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Entered date | Site | Region | Reactor type | Event description | |
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ENS 57418 | 10 November 2024 07:59:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via phone and email: On November 10, 2024, at 0337 CST, Grand Gulf Nuclear Station (GGNS) was operating in mode 1 at 100 percent power when a manual scram was initiated due to degrading main condenser vacuum. The cause of the degrading main condenser vacuum is not known at this time and is being investigated. All control rods fully inserted and there were no complications. Reactor pressure was initially maintained with main turbine bypass valves. Reactor water level was initially maintained with main feedwater and condensate. At 0457, operators transitioned pressure control to safety relief valves and began using reactor core isolation cooling (RCIC) to maintain reactor water level. This was performed using plant procedures due to degrading vacuum. GGNS is currently in mode 3. Reactor level is being maintained with RCIC and pressure is being maintained using the safety relief valves. The manual reactor protection system (RPS) actuation is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) and the RCIC actuation is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At the time of the notification, main steam isolation valves had shut on low vacuum.
The following update was provided by the licensee via phone and email: This update is being made to report the following occurrences which took place after the scram reported in event number 57418. On November 10, 2024, at 0545 CST, a group 1 containment isolation signal resulted in the closure of all MSIVs. The signal was due to continued degradation of condenser vacuum post-trip. At 0620, an automatic RPS actuation occurred when reactor water level lowered to level 3. This RPS actuation occurred with all control rods fully inserted. Reactor water level lowered following closure of an open safety relief valve and was recovered to within the established band. The events are being reported as specified system actuations in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector has been informed of the update. Notified R4DO (Dixon) |
ENS 57349 | 28 September 2024 00:35:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via phone and email: At 1822 CST on September 27, 2024, Grand Gulf Nuclear Station (GGNS) was conducting surveillance testing on the high pressure core spray (HPCS) division Ill diesel generator. Following initiation of the test signal, the HPCS pump room cooler start time exceeded the surveillance procedure allowance of less than or equal to 20 seconds. The HPCS pump room cooler started in 26.2 seconds. HPCS was already inoperable for performance of the surveillance testing. The event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function. Troubleshooting is in progress. HPCS, a single-train system, will remain inoperable until the condition is corrected. All sources of offsite power are available. No other safety systems are inoperable. Reactor core isolation cooling was verified to be operable per GGNS technical specification 3.5.1.B.1. The NRC Senior Resident Inspector has been notified.
Investigation of the delayed start time of the HPCS pump room cooler indicated that the condition would not have challenged the ability of the room cooler to maintain temperatures less than the temperature limit of 150 degrees Fahrenheit. As a result, HPCS remained capable of fulfilling its safety function. Therefore, EN 57349 is being retracted. The NRC senior resident inspector has been notified of this retraction. Notified R4DO (O'Keefe) |
ENS 57338 | 25 September 2024 02:06:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via phone or email: On September 24, 2024, at 2204 CDT, Grand Gulf Nuclear Station (GGNS) was conducting surveillance testing on the high pressure core spray (HPCS) division III diesel generator. During testing, the HPCS pump breaker unexpectedly tripped after the HPCS diesel generator started and powered the safety bus. The breaker performed its motor protection function and tripped due to an over-frequency indication. The event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function. Troubleshooting is in progress. HPCS, a single-train system, will remain inoperable until the condition is corrected. All sources of offsite power are available. No other safety systems are inoperable. Reactor core isolation cooling was verified to be operable per GGNS Technical Specification 3.5.1.B.1. The NRC Senior Resident has been notified. |
ENS 57138 | 23 May 2024 11:24:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: During a security inspection, it was determined that some past events at Entergy sites that were not reported may have met the reporting criterion of 10 CFR 26.719(b)(4). As a result, the following event at Grand Gulf, Unit 1 is now being conservatively reported: On May 11, 2023, a condition report was written to document that an individual who should have been placed in a follow-up fitness for duty program was not tested according to this program. The resident inspector has been notified. |
ENS 57053 | 26 March 2024 16:21:00 | Grand Gulf | NRC Region 4 | The following information was provided by the licensee via phone and email: On March 26, 2024 at 1115 CDT, Grand Gulf Nuclear Station experienced an actuation of the reactor protection system (RPS) due to high reactor coolant system pressure. The plant was in Mode 4 at zero percent power and performing scram time testing. All rods were fully inserted at the time of the RPS actuation, and all required equipment responded as designed. This actuation is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). The cause of the event is under investigation. The NRC resident inspector has been notified. | |
