations stabilized the plant in mode 3. Decay heat is being removed by steam discharge to the main condenser using the turbine bypass valves. St. Lucie Unit 1 was not affected and remains at 100 percent power.
This event is being reported pursuant to 10 CFR 50.72 (b)(2)(iv)(B).
The NRC Resident Inspector has been notified. | ENS 57141 | Quad Cities | 23 May 2024 16:46:00 | Automatic Scram Due to Turbine Trip Signal | The following information was provided by the licensee via email:
At 2223 CDT on May 23, 2024, with Quad Cities Unit 2 at 38 percent power, the reactor automatically tripped due to a turbine trip signal resulting in main stop valve closure, creating a valid reactor protection system signal. Reactor vessel level reached the low-level set-point following the scram, resulting in valid Group II and Group III containment actuation signals. The trip was not complex with all systems responding as expected post-trip. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) for the Group II and Group III isolation.
Operations responded using their emergency operating procedures and stabilized the plant in mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves.
Unit 1 remains at 100 percent power.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
Unit 2 was at a reduced power for maintenance. | ENS 57132 | Beaver Valley | 19 May 2024 04:30:00 | Manual Reactor Trip | The following information was provided by the licensee via email:
At 0030 (EDT) on 5/19/24, with Beaver Valley Unit 1 in mode 1 at 14 percent power, the reactor was manually tripped due to inability to control the A steam generator water level. The trip was not complex, with all systems responding normally post-trip. The turbine driven auxiliary feedwater pump automatically started on a valid actuation signal. All control rods inserted into the core. Operations responded and stabilized the plant. Decay heat is being removed by the feedwater system and the main condenser. Beaver Valley Unit 2 is unaffected.
Due to the reactor protection system 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). Due to the emergency safety feature system actuation (automatic start of the turbine driven auxiliary feedwater pump) while critical, this event is being reported as an eight-hour, non-emergency notification per 10CFR 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 verbally notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
Unit 1 is stable on off-site power, normal configuration. All emergency systems are available. | ENS 57107 | Braidwood | 5 May 2024 08:38:00 | Automatic Reactor Trip Due to Lowering Steam Generator Water Level | The following information was provided by the licensee via email and phone:
At 0338 CDT, with the unit 1 in mode 1 at 6 percent power, the reactor automatically tripped due to lowering steam generator water level. The trip was uncomplicated with all systems responding normally post-trip. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) for an actuation of the auxiliary feedwater system.
Operations responded using procedure 1BwEP-0 and stabilized the plant in mode 3. Decay heat is removed by steam dumps via the main condenser. 1A and 1B auxiliary feedwater pumps were actuated manually prior to the reactor trip in an attempt to restore steam generator water level. Unit 2 is not affected.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
- * * UPDATE ON 07/05/2024 AT 0450 EDT FROM MATTHEW WHITE TO TENISHA MEADOWS * * *
The following information was provided by the licensee via email and phone:
At 0338 CDT, with the unit 1 in mode 2 at 3 percent power, the reactor automatically tripped due to lowering steam generator water level. The trip was uncomplicated with all systems responding normally post-trip. 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 10CFR50.72(b)(3)(iv)(A) for an actuation of the auxiliary feedwater system, eight-hour notification.
Operations responded using procedure 1BwEP-0 and stabilized the plant in mode 3. Decay heat is being removed by steam dumps via the main condenser. 1A and 1B auxiliary feedwater pumps were actuated manually prior to reactor trip in an attempt to restore steam generator water level. Unit 2 is not affected.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
Notified R3DO (Hartman) |
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