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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56345 | 1 January 2023 11:04:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-DAY Optional Telephonic Notification of Invalid Actuation of Auxiliary Feedwater Pump | 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. | Auxiliary Feedwater | |
| ENS 50720 | 16 November 2014 04:55:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of 1A Emergency Diesel Generator (Edg) | 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 1A EDG. The 1A EDG start resulted from a degraded component during the testing of the 1A Emergency Load Sequencer. At 2355 (EST) on November 15, 2014, the 1A EDG auto started during performance of the monthly 1A Emergency Load Sequencer test. The test was terminated by personnel prior to a full actuation of the Emergency Load Sequencer due to the unexpected response of the sequencer. The 1A EDG started and functioned normally. Troubleshooting identified a degraded relay downstream of the under voltage sensing circuit which made up the invalid 2/3 logic necessary to start the EDG. There were NO actual plant conditions or parameters (i.e. under voltage, degraded voltage, safety injection or manual initiation) involved in this actuation. The degraded relay would NOT have prevented the 1A Emergency Load Sequencer or the EDG from performing their safety related functions. Following troubleshooting, replacement of the relay and an evaluation for extent of condition, the 1A Emergency Load Sequencer and EDG were returned to service. The health and safety of the public was not affected by this issue. The NRC Resident Inspector has been notified. | Emergency Diesel Generator | |
| ENS 48550 | 2 December 2012 16:42:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Report - Invalid Auxiliary Feedwater and Nuclear Service Water Pump Actuation | The Unit-2 AMSAC (Anticipated Transient Without Scram Mitigation Actuation Circuitry) actuation generated a Unit-2 turbine trip signal. The Unit-2 turbine was already tripped, but the 2A and 2B Auxiliary Feedwater and 2B Nuclear Service Water pump started. AMSAC actuation occurred during calibration of AMSAC actuation pressure switches. The licensee notified the NRC Resident Inspector.
This notification retracts an eight (8) hour notification per 10CFR50.72(b)(3)(iv)(A) which was made December 2, 2012 and documented as NRC Event Notification (EN) # 48550. The December 2, 2012 actuation of the Auxiliary Feedwater System was initially reported under 10CFR 50.72(b)(3)(iv)(A), valid actuation of the Auxiliary Feedwater system as listed in paragraph 10CFR50.72(b)(3)(iv)(B)(6). McGuire Nuclear Station (MNS) has subsequently determined that the actuation signal, which was caused by a test signal during calibration of the AMSAC (Anticipated Transient Without Scram Mitigation Actuation Circuitry) actuation pressure switches, constitutes an invalid actuation as described in Revision 2 of NUREG-1022 (Event Reporting Guidelines 10CFR50.72 and 50.73). Specifically, valid actuations result from signals initiated in response to actual plant conditions or parameters satisfying the requirements for initiation of the safety function of the system. A test signal is not representative of an actual plant condition and was therefore an invalid actuation signal and does not meet the NRC 8-hour reporting criteria under paragraph 10 CFR50.72(b)(3)(iv)(B)(6). In addition to retracting the 10CFR50.72(b)(3)(iv)(B)(6) notification, MNS is notifying the NRC Operations Center that the December 2, 2012 event met the reporting criteria specified in 10CFR50.73(a)(2)(iv)(A). Specifically, an invalid actuation of the auxiliary feed water system occurred while the systems was in service. The event did not involve an actuation of the reactor protection system (RPS) when the reactor was critical; therefore, MNS is opting to notify the NRC Operations Center within 60 days in lieu of a 60 day written licensee Event Report (LER), as allowed by 10CFR 50.73(a)(1) and 10CFR50.73(a)(2)(iv)(A). This notification satisfies 10CFR50.73(a)(2)(iv)(A) reporting requirements in lieu of a written LER. The 2A and 2B trains of the auxiliary feed water were actuated by an invalid signal. Each train's actuation was complete and systems operated as designed. The licensee notified the NRC Resident Inspector. Notified the R2DO (Sykes). | Service water Reactor Protection System Auxiliary Feedwater Auxiliary Feed Water | 05000370/LER-2012-002 |
| ENS 48443 | 30 September 2012 03:37:00 | 10 CFR 50.73(a)(1), Submit an LER | Inadvertent Alignment of Nuclear Service Water to Standby Nuclear Service Water Pond | On September 29, 2012, McGuire Nuclear Station experienced an inadvertent alignment of the Nuclear Service Water (RN) system suction and discharge to the Standby Nuclear Service Water Pond (SNSWP). This event occurred when a Unit 2 'B' Train blackout signal was inadvertently generated as a result of a tagging restoration/coordination error. This error resulted in the Unit 2 Train 'B' load sequencer sensing an under-voltage condition on 4160V Essential Switchgear 2ETB, which was de-energized at the time for maintenance activities. Further evaluation determined that the blackout signal which automatically aligned RN to the SNSWP was not in response to actual plant conditions or parameters satisfying the requirements for initiation of a blackout signal or the SNSWP safety function. Since alignment of RN to the SNSWP was not in response to a valid signal, this represented an invalid actuation reportable per the requirements of 10 CFR 50.73(a)(2)(iv)(A). As allowed by 10 CFR 50.73(a)(1), McGuire is providing a telephone notification of this invalid actuation in lieu of submitting a written LER. The following additional information is being provided as part of the telephone notification of this event: 'B' Train of RN actuated to align Unit 1 and Unit 2 RN to the SNSWP. 'B' Train actuation of Unit 1 and Unit 2 RN to the SNSWP functioned successfully and was complete. The NRC Resident Inspector has been notified. | Service water | |