ENS 56938 | 29 January 2024 16:56:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At 1005 CST on January 29, 2024, Grand Gulf Nuclear Station was conducting surveillance testing on the high pressure core spray system. During testing, the 1E22F012 minimum flow valve failed to return to the full closed position. The valve went from full open indication to dual indication. The event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function. Troubleshooting is in progress. The NRC Senior Resident has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All off-site power is available. No other systems are out of service and there are no compensatory measures taken. There is no increase to plant risk. |
ENS 56894 | 16 December 2023 08:22:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: On December 16, 2023, at 0350 CST, Grand Gulf Nuclear Station was operating in mode 1 at 81 percent power when an automatic scram occurred due to a turbine trip signal. Before the scram the unit was performing a rod sequence exchange, and no critical work was underway. The cause of the turbine trip signal is not known at this time and is being investigated. All control rods fully inserted, there were no complications, and all plant systems responded as designed. Reactor water level is being maintained by main feedwater and condensate. Reactor pressure is being maintained with main turbine bypass valves. No radiological releases have occurred due to this event. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of the reactor protection system when the reactor is critical and specified system actuation due to expected reactor water level 3 isolation signals on a reactor scram. The NRC Senior Resident Inspector has been notified of this event. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Group 2 and Group 3 isolations occurred on the Level 3 isolation signal. |
ENS 56724 | 7 September 2023 10:01:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: On September 6 at 15:00 CDT, Grand Gulf Nuclear Station personnel identified a bottle of vanilla extract in a kitchen area located within the Protected Area. Ingredients were listed as 'pure vanilla extract in water and alcohol. The percentage by volume of alcohol was not specified. It was subsequently determined that the alcohol by volume was likely 35 percent. The NRC Resident Inspector has been notified. |
ENS 56696 | 24 August 2023 21:30:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: On August 23, 2023 at 2100 CDT, Grand Gulf Nuclear Station was notified that a non-licensed supervisor violated the station's Fitness for Duty policy. The employee's unescorted access at Grand Gulf Nuclear Station has been terminated. This event was determined to be reportable under 10 CFR 26.719(b)(2)(ii). The NRC Resident Inspector has been notified. |
ENS 56598 | 29 June 2023 15:41:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: A non-licensed supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. |
ENS 56282 | 20 December 2022 00:24:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At 2101 (CST) on December 19, 2022, a manual reactor scram was initiated at Grand Gulf Nuclear Station (GGNS). Following the reactor scram, the high pressure core spray (HPCS) system was used to maintain reactor water level. The manual (reactor protection system) RPS actuation is being reported in accordance with 10 CFR 50.72(b)(2) and the HPCS actuation is being reported in accordance with 10 CFR 50.72(b)(3). At 2058, GGNS experienced a loss of a condensate booster pump. At 2101, the `A' reactor feedwater pump tripped and the reactor was manually scrammed. All control rods were fully inserted into the core. At 2104, the `B' reactor feedwater pump tripped and HPCS was manually started. HPCS was manually injected to maintain reactor water level at 2121. The `A' reactor feedwater pump was successfully restarted at 2126. GGNS is currently in Mode 3. Reactor level is being maintained with the `A' reactor feedwater pump and pressure is being maintained with the turbine bypass valves. The NRC Resident Inspector was notified. |
ENS 56192 | 31 October 2022 15:29:00 | Grand Gulf | NRC Region 4 | The following information was provided by the licensee via email: On February 22, 2021 while in Mode 1 and at 100 percent power, Grand Gulf Nuclear Station (GGNS) identified through surveillance testing that the 208 foot elevation outer containment personnel airlock door failed its technical specification leakage test. Analysis indicated that the airlock equalizing valves were leaking due to lack of lubrication during installation. Subsequent analysis determined that the lubrication was to have been performed during a vendor's qualification / dedication process. GGNS completed a substantial safety hazard Evaluation and determined that the failure to lubricate the valve components constituted a substantial safety hazard. The NRC Resident (Inspector) has been notified. This is a non-emergency notification required by 10 CFR 21.21(d)(3)(i). A written notification will be provided within 30 days. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: This condition has been corrected. This report is submitted to meet 10 CFR Part 21 reporting requirements. | |
ENS 56185 | 27 October 2022 19:49:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At 1228 CDT on October 27, 2022, Grand Gulf Nuclear Station (GGNS) was in Mode 1 at 88 percent power when a failure of a draw down surveillance resulted in the loss of secondary containment. During the performance of the surveillance GGNS was unable to maintain secondary containment pressure, as required by Technical Specification Surveillance Requirement 3.6.4.1.4, greater than or equal to 0.266 inches of water vacuum for 1 hour at a flow rate of less than or equal to 4000 cfm. The test was secured. Secondary containment was declared inoperable and Technical Specification 3.6.4.1 A.1 was entered at 1228 CDT. Secondary containment was restored to operable status at 1240 CDT by restoring the configuration to a previously known operable condition. This event is being reported as an event or condition that could have prevented the fulfillment of a safety function. The NRC Resident Inspector was notified. |
