Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55691 | 6 January 2022 15:44:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to a Fire in the Aux Cable Vault | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: On 01/06/22 at 1044 (EST), an Unusual Event was declared due to a Fire Detection Actuation in the Unit 1, auxiliary cable vault (EAL H.U 4.1). No fire was detected. Unit 1 and Unit 2 remain at 100 percent power. The Llcensee notified the NRC Resident Inspector, the state, and local authorities. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).
At 1441 (EST), DC Cook Unit 1 terminated their notification of unusual event. The basis for termination was that the inspection identified no damage to cables or cable trays. The fire protection system is out of service for the auxiliary cable vault with compensatory measures in effect. The licensee has notified the state and local authorities and will notify the NRC Resident Inspector. Notified R3DO (Skokowski), IRD MOC (Grant), NRR EO (Felts), IR (Kennedy)(email), NRR (Veil)(email), R3 DRA (Shuaibi)(email), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). | ||
| ENS 52967 | 13 September 2017 04:47:00 | 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 Letdown Relief Valve Discharge to the Pressurizer Relief Tank | At 0047 EDT, the licensee declared a notification of unusual event under emergency action level (EAL) S8 due to actuation of the letdown relief valve which resulted in reactor coolant system leakage to the pressurizer relief tank exceeding 10 gpm. The plant was in mode 3 at the time making preparations to proceed to cold shutdown to support their refueling outage. Operators were in the process of reducing reactor coolant system letdown from 120 gpm to 45 gpm when the letdown system relief valve lifted. The relief discharged to the pressurizer relief tank at approximately 12 gpm. Operators isolated the letdown line which reduced the leakage to approximately 1 gpm. Plant staff is in the process of determining where the 1 gpm leakage is from and evaluating the basis for terminating the unusual event. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email).
At 0800 EDT, the licensee terminated the notification of unusual event. The basis for termination was that the letdown line was isolated which reduced leakage to less than the EAL threshold of 10 gpm. The cause of the letdown relief lifting is still under investigation. The licensee has notified the NRC Resident Inspector and will be notifying the state of Michigan and Berrien County. The licensee has issued a press release to the media concerning this event. Notified R3DO (Riemer), IRD MOC (Stapleton), NRR (Miller), DHS SWO, DHS NICC, FEMA Ops Center, FEMA National Watch Center (email) and Nuclear SSA (email).
The condition reported in Event Notification #52967 pursuant to 10 CFR 50.72(a)(1)(i) has been evaluated, and determined not to have met the threshold for classification as an Unusual Event under Emergency Action Level (EAL) S-8 and is being retracted. During the events of 9/13/17, Control Room staff calculated Reactor Coolant System (RCS) leakage to the Pressurizer Relief Tank (PRT) through the Letdown Relief Valve to be greater than the EAL S-8 threshold of 10 gallons per minute. Subsequent review of trends associated with PRT level increase during the event determined that the RCS leakage to the PRT was less than 10 gallons per minute and therefore did not represent an Unusual Event under EAL S-8. The NRC Resident Inspector was notified of this retraction. Notified R3DO (Riemer). | Reactor Coolant System | |
| ENS 52649 | 30 March 2017 07:10:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Loss of All Control Room Annunciators | The Unit 1 DC Cook Nuclear Plant (CNP) Annunciator System failed on Thursday, March 30, 2017 at 0255 (EDT). The failure resulted in a complete loss of all alarm function of the Annunciator System in the Unit 1 Control Room. Unit 2 was unaffected by this failure. At 0310 (EDT), an Unusual Event (UE) was declared due to System Malfunction S-6, Loss of Alarms or Indication, due to an unplanned loss of safety system annunciators and/or indications in the Control Room for greater than 15 minutes. The Unit 1 PPC (Plant Process Computer) and ERDS (Emergency Response Data System) remain functional and available. This notification is being made in accordance with 10 CFR 50.72(a)(1)(i) due to the declaration of an Emergency Classification specified in the licensee's approved Emergency Plan. The licensee has notified the NRC Resident Inspector, the State and local agencies. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.