| ENS 45913 | 16 April 2010 09:21:00 | 10 CFR 50.73(a)(1), Submit an LER | Inadvertent Steam Admission to Afw Turbine | During maintenance on sliding links, the steam admission valve (SA-48) for the Auxiliary Feedwater (AFW) turbine inadvertently opened. Inadequate isolation from the steam header allowed steam flow through SA-77 steam drain valve into the turbine. This small amount of steam caused the pump to rotate at approximately 1000 rpm for approximately 2 minutes. Due to the low discharge pressure, no water was injected into the steam generator during this actuation. The NRC Resident Inspector has been notified. | Steam Generator Auxiliary Feedwater | |
| ENS 45006 | 23 February 2009 08:06:00 | 10 CFR 50.73(a)(1), Submit an LER | Inadvertent Actuation of Turbine Auxiliary Feedwater Pump | On February 23, 2009 at 0406, with Unit 1 at 100% power level, McGuire Nuclear Station experienced an inadvertent actuation of the Unit 1 Turbine Driven Auxiliary/Emergency Feedwater (TDAFW) Pump. This event occurred when power was removed to the steam admittance solenoid valves for the Unit 1 TDAFW Pump prior to isolating the steam supply to the pump. Removing power to the steam admittance valves caused them to fail open, starting the pump and injecting water into all four Unit 1 Steam Generators (S/Gs). Flow to the S/Gs was isolated by manually closing the Unit 1 TDAFW discharge isolation valve to each S/G. During recovery from the event, power was restored to the steam admittance solenoid valves for the running Unit 1 TDAFW Pump. Restoration of power generated a pump auto start signal which resulted in inadvertent automatic closure of both trains of blowdown containment isolation valves and both trains of sample containment isolation valves for each Unit 1 S/G. Subsequent evaluation of the event concluded that the actuation of the Unit 1 TDAFW Pump, S/G blowdown containment isolation valves, and S/G sample containment isolation valves was not the result of a valid signal initiated in response to actual plant conditions or parameters satisfying the requirements for initiation of the safety function provided by the respective component. In addition, the actuation of these components was not the result of an intentional manual initiation. Therefore, actuation of the Unit 1 TDAFW Pump, S/G blowdown containment isolation valves, and S/G sample containment isolation valves represented invalid actuations which are not reportable per the requirements of 10 CFR 50.72(b)(3)(iv)(A). Although the actuation of these components represented invalid actuations, they were not pre-planned, the systems were not removed from service, and the safety function provided by the components had not already been completed. Therefore, McGuire is reporting actuation of the Unit 1 TDAFW Pump, S/G blowdown containment isolation valves, and S/G sample containment isolation valves in accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A). Note that closing the Unit 1 TDAFW Pump discharge isolation valve to each S/G to isolate flow rendered the Unit 1 TDAFW inoperable. However, these valves were opened and the Unit 1 TDAFW Pump was restored to an operable status within the required completion time specified in the Auxiliary Feedwater System Technical Specification. 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) other than actuation of the Reactor Protection System when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC within 60 days after discovery of the event instead of submitting a written LER. In these cases the telephone report is not considered an LER. McGuire is exercising this option by providing this telephone notification. The following additional information is being provided as part of the telephone notification of this event: The Unit 1 TDAFW Pump injected water into all four Unit 1 S/Gs for approximately 3 and 1/2, minutes before flow was isolated by manually closing the Unit 1 TDAFW discharge isolation valve to each S/G. Subsequent evaluation determined that Unit 1 reactor power did not exceed 100% during the event. The actuation of the Unit 1 TDAFW Pump was complete and successful. This event actuated both trains of blowdown containment isolation valves and both trains of sample containment isolation valves for each Unit 1 S/G. Each train's actuation was complete and successful. The licensee has notified the NRC Resident Inspector. The TDAFW pump was being removed from service, and the steam admittance solenoid valves should have been isolated prior to removing power to them. | Steam Generator Feedwater Reactor Protection System Auxiliary Feedwater | |
| ENS 41635 | 9 April 2005 14:39:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Specified System Actuation | This report is being made under 10CFR50.73(a)(2)(iv)(A) - Invalid Safety System Actuation. At 10:39:06 on April 9, 2005, the steam supply valve to Unit 2 turbine-driven auxiliary feedwater pump, 25A-48ABC, was manually failed open during a maintenance activity causing the pump to start. There was no valid actuation signal. The train of auxiliary feedwater started and functioned successfully. The actuation was complete and lasted for 1 minute and 25 seconds. The licensee notified the NRC Resident Inspector. | Auxiliary Feedwater | |
| ENS 41151 | 20 October 2004 00:20:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Turbine Driven Auxiliary Feedwater Actuation | On October 19, 2004, McGuire Nuclear Station Unit 2 experienced an inadvertent actuation of the Turbine Driven Auxiliary Feedwater (TDCA) Pump. This event occurred when the steam supply valve to the pump failed open due to low pressure in the nitrogen supply to the valve's actuator. Further evaluation determined that the inadvertent actuation of the TDCA Pump was not in response to actual plant conditions or parameters satisfying the requirements for actuation of the pump. Since the TDCA Pump was not started in response to a valid signal, this represented an invalid actuation reportable per the requirements of 10 CFR 50.73 (a) (2) (iv) (A). However, as per 10 CFR 50.73(a)(1), McGuire is providing a telephone notification of this invalid actuation instead of submitting a written LER. The following additional information is being provided as part of the telephone notification of this event: - The Unit 2 TDCA Pump actuated and injected water into all four of the Unit 2 Steam Generators - The actuation of the Unit 2 TDCA Pump was successful and complete. The licensee stated the total injection time was approximately 16 minutes and that a very small power increase was observed during the event. The NRC Resident Inspector has been notified by the licensee. | Steam Generator Auxiliary Feedwater |