ENS 56171 | 20 October 2022 11:31:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At 0427 CDT on October 20, 2022, Grand Gulf Nuclear Station (GGNS) was in Mode 1 at 100 percent power when a failure of a draw down surveillance resulted in the loss of secondary containment. During the performance of the surveillance GGNS was unable to maintain secondary containment pressure, as required by Technical Specification Surveillance Requirement 3.6.4.1.4, greater than or equal to 0.266 inches of water vacuum for 1 hour at a flow rate of less than or equal to 4000cfm. The test was secured. Secondary containment was declared inoperable and Technical Specification 3.6.4.1 A.1 was entered at 0427 CDT. Secondary containment was restored to operable status at 0520 CDT by restoring the configuration to a previously known operable condition. This event is being reported as an event or condition that could have prevented the fulfillment of a safety function. The NRC Resident Inspector was notified. |
ENS 56118 | 19 September 2022 19:29:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At approximately 1520 CDT on September 19, 2022, Grand Gulf Nuclear Station (GGNS) requested transport for treatment of a non-responsive individual, a contract employee, to an offsite medical facility. The offsite medical facility notified GGNS at approximately 1630 CDT that the individual had been declared deceased. The fatality was not work-related, and the individual was outside of the Radiological Control Area. This is a four-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(xi) related to the notification of a government agency. The contractor's employee will be notifying the Occupational Safety and Health Administration. The NRC Senior Resident Inspector has been notified. |
ENS 56059 | 20 August 2022 02:11:00 | Grand Gulf | NRC Region 4 | GE-6 | 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.
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. |
ENS 56058 | 19 August 2022 20:46:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via email: At 1215 CDT on 8/19/2022, with Grand Gulf Nuclear Station in Mode 1 and at 100 percent power, four Automatic Depressurization System (ADS) valves were rendered inoperable due to a loss of system pressure. The station entered Technical Specification 3.5.1 Condition G. This event is being reported under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function. There were no other systems affected as a result of this condition. The NRC Senior Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Plans are to remain in Mode 1 until corrected or until driven by the Technical Specifications to shut down (12-hour LCO from 1215 CDT on 8/19/2022).
Grand Gulf Nuclear Station (GGNS) is performing this notification to retract event EN 56058 that was reported on August 19, 2022. Previously, GGNS notified the NRC that four Automatic Depressurization System (ADS) valves were inoperable due to a loss of system pressure. Based upon further investigation, the condition reported in EN 56058 was found to affect only a single ADS valve. As a result, it was determined that an event or condition that could have prevented the fulfillment of a safety function did not exist at GGNS. Sufficient redundancy existed to perform the safety function. The NRC Resident Inspector has been notified of the retraction. R4DO (Kellar) was notified. |
ENS 55973 | 30 June 2022 18:07:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via phone and email: At 1445 (CDT) on June 30, 2022, with Grand Gulf Nuclear Station in Mode 1 and at 100 percent power, the reactor was manually scrammed due to the loss of balance of plant (BOP) transformer 23. All control rods fully inserted into the core and all systems responded appropriately. Reactor level is being maintained with condensate and feedwater. Reactor pressure is being maintained with turbine bypass valves. The cause of the loss of BOP transformer 23 is under investigation at this time. Standby Service Water 'A' and 'B' were manually initiated to supply cooling to Control Room A/C, ESF switchgear room coolers, and plant auxiliary loads. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B) as an event or condition that resulted in actuation of the Reactor Protection System and 10 CFR 50.72(b)(3)(iv)(A) due to the actuation of Standby Service Water. The NRC Senior Resident Inspector was notified. |
ENS 55915 | 26 May 2022 10:34:00 | Grand Gulf | NRC Region 4 | GE-6 | The following information was provided by the licensee via phone and email: On May 26, 2022, at 0753 CDT, the Grand Gulf Nuclear Station was notified of a spurious actuation of a single Alert Notification System siren in Tensas Parish, Louisiana. The actuation occurred during siren testing conducted at approximately 0630 CDT - no emergency conditions are present at Grand Gulf Nuclear Station. A press release from Entergy is not planned at this time. This condition is reportable under 10 CFR 50.72(b)(2)(xi) as a notification of an offsite government agency. The NRC Senior Resident Inspector has been notified. |
ENS 55561 | 4 November 2021 09:12:00 | Grand Gulf | NRC Region 4 | GE-6 | A non-licensed employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. |
ENS 55451 | 9 September 2021 04:19:00 | Grand Gulf | NRC Region 4 | GE-6 | At 0033 CDT on September 9, 2021, Grand Gulf Nuclear Station (GGNS) was operating at 70 percent power when the High Pressure Core Spray (HPCS) was declared inoperable. The inoperability determination was made due to control room annunciations. In accordance with GGNS Technical Specification 3.5.1.B.1, the Reactor Core Isolation Cooling system was verified to be operable. Troubleshooting is in progress. This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function. The NRC Resident Inspector has been notified. |
ENS 55056 | 7 January 2021 03:18:00 | Grand Gulf | NRC Region 4 | GE-6 | An Unusual Event was declared at Grand Gulf Nuclear Station at 0124 (CST) on 01/07/2021 due to Unidentified Drywell Leakage exceeding 10 GPM for 15 minutes. Unidentified leakage has reduced to less than 0.44 GPM as of 0213 CST on 01/07/2021. The cause of the increase leakage rate is under investigation. The licensee notified the NRC Resident Inspector. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
At 0356 CST, Grand Gulf Nuclear Station terminated the Unusual Event following plant parameters returning to normal. The current leakage rate is 0.3 gallons per minute and stable. The NRC Resident Inspector has been notified. Notified R4DO (Kozal), IRD MOC (Gott), NRR EO (Felts), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). |
ENS 55030 | 11 December 2020 15:15:00 | Grand Gulf | NRC Region 4 | GE-6 | On December 11, 2020 at 1204 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 100 percent Reactor Power after a Main Turbine and Generator Trip. All Control Rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Branch Chief has been notified. |
ENS 54986 | 6 November 2020 05:00:00 | Grand Gulf | NRC Region 4 | GE-6 | On November 6, 2020, at 0239 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 84 percent Reactor Power after a Main Turbine and Generator Trip. All control rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Resident has been notified. |
ENS 54935 | 7 October 2020 10:25:00 | Grand Gulf | NRC Region 4 | A non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The licensee informed the NRC Resident Inspector. | |
ENS 54908 | 24 September 2020 06:31:00 | Grand Gulf | NRC Region 4 | On September 24, 2020, at 0258 CDT, Grand Gulf Nuclear Station (GGNS) was notified that one Emergency Notification Siren located on US Hwy 61 had actuated. Claiborne County was informed that no emergency exists at GGNS. The alarming siren has since been secured. Notification is being provided to the NRC in regards to the potential for media inquiry. The licensee informed the NRC Resident Inspector. | |
ENS 54855 | 25 August 2020 02:26:00 | Grand Gulf | NRC Region 4 | On August 24, 2020 at 2305 CT at Grand Gulf Nuclear Station (GGNS) an Automatic Reactor Scram occurred after a trip of the Reactor Feed Pump B and subsequent lowering of reactor water level to 11.4 inches Narrow Range. The scram occurred with Reactor Power at 14% and the main generator offline. All control rods fully inserted and there were no complications. All systems responded as designed. Main Steam Isolation Valves were manually closed to control reactor cooldown, Currently GGNS reactor pressure is being maintained at 450-600psig. Reactor water level is being maintained with condensate through startup level control. No radiological releases have occurred due to this event from the unit. The NRC Resident has been notified. Decay heat is being removed via the main condenser. Notified R4DO. | |
ENS 54824 | 8 August 2020 05:34:00 | Grand Gulf | NRC Region 4 | On August 8, 2020, at 0127 CDT, Grand Gulf Nuclear Station was manually shut down due to a turbine high pressure control valve malfunction. Reactor pressure is being controlled with bypass control valves to the main condenser. Reactor level is being maintained with condensate and feedwater through startup level control. The plant is stable in MODE 3 and proceeding to cold shutdown. The cause of the 'D' high pressure control valve malfunction is under investigation at this time. All rods fully inserted and there were no complications. All systems responded as designed. 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. Additionally, at 0159 CDT, with all rods fully inserted and after the 0127 CDT manual reactor Scram, an automatic valid RPS actuation signal was received. This event is also being reported under 10 CFR 50.72(b)(3)(iv)(A), as an event or condition that results in a valid actuation of any of the systems listed in 10 CFR 50.72(b)(3)(iv)(B). | |
ENS 54741 | 8 June 2020 01:08:00 | Grand Gulf | NRC Region 4 | On June 7, 2020, at 2238 CDT Grand Gulf Nuclear Station (GGNS) was notified by Claiborne County that one Emergency Notification Siren located on US Hwy 61 South had actuated. Claiborne County was informed that no emergency exists at GGNS. The alarming siren has since been secured. Notification is being provided to the NRC in regards to the potential for media inquiry. The licensee informed the NRC Resident Inspector. | |
ENS 54725 | 25 May 2020 08:44:00 | Grand Gulf | NRC Region 4 | An (automatic) reactor SCRAM occurred at 0433 CDT, on 05/25/2020, from 66 percent core thermal power. The cause of the SCRAM was due to a Main Turbine Trip. The cause of the Turbine Trip is under investigation. All systems responded as designed. No loss of offsite power or (Emergency Safety Feature) (ESF) power occurred. No (Emergency Core Cooling System) (ECCS) or Emergency Diesel Generator initiations occurred. Main Steam Isolation valves remained open and no radioactive release occurred due to this event. The plant is stable in mode 3. 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 NRC Resident Inspector has been notified. Decay heat removal is through the Feedwater and Condensate System. | |
ENS 54371 | 6 November 2019 01:17:00 | Grand Gulf | NRC Region 4 | 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.
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). | |
ENS 54271 | 12 September 2019 00:49:00 | Grand Gulf | NRC Region 4 | On September 11, 2019 at 1719 CDT, plant personnel identified a condition in which the 208 foot elevation inner primary containment airlock door was not in its fully seated and latched position while the 208 foot elevation outer primary containment airlock door was opened. The 208 foot elevation outer containment airlock door was subsequently closed by the individual exiting the area. The time that both 208 foot elevation containment airlock doors were not in their fully seated and latched positions was less than 1 minute. Following this occurrence, maintenance personnel inspected the 208 foot elevation inner containment airlock door and re-positioned this door to its fully seated and latched position. There was no radioactive release as a result of this event. This condition requires an 8-hour non-emergency notification in accordance with 10CFR50.72(b)(3)(v)(C) as an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. The NRC Resident Inspector has been notified. | |
ENS 54244 | 28 August 2019 19:10:00 | Grand Gulf | NRC Region 4 | On Wednesday, August 28, 2019, at 1316 CDT, Grand Gulf Nuclear Station experienced a power loss to the Control Room High Pressure Core Spray (HPCS) Instrumentation Panel due to an internal inverter failure. The power loss caused the loss of the HPCS System (a single train system). The minimum flow valve (a Primary Containment Isolation Valve) for HPCS opened due to this power loss as well. This valve was manually closed in response to this, and the outboard isolation requirement for the associated penetration (which) is closed (for the) system remained intact throughout this event. No other accident mitigation systems were affected by this event. The cause of this event is under investigation at this time. The NRC Resident Inspectors were notified. This Condition is an 8-hour reportable condition as an event or condition that could have prevented the fulfillment of a safety function, in accordance with 10 CFR 50.72(b)(3)(v)(D). | |
ENS 54201 | 5 August 2019 17:06:00 | Grand Gulf | NRC Region 4 | On August 5, 2019, at 0936 CDT, Grand Gulf entered Technical Specification (TS) 3.6.4.1 due to a Secondary Containment personnel door, 1A401B, not being able to meet its design function. Door 1A401B was unable to be closed and latched. This condition is being reported as a loss of safety function. The station also entered 05-S-01-EP-4, Auxiliary Building Control (Secondary Containment) to address Auxiliary Building differential pressure due to the opened Secondary Containment penetration. Actions were taken to close and latch Door 1A401B. Secondary Containment has been declared operable. TS 3.6.4.1 and 05-S-01-EP-4 were exited. The NRC Resident Inspector was notified of the condition. | |
ENS 54062 | 12 May 2019 15:28:00 | Grand Gulf | NRC Region 4 | 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.