Unit 1 DC Cook Nuclear Plant Annunciator System has been returned to functional. Unusual Event Classification was terminated at 0817 EDT on 3/30/17. The NRC Resident Inspector will be notified. Notified R3DO (Cameron), NRR EO (Miller), and IRD (Grant). Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail. | ||
| ENS 52065 | 6 July 2016 04:38:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip and Unusual Event Declaration Due to Steam Leak in Turbine Building | On July 6, 2016, at 0038 (EDT), DC Cook Unit 2 Reactor was manually tripped and at 0050 (EDT) an Unusual Event (N-7 'Unanticipated Explosion') Emergency Declaration was made due to steam leak and associated damage to the turbine building. In accordance with Emergency Plan procedures, notifications of Berrien County and State of Michigan were completed. The licensee has notified the NRC Senior Resident Inspector. The Unusual Event was terminated at 0207 (EDT). This notification is being made in accordance with 10 CFR 50.72 (a)(1)(i) due to declaration of an emergency class. Original notification to NRC made at 0100 EDT via ENS. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation and 10 CFR 50.72(b)(2)(xi) Offsite Notification, as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. The DC Cook NRC Resident Inspector has been notified. A press release is planned. Unit 2 is being supplied by offsite power. All control rods fully inserted. Decay heat is being removed via Steam Generator PORVs (Power Operated Relief Valve). Preliminary evaluation indicates all plant systems functioned normally following the reactor trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via email. | Steam Generator Reactor Protection System Auxiliary Feedwater Control Rod | |
| ENS 47194 | 23 August 2011 18:24:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of an Unusual Event Due to a Seismic Event | At 1424 (hrs. EDT) on Tuesday, August 23, 2011, an Unusual Event was declared for Unit 1 and Unit 2 based on Emergency Plan criterion N-1, 'Natural of Destructive Phenomena Inside the Protected Area'. The Unusual Event was declared following detection of ground motion by persons on site with confirmation based on United States Geological Survey information. Plant operation was not impacted by the event. Site structure and system inspections are in progress in accordance with the Abnormal Operating Procedure for earthquake. No damage has been identified. In accordance with Emergency Plan procedures, notifications of Berrien County and State of Michigan were completed. The licensee has notified the NRC Senior Resident Inspector. A follow-up notification will be made after the Unusual Event is terminated. This notification is being made in accordance with 10 CFR 50.72 (a)(1)(i) due to declaration of an emergency class.
A press release has been issued regarding the seismic event. This notification update is being made in accordance with 10 CFR 50.72 (b)(2)(xi) for news release or notification of other government agency. Notifications were made to the following local media: St. Joseph Herald Palladium, South Bend Tribune, Niles Daily Star, WSJM Radio, WNDU TV, WSBT TV, and WSJV TV. Notification was also made to the Platt News Service. The licensee has notified the NRC Resident Inspector.
The Unusual Event due to Seismic Event was terminated at 1723 EDT following an examination of plant systems which revealed no damage due to the seismic event. A press release has been issued regarding the termination of the Unusual Event. This notification update is being made to notify of the Unusual Event termination and also notify of the press release describing the Unusual Event termination in accordance with 10 CFR 50.72 (b)(2)(xi) for news release or notification of other government agency. The licensee has notified the NRC Resident Inspector and state and local authorities. Notified R3DO (Passehl), IRD (Gott), DHS (Flinter), FEMA (Via), USDA (Kraus), and DOE (Bailey). | ||
| ENS 46037 | 23 June 2010 18:28:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Declaration of Unusual Event Due to Seismic Event | At 1428 (EDT) on Wednesday, June 23, 2010, an Unusual Event was declared for Unit 1 and Unit 2 based on Emergency Plan criterion N-1 'Natural or Destructive Phenomena Inside the Protected Area'. The Unusual Event was declared following detection of ground motion by persons on site, with confirmation based on United States Geological Survey information. Plant operation was not impacted by the event. Site structure and system inspections are in progress in accordance with the Abnormal Operating Procedure for Earthquake. No damage has been identified. In accordance with Emergency Plan procedures, notifications of Berrien County and State of Michigan were completed. The licensee has notified the NRC Senior Resident Inspector. A follow-up notification will be made after the Unusual Event is terminated. This notification is being made in accordance with 10 CPR 50.72 (a)(1)(i) due to declaration of an emergency class.
The licensee provided the following information as an update: A press release has been issued regarding the seismic event. This notification update is being made in accordance with 10 CFR 50.72 (b)(2)(xi) for news release or notification of other government agency. The licensee informed state/local agencies and the NRC Resident Inspector. Notified R3DO (Lara).
