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	Start date	Site	Reporting criterion	System	Event description
ENS 56987	2 January 2024 04:33:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary containment Reactor Building Ventilation	The following information was provided by the licensee via phone and email: This 60-day optional telephone notification is being made in lieu of a Licensee Event Report (LER) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 2333 EST on January 1, 2024, an invalid actuation of group 6 primary containment isolation valves (PCIVs) (i.e., containment atmospheric control/monitoring (CAC/CAM) and post-accident sampling system (PASS) isolation valves) occurred. Reactor building ventilation isolated and standby gas treatment started per design. No manipulations associated with the isolation or reset logic were ongoing at the time. Troubleshooting determined that the group 6 isolation signal resulted from spurious relay contact actuation in the main stack radiation high-high isolation logic due to relay contact oxidation. The main stack radiation monitor is a shared component that sends isolation signals to Unit 1 and Unit 2. There were no Unit 1 actuations. Only the relay contacts associated with Unit 2 actuated. The relay has been replaced. The actuation was not initiated in response to actual plant conditions. It was not an intentional manual initiation and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. During this event the PCIVs functioned successfully, and the actuations were complete. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector had been notified.
ENS 56988	28 December 2023 13:15:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Emergency Diesel Generator	The following information was provided by the licensee via phone and email: This 60-day optional telephone notification is being made in lieu of a Licensee Event Report (LER) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 0815 EST on December 28, 2023, an invalid actuation of the four emergency diesel generators (EDGs) occurred. It was determined that this condition was likely caused by spurious operation of the undervoltage relay for the startup auxiliary transformer feeder breaker to the `1D' balance of plant bus which was being fed by the unit auxiliary transformer at the time, per the normal lineup. This non-safety related EDG actuation logic was disabled, and additional investigation is planned during the upcoming refueling outage. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. During this event, the four EDGs functioned successfully, and the actuations were complete. All emergency buses remained energized from offsite power and, therefore, the EDGs did not tie to their respective buses. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector had been notified.
ENS 56897	2 November 2023 01:11:00	Hatch	10 CFR 50.73(a)(1), Submit an LER	Secondary containment Main Steam Isolation Valve Reactor Core Isolation Cooling Primary containment Reactor Water Cleanup	The following information was provided by the licensee via email and phone: At 2011 EDT on 11/01/23, with Unit 2 in Mode 3 at 0 percent power, Unit 2 received multiple spurious actuations. These actuations consisted of a partial group 1 and a partial group 5 primary containment isolation and a partial secondary containment isolation. The partial Group 1 isolation resulted in the closure of two main steam isolation valves (MSIVs); all other MSIVs were already closed. The partial group 5 isolation auto closed one of the reactor water cleanup (RWCU) isolation valves. The partial secondary containment isolation resulted in the closure of the inboard refueling floor and reactor building secondary containment isolation valves (SCIVs). Additionally, at 2238 EDT, Unit 2 again received multiple spurious actuations. These actuations consisted of a partial group 5 primary containment isolation and a partial secondary containment isolation. The partial group 5 isolation auto closed one of the RWCU isolation valves The partial secondary containment isolation resulted in the closure of the inboard refueling floor and reactor building SCIVs. And again, at 2354 EDT, Unit 2 received spurious actuations which consisted of a partial secondary containment isolation which resulted in the closure of the inboard refueling floor and reactor building SCIVs. The spurious actuations seen on 11/1/23 are triggered at -35 inches reactor water level (RWL) for group 5 and secondary containment isolations and at -101 inches RWL for group 1 isolations. It was determined that a combination of the RWL fluctuating above and below the wide range instrument reference leg tap, the reactor vessel pressure being lowered, and reactor core isolation cooling introducing colder water conditions near the reference leg tap of the wide range instrument caused the spurious actuations. Using multiple RWL indications for each of the instances mentioned above, the actuations were confirmed to be spurious as RWL was being controlled in a band of +55 inches to +85 inches at the time of the actuations. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in an invalid actuation of a partial group 1, a partial group 5, and partial secondary containment logic. The NRC Resident has been notified.
ENS 56781	8 August 2023 18:07:00	Diablo Canyon	10 CFR 50.73(a)(1), Submit an LER		The following information was provided by the licensee via phone and email: This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A). On August 8, 2023, at 1107 hours pacific daylight time (PDT) with Unit 1 in Mode 1 at 100 percent power, an invalid actuation occurred when Unit 1 4-kV vital bus 'G' was automatically transferred from auxiliary power to startup power due to an invalid bus under voltage signal, which occurred during planned maintenance activities. As a result of the actuation signal, auxiliary salt water and containment fan cooling units transferred automatically and started as designed. Plant systems responded as expected. This event was entered into the Diablo Canyon Power Plant corrective action program for resolution. There was no plant or public safety impact. The NRC Senior Resident Inspector has been notified.
ENS 56779	7 August 2023 18:39:00	Vogtle	10 CFR 50.73(a)(1), Submit an LER	Reactor Coolant System Automatic Depressurization System	The following information was provided by the licensee via phone and email: At 1439 EDT on August 7, 2023, a spurious level spike on the unit 4 reactor coolant system (RCS) level instrument (4-RCS-LT160A, 'Hot Leg 1 Level') caused actuation of containment isolation, reactor trip, automatic depressurization system (ADS) stage 4, and in containment refueling water storage tank (IRWST) isolation signals. The spurious level changes caused an invalid signal based on the incidental response of the 4-RCS-LT160A instrumentation due to water spray that was being used for reactor vessel cleaning (being performed prior to initial fuel loading). The level fluctuations resulted in engineered safety features actuation signals (containment isolation, ADS stage 4, and IRWST isolation signals) and a reactor trip signal, with the reactor trip signal already present. Three containment isolation valves closed due to the containment isolation signal that was generated. These valves were: 4-CAS-V014, 'instrument air supply containment isolation, air-operated valve,' 4-SFS-V034, 'spent fuel pool cooling system suction header containment isolation, motor-operated valve,' and 4-SFS-V035, 'spent fuel pool cooling system suction header containment isolation, motor-operated valve.' The other automatic containment isolation valves were either already closed at the time of the event or properly removed from service. All affected equipment functioned properly. The other actuation signals that were observed during this event (ADS stage 4, IRWST isolation, and reactor trip) did not result in any equipment changing position or automatically operating (i.e., the actuation signals occurred while the systems were properly removed from service). Units 1, 2, and 3 were not affected. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified.
ENS 56787	18 June 2023 04:00:00	North Anna	10 CFR 50.73(a)(1), Submit an LER	Emergency Core Cooling System	The following information was provided by the licensee via phone and email: This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid specific system actuation of the North Anna Power Station Unit 1 Emergency Core Cooling System (ECCS). On 6/18/2023, a comparator card power supply associated with 1-CH-PC-1121A, charging pressure low-standby pump start signal comparator, failed and caused the `A' and `B' charging pumps to auto-start and the previously running `C' charging pump to trip and lock-out. This event is considered an invalid system actuation because the actuation was not initiated in response to actual plant conditions or parameters and was not a manual initiation. The ECCS pumps functioned as expected in response to the actuation. The `A' Charging pump was shut down in accordance with plant procedures following replacement of the comparator card. There was no impact on the health and safety of the public or plant personnel. The reportability requirement was determined beyond the 60-day notification requirement on 9/21/2023. The NRC Resident Inspector has been notified.
