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| Entered date | Event description | |
|---|---|---|
| ENS 56650 | 1 August 2023 15:53:00 | The following information was provided by the licensee via email: On 08/01/2023 at 0955 EDT, the Fermi 2 active seismic monitoring system provided indication of a potential seismic activity event. Plant abnormal procedures were entered, and compensatory measure were met and remain in place. Neither the (United States Geological Survey) (USGS) nor the next closest nuclear power plant could confirm or validate the readings obtained at Fermi. The seismic monitoring system was declared nonfunctional to validate the calibration of the system. Femi 2 has two active seismic monitors: one on the reactor pressure vessel pedestal and one in the high-pressure core injection (HPCI) room. Only the HPCI room accelerometer was declared inoperable. The HPCI accelerometer is the sole 'trigger' for the seismic recording system, which outputs peak accelerations experienced during a seismic event. This is used in assessment of the magnitude of an earthquake for EAL HU 2.1. The loss of the active seismic monitoring system is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). No seismic activity has been felt onsite and the USGS recorded no seismic activity in the area. The NRC Resident Inspector has been notified. |
| ENS 56295 | 4 January 2023 08:28:00 | The following information was provided by the licensee via email: At 0148 EST on January 4, 2023 it was identified that P4400F603B, Division 2 Emergency Equipment Cooling Water (EECW) Supply Isolation Valve, lost position indication. Division 2 EECW System was declared inoperable due to the potential that this valve may not be capable of performing its safety function to automatically isolate the safety related Division 2 EECW system from the non-safety related Reactor Building Closed Cooling Water (RBCCW) system. Because the Division 2 EECW system provides cooling to the High Pressure Coolant Injection (HPCI) room cooler, HPCI was also declared inoperable; therefore, this condition is being reported as an eight-hour, non--emergency notification per 10 CFR 50.72(b)(3)(v)(D). At 0240 EST, position indication was restored and Division 2 EECW and HPCI was returned to operable following inspection of the associated motor control center (MCC) and testing of the associated fuses. The cause of the loss of indication is under investigation. The Senior NRC resident inspector has been notified.
The following retraction was received from the licensee via email: The purpose of this notification is to retract a previous Event Notification, EN 56295, reported on 1/4/2023. Following the initial EN, further analysis of the condition was performed utilizing a gothic analysis model to perform HPCI room heat-up calculations. Based on the initial conditions at the time of the indication loss, specifically HPCI room and Suppression Pool temperature, it was determined that the resulting worst case post-accident room temperature was sufficiently low enough to provide margin to HPCI operability without the room cooler in service for the required mission time. No other concerns were noted during the event. Therefore, HPCI remained operable and there was no loss of safety function. The event did not involve a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). Therefore, the NRC non-emergency 10 CFR 50.72(b)(3)(v)(D) report was not required and the NRC report 56295 can be retracted and no Licensee Event Report under 10 CFR 50.73(a)(2)(v)(D) is required to be submitted. The NRC Senior Resident Inspector has been notified. Notified R3DO (Ruiz). |
| ENS 56241 | 28 November 2022 08:38:00 | The following information was provided by the licensee via email: At 0400 EST on November 28, 2022, during the performance of Division 2 Residual Heat Removal (RHR) cooling tower fan operability and RHR Service Water valve lineup verification, it was reported that the Mechanical Draft Cooling Tower (MDCT) Fan 'B' was making a loud metallic noise. The cause of the metallic noise is unknown at this time. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system. The EECW system cools various safety related components including the High Pressure Coolant Injection (HPCI) system room cooler. An unplanned HPCI inoperability occurred based on inoperable cooling water to the HPCI room cooler, per LCO 3.0.6. Investigation into the Division 2 MDCT Fan 'B' abnormal noise is in progress. This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. The NRC Resident Inspector has been notified.
