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The following information was provided by the licensee via fax or email: At 2342 CDT on August 19, 2022, with Grand Gulf Nuclear Station in Mode 1 and at 40 percent power, the station initiated a normal shutdown to comply with its Technical Specifications (TS). The station entered Mode 3 at 0000 CDT August 20, 2022 to comply with (LCO) 3.5.1 Condition G Action G.1 due to the condition reported to NRC previously (EN 56058). This event is being reported under 10 CFR 50.72(b)(2)(i) as a shutdown required by the plant's technical specifications. The NRC Senior Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The plant is now in a 36-hour LCO to be in Mode 4 due to Low Low Set Valves inoperability per TS 3.6.1.6.

• * * RETRACTION ON 10/14/2022 AT 1311 FROM JEFF HARDY TO LAUREN BRYSON * * *

Grand Gulf Nuclear Station (GGNS) is performing this notification to retract event EN 56059 that was reported on August 20, 2022. Previously, GGNS notified the NRC that it had initiated a shutdown required by Technical Specifications to comply with Limiting Condition of Operation (LCO) 3.5.1 Condition G.1 due to the inoperability of four Automatic Depressurization System (ADS) valves. Following the shutdown, GGNS completed walkdowns and determined that the condition affected only one ADS valve. As a result, the shutdown to satisfy the required actions of TS LCO 3.5.1 Condition G.1 was not required. The NRC Resident Inspector has been notified of the retraction. R4DO (Kellar) was notified.

On November 5, 2019 at 1811 CST, station service water A and the Division 1 diesel generator (DG) were declared inoperable based on the results of an engineering evaluation of a Class 3 piping leak. This was determined to be a potential inability to fulfill a safety function due to concurrent inoperability of two emergency diesel generators. Division 3 DG was inoperable due to planned maintenance on November 4, 2019 at 0000 CST. This event is being reported an 8-hour non-emergency notification per 10 CFR 50.72 (b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function (Accident Mitigation). Division 3 DG and high pressure core spray have been restored, and the fulfillment of the accident mitigation safety function has been restored. The NRC Senior Resident Inspector has been notified.

• * * RETRACTION ON 11/11/19 AT 1739 EST FROM GABRIEL HARGROVE TO BETHANY CECERE * * *

This was initially reported under 10 CFR 50.72(b)(3)(v)(D). However, subsequent engineering evaluation determined that the condition did not affect safety system operability. The evaluation determined that the leakage was within allowable limits and piping structural integrity was not challenged at this time nor in the past three years. The Division 1 DG and SSW A were at the time of discovery OPERABLE and EN54371 is being retracted. The licensee will notify the NRC Resident Inspector. Notified R4DO (Drake).

At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 (CST), with reactor power just above the point of adding heat, IRM (Intermediate Range Monitor) channels A, C, and D received a spurious upscale trip signal which immediately cleared. Upon investigation, operability of RPS (Reactor Protection System) scram function for Intermediate Range Detectors was placed in question. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. The licensee notified the NRC Resident Inspector.

• * * UPDATE ON NOVEMBER 26, 2017, AT 1850 FROM GRAND GULF TO MICHAEL BLOODGOOD * * *

At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 (CST), with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. This Revised Statement to Event Notification # 53090 is being made to make it clear that only four IRM channels (A, C, D, G) were Inoperable and that the IRM RPS SCRAM function was still available from the four remaining Operable IRM channels (B, E, F, and H). The licensee notified the NRC Resident Inspector. Notified R4DO (O'Keefe)

• * * RETRACTION ON 01/16/2018 AT 1629 EST FROM JASON COMFORT TO DAVID AIRD * * *

On 11/25/17, at 0149 (CST), with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event was initially being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. After the trip alarms were received, the Operators spent approximately twenty minutes investigating possible causes and implications, and consulted with Reactor Engineering and the Shift Technical Advisor. The investigation showed that the plant was stable and the upscale IRM alarms were spurious. A review of plant technical specifications by the operators determined that a plant shutdown was not required. After further discussions, Operations concluded that a shutdown to allow further investigation of the issue was the prudent course of action. Prior to shutting down, Operations spent approximately twenty minutes reviewing procedures, notifying personnel to exit containment, and conducting a brief. The shutdown was then conducted by inserting a manual reactor scram by placing the reactor mode switch in SHUTDOWN. This was initially reported under 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the RPS. Based on the sequence of events, and Operator actions in conducting the shutdown, the event is considered 'part of a pre-planned sequence during testing or reactor operation' as specified in 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.73(a)(2)(iv)(A). In accordance with NUREG-1022, Section 3.2.6, the event is not reportable as an actuation of RPS. The licensee notified the NRC Resident Inspector. Notified R4DO (Taylor).

