Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 50386 | 21 August 2014 04:03:00 | At 0210 EDT on August 21, 2014, D.C. Cook made notifications to the State of Michigan, local authorities and the National Response Center due to a suspected release of approximately 8,700 gallons of diesel fuel oil to the environment. The level in the buried fuel oil storage tank for the Train B Emergency Diesel Generator was found to be approximately 8,700 gallons less than measurements taken within the last 24 hours. The tank is located within the plant protected area. At this time the suspected fuel oil plume has not left the site. The NRC Resident Inspector was notified. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) and NUREG 1022 section 3.2.12, due to notification of offsite agencies.
An event investigation determined that no spill occurred. The discrepancy in level was due to maintenance activities that caused an error in level indication. No actual loss of inventory from the fuel oil storage tank occurred. Offsite agencies have been notified that this spill event is being retracted (to the State and Offsite agencies). The NRC Resident Inspector was notified. Notified the R3DO (Passehl). |
| ENS 50188 | 11 June 2014 01:23:00 | On 6/10/14 at approximately 2327 EDT, the Operations Shift Manager was made aware that the Berrien County Sheriffs Department (BCSD) had been notified of an Emergency Siren that had actuated. BCSD was notified by local residents. BCSD reset the emergency siren and a local police officer verified the siren was no longer actuating. The cause of the actuation is under investigation at this time. The siren remains in service pending further investigation. There are a total of 70 sirens and all remain functional. This notification is being made under 10 CFR 50.72(b)(2)(xi), Offsite Notification, as a four (4) hour report. The licensee has notified the NRC Resident Inspector. |
| ENS 49220 | 28 July 2013 13:43:00 | On July 28, 2013, at 1018 EDT, DC Cook Unit 2 Reactor was manually tripped due to lowering steam generator level caused by an automatic trip of the west main feed pump. The west main feed pump tripped on low suction pressure resulting from a secondary plant transient. The cause of the secondary transient is still under investigation. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation, 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 (8) hour report. The DC Cook Sr. Resident NRC Inspector has been notified. The electrical grid is stable and Unit 2 is being supplied by offsite power. All control rods fully inserted. Decay heat is being removed via steam dumps to the main condenser. 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. There was no affect on Unit 1.
Additional information received determined the Turbine Driven Auxiliary Feedwater Pump discharge valve to Steam Generator #2 did not position, as required, following the reactor trip. The affected discharge valve opened as expected during pump start. The valve closed instead of throttling to the intermediate position upon subsequent high flow demand. Feedwater flow to Steam Generator #2 was maintained by the East Motor Driven Auxiliary Feedwater Pump. The NRC Resident Inspector has been notified of this update. Notified R3DO (Orth). |
| ENS 46339 | 18 October 2010 09:34:00 | At approximately 10:00 a.m. on Monday, October 18, 2010, the Cook Nuclear Plant (CNP) Unit 2 Plant Process Computer (PPC) will be removed from service for scheduled power supply distribution panel preventive maintenance. This will remove Unit 2 PPC data input to ERDS rendering the system non functional for providing data to the NRC Operations Center. The scheduled maintenance will also affect the Safety Parameter Display System (SPDS), the Real Time Data Repository (RDR), and PPC data to Emergency Response Facilities at CNP. The scheduled maintenance is expected to take up to 6 hours to complete. Compensatory measures exist within the CNP Emergency Response procedure to provide plant data via the Emergency Notification System to the NRC Operations Center until the ERDS can be returned to service. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability (e.g., significant portion of control room indication, Emergency Notification System, or offsite notification system). CNP Unit 2 is currently defueled.
Functionality has been restored to ERDS following restoration of the Unit 2 PPC at 1422. SPDS, RDR, and PPC data to Emergency Response Facilities at CNP have also been restored to service at 1422. The NRC Resident Inspector has been notified. Notified R3DO(Orth). |
| ENS 46089 | 13 July 2010 08:15:00 | At 0810 EDT on Tuesday, July 13, 2010, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems have been removed from service for scheduled maintenance. Under certain accident conditions the TSC may become unavailable due to the inability of the air conditioning and charcoal filtration systems to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary. TSC ventilation system maintenance is scheduled to be completed by 1800 EDT on Tuesday, July 13, 2010. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an emergency response facility. * * * UPDATE FROM DEAN BRUCK TO CHARLES TEAL ON 7/13/10 AT 1730 EDT * * * The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1730 EDT. Notified R3DO (Dickson). |
| ENS 45831 | 12 April 2010 03:01:00 | At 04:00 on Monday, April 12, 2010, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems will be removed from service for scheduled maintenance. Under certain accident conditions the TSC may become unavailable due to the inability of the air conditioning and charcoal filtration systems to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary. TSC ventilation system maintenance is scheduled to be completed by 22:00 on Monday, April 12, 2010. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility.
The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1415. The NRC resident inspector has been informed. Notified R3DO (Orth). |
| ENS 44992 | 15 April 2009 07:31:00 | At 0415 on Wednesday, April 15, 2009, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system and charcoal filter was removed from service for scheduled preventive maintenance. The charcoal bed filtration system is also out of service in support of the maintenance on the TSC ventilation system. Under certain accident conditions the TSC may become unavailable due to the inability of the filtration system to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary based upon results of procedurally required monitoring of TSC radiological conditions. The TSC ventilation system maintenance is scheduled to complete at 1600 on Wednesday, April 15, 2009. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss an emergency response facility.
At 1255 on Wednesday, April 15, 2009 the planned maintenance and testing was completed. The TSC ventilation system and charcoal filter have been returned to service restoring full availability to the TSC. The licensee has notified the NRC Senior Resident Inspector." Notified R3DO (Laura Kozak) |
| ENS 44311 | 23 June 2008 03:26:00 | UNAVAILABILITY OF TSC CHARCOAL FILTER FOR SCHEDULED MAINTENANCE At 0300 on Monday, June 23,2008, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system charcoal filter was removed from service for planned charcoal bed maintenance. The balance of the TSC ventilation is not affected by the charcoal bed maintenance and remains available. Under certain accident conditions the TSC may become unavailable due to the inability of the filtration system to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary based upon results of procedurally required monitoring of TSC radiological conditions. Charcoal filter maintenance is scheduled to complete at 1000 on Wednesday, June 25, 2008. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss an emergency response facility.
At 0905 on Tuesday, June 24, 2008, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system charcoal filter was removed from service for planned charcoal bed maintenance. The balance of the TSC ventilation is not affected by the charcoal bed maintenance and remains available. The charcoal filter was removed from service at 0300 on Monday, June 23, 2008 (as previously reported via EN # 44311), and subsequently restored to available status at 1614. Under certain accident conditions the TSC may become unavailable due to the inability of the filtration system to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary based upon results of procedurