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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 1039 CDT the reactor was manually (scrammed) due to a partial loss of plant service water. The loss of plant service water was caused by a loss of (balance of plant) BOP transformer 23. Reactor power was reduced in an attempt to restore pressure to plant service water. Reactor level is being maintained with condensate and feedwater. Reactor pressure is being maintained with bypass control valves. Standby Service Water A and B were manually initiated to supply cooling to Control Room A/C and (Engineered Safety Feature) ESF switchgear room coolers. The cause is under investigation. The NRC Resident Inspector has been notified. 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 and also reported under 10 CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of RPS and Standby Service Water. The plant is currently in a normal electrical lineup.

• * * UPDATE ON 5/12/19 AT 1846 EDT FROM GERRY ELLIS TO JEFFREY WHITED * * *

This is an update to the original notification. The Drywell and Containment exceeded the technical specification (TS) temperature limits of 135 degrees F (TS Limiting Condition of Operation (LCO) 3.6.5.5) and 95 degrees F (TS LCO 3.6.1.5), respectively. An 8-hour notification is being added for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material per 10 CFR 50.72(b)(3)(v)(C). Notified R4DO (Alexander).

At 1208 CDT on April 13, 2018, GGNS (Grand Gulf Nuclear Station) identified cracks in the primary containment concrete penetration (outer wall) around feed water line 'B'. There are no available dimensions for crack width or depth until further inspections are performed. In accordance with NUREG 1022, Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73, Section 3.2.4, any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers being seriously degraded, requires that when a principal safety barrier is declared inoperable the condition must be reported under 10 CFR 50.72 (b)(3)(ii). The licensee has notified the NRC Resident Inspector.

• * * RETRACTION FROM GERRY ELLIS TO HOWIE CROUCH AT 2012 EDT ON 4/15/18 * * *

Grand Gulf Nuclear Station (GGNS) personnel performed an inspection of the wall around feed water line 'B'. This inspection included the protective coating in the identified area and a partial inspection of the underlying concrete. The inspection of the protective coating found a collection of non-linear anomalies, chipping, and flaking. The inspection found non-significant linear indications in the concrete. Grand Gulf Nuclear Station determined that the collection of non-significant coating imperfections and non-significant indications in the concrete do not constitute serious degradation of primary containment. The indications do not adversely impact the operability, mission time, or safety-function (as described per Technical Specification 3.6.1.1, Primary Containment) of the containment structure. The as-found conditions have been entered into the GGNS corrective action program for final disposition. The containment structure is operable, therefore, GGNS is retracting this event notification. The licensee has notified the NRC Resident Inspector. Notified R4DO (Kellar).

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).

On August 22, 2017 at 2321 hours, Grand Gulf Nuclear Station entered Technical Specification conditions for three Limiting Condition for Operations (LCOs) not met due to Residual Heat Removal 'A' (RHR 'A') being declared inoperable. LCOs not met:

  1) 3.5.1 for one low pressure ECCS (Emergency Core Cooling System) injection/spray subsystem.
  2) 3.6.1.7 for one RHR containment spray subsystem, and
  3) 3.6.2.3 for one RHR suppression pool cooling subsystem.

The station has made the decision to shutdown the plant based on the results of troubleshooting performed on the RHR 'A' pump. The restoration of RHR 'A' pump will not be completed prior to the end of the 7 day LCO completion time. Grand Gulf Nuclear Station initiated plant shutdown required by Technical Specifications 3.5.1, 3.6.1.7, and 3.6.2.3 at 1200 hours CDT on 08/29/2017 due to expected restoration of RHR 'A' exceeding the completion time of 7 days prior to restoring operability. The licensee notified the NRC Resident Inspector.