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). | |
ENS 53894 | 23 February 2019 19:05:00 | Grand Gulf | NRC Region 4 | Actuation of RPS (Reactor Protection System) with the reactor critical. Reactor scram occurred at 1458 (CST) on 2/23/2019 from 100% power. The cause of the scram was due to Turbine Control Valve Fast Closure. All control rods are fully inserted. Currently reactor water level is being maintained by the Condensate Feedwater System in normal band and reactor pressure is being controlled via Main Turbine Bypass valves to the main condenser. No ECCS (Emergency Core Cooling System) initiation signals were reached and no ECCS or Diesel Generator initiation occurred. The Low-Low Set function of the Safety Relief Valves actuated upon turbine trip. This was reset when pressure was established on main turbine bypass valves. The cause of the turbine trip is still under investigation. There were no complications with scram response. The licensee notified the NRC Resident Inspector. There was no maintenance occurring on the main turbine at the time of the scram. | |
ENS 53870 | 13 February 2019 09:42:00 | Grand Gulf | NRC Region 4 | On 1/17/2019 at 0619 CST, a non-licensed employee supervisor failed to report to perform a fitness for duty test. The individual's access to the site was terminated. The NRC Resident Inspector will be notified. | |
ENS 53788 | 12 December 2018 17:29:00 | Grand Gulf | NRC Region 4 | EN Revision Text: MANUAL REACTOR SCRAM DUE TO FAILED OPEN TURBINE BYPASS VALVE At 1351 CST, the reactor was manually shutdown due to 'A' Turbine Bypass Valve opening. The Main Steam Line Isolation Valves were manually closed to facilitate reactor pressure control. Reactor level is being maintained through the use of Reactor Core Isolation Cooling System, Control Rod Drive System, and High Pressure Core Spray System. High Pressure Core Spray System was manually started to initially support reactor water level control. Reactor Pressure is being controlled through the use of the Safety Relief Valves and the Reactor Core Isolation Cooling System. The plant is stable in MODE 3. The cause of the 'A' Turbine Bypass Valve opening is under investigation at this time. The NRC Resident Inspector has been notified.
This is an update to EN # 53788 to correct an error on the event classification block of the form. The original notification did not have the block for 8 hour notification for Specified System Actuation checked. The actuation of Reactor Core Isolation Cooling System was discussed in original notification. The licensee notified the NRC Resident Inspector. Notified R4DO (Taylor). | |
ENS 53608 | 14 September 2018 21:09:00 | Grand Gulf | NRC Region 4 | At 1644 (CDT) a manual reactor scram was inserted by placing the Reactor Mode Switch to Shutdown. At 1643 (CDT) the Condensate Booster Pump A tripped on low suction pressure. At 1644 (CDT) the Reactor Feed Pump A tripped on low suction pressure. A Recirculation Flow Control Valve runback occurred as designed. Reactor Water level was approaching the Automatic Low Water Level 3 (11.4 inches) scram set point and manual actions were taken by placing the Mode Switch to Shutdown before the low level set point was reached. All systems responded as expected following the manual scram. The plant is stable in mode 3. This 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. The NRC Senior Resident Inspector has been notified. All control rods fully inserted, and decay heat is being removed through the turbine bypass valves to the main condenser. The licensee is investigating the cause of the event. | |
ENS 53566 | 27 August 2018 13:15:00 | Grand Gulf | NRC Region 4 | On 27 August 2018 at 0918 CDT Grand Gulf Control Room was informed that the onsite credit union silent alarm was actuated. The credit union is located outside of the Secure Owner Controlled Area (SOCA), but is located within the Owner Controlled Area. GGNS (Grand Gulf Nuclear Station) Security entered an elevated security position at 0920 (CDT) and requested assistance from local law enforcement. Claiborne County Sheriff's Department responded to the site. Investigation of the area conducted with the assistance of GGNS Security personnel determined that the cause of the notification was not valid. GGNS Security stood down from the elevated security positon at 0945 (CDT). Pursuant to 10 CFR 50.72(b)(2)(xi), this issue is being reported as any event or situation, related to the health and safety of the public or on-site personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made. | |
ENS 53399 | 12 May 2018 06:58:00 | Grand Gulf | NRC Region 4 | GE-6 | On 5/11/2018, at 2327 hours CDT, with the plant in Mode 5, Grand Gulf Nuclear Station was making preparations for surveillance test 06-OP-1P75-R-0003, Standby Diesel Generator 1 Functional Test. The Grand Gulf Nuclear Station experienced an auto-start of the Division 1 (Emergency) Diesel Generator (EDG) when the 15AA Bus Potential Transformer (PT) fuse drawer was racked out instead of the line PT fuse drawer for Bus 15AA feeder breaker 152-1514. This resulted in the 15AA Incoming Feeder Breaker 152-1511 from Engineered Safety Features Transformer 12 opening, de-energizing the 15AA Bus. The Division 1 EDG started and energized Bus 15AA. The Division 1 LSS SYSTEM FAIL annunciator was received and Standby Service Water A failed to start due to the 15AA Bus PT fuse drawer being racked out. Standby Gas Treatment Train B was manually initiated per the Loss Of AC Power Off Normal Emergency Procedure. Station equipment operated as expected based on the PT fuse drawer that was racked out. The Division 1 EDG was manually tripped from the Control Room because cooling from the Standby Service Water A was not available. RHR (residual heat removal) B was in Shutdown Cooling (mode) and was verified not affected The licensee has notified the NRC Resident Inspector. |