ENS 56625	17 May 2023 10:39:00	Columbia	10 CFR 50.73(a)(1), Submit an LER	High Pressure Core Spray Main Steam	The following information was provided by the licensee email: At 0339 CDT on May 17, 2023, diesel generator 3 (DG3) had an auto-start during a surveillance test of excess flow check valves in containment atmosphere instrument sensing lines. During the surveillance, workers failed to recognize residual pressure in the system from the test. Per procedure, MS-PS-47C (main steam pressure switch) was placed back in service, resulting in initiation logic for both the high pressure core spray (HPCS) system and DG3 auto-start. Because the HPCS system was tagged out of service for maintenance it did not actuate. The auto-start of DG3 was an expected response to the high drywell pressure indication. The signals cleared, and DG3 was shutdown per procedure. As indicated in 10 CFR 50.73(a)(1), in the case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv)(A), the licensee may, at its option, provide a telephonic notification to the NRC Operations Center within 60 days of discovery of the event instead of submitting a written licensee event report. This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) for invalid actuations reported under 10 CFR 50.73 (a)(2)(iv)(A). This actuation was invalid since it was caused by programmatic issues in quality of procedural guidance and not the result of actual plant conditions warranting auto-start of DG3. The actuations were not initiated in response to actual plant conditions, this was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation. Therefore, this event has been determined to be an invalid actuation. Diesel generator 3 system responded as designed to the actuation signal. The HPCS system did not actuate since it was tagged out of service. There was no impact on the health and safety of the public or plant personnel. The following information is provided as specified in NUREG-1022: (a) The diesel generator 3 was actuated. (b) The actuation of DG3 was complete. (c) The DG3 train was started and functioned successfully. The NRC Resident Inspector has been notified.
ENS 56584	28 April 2023 09:02:00	Monticello	10 CFR 50.73(a)(1), Submit an LER	Primary containment Standby Gas Treatment System	The following information was provided by the licensee email: This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to report an invalid actuation of Division 2 Primary Containment Isolation logic at the Monticello Nuclear Generating Plant (MNGP) that occurred while in a refueling outage. At approximately 0402 Central Daylight Time (CDT) on April 28, 2023 and at approximately 1611 and 2143 CDT on May 4, 2023, momentary losses of 'Y80 Division 2 Uninterruptible 120VAC Class 1E Distribution Panel', which provides power to Division 2 Primary Containment Isolation logic, resulted in a partial Primary Containment Group 2 Isolation (gas systems), initiation of the Standby Gas Treatment system, and the shift of Control Room ventilation to the high radiation mode. The momentary losses of 'Y80' were due to an intermittent, age-related degradation issue with the 'Uninterruptible Power Supply Y81, Division 2 120VAC Class 1E Inverter', which resulted in a temporary loss of output plus a lack of static switch transfer from the inverter supply to the alternate source as designed. The actuations were not initiated in response to actual plant conditions, these were not intentional manual initiations, and there were no parameters satisfying the requirements for initiation. Therefore, these events have been determined to be invalid actuations that were attributed to the same cause. All systems responded as designed to the actuation signal. Operations reset the partial Primary Containment Group 2 Isolation signal, shutdown the Standby Gas Treatment system, and restored Control Room ventilation per the procedure. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 56464	16 February 2023 12:05:00	Limerick	Other Unspec Reqmnt 10 CFR 50.73(a)(1), Submit an LER	Service water	The following information was provided by the licensee via email: This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid specific system actuation of the Emergency Service Water (ESW) System. On 2/16/2023, while performing a calibration planned maintenance (PM) for a jacket water pressure indicator during a D13 diesel generator system outage window, the 'C' ESW pump unexpectedly auto-started. Subsequent investigation identified that the affected jacket water pressure indicator shares a common sensing line with a jacket water pressure switch that provides a back-up to the engine speed switch for the engine running signal. At the time the jacket water pressure indicator calibration PM was being performed, the power circuits for D13 diesel generator instrumentation were energized. Pressurization of the energized jacket water pressure switch during the pressure indicator calibration activity resulted in initiation of a false engine running signal to the `C' ESW pump start logic. This event is considered an invalid system actuation because the 'C' ESW pump started in response to a false signal that the D13 EDG was running when the D13 EDG did not start. The actuation was not initiated in response to actual plant conditions or parameters and was not a manual initiation. The ESW system functioned as expected in response to the actuation. The affected ESW pump was shut down in accordance with plant procedures. There was no impact on the health and safety of the public or plant personnel. The licensee notified the NRC Resident Inspector.
ENS 56345	1 January 2023 11:04:00	McGuire	10 CFR 50.73(a)(1), Submit an LER	Auxiliary Feedwater	The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of a Licensee Event Report as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to 10 CFR 50.73(a)(2)(iv)(A) for an invalid system actuation. On January 1, 2023, at approximately 0604 EST, static inverter KXA failed causing a loss of power to shared 120-VAC auxiliary control panel board KXA. Operations entered the appropriate procedures to assist in diagnosing and responding to the event. As expected, the solenoid valves in the instrument lines to steam supply valves 1SA-48ABC and 1SA-49AB deenergized, causing 1SA-48ABC and 1SA-49AB to open and admit steam to the unit 1 turbine driven auxiliary feedwater pump (TDAFWP). Operations reduced turbine load to maintain reactor power less than 100 percent. At approximately 0641 EST, power was restored to the KXA panelboard and the TDAFWP was secured. All systems functioned as required. Actuation of the TDAFWP was not initiated in response to actual plant conditions or parameters satisfying the requirements for initiation of the system nor was the actuation due to an intentional manual initiation. Therefore, this actuation is considered an invalid actuation. The NRC Resident Inspector has been notified.
ENS 56347	25 December 2022 11:37:00	Calvert Cliffs	10 CFR 50.73(a)(1), Submit an LER	Emergency Diesel Generator	The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of an LER (Licensee Event Report) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 0637 EST on December 25, 2022, the 2B EDG inadvertently started and ran unloaded without a valid undervoltage or safety injection actuation signal. It was determined that this condition was caused by the failure of the emergency start button due to age-related degradation. The button is normally held depressed (closed) by the glass enclosure in standby. To start the EDG using the Emergency Start Button, the button is released (open) when the glass enclosure is broken, which sends a start signal to the EDG. During troubleshooting, the resistance across the button contacts was measured at zero volts DC, indicating the button had failed to an open state causing the EDG to start. The button fell apart when the glass enclosure was removed. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the emergency diesel generator. The NRC Resident Inspector has been notified.
ENS 56274	24 November 2022 21:21:00	Watts Bar	10 CFR 50.73(a)(1), Submit an LER		The following information was provided by the licensee via email: This 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report an invalid Containment Ventilation Isolation (CVI) actuation at Watts Bar Nuclear Plant (WBN) Unit 1. On November 24, 2022, at 1621 Eastern Standard Time (EST), the Train B CVI actuated due to an invalid high radiation signal from 1-RM-90-131, Containment Purge Air Exhaust Monitor. Upon investigation, the high radiation signal was caused by a failed power supply. Corrective action included replacing the power supply, 1-RM-90-131 ratemeter, and restoring the system to service. Prior to and following the invalid high radiation alarm, all radiation monitors except 1-RM-90-131 were stable at their normal values; therefore, the CVI was invalid. Control room operators performed appropriate checks and confirmed that all required automatic actuations occurred as designed. This event has been entered into the corrective action program as Condition Report 1819098. The NRC Resident Inspector was notified.
ENS 56280	12 November 2022 04:33:00	Peach Bottom	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System Primary containment Reactor Building Ventilation	The following information was provided by the licensee via email: This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) for an invalid actuation of a primary containment isolation signal affecting more than one system. On November 11, 2022, at 2333 hours EST, Peach Bottom experienced an unplanned loss of the #343 Off-Site Startup Source. Due to the temporary loss of power during automatic bus transfers, several systems experienced Primary Containment Isolation System (PCIS) Group II and Group III (GP II/III) isolation signals. Plant Systems impacted by isolation valve closure included: Reactor Water Clean Up (RWCU), Containment Atmospheric Control (CAC), Traversing In-Core Probe (TIP) Purge, Primary Containment Floor and Equipment Drains, and the Instrument Nitrogen system. All equipment responded as designed. Plant conditions which initiate PCIS GP II isolation signals are Reactor Vessel Low Water Level, High Drywell Pressure, RWCU system High Flow or RWCU Non-Regenerative Heat Exchanger High Outlet Temperature. The PCIS GP III actuations are initiated by the Reactor Vessel Low Water Level, Primary Containment High Pressure, Reactor Building Ventilation High Radiation or Refuel Floor Ventilation High Radiation. At the time of the event, none of these actual plant conditions existed; therefore, the actuation of the PCIS was invalid. The loss of the #343 Off-Site Startup Source was caused by a failed printed circuit card in the programable logic controller (PLC) for the 3435 breaker. There is no time-based maintenance strategy for PLC replacement. The PLC circuit card was replaced, and the breaker restored to full qualification and service. Preventive maintenance strategy will be enhanced to address the identified vulnerability. The licensee has notified the NRC Resident Inspector.
ENS 56287	9 November 2022 14:06:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary containment Reactor Building Ventilation	The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of an LER (Licensee Event Report) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 0906 Eastern Time (EST) on November 9, 2022, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring and Post Accident Sampling isolation valves) occurred. In addition, per design, Reactor Building Ventilation isolated and Standby Gas Treatment started. It was determined that this condition was caused by faulty test equipment that was being used during preparation for the Main Stack Radiation Monitor High Radiation Response Time test. This test requires connecting a recording device to monitor for the test start signal on a Unit 2 relay associated with the Main Stack High Radiation signal. The recorder faulted which caused the associated fuse to blow and resulted in Unit 2 receiving a Main Stack High Radiation signal and Group 6 PCIV actuation. It was verified that the radiation monitor was not in trip electrically (i.e., there was no high radiation condition). The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. During this event the PCIVs functioned successfully, and the actuations were complete. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified.
ENS 56283	2 November 2022 23:29:00	Limerick	10 CFR 50.73(a)(1), Submit an LER	Service water Emergency Diesel Generator	The following information was provided by the licensee via email: This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid specific system actuation of the Emergency Service Water System (ESW). On 11/2/2022, during normal reactor operations, multiple main control room alarms were received for D12 Emergency Diesel Generator (EDG) running and Unit 1 Division 2 Safeguard Battery Ground. The D12 EDG did not start; however, the 'B' ESW Pump auto started. Subsequent troubleshooting determined that the cause of the D12 EDG running alarms and the inadvertent auto start of the 'B' ESW Pump was a malfunction on the D12 EDG speed switch. This event is considered an invalid system actuation because the 'B' ESW Pump started in response to a false signal that the D12 EDG was running when D12 EDG did not start. This was a complete actuation of the ESW System and the system functioned as expected in response to the actuation. The affected ESW Pump was shut down in accordance with plant procedures and the degraded D12 EDG speed switch was replaced. There was no impact on the health and safety of the public or plant personnel. The licensee notified the NRC Resident Inspector.
ENS 56202	6 September 2022 14:21:00	Waterford	10 CFR 50.73(a)(1), Submit an LER		The following information was provided by the licensee via email: This 60-day telephonic notification is being made in lieu of a licensee event report submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid engineered safety feature actuation signal. On September 6, 2022, at Waterford 3, while performing a plant protection system (PPS) power supply check, technicians observed an abnormally high voltage output. When the technicians opened the PPS bay cabinet door to adjust the voltage, they then observed low voltage indications. The direct cause of this issue is believed to be vibration induced relay chattering or an intermittent connection issue when opening the rear doors of PPS cabinets. This resulted in half the logic being met for the Engineered Safety Feature Actuation Signal (ESFAS) signals to fully actuate. The ESFAS signal opened the following valves: EFW-228A (EFW to SG 1 Primary Isolation), EFW-229A (EFW to SG 1 Backup Isolation), EFW-228B (EFW to SG 2 Primary Isolation) and EFW-229B (EFW to SG 2 Backup Isolation). This was a partial actuation of ESFAS. Affected plant systems functioned successfully. The inadvertent actuation was caused by a spurious signal and was not a valid signal resulting from actual parameter inputs. The 1992 Statements of Consideration define an invalid signal to include spurious signals including jarring of a cabinet door. In accordance with 10 CFR 50.73(a)(1) a telephone notification is being made in lieu of submitting a written licensee event report. The NRC Senior Resident Inspector has been notified. These events did not result in any adverse impact to the health and safety of the public.
ENS 56138	6 August 2022 10:28:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary containment Reactor Building Ventilation	The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of an LER submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for invalid actuations of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 0628 Eastern Daylight Time (EDT) on August 6, 2022, an invalid actuation of group 6 Primary Containment Isolation Valves (PCIVs) (i.e., containment atmospheric control/monitoring and post accident sampling isolation valves) occurred. The group 6 isolation signal resulted from the reactor building ventilation radiation monitor `A' channel exceeding the setpoint value. This condition recurred at approximately 1305 EDT on August 12, 2022. In both instances, the `B' channel, located in the same plenum, remained steady and below the setpoint value through the entire event. This, along with readings made by radiation protection technicians, confirmed that there were no actual high radiation conditions in the reactor building exhaust in either instance. Following each invalid actuation, upon returning unit 2 reactor building ventilation to service, the `A' channel readings returned to be consistent with the `B' channel. It was determined that these invalid actuations likely resulted from degradation of circuit components associated with the radiation monitor. The `A' channel radiation monitor was replaced on September 22, 2022. During these two events, the PCIVs functioned successfully and the actuations were complete. The actuations were not initiated in response to actual plant conditions, they were not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, these events have been determined to be invalid actuations. These events did not result in any adverse impact to the health and safety of the public.
ENS 56094	28 July 2022 22:05:00	South Texas	10 CFR 50.73(a)(1), Submit an LER	Steam Generator Auxiliary Feedwater	The following information was provided by the licensee via fax: Auxiliary Feedwater Pump #12 actuation and isolation of the Steam Generator Blowdown for 'A', 'B' and 'C' Steam Generators. Per 10 CFR 50.73(a)(1), the telephone notification is made under 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation. On 7/28/2022 at 1705 CDT, the Unit 1 Control Room received alarm SPQD0183 'SG LO-LO LVL TRN B ACT' and actuation of the Auxiliary Feedwater Pump #12 and isolation of the Steam Generator Blowdown for 'A', 'B' and 'D' Steam Generators. This event was classified as an unplanned entry into Technical Specification Shutdown LCO equal to or less than 24 hours 'Simple Restoration', due to the availability of CRMP. This alarm occurred several times and with each occurrence the alarm was short lived (1 second or less). Operations placed Auxiliary Feedwater Pump #12 in the Pull-To-Lock position to prevent starting of the pump with each alarm occurrence. During troubleshooting it was determined that SSPS Logic 'R' train was generating the intermittent alarm condition. A Logic board and a Safeguard Driver board were replaced which was identified as the possible cause. Operations performed applicable sections of the Logic test to ensure SSPS 'R' train operable. The event had no effects/consequences on the unit. The Logic board and Safeguard Driver board in SSPS 'R' train were both replaced as the possible causes, and therefore both boards were sent to Westinghouse to determine which board was at fault. The NRC Resident Inspector has been notified.