At 2359 EDT on June 7, 2015, the Grand Gulf Nuclear Station declared a Notice of Unusual Event in accordance with Emergency Action Level HU4 for a fire in the protected area lasting greater than 15 minutes. The fire started in the wiring of a terminal box for Electro Hydraulic Pump C, the running pump located in the turbine building. The running pump was then deenergized by operators and the standby pump started. The site fire brigade responded and extinguished the fire. The emergency was terminated at 0030 on June 8, 2015. The licensee notified state and local agencies and will inform the NRC Resident Inspector. Notified DHS SWO, FEMA Ops Center, NICC Watch Officer, and FEMA NWC and Nuclear SSA via email.

• * * RETRACTION AT 1645 ON 7/9/2015 FROM KEITH HUFF TO MARK ABRAMOVITZ * * *

The notification of an Unusual Event is being retracted because the event did not meet the definition of 'fire' in NEI 99-01 Revision 5, 'Methodology of the Development of Emergency Action Levels'. The document was endorsed by the NRC on February 22, 2008 (see ADAMS ascension # ML080450149) and is part of the Grand Gulf Nuclear Station's current licensing basis. Per the guidance, a 'fire' is defined as: 'Combustion characterized by heat and light. Sources of smoke such as slipping drive belts or overheated electrical equipment do not constitute as 'fires'. Observation of flame is preferred but is NOT required if large quantities of smoke and heat are observed.' According to eyewitness reports from personnel, flames were not observed at any time and evidence of large quantities of heat and smoke were not observed. Additionally, the definition of 'fire' specifically excludes overheated electrical equipment. This information leads to the conclusion that the event did not meet the definition of a 'fire' per NEI 99-01 Revision 5. Therefore, the event is not an immediately reportable Unusual Event under 10 CFR 50.72(a)(1)(i). The licensee notified the NRC Resident Inspector and will notify the state and local governments. Notified the R4DO (Haire) and NRR EO (Morris via e-mail).

At 1743 CDT on 05/12/13, Grand Gulf Nuclear Station declared an Unusual Event due to a fire lasting greater than 15 minutes in an auxiliary transformer inside the Protected Area (PA). The transformer was isolated. The plant continues to operate at 100% power. The license remains in a Unusual Event pending further investigation. The licensee notified the NRC Resident Inspector and State and Local Authorities. Notified DHS SWO, FEMA, and DHS NICC.

• * * UPDATE FROM ROBERT BRINKMAN TO JOHN SHOEMAKER AT 2112 EDT ON 5/12/13 * * *

The Licensee terminated the Unusual Event at 1921 CDT on 5/12/13 based on electrically isolating the auxiliary transformer and termination of smoke coming from the transformer. At no time were flames seen during this event. The transformer is located outside of the turbine building and is used to supply various loads and office space during outages. There was no other impact on the plant. The licensee notified the NRC Resident Inspector and State and Local Authorities. Notified R4DO (Drake), NRR EO (Bahadur), IRD (Marshall), DHS SWO, FEMA, and DHS NICC.

• * * RETRACTION FROM CHRISTOPHER ROBINSON TO JOHN SHOEMAKER AT 1057 EDT ON 5/29/13 * * *

EN #49025 documents an emergency declaration of Notification of Unusual Event due to a fire lasting greater than 15 minutes within the protected area. The basis for retraction is that this event did not meet the definition of FIRE in NEI 99-01 Rev 5, 'Methodology for the Development of Emergency Action Levels'. This document was endorsed by the NRC on February 22, 2008 (see ADAMS ascension # ML080450149) and is part of the Grand Gulf Nuclear Station's current licensing basis. Per the guidance, a FIRE is defined as: Combustion characterized by heat and light. Sources of smoke such as slipping drive belts or overheated electrical equipment do not constitute FIRES. Observation of flame is preferred but is NOT required if large quantities of smoke and heat are observed. Grand Gulf performed interviews of operators and personnel responding to the event and subsequently examined photos of the affected auxiliary transformer. According to eyewitness reports from personnel, flames were not observed at any time nor was there any light emanating from the source of smoke. Personnel also reported that at the immediate vicinity of the smoke source, heat was not at a level which would be indicative of a fire. Photos of the affected transformer did not show signs of charring, burns, warping, or deformation as would be expected during a FIRE. Additionally, the definition of a FIRE specifically excludes overheated electrical equipment. Notified R4DO (Azua), NRR EO (Chernoff), and IRD (Morris).