ENS 53374 | 1 May 2018 20:42:00 | Grand Gulf | NRC Region 4 | GE-6 | At 1551 hrs (CDT) on 5/1/2018, with the plant in Mode 5, a division one Reactor Pressure Vessel (RPV) Level 1 signal was received; however there was no actual change in RPV level. RPV Level remained at High Water Level supporting refuel operations. This caused an actuation of division one Load Shed and Sequencing system that shed and then re-energized the 15 bus. Division one diesel generator started from standby. Residual Heat Removal pump 'A', which was in shutdown cooling mode, was lost during the bus shed, and was re-sequenced upon re-energization of the 15 bus. Upon restoration of shutdown cooling, the RHR pump discharged into the RPV. RCS temperature increased approximately 5 degrees Fahrenheit as a result of the loss of shutdown cooling. The cause of the actuation signal is under investigation. In accordance with NUREG 1022, Event Reporting Guidelines, this event is conservatively reported under 10 CFR 50.72(b)(2)(iv)(A) as an event that results in emergency core cooling system discharge into the RCS as a result of a valid signal, under 10 CFR 50.72(b)(3)(iv)(B)(8) as an event that results in the actuation of emergency ac electrical power systems, and under 10 CFR 50.72(b)(3)(v)(B) as an event or condition that at the time of discovery could have prevented the fulfillment of a safety function (remove residual heat). The licensee notified the NRC Resident Inspector. |
ENS 53335 | 13 April 2018 21:04:00 | Grand Gulf | NRC Region 4 | GE-6 | 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.
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). |
ENS 53317 | 5 April 2018 18:23:00 | Grand Gulf | NRC Region 4 | GE-6 | On Thursday, April 5, 2018, at approximately 1117 hours Central Daylight Time, Entergy contract personnel opened the personnel hatch allowing access to the roof of the Secondary Containment Building for the purposes of performing an inspection of various items located on the roof. During the time period the individuals were on the roof, the hatch was left open. An individual was adjacent to the door with a radio and had constant communication link with the control room operator. Pursuant 10 CFR 50.72(b)(3)(v)(C), and 10 CFR 50.72(b)(3)(v)(D) this event is being reported as an event or condition that could have prevented the fulfillment of a safety function. Because the site had an individual briefed and at the door in constant communications with the control room to close the hatch if condition required such an action, this event is not viewed as an actual loss of safety function. The NRC Resident Inspector was notified. |
ENS 53304 | 31 March 2018 10:00:00 | Grand Gulf | NRC Region 4 | GE-6 | At 0206 (CDT) on March 31, 2018, with the plant in Mode 1 at 100% rated core thermal power, Grand Gulf Nuclear Station experienced a loss of Secondary Containment. During the performance of a Standby Gas Treatment System (SGTS) drawn down test with Auxiliary Building train bay door (1A319A) as the secondary containment boundary, Grand Gulf was unable to maintain secondary containment pressure, as required by SR (surveillance requirement) 3.6.4.1.4, greater than or equal to 0.266 inches of water vacuum for 1 hour. Following initial vacuum draw down, secondary containment pressure degraded to 0.225 inches of water vacuum with operators in the field reporting air leakage from door 1A319A. The test was secured and Secondary Containment was declared inoperable and Technical Specification 3.6.1.4 A.1 was entered. Following completion of the failed surveillance test, Secondary Containment was returned to an operable status at 0315 hours on March 31, 2018, by returning the system to a previously known operable configuration by closing doors 1A310, 1A312 and 1A319. This is being report under 10 CFR 50.72(b)(3)(v)(C). The licensee has notified the NRC Resident Inspector. |