ENS 56047	23 July 2022 00:49:00	Wolf Creek	10 CFR 50.73(a)(1), Submit an LER	Feedwater Auxiliary Feedwater	The following information was provided by the licensee via email: This 60-day telephone notification is being made under the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of the auxiliary feedwater system. At 1949 Central Daylight Time (CDT), on 7/22/22, an invalid actuation of the auxiliary feedwater system occurred due to human error. At the time of the event, Wolf Creek Generating Station was coming out of a forced outage. Plant conditions were 47 percent power with operators increasing power approximately 10 percent per hour. At this power level there was one main feedwater pump in service and Operations was performing the procedure to place the second main feedwater pump into service. A control room operator was verifying that the control oil switches were not tripped for the main feedwater pumps by verifying the bulbs for both the 'A' and 'B' trains were not lit. To verify the unlit bulbs were not burnt out, the operator was pushing the lamp test buttons. The operator successfully verified the 'A' train, but on the 'B' train the operator mistakenly pushed the bi-stable which is located directly above the bulb rather than the lamp test button. This bi-stable is the low oil pressure switch for the 'A' main feedwater pump. Because the second feedwater pump was not running yet, this caused a 'two out of two' signal for low oil pressure and caused an auxiliary feedwater system actuation. The auxiliary feedwater system responded correctly and was returned to standby condition. The Senior Resident Inspector has been notified.
ENS 55972	2 May 2022 04:05:00	Callaway	Other Unspec Reqmnt 10 CFR 50.73(a)(1), Submit an LER	Service water	The following information was provided by the licensee via phone and email: This non-emergency notification is being made pursuant to the provisions of 10 CFR 50.73(a)(1) to report the occurrence of an invalid automatic actuation satisfying the reporting criterion of 10 CFR 50.73(a)(2)(iv)(A), specifically for the actuation of one train of the Essential Service Water (ESW) system that occurred on May 1, 2022. On May 1, 2022, with the plant shut down and the core offloaded, control room personnel were performing a fast power transfer from Engineered Safety Feature (ESF) transformer XNB02 to ESF transformer XNB01. In anticipation of this activity, the `B' load shedder and emergency load sequencer (LSELS) had been removed from service. Also, at the time, a portion of the `A' ESW train was isolated to support performance of a local leak rate test (LLRT) of a containment isolation valve in the affected portion of `A' ESW train piping. Service Water was supplying cooling water flow to `A' train loads (in lieu of ESW cooling water). When the power transfer was performed, an unexpected automatic start of the `A' ESW pump, along with some associated, automatic valve repositioning, occurred. The actuation occurred due to inadvertent satisfaction of automatic start logic for the ESW pump. The logic is intended to detect loss of ESW flow when the opposite train LSELS isolates Service Water during an undervoltage condition on a safety bus. The flow transmitter involved in the actuation is situated in a portion of the ESW piping that was isolated for the LLRT. The low-flow signal from the transmitter was consequently not reflective of low cooling water flow to plant loads in light of the fact that cooling water flow was being supplied to plant loads and the transmitter was locally isolated. In regard to the ESW train actuation, therefore, although the undervoltage signal was considered a valid signal due to the voltage drop caused by the fast transfer activity, the low-flow signal from the noted transmitter was considered to be invalid. For this invalid actuation, it was concluded that the actuation was not part of a pre-planned sequence, that the affected system was not properly removed from service during the occurrence, and that the safety function had not already been performed relative to the occurrence. (The) NRC Resident Inspector has been notified and an email of this report has been sent to hoo.hoc@nrc.gov.
ENS 55926	12 April 2022 03:45:00	Palo Verde	10 CFR 50.73(a)(1), Submit an LER	Auxiliary Feedwater Spray Pond	The following information was provided by the licensee via email: The following event description is based on information currently available. If, through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10 CFR 50.73. This telephone notification is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe invalid actuations of the Palo Verde Nuclear Generating Station (PVNGS) Unit 1 B Train Auxiliary Feedwater (AF) system and Essential Spray Pond (ESP) system that occurred while in a refueling outage. On April 11, 2022, at approximately 2045 Mountain Standard Time, an automatic start of the Unit 1 B Train AF and ESP systems occurred during restoration from a surveillance test. The station was conducting a surveillance test during a Unit 1 refueling outage to verify the proper responses of the Engineered Safety Features Actuation Systems to simulated design basis events. The test portion was completed satisfactorily; however, during the restoration portion, the load sequencer inadvertently cycled between Mode 0 and Mode 1 three times in immediate succession. At the time of the system actuations, one of the actuation signals associated with this portion of the test had been reset per procedure. Another actuation signal was still in while restoration steps were ongoing, but the sequencer was not expected to cycle between Modes. The system actuations did not occur as a result of actual plant conditions or parameters and are therefore invalid. The Unit 1 B Train AF and ESP system actuations were complete and the systems started and functioned successfully. For the systems that did not actuate, the reasons are clearly understood as those systems were in an overridden condition due to test configuration. The spurious actuation was not able to be replicated and a direct cause was not identified. There were no adverse impacts to public health and safety nor to plant employees. The NRC Resident Inspectors have been informed.
ENS 55859	7 March 2022 04:40:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Service water Emergency Diesel Generator Primary Containment Isolation System Reactor Core Isolation Cooling Shutdown Cooling Core Spray Residual Heat Removal Emergency Core Cooling System	The following information was provided by the licensee via fax or email: This 60-day telephone notification is being made in lieu of an LER submittal per 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for invalid actuations of systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 0040 Eastern Standard Time (EST) on March 7, 2022, Unit 1 received inadvertent High-Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) initiation signals. Subsequently, at approximately 0148 EST on March 7, 2022, Unit 1 received inadvertent Low-Pressure Coolant Injection (LPCI) and Core Spray initiation signals. In addition, all four Emergency Diesel Generators auto started, Group 10 (Instrument Air) Primary Containment Isolation System actuations occurred, and the Residual Heat Removal (RHR) Service Water Booster pumps tripped resulting in a brief interruption (approximately 9 minutes) to the Shutdown Cooling (SDC) heatsink. Jumpers, installed per planned refueling outage activities, prevented discharge of Emergency Core Cooling Systems into the reactor. HPCI, RCIC, and RHR Loop `A' were removed from service and under clearance. RHR SDC remained operable via RHR Loop `B' and forced circulation was maintained in the reactor. At the time of these events, Unit 1 was shutdown for refueling and the `A' and `C' reactor water level transmitters had been isolated in preparation for planned replacement. Leak-by of the instrument isolation valves occurred on both transmitters. Leak-by on the `C' instrument occurred at a faster rate with the `A' instrument providing the confirmatory signals resulting in Low Level 2 (LL2) and Low Level 3 (LL3) indication at approximately 0040 EST and 0148 EST, respectively. All actuations occurred as designed for LL2 and LL3 signals. During these events, reactor water level remained stable at the Reactor Vessel Head Flange and the `B' and `D' reactor water level transmitters remained off-scale-high, as expected under these conditions. Therefore, the actuations were not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system (i.e., there was no low reactor water level condition). Considering the above, these actuations were invalid. There was no impact on the health and safety of the public or plant personnel.
ENS 55756	4 January 2022 18:16:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System Primary containment Reactor Building Ventilation	The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of an LER (Licensee Event Report) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 1316 Eastern Standard Time (EST) on January 4, 2022, during performance of isolation logic periodic testing associated with Primary Containment Isolation System Groups 2 and 6, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring (CAC/CAM) and Post Accident Sampling (PASS) isolation valves) occurred. This resulted in a Division I CAC isolation signal, a full CAM isolation, and a full PASS isolation. Reactor Building Ventilation isolated and Standby Gas Treatment started per design. No manipulations associated with the isolation or reset logic were ongoing at the time. Troubleshooting determined that the Group 6 isolation signal resulted from a high resistance contact on a relay associated with the main stack radiation high-high isolation logic. This condition interrupted electrical continuity and prevented the Group 6 logic from resetting. Following cleaning of the relay contacts, the isolation logic remained in the reset state. The main stack radiation monitor is a shared component that sends isolation signals to Unit 1 and Unit 2. It was verified that the radiation monitor was not in trip electrically and there were no Unit 2 actuations. Therefore, the actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. As a result, this event has been determined to be an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified.