The following information was provided by the licensee via email: The purpose of this notification is to retract a previous Event Notification 56241 reported on 11/28/2022. On 11/28/22, an event notification to the NRC was made when mechanical draft cooling tower (MDCT) Fan B was declared inoperable and issued Limited Condition of Operation (LCO) 2022-0428 for Division 2 MDCT Fan B abnormal noise. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS) (Technical Specification (TS) 3.7.2). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system (TS 3.7.2), which cools various safety related components, including the High-Pressure Coolant Injection (HPCI) system room cooler (TS LCO 3.0.6). Subsequent inspection and evaluation determined that the brake noise is expected while fans are running at low speeds. This is supported by plant technical procedure, 24.205.10 `Div. 2 RHR Cooling Tower Fan Operability and RHRSW Valve Line-up Verification' (line item 2.2 in Precautions and Limitations) which states `Chatter from the brakes of the MDCT Fans is expected and no cause for discontinuing the test.' The equipment vendor stated that brake chatter is possible and common given that the internal components are free to move along the splined connections. Internal Operating Experience from experienced station operators and maintenance technicians confirmed that the condition is normal and expected. Both Division 2 MDCTs exhibited the same behavior at low speed and passed surveillance testing satisfactorily. No other concerns were noted during fan operation. Therefore, HPCI remained operable and there was no loss of safety function. The event did not involve a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). EN 56241 is retracted and no Licensee Event Report under 10 CFR 50.73(a)(2)(v)(D) is required to be submitted. The NRC Resident Inspector has been notified. Notified R3DO (Stoedter). |
| ENS 55964 | 25 June 2022 01:00:00 | The following information was provided by the licensee via email: At 2338 EDT, on June 24, 2022, with the unit in Mode 1 at 100 percent power, the reactor automatically scrammed due to an RPS actuation following a Main Turbine Trip. The cause of the turbine trip is not known at this time. The scram was not complex, with systems responding normally post-scram. Operations responded and stabilized the plant. Reactor water level has been recovered and maintained at the normal level. Decay Heat is being removed by the Main Steam system to the main condenser using the Turbine Bypass Valves. All Control Rods inserted into the core. The transient occurred with no surveillances or activities in progress. Investigation into the cause of the Turbine Trip is in progress. 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 low reactor water level caused an isolation of Primary Containment (Groups 4/13/15) as expected. The Primary Containment Isolation Event is being reported under 10 CFR 50.72(b)(3)(iv)(A). There was no impact to the health and safety of the public or plant personnel. The NRC resident has been notified. |
| ENS 55732 | 4 February 2022 20:30:00 | The following information was provided by the licensee via email: At 1700 EST, on February 4, 2022 with the unit in Mode 1 at 58 percent power, the reactor automatically scrammed due to low Reactor water level due to a transient on the Feedwater System while preparing to shutdown for a refueling outage. The scram was not complex, with systems responding normally post-scram. Operations responded and stabilized the plant. Reactor water level has been recovered and maintained at normal level. Decay Heat is being removed by the Main Steam system to the main condenser using the Turbine Bypass Valves. All Control Rods inserted into the core. The transient occurred while in the process of removing the South Reactor Feed Pump from service. While reducing speed on the South, the North Reactor Feed Pump increased in speed and tripped on low suction. The plant was preparing to shut down for a refueling outage when the trip occurred. 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, in preparation of plant shutdown, Primary Containment De-Inerting was in progress. The low Reactor water level caused an isolation of Primary Containment (Groups 4/13/15). The Primary Containment Isolation Event is being reported under 10 CFR 50.72(b)(3)(iv)(A). There was no impact to the health and safety of the public or plant personnel. The NRC resident has been notified. |
| ENS 55423 | 22 August 2021 12:10:00 | At 0529 EDT on August 22, 2021, HPCI ((High Pressure Coolant Injection System)) was declared inoperable due to receiving the HPCI Inverter Circuit Failure annunciator. The cause of the annunciator was a fuse failure. The cause of the fuse failure is unknown at this time and is under investigation. Concurrent with the HPCI fuse failure was a similar fuse failure within the Division 2 EDG ((emergency diesel generators)) Load Sequencer which renders the Division 2 EDGs inoperable. Relation to the HPCI issue is unknown and is part of the investigation. The RCIC ((Reactor Core Isolation Cooling System)) was verified operable per Tech Spec 3.5.1 E.1. In addition, offsite circuits were verified operable per Tech Spec 3.8.1.B. Division 1 EDGs remain operable. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. There was no impact on the health and safety of the public or plant personnel. The Senior NRC Resident Inspector has been notified. |