ENS 53227 | 23 February 2018 18:04:00 | Grand Gulf | NRC Region 4 | GE-6 | On February 18, 2018, Grand Gulf Nuclear Station experienced the concurrent inoperability of two Emergency Diesel Generators (DG). This event is being reported as a late 8-hour non-emergency notification per 10 CFR 50.72(b)(3)(v)(D) as an 'Event or Condition that Could Have Prevented Fulfillment of a Safety Function (Accident Mitigation).' On February 14, 2018 at 0100 (CST), the Division 2 Diesel Generator was declared inoperable, and subsequently removed from service for maintenance. On February 18, 2018 at 0006 (CST), the Division 3 Diesel Generator Jacket Water temperature exceeded the trip setpoint and Division 3 Diesel Generator was declared inoperable. The Division 2 Diesel Generator was restored and declared operable on February 18, 2018 at 0355 (CST), and the Division 3 Diesel Generator was restored and declared operable on February 18, 2018 at 1240 (CST). As a result, Technical Specification Condition 3.8.1.E was entered at 0006 (CST) on February 18, 2018 and exited at 0355 (CST) on February 18, 2018. Technical Specification Bases 3.8.1.E.1 states 'With two DGs inoperable, there is one remaining standby AC source. Thus, with an assumed loss of offsite electrical power, insufficient standby AC sources are available to power the minimum required ESF functions.' Offsite power was available throughout this event and there was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
ENS 53201 | 10 February 2018 22:37:00 | Grand Gulf | NRC Region 4 | GE-6 | On 2/10/18 at 1835 CST at Grand Gulf Nuclear Station, while the 208 ft. Containment Airlock Outer Door was tagged-out for planned maintenance, the 208 ft. Containment Inner Door was determined to be inoperable. Grand Gulf had performed 06-ME-1M23-R-0001, Personnel Airlock Door Seal Air System Leak Test, on the 208 ft. Containment Airlock Inner Door which had been deemed satisfactory. While performing planned maintenance on the outer door an additional review of the paperwork determined that the test was actually unsatisfactory on the inner door. TS 3.6.1.2 Condition C was entered at 1835 CST on 2/10/18 for both 208 ft. Containment Airlock Doors being inoperable. Maintenance of the Outer Door is expected to be completed, and the airlock returned to operable status, prior to TS required action completion time. The licensee notified the NRC Resident Inspector. |
ENS 53188 | 30 January 2018 21:56:00 | Grand Gulf | NRC Region 4 | GE-6 | On 1/30/2018 at 1750 (CST), the Reactor Pressure Control Malfunctions ONEP (Off Normal Event Procedure) was entered due to main turbine load oscillations of approximately 30 MWe peak to peak. At 1822 (CST), a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown due to continued main turbine load oscillations. Reactor SCRAM ONEP, Turbine Trip ONEP, and EP-2 were entered. Reactor water level was stabilized at 36 inches narrow range on startup level and reactor pressure stabilized at 933 psig using main turbine bypass valves. Reactor Water Level 3 (11.4 inches) was reached which is the setpoint for Group 2 (RHR to Radwaste Isolation) and Group 3 (Shutdown Cooling Isolation). No valve isolated in these systems due to all isolation valves in these groups being in their normally closed position. The lowest Reactor Water level reached was -36 inches wide range. No other safety system actuations occurred and all systems performed as designed. 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 and also reported under 10CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of RPS. The MSIVs are open with decay heat being removed via steam to the main condenser using the bypass valves. Off site power is stable, and the plant is in a normal shutdown electrical lineup. RCIC (Reactor Core Isolation Cooling) was out of service for maintenance, and the reactor water level did not reach the system activation level. The cause of the main turbine load oscillations being investigated. The licensee notified the NRC Resident Inspector. |
ENS 53117 | 12 December 2017 20:34:00 | Grand Gulf | NRC Region 4 | GE-6 | At approximately 1330 CST on Tuesday, December 12, 2017, Grand Gulf Nuclear Station declared Division 3 'C' Battery inoperable due to questions concerning battery terminal connection continuity. Technical Specification 3.8.4, DC Sources - Operating, Condition E, Required Action E.1, requires the station to declare the High Pressure Core Spray System inoperable immediately. The Division 3 'C' Battery and High Pressure Core Spray System was declared operable and the LCOs (Limiting condition of operation) were declared met at 1731CST on Tuesday, December 12, 2017. Based on field measurements of terminal torque and resistance, the as-found and as-left terminal resistance micro-ohm readings indicated satisfactorily all times. Formal evaluation of the as-found condition of the battery is in progress. This report is to notify the NRC of a loss of safety function on the High Pressure Core Spray System. The NRC Resident Inspector was notified. |
ENS 53115 | 12 December 2017 17:40:00 | Grand Gulf | NRC Region 4 | GE-6 | At approximately 0918 CST on Tuesday, December 12, 2017, the Grand Gulf Nuclear Station experienced a loss of the Engineered Safety Features (ESF) Transformer 11 which was powering the Division 1 ESF bus. Subsequently, the station experienced an automatic start of the Division 1 Emergency Diesel Generator (EDG), partial isolation of the primary and secondary containment buildings and the isolation of the Reactor Core Isolation Cooling System (RCIC). It is not currently understood why the RCIC system isolated during this event. A team is investigating this issue separately from the loss of the ESF 11 transformer. The cause of the event is under investigation at this time. No other issues or unexpected events occurred. The NRC Resident Inspector has been notified of the event. |