ENS 55708	29 November 2021 17:28:00	Monticello	10 CFR 50.73(a)(1), Submit an LER	Secondary containment Primary containment Reactor Building Ventilation Standby Gas Treatment System	The following information was provided by the licensee via email: This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of secondary containment relays in accordance with 10 CFR 50.73(a)(2)(iv)(A). On November 29, 2021, the `B' Fuel Pool radiation monitor spiked high during restoration following the performance of the 0068 procedure `Spent Fuel Pool & Reactor Building Exhaust Plenum Monitor Calibration' due to cable to radiation monitor connector degradation from handling. This resulted in a Partial Primary Containment Group II isolation (gas systems), initiation of Standby Gas Treatment system, and isolation of the Reactor Building Ventilation system. All systems responded as designed to the actuation signal. Operations reset the Partial Primary Containment Group II isolation signal, shutdown Standby Gas Treatment System, and restored Reactor Building Ventilation system per procedures. At the time of the occurrence, the `A' Fuel Pool radiation monitor was reading normal at approximately 1.5 mr/hr. The `B' Fuel Pool radiation monitor spiked above the 50 mr/hr setpoint and continued to read erratically. Work was performed to clean and reconnect the connector and testing per 0068 procedure verified the condition was corrected. The `B' Fuel Pool radiation monitor returned to service. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55660	20 October 2021 13:05:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System Reactor Building Ventilation Reactor Water Cleanup	The following information was provided by the licensee via email: This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of the Reactor Protection System (RPS). On October 20, 2021, at approximately 0705 hours Central Daylight Time (CDT), Browns Ferry, Unit 1, 1B RPS bus unexpectedly lost power. The loss of the bus resulted in a half scram, automatic Primary Containment Isolation System (PCIS) Groups 2, 3, 6, and 8 isolations, and Trains A, B, and C SBGT (Stand-By Gas Treatment) and A CREV (Control Room Emergency Ventilation system) started. All systems responded as expected. At 0720 hours CDT, the bus was placed on the alternate power supply and the half scram and PCIS isolations were reset. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. The PCIS Group 6 actuations are initiated by Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation (Reactor Zone or Refuel Zone). The PCIS Group 8 actuations are initiated by Low Reactor Vessel Water Level (Level 3) or High Drywell Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. The cause of the RPS bus loss was a trip of the underfrequency relay due to drift of the relay setpoint. The relay was replaced and 1B RPS bus was returned to the normal power supply on October 21, 2021, at 0510 hours CDT. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1729592. The NRC Resident Inspector has been notified of this event.
ENS 55609	17 October 2021 18:58:00	Ginna	10 CFR 50.73(a)(1), Submit an LER	Reactor Coolant System	This 60-day telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report one invalid actuation of the Unit 1 Containment Isolation System Train "A" in accordance with 10 CFR 50.73(a)(2)(iv)(A). On October 17, 2021 at approximately 1358 (EDT), a DC breaker was opened to perform an inspection of a Containment Isolation (CI) rack. A CI signal was produced and resulted in a loss of Letdown during filling and venting the Reactor Coolant System (RCS) with the RCS at 344 psig. RCS pressure began to rise, and prompt actions were taken by the Control Room to secure a Charging Pump within 20 seconds. The RCS pressure rise continued and both Pressure Operated Relief Valves cycled at 409.9 psig as designed, lowering RCS pressure. The CI Train "A" was not part of a pre-planned sequence and the event resulted in the invalid actuation of Train "A" Containment Isolation valves in more than one system. All valves functioned successfully. The DC breaker was closed, CI signal reset, and associated CI valves re-opened. All systems functioned as required and returned to normal service. The NRC Senior Resident Inspector has been notified.
ENS 55602	30 September 2021 14:07:00	Beaver Valley	10 CFR 50.73(a)(1), Submit an LER	Emergency Diesel Generator	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid specific system actuation. At 0907 (EDT) on September 30, 2021, with Unit 1 in Mode 1, at 100 percent power, an actuation of the 1-1 emergency diesel generator (EDG) occurred during loss of voltage relay functional testing. The 1-1 EDG auto-start was due to human error during performance of the test procedure when the bus 1AE undervoltage signal was improperly defeated and a simulated undervoltage signal was applied. No actual undervoltage condition was present during this event. The 1-1 EDG automatically started as designed when the bus undervoltage signal was received. This was a complete actuation of an EDG to start and come to rated speed, and all affected systems functioned as expected in response to the actuation. Following the actuation, the relays were restored and the 1-1 EDG was shut down in accordance with plant procedures. This event is considered an invalid system actuation reportable under 10 CFR 50.73(a)(2)(iv)(A). The actuation was not initiated in response to actual plant conditions or parameters and was not a manual initiation. Therefore, in accordance with 10 CFR 50.73(a)(1), this telephone notification is provided within 60 days after discovery of the event instead of submitting a written Licensee Event Report. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55345	13 May 2021 11:00:00	Limerick	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System HVAC Standby Gas Treatment System Reactor Enclosure Recirculation System	This 60-Day telephone notification is being made per the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of containment isolation signal affecting more than one system. On May 13, 2021, during the restoration of the Unit 2 Refuel Floor High Radiation Isolation Logic an invalid isolation signal was received. The condition requiring an isolation signal was verified not to be present prior to restoring the logic; however, it was not recognized that a previous isolation signal was latched in and had not been reset. When the isolation logic was restored, the Primary Containment Isolation System (PCIS) isolated on the invalid signal. The systems successfully completed the isolation per the plant design and plant configuration. The following systems actuated due to the Unit 2 PCIS Group 6C Isolation: - Isolation of Containment Hydrogen and Oxygen Sampling Valves, - Start of the 2A Reactor Enclosure Recirculation System, - Trip of the Units 1 and 2 Refuel Floor HVAC, - Start of the A and B Trains of Standby Gas Treatment Systems. The NRC Resident Inspector was notified.
ENS 55281	2 April 2021 01:23:00	Waterford	10 CFR 50.73(a)(1), Submit an LER	Feedwater	This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Engineered Safety Feature actuation signal. On April 1, 2021, at Waterford 3, while performing a replacement of power supplies on the Plant Protection System, a spurious signal caused a partial actuation of the Emergency Feedwater Actuation Signal. A partial Emergency Feedwater (EFW) logic trip path was met causing the opening of valves EFW-228A (EFW to SG 1 Primary Isolation), EFW-229A (EFW to SG 1 backup isolation), EFW-228B (EFW to SG 2 Primary Isolation), and EFW-229B (EFW to SG2 Backup Isolation). This inadvertent actuation was spurious and was not a valid signal resulting from parameter inputs. The 1992 Statements of Consideration (57 FR 41378) define an invalid signal to include spurious signals. Therefore, this actuation is considered invalid. This event was entered into the Waterford 3 corrective action program for resolution. This event did not result in any adverse impact to the health and safety of the public. The plant responded as expected. In accordance with 10 CFR 50.73(a)(1) a telephone notification is being made in lieu of submitting a written Licensee Event Report. The NRC Senior Resident Inspector has been notified.
ENS 55287	1 April 2021 18:02:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System Reactor Building Ventilation Reactor Water Cleanup Control Room Emergency Ventilation	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of the 2A Reactor Protection System (RPS). On April 1, 2021, at 1302 (CDT), Browns Ferry Unit 2, 2A RPS (Motor Generator) MG set tripped causing a half scram. Unit 2 experienced an unexpected trip of the 2A RPS MG Set that resulted in automatic Primary Containment Isolation System (PCIS) Group 2, 3, 6, and 8 isolations and Trains A, B, and C Standby Gas Treatment (SGT) and Train A Control Room Emergency Ventilation (CREV) starts. At the time of the event, Unit 2 was in a refueling outage and the rods were already fully inserted. All systems responded as expected. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. The PCIS Group 6 actuations are initiated by Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation (Reactor Zone or Refuel Zone). The PCIS Group 8 actuations are initiated by Low Reactor Vessel Water Level (Level 3) or High Drywell Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. Based on the troubleshooting conducted, the cause was determined to be a loose wiring connection in the motor circuit. The lugs were replaced with ring lugs. Operations reset the 2A RPS Half Scram and PCIS in accordance with 2-AOI-99-1 on April 1, 2021, at 1324 CDT thus correcting the condition and returning RPS to service. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1683358. The NRC Resident Inspector has been notified of this event.
