Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55056 | 7 January 2021 07:24:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Rise in Drywell Unidentified Reactor Coolant System Leakage | 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). | Reactor Coolant System | |
| ENS 51137 | 8 June 2015 03:59:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event - Fire in Protected Area Lasting Greater than 15 Minutes | 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.
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). | ||
| ENS 49136 | 19 June 2013 19:10:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Co2 Release in the Auxiliary Building | At 1410 CDT, Grand Gulf declared an Unusual Event for EAL H.U.5, release of toxic and flammable gases adverse to normal operation of the plant. CO2 was discharged in the electrical switchgear room in the auxiliary building. No injuries or fatalities were found after an initial search of the area. The cause of the CO2 discharge is under investigation. The NRC Resident Inspector was notified. Notified DHS SWO, FEMA, DHS NICC, and Nuclear SSA via email.
All areas of the auxiliary building have been verified to have no oxygen deficiency." The Unusual Event was terminated at 1628 CDT. The NRC Resident Inspector was notified. Notified R4DO (Walker), NRR EO (Giitter), and IRD (Marshall). Notified DHS SWO, FEMA, DHS NICC, and Nuclear SSA via email. | ||
| ENS 49025 | 12 May 2013 22:43:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Due to Fire on Auxiliary Transformer Inside Protected the Area | 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.
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.
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). | ||
| ENS 47825 | 11 April 2012 23:26:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Due to a Fire in the 'A' Main Condenser | At 1811 (CDT) hours a fire was reported inside the 'A' Main Condenser. The fire brigade was dispatched to combat the fire and the area was evacuated. An Unusual Event (HU4) was declared at 1826 (CDT) hours due to the fire being in the Protected Area boundary and not extinguished within 15 minutes of detection. The Claiborne County, Mississippi Fire Department was notified to provide assistance. At 1847 (CDT) hours the fire was reported to be extinguished. The Unusual Event was terminated at 1900 (CDT) hours. The source of the fire is still under investigation. There were no personnel injuries. The licensee notified the NRC Resident Inspector, Mississippi Emergency Management, Governor Office of Homeland Security, Claiborne County Sheriffs Department, Tensas Sheriffs Office, Mississippi Highway Patrol, and the Louisiana Department of Environmental Quality. Notified DHS SWO, FEMA, NICC and Nuclear SSA via email. | Main Condenser | |
| ENS 44662 | 17 November 2008 15:25:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Fire in Protected Area Lasting Greater than 15 Minutes | Grand Gulf declared an unusual event at 0925 CST based on a fire in the protected area lasting longer than 15 minutes. The fire was discovered at 0911 CST under the B reactor feedwater pump. The fire involved oil accumulated under the feedwater pump. The fire brigade responded and extinguished the fire at 0935 CST. The B reactor feedwater pump was tripped offline and reactor power was reduced to 48% power due to the reduction in feedwater flow. The reactor is stable and there is no ongoing threat from the fire. There is no apparent damage to plant equipment and the cause of the oil leak is unknown at this time. The licensee plans to exit the UE when the licensee confirms there is no concern from fire reflash. The license has notified the required State and local authorities. The NRC Resident Inspector has been notified.
Fire confirmed at 0911 CST in 'B' Reactor Feed Pump Turbine room. Plant power was reduced by Control Room; then "B" Reactor Feed Pump Turbine was tripped in order for the Fire Brigade to combat the fire. Unusual Event declared due to Fire in Protected Area lasting greater than 15 minutes. (HU4). Fire reported out at 0935. No external assistance is needed. Unusual Event terminated at 1134 CST. Licensee has notified the NRC Resident Inspector, and state and local agencies. Notified R4 RA (Collins), R4 (Cain), NRR (Leeds), NRR (Thorp), IRD (Grant), FEMA (Barden), DHS (Moore). | Feedwater |