The Unusual Event due to Seismic Event was terminated at 1955 EDT following an examination of plant systems which revealed no damage due to the seismic event. A press release has been issued regarding the termination of the Unusual Event. This notification update is being made to notify of the Unusual Event termination and also notify of the press release describing the Unusual Event termination in accordance with 10 CFR 50.72 (b)(2)(xi) for news release or notification of other government agency. The licensee notified state/local agencies and the NRC Resident Inspector. Notified the R3DO (Lara), NRR EO (Cunningham), DHS (Inzer), and FEMA (Hollis). | ||
| ENS 44507 | 21 September 2008 00:18:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unit 1 Manual Reactor Trip from 100% Power Due to a Fire in the Main Turbine | D.C. Cook Unit 1 declared an Unusual Event (EAL H4 & H5) due to a fire in the Main Turbine. The reactor was manually tripped from 100 percent. The fire occurred at the upper level of the turbine building (Level 633), and was extinguished by the fire suppression system and local fire brigade. Three fire pumps are running at this time. No injuries were reported. All rods fully inserted, auxiliary feed water initiated and decay heat is being removed via atmospheric relief valves. Unit 1 is currently shutdown and stable in Mode 3, Hot Standby. Main steam stop valves are closed. Main condenser vacuum was broke. Unit 2 was not affected. All Unit 1 safety-related equipment is in-service and available. The licensee is currently assessing the extent of damage. The licensee will inform the NRC Resident Inspector. Notified DOE (Morrone), USDA (Shaf) and HHS (Mammarelli) that the NRC entered Monitoring Mode at 2045 EDT.
On September 20, 2008 at 20:05 the DC Cook Unit 1 Reactor was manually tripped after a malfunction occurred on the main turbine generator causing high vibration. A fire in the Unit 1 Main Generator resulted from this malfunction. A Notification of Unusual Event was declared September 20, 2008 at 20:18 due to Event classifications H-4, Fire within the protected area not extinguished within 15 minutes and H-5, Toxic or Flammable gas release affecting plant operation. The Unit 1 Main Generator Fire was reported extinguished at September 20, 2008 at 20:28. The Unit 1 plant trip was uncomplicated and all Automatic Control systems functioned as expected. All control rods inserted on the Reactor trip. The Turbine and both Motor Driven Auxiliary Feedwater pumps automatically started and fed all four Steam Generators as designed. The Steam Generator Stop Valves were manually closed to arrest plant cooldown. The cause of the Main Generator fire has not yet been determined, but the investigation is ongoing. No radiological release resulted from this event. This event is being reported as a four hour report required by 10CFR50.72(b)(2)(iv)(B) due to the Reactor Protection System automatic actuation and as an eight hour report required by 10CFR50.72(b)(3)(iv)(A) for the automatic actuation of the Auxiliary Feedwater system. The Notification of Unusual Event was reported separately. Unit 1 is stable in Mode 3. Shutdown Margin was satisfactorily verified. The main condenser was isolated as the primary heat sink. Steam Generator Power Operated Relief Valves are removing core decay heat in automatic control due to breaking main condenser vacuum. Main condenser vacuum was broken to stop the Unit 1 main turbine generator due to high vibration. Preparations are in progress to cooldown Unit 1 to Mode 5, Cold Shutdown. The Fire Suppression Water System was actuated and one of two 565,000 gallon tanks was drained. The second 565,000 gallon Fire Suppression Water tank was placed in service to restore the Fire Suppression Water system function. The licensee notified the NRC Resident Inspector, local and state authorities. The licensee will likely make a press release. Notified R3RA (Caldwell), R3DO (Stone), NRR (Leeds and Galloway) IRD (McDermott), DHS (Gomez) and FEMA (Kuzia).
At 0409 the licensee terminated from the Notice of Unusual Event. The licensee has established the forced outage recovery team. No fires exist and no conditions conducive to fires exist due to the event. The licensee has established the integrity of the fire protection system. Notified R3RA (Caldwell), R3DO (Stone), NRR (Galloway), IRD (Grant), DHS (Jason), DOE (Maroni), FEMA (Sweetser), USDA (Phillip), and HHS (Nathan). | Steam Generator Reactor Protection System Auxiliary Feedwater Main Turbine Main Condenser Control Rod Main Steam | |
| ENS 44147 | 18 April 2008 10:02:00 | 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 Declared Due to Seismic Activity | At 06:02 on April 18 2008, DC Cook Units 1 and 2 entered the Emergency Plan for a confirmed seismic event based on ground motion felt by plant personnel. An immediate notification to the NRC is required under 10 CFR 50.72(a)(3) for entry into the Emergency Plan. The ground motion sensed by plant personnel was confirmed with the National Earthquake Center. A magnitude 5.4 preliminary (Richter scale) earthquake was confirmed in Southern Illinois at LATITUDE 38.481 North/LONGITUDE 87.826 West. The Earthquake Abnormal Operating Procedures were entered for both Units. Ground motion was not felt by the control room operating crews, but was noted and reported by other plant personnel. Plant Process Computer trends of Unit 1 RWST level, South Boric Acid Storage Tank Level and North Chemical and Volume Control System Hold Up Tank Level indicated ground motion. No damage to plant equipment was noted during the initial evaluation of plant status. Investigation of the plant impact of the sensed ground motion is in progress. The NRC Resident Inspectors were notified by phone call. Current Plant status: Unit 1 is shutdown in Mode 6 with Residual Heat Removal Cooling. Unit 2 is operating in Mode 1 at 100% power. AEP system Operations was contacted and the GRID was described as stable and no electrical operations relating to the earthquake event. The Seismic Monitoring system was INOPERABLE as required by TRO 8.3.2, Cond. B, during the event for routine surveillance. This surveillance has been in progress since 03/26/08. No alarms were generated by the seismic monitoring system during this event.