ENS 55263	23 March 2021 04:37:00	Perry	10 CFR 50.73(a)(1), Submit an LER	Emergency Core Cooling System	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid specific system actuation. On March 23, 2021, during the performance of the Division 1 ECCS ((Emergency Core Cooling System)) Integrated Test, the Division 1 Diesel Generator (DG) unexpectedly started. While performing the local lockout testing, per the procedure, a step was performed that initiated the unexpected DG start. The following step was to verify the diesel did NOT start. It was later determined that this was a procedural deficiency. The DG started and ran as designed. The DG did not tie to the safety bus as no undervoltage condition was detected. This event is considered an invalid system actuation reportable under 10 CFR 50.73(a)(2)(iv)(A). The actuation was not initiated in response to actual plant conditions or parameters and was not a manual initiation. Therefore, this notification is provided via a 60-day optional phone call in accordance with 10 CFR 50.73(a)(1) instead of submitting a written Licensee Event Report. All affected systems functioned as expected in response to the actuation. The DG was shut down in accordance with plant procedures and the testing procedure corrected. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55240	10 March 2021 13:15:00	LaSalle	10 CFR 50.73(a)(1), Submit an LER	Secondary containment Reactor Building Ventilation	This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of containment isolation valves in more than one system required by 10 CFR 50.73(a)(2)(iv)(A). On March 10, 2021, at 0815 (CST), during the Unit 2 Refueling Outage (L2R18), while performing a test to verify functionality of an isolation relay following replacement of the relay, a Group 4 isolation signal was actuated. The Group 4 isolation logic affects both the Reactor Building Ventilation (VR) and Containment Vent and Purge (VQ) system (for both units). All equipment responded as designed to the Group 4 isolation, including startup of Standby Gas Treatment (SBGT) to maintain secondary containment pressure (for both units). Investigation determined that the cause of the isolation was an inadvertent contact of the self-retracting grip jumper between two adjacent terminals that caused a short to ground and a blown fuse during the test performance. The fuse was replaced and systems restored as needed for the plant condition. The containment isolation was not due to actual plant conditions or parameters meeting design criteria for containment isolation. Therefore, this is considered an invalid actuation. The NRC Resident Inspector has been informed of this notification.
ENS 55188	18 February 2021 03:20:00	Hatch	10 CFR 50.73(a)(1), Submit an LER		At 2320 EST on 02/17/2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Group 2 containment isolation logic occurred on the inboard valves. The reason for the actuation was most likely due to air entrapment in reactor water level sensing lines following maintenance. Group 2 inboard isolation valves in the drywell floor and equipment drain system and the fission product monitor system automatically isolated as designed. As a corrective action, the variable leg and reference leg of the instrumentation were backfilled with water to ensure all air was removed from the line. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that results in an invalid actuation of the Group 2 containment isolation system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55191	17 February 2021 19:07:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System Primary containment Reactor Building Ventilation	This 60-day optional telephone notification is being made in lieu of an LER submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 1507 EDT on February 17, 2021, during performance of isolation logic periodic testing associated with Primary Containment Isolation System Groups 2 and 6, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring and Post Accident Sampling isolation valves) occurred. The Group 6 isolation signal resulted from the reactor building ventilation radiation monitor `B' Channel exceeding the setpoint value. This condition likely resulted from the radiation monitor electronics being impacted by humidity levels, which exceeded the instrument design requirements that developed in the area over time as a result of the Unit 2 reactor building ventilation being secured per the test procedure. The `A' Channel, located in the same plenum, remained steady and below the setpoint value through the entire event. This, along with readings made by a Radiation Protection Technician, confirmed that there was no actual high radiation condition in the reactor building exhaust. Upon returning Unit 2 reactor building ventilation to service, the `B' Channel readings returned to be consistent with the `A' Channel. The PCIVs functioned successfully and the actuation was complete. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified.
ENS 55187	13 February 2021 03:23:00	Hatch	10 CFR 50.73(a)(1), Submit an LER		At 2323 EST on 02/12/2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Group I containment isolation logic occurred during fluid flushing of turbine stop valves. The reason for the actuation was due to a maintenance activity resulting in turbine stop valve movement with no condenser vacuum which is a Group I isolation signal. Two Group I isolation valves, 2B31F019 and 2B31F020, reactor water sample valves, automatically isolated as designed when the system actuation signal was received. The other Group I valves had already been removed from service as part of the refueling outage schedule. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that results in an invalid actuation of the Group I containment isolation system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 55130	11 January 2021 16:52:00	Sequoyah	10 CFR 50.73(a)(1), Submit an LER		This 60-day telephone notification is being submitted in accordance with 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A). The event was an invalid actuation of the Unit 1 Containment Ventilation Isolation (CVI) system. On January 11, 2021 at 1152 Eastern Standard Time (EST) with Unit 1 at 100% power, Train 'A' of the CVI System actuated due to an invalid high radiation signal from 1-RM-90-130, Containment Purge Air Exhaust Monitor. The cause of the signal was determined to be a failed sample pump associated with the radiation monitor. 1-RM-90-130 was in service at the time of the invalid signal. The Train 'A' Containment Ventilation Isolation signal was a full actuation of that train and the system functioned as designed. Prior to and following the invalid high radiation alarms, all radiation monitors except 1-RM-90-130 were stable at their normal values; therefore, the CVI was invalid. Control room operators performed appropriate checks and confirmed that all required automatic actuations occurred as designed. The failed pump was replaced and returned to service. This event was entered into the corrective action program as CR 1663398. The NRC Resident Inspector was notified.
ENS 55032	11 December 2020 07:00:00	Palo Verde	10 CFR 50.73(a)(1), Submit an LER		On October 13, 2020, at approximately 02:25 (MST), an automatic start of the Unit 1 'A' Train EDG and SP systems occurred following the restoration of power to the 'A' Train 4160 Volt Class Bus. The station was conducting a surveillance test during a Unit 1 refueling outage to verify the proper responses of the EDG and the Engineered Safety Features Actuation Systems to simulated design basis events. During the test, technicians installed a jumper across incorrect relay points that caused the running Unit 1 'A' Train EDG to trip, resulting in a loss of power to the 'A' Train 4160 Volt Class Bus. Following restoration of normal offsite power to the 'A' Train 4160 Volt Class Bus, the Loss of Power Actuation signal was reset, however, EDG start relay logic was not reset at the EDG Local Panel. This resulted in the Unit 1 'A' Train EDG and SP system actuations with the EDG running unloaded. The system actuations did not occur as a result of valid plant conditions or parameters and are therefore invalid. The Unit 1 'A' Train EDG and SP system actuations were complete and the systems started and functioned successfully. The event was attributed to a human performance error and entered into the corrective action program. There was no adverse impact to public health and safety nor to plant employees. The NRC Resident Inspectors have been informed.
ENS 55079	1 December 2020 14:46:00	Robinson	10 CFR 50.73(a)(1), Submit an LER	Service water Emergency Diesel Generator Auxiliary Feedwater Residual Heat Removal	This 60-day optional telephone notification is being made in lieu of an LER submittal, as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At 0946 hrs on December 1, 2020, with unit 2 in Mode 5 at 0% power, an invalid actuation of the Emergency Diesel Generators (EDG) 'A' and 'B', 'A' Residual Heat Removal (RHR) Pump, 'A' Service Water Booster Pump (SWBP), and Auxiliary Feed Water (AFW) Pumps 'A' and 'B' occurred. The actuation was caused by a Safety Injection (SI) signal while installing simulations to support Reactor Safeguards testing. The SI signal occurred when two out of three logic was met for Low Pressurizer Pressure, which was caused by a high resistance connection to a test point from a loose test lead. All aligned equipment, 'A' and 'B' EDGs, 'A' RHR Pump, 'A' SWBP and 'A' and 'B' AFW Pumps, responded properly to the auto-start signal and the actuation was complete. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector was notified.
ENS 55026	7 November 2020 00:08:00	Millstone	10 CFR 50.73(a)(1), Submit an LER	Steam Generator Emergency Diesel Generator Emergency Core Cooling System	This 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report an invalid actuation of the 'B' train High Head Safety Injection Pump (3SIHP1B), the 'B' train Low Pressure Safety Injection Pump (3RHSP1B) and four Steam Generator Blowdown Containment isolation valves at Millstone Nuclear Power Station Unit 3. At 1908 EST on November 6, 2020, with Unit 3 in Mode 3, a partial invalid actuation of 'B' train Emergency Core Cooling System (ECCS) components occurred. The 'B' train SIH pump and the 'B' train RHS pump had started, and ran successfully on recirculation. Four Steam Generator Blowdown Containment isolation valves also closed. Due to this condition the 'B' Emergency Diesel Generator and the 'B' Emergency Generator Load Sequencer (EGLS) were declared inoperable and the required Technical Specification action statements were entered. Troubleshooting determined that this actuation was caused by a failure of one of the circuit boards in the 'B' train EGLS that caused a partial 'B' train 'SIS only' signal. Other 'B' Train components received the 'SIS only' signal but did not start because they were already running or were a backup to an already running component. Troubleshooting discovered a failed NAND gate on the 'B' Train EGLS XA93 circuit card. The card was replaced, retested, and the Technical Specification action statements were exited. The pumps and valves responded in accordance with plant design. No other equipment was affected during this event. There were no safety consequences or impacts on the health and safety of the public. The event was entered into the station's corrective action program. The actuation was not due to actual plant conditions or parameters meeting design criteria for an ECCS actuation. Therefore, this is considered an invalid actuation. The NRC Resident Inspector was notified.
ENS 54932	6 August 2020 22:49:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System Reactor Building Ventilation Reactor Water Cleanup Control Room Emergency Ventilation	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system. On August 6, 2020, at approximately 1749 CDT, Browns Ferry Nuclear Plant (BFN), Unit 2 experienced a loss of Reactor Protection System (RPS) Bus 2A. Primary Containment Isolation System (PCIS) Groups 2, 3, 6, and 8 isolated in response to this event. The PCIS isolations caused the initiation of Standby Gas Treatment (SBGT) trains A, B, and C, and Control Room Emergency Ventilation (CREV) subsystem A. Unit 2 declared RCS leakage detection instrumentation inoperable and entered TS LCO 3.4.5 condition A, B, and D with required action D.1 to enter LCO 3.0.3 immediately. Unit 2 entered TS LCO 3.0.3 with required actions to be in Mode 2 within 10 hours, Mode 3 within 13 hours, and Mode 4 within 37 hours. Upon investigation, it was discovered that an age-related overheating condition resulted in the failure of the 2A RPS Motor Generator (MG) set, causing the feeder beaker from the 2A 480v Remote Motor-Operated Valve distribution board to trip. On August 6, 2020, at approximately 1808 CDT, Operations personnel commenced restoration of Unit 2 to normal after transferring 2A RPS to its alternate power supply. The 2A RPS MG Set drive motor was replaced on August 24, 2020. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel (RV) Low Water Level or Drywell High Pressure. Plant conditions which initiate PCIS Group 3 actuations are RV Low Water Level or Reactor Water Cleanup Area High Temperature. Plant conditions which initiate PCIS Group 6 actuations are RV Low Water Level, High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation. Plant conditions which initiate PCIS Group 8 actuations are Reactor Vessel (RV) Low Water Level or Drywell High Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. All affected safety systems responded as expected. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1628707. The NRC Resident Inspector has been notified of this event.
ENS 54931	6 August 2020 06:28:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Service water Core Spray Emergency Equipment Cooling Water	This 60-day telephone notification is being made under reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of an emergency service water system component that does not normally run and which provides an ultimate heat sink. On August 6, 2020, at approximately 0128 CDT, the A3 Emergency Equipment Cooling Water (EECW) pump received an auto-start signal while performing Post-Maintenance Testing (PMT) on the 3C Core Spray pump. Normally, the involved EECW pump would be started prior to testing to prevent an auto-start; however, in this case the pump was not running prior to the test. When the 3C Core Spray pump breaker was closed while in the test position, an unanticipated actuation of the A3 EECW pump occurred. Work was stopped and the workers reported to the Control Room to evaluate the condition. Based on a review of this event, individuals involved were coached on understanding system response prior to performing work. The A3 EECW pump responded in accordance with the plant design. No other plant equipment was affected during this event. There were no safety consequences or impacts on the health and safety of the public. The event was entered into TVA's corrective action program for evaluation and resolution. Reference corrective action document CR 1628479. The NRC Resident Inspector has been notified of this event.
ENS 54870	23 July 2020 13:56:00	Watts Bar	10 CFR 50.73(a)(1), Submit an LER		This 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report two invalid Containment Ventilation Isolation (CVI) actuations at Watts Bar Nuclear Plant (WBN) Unit 1. On July 23, 2020, at 0956 Eastern Daylight Time (EDT), the Train A CVI actuated due to an invalid high radiation signal from 1-RM-90-130, Containment Purge Air Exhaust Monitor. Upon investigation, the high radiation signal was caused by a failed power supply. Corrective action included replacing the power supply, 1-RM-90-130 detector, and restoring the system to service. On August 7, 2020, at 2017 EDT, the Train A CVI actuated due to an invalid high radiation signal from 1-RM-90-130, Containment Purge Air Exhaust Monitor. Upon investigation, a small tear was identified in the foil covering the scintillation detector. This defect caused erratic indication and the system actuation. The foil was replaced and the system was restored to service. Prior to and following the invalid high radiation alarms, all radiation monitors except 1-RM-90-130 were stable at their normal values; therefore, the CVI was invalid. Control room operators performed appropriate checks and confirmed that all required automatic actuations occurred as designed. These events were entered into the corrective action program as CR 1625135 and CR 1628904. The NRC Resident Inspector was notified.
ENS 54820	8 June 2020 08:24:00	Peach Bottom	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System	This report is being made as required by 10 CFR 50.73(a)(2)(iv)(A) to describe an automatic actuation of containment isolation valves in more than one system. Because the actuation was invalid, this 60-day telephone notification is being made instead of a written LER (licensee event report), in accordance with 10 CFR 50.73(a)(1). On 06/08/2020, at approximately 0424 EDT, a trip of the Unit 3 'A' reactor protection system (RPS) MG-Set resulted in a partial activation of the primary containment isolation system and inboard containment isolation valves closed in multiple systems. All affected Group III containment isolation valves were verified to be closed. It was determined that the normal power supply for the Unit 3 'A' RPS had failed. Power was transferred from the normal to the alternate source and the RPS 'A' channel was reset. Investigation determined that the 3A RPS MG Set motor contactor coil winding had failed due to an internal short circuit. The motor contactor has been replaced. The containment isolation was not due to actual plant conditions or parameters meeting design criteria for containment isolation. Therefore, this is considered to be an invalid actuation. The NRC Resident Inspector has been informed of this notification.
ENS 54709	16 March 2020 06:02:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System Shutdown Cooling Residual Heat Removal Reactor Water Cleanup	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system. On March 16, 2020, at approximately 0102 CDT, Browns Ferry Nuclear Plant (BFN), Unit 3 received motor trip-out alarms and diagnosed Group 2 and 3 Primary Containment Isolation System (PCIS) Isolations, 3C Residual Heat Removal (RHR) Pump tripping and Reactor Water Cleanup (RWCU) system isolating. All affected safety systems responded as expected. BFN, Unit 3, was nearing the end of the U3R19 refueling outage at the time of the event, and was still dependent on the Shutdown Cooling (SDC) system. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. At the time of the event, these conditions did not exist: therefore, the PCIS actuation was invalid. The event was determined to have been caused by clearance restoration activities in an unprotected control panel. A fuse re-installation inadvertently created a fault condition between two different plant 120 VAC power sources when the fuse holder's lower spring clip contacted a different fuse. This was a result of age-related degradation of the fuse holder, its close proximity to other fuses, and the lack of insulating isolation barriers between fuses. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1594925. The NRC Resident Inspector has been notified of this event.
ENS 54701	14 March 2020 19:44:00	Palo Verde	10 CFR 50.73(a)(1), Submit an LER	Service water Spray Pond	The following event descriptions are based on information currently available. If through subsequent reviews of these events additional information is identified that is pertinent to the events or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10 CFR 50.73. This telephone notification is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(2)(iv)(A) and 50.73(a)(1) to describe invalid actuations of both trains of the Palo Verde Nuclear Generating Station (PVNGS) Unit 3 essential spray pond (SP) system, which serves as an emergency service water system that does not normally run and serves as an ultimate heat sink as described in 10 CFR 50.73(a)(2)(iv)(B)(9). This notification covers two similar, but separate invalid actuations occurring in Unit 3 on March 14, 2020 at 12:44 (MST) and again on April 25, 2020 at 12:10 (MST). On each day, an invalid actuation of the Unit 3 train "B" Fuel Building Essential Ventilation Actuation Signal (FBEVAS) occurred during performance of the Balance of Plant Engineered Safety Features Actuation System weekly auto test. The auto/manual pushbutton was depressed to initiate the test and the sequencer immediately tripped FBEVAS train "B" with subsequent cross trip of FBEVAS train "A". These actuations resulted in complete and successful actuations of both trains of essential spray pond pumps. The events were entered into the PVNGS corrective action program and a station evaluation is in progress. There was no adverse impact to public health and safety nor to plant employees. The NRC resident inspectors have been informed.
ENS 54697	9 March 2020 01:21:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System Reactor Building Ventilation Reactor Water Cleanup Control Room Emergency Ventilation	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system. On March 8, 2020, at approximately 2021 CDT, Browns Ferry Nuclear Plant Unit 2 experienced an unexpected loss of the 2A Reactor Protection System (RPS). This resulted in Primary Containment Isolation System (PCIS) groups 2, 3, 6, and 8 isolations, and the initiation of Standby Gas Treatment Trains A and B, and Control Room Emergency Ventilation System Train A. All affected safety systems responded as expected. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. The PCIS Group 6 actuations are initiated by Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation (Reactor Zone or Refuel Zone). The PCIS Group 8 actuations are initiated by Low Reactor Vessel Water Level (Level 3) or High Drywell Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. The RPS MG Set trip was believed to have been caused by an intermittent short across a spike suppressor, which led to a loss of generator output signal to a voltage regulator. The affected components have been replaced. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Report 1593265. The NRC Resident Inspector has been notified of this event.
ENS 54675	5 March 2020 14:25:00	Brunswick	10 CFR 50.73(a)(1), Submit an LER	Primary containment	This 60-day optional telephone notification is being made in lieu of an LER (licensee event report) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 1025 Eastern Standard Time (EST) on March 5, 2020, with Unit 1 shutdown in Mode 5 for refueling, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring and Post Accident Sampling isolation valves) occurred. The invalid actuation occurred when power was lost as a result of the Inboard Isolation Logic Fuse being removed per a planned clearance hang to support maintenance. The PCIVs functioned successfully and the actuation was complete. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The licensee has notified the NRC Resident Inspector.
ENS 54431	1 November 2019 00:19:00	Comanche Peak	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Auxiliary Feedwater Main Steam Line	This report describes an invalid actuation of the Unit 2 Turbine Driven Auxiliary Feedwater Pump that occurred on October 31, 2019. This report is being made in accordance with 10CFR50.73(a)(1), which states, in part, 'In the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than actuation of the Reactor Protection System (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER.' On October 31, 2019, Comanche Peak Nuclear Power Plant Unit 2 was in Mode 1 operating at 100% power. At 1919 CDT, the Main Steam Line 2-01 steam supply valve to the TDAFWP opened due to a loss of continuity between the fuse supplying control power to the valve positioner and the fuse clips. Operators initiated a 50MW load reduction to maintain power less than 100%. The steam supply to the TDAFWP was closed, the TDAFWP was stopped, and the fuse clips were tightened. Unit 2 was returned to full power at 2055 CDT. The specific train and system that actuated was the third AFW train on Unit 2. The train actuation was complete and during the TDAFWP start the system started and functioned correctly. The NRC Resident Inspector was notified.
ENS 54332	20 August 2019 16:33:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Reactor Protection System Primary Containment Isolation System Reactor Building Ventilation Reactor Water Cleanup Control Room Emergency Ventilation	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system. On August 20, 2019, at approximately 1133 hours Central Daylight Time (CDT), Browns Ferry Nuclear Plant (BFN), Unit 2 experienced an unexpected loss of the 2A Reactor Protection System (RPS). This resulted in Primary Containment Isolation System (PCIS) groups 2, 3, 6, and 8 isolations, and initiation of Standby Gas Treatment Trains A, B, and C and Control Room Emergency Ventilation System Train A. All affected safety systems responded as expected. Plant conditions which initiate PCIS Group 2 actuations are Reactor Vessel Low Water Level (Level 3) or High Drywell Pressure. The PCIS Group 3 actuations are initiated by Reactor Vessel Low Water Level (Level 3) or Reactor Water Cleanup Area High Temperature. The PCIS Group 6 actuations are initiated by Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High radiation (Reactor Zone or Refuel Zone). The PCIS Group 8 actuations are initiated by Low Reactor Vessel Water Level (Level 3) or High Drywell Pressure. At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. The cause of the RPS MG Set trip was dirty potentiometer windings on an Over Voltage Relay. The dirt prevented the potentiometer's wiper from contacting its windings, resulting in erratic setpoint values. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program as Condition Reports 1542603, 1542608, and 1542569. The NRC Resident Inspector has been notified of this event.
ENS 54300	31 July 2019 21:50:00	Browns Ferry	10 CFR 50.73(a)(1), Submit an LER	Primary Containment Isolation System Reactor Building Ventilation Control Room Emergency Ventilation	This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system. On July 31, 2019, at approximately 1650 hours Central Daylight Time (CDT), Browns Ferry Nuclear Plant (BFN), Unit 1 experienced a Primary Containment Isolation System (PCIS) Group 6 isolation during performance of surveillance procedure 1-SR-3.3.6.2.3(A), Reactor/Refueling Zone Ventilation Radiation Monitor 1-RM-90-140/142 Calibration and Functional Test. The Group 6 isolation caused the initiation of Standby Gas Treatment (SBGT) Trains A, B, and C, and Control Room Emergency Ventilation (CREV) subsystem B. Unit 1 H2O2 Analyzer and Drywell Radiation Monitor CAM, 1-RM-90-256, were declared Inoperable and Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.5 Condition B was entered. All affected safety systems responded as expected. Plant conditions which initiate PCIS Group 6 actuations are Reactor Vessel Low Water Level (Level 3), High Drywell Pressure, or Reactor Building Ventilation Exhaust High Radiation (Reactor Zone or Refuel Zone). At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS was invalid. This condition was the result of two cleared fuses in the alarm logic. The apparent cause is a ground fault on the A6 Open Drain Input/Output Module. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Acton Program as Condition Report 1537358. The NRC Resident Inspector has been notified of this event.

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