At 0905 EDT on 04/18/08, the licensee terminated the Unusual Event based on completion of system walk downs which confirmed no damage to the facility. The licensee informed the NRC Resident Inspector. Notified R3DO (Kozak), NRR (MJ Ross-Lee), IRD (McDermott), FEMA (Liggett) and DHS (Barnes).
A press release regarding the declaration of the emergency was issued and a subsequent press release is planned to address the termination. The offsite notifications are being reported under 10 CFR 50.72(b)(2)(xi)." The licensee informed the NRC Resident Inspector. Notified R3DO (Kozak).
At 11:45 on April 18, 2008, D.C. Cook Units 1 and 2 entered the Emergency Plan for a confirmed seismic event based on ground motion felt by plant personnel. An immediate notification to the NRC is required under 10 CFR 50.72(a)(3) for entry into the Emergency Plan. The ground motion sensed by plant personnel was confirmed with the National Earthquake Center. A magnitude 4.6 (preliminary on Richter scale) earthquake-aftershock was confined in Southern Illinois at LATITUDE 38.483 North/LONGITUDE 87.39 West at 10:14 CDT / 11:14 EDT. The Earthquake Abnormal Operating Procedures were entered for both Units. Ground motion was not felt by the control room Operating crews, but was noted and reported by other plant personnel. No damage to plant equipment was noted during the initial evaluation of plant status. Investigation of the plant impact of the sensed ground motion is in progress. The NRC Resident Inspectors were notified in person. Current Plant status: Unit 1 is shutdown in Mode 6 with Residual Heat Removal Cooling. Unit 2 is operating in Mode 1 at 100% power. AEP System Operations was contacted and the GRID was described as stable with no electrical operations relating to the earthquake event. The Seismic Monitoring system was INOPERABLE as required by TRO 8.3.2, Condition B during the event for routine Surveillance. This Surveillance has been in progress since 03/26/08. No alarms were generated by the seismic monitoring system during this event. One of four channels is currently out of service. The three remaining seismic monitor channels indicated no ground acceleration above the lowest instrument activation level of 0.02g. D.C. Cook intends to issue a press release regarding the declaration of the Notification of Unusual Event emergency classification. The offsite notifications are being reported under 10 CFR 50.72(b)(2)(xi).
At 16:00 on April 18, 2008, DC Cook terminated the Unusual Event specified in EN 44147 for the aftershock response described above. A press release regarding the emergency event termination is anticipated. The offsite notifications are being reported under 10 CFR 50.72(b)(2)(xi). The licensee notified the NRC Resident Inspector. Notified R3DO (Kozak), NRR EO (Ross-Lee), IRD (McDermott), DHS (Gomez), FEMA (Burckhardt). | Residual Heat Removal | |
| ENS 40402 | 19 December 2003 23:44:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event | At 1844 on 12/19/2003, D.C. Cook Unit 2 received seal injection low flow alarms. Upon investigation, a leak of approximately 30 gpm was identified on the North Seal Injection Filter housing. The abnormal procedure for RCS leakage was entered. An Unusual Event was declared at 1853. A team was dispatched to place the South Seal Injection Filter in service and isolate the North Seal Injection Filter. At 1929, the leak was isolated. The licensee is reviewing UE termination criteria at this time. The Licensee notified the NRC Resident Inspector.
At 2015 EST on 12/19/03 D.C. Cook terminated the Unusual Event. Notified DIRO (Wessman), R3DO (Kozak), NRREO (Black), NSIR (Weber), FEMA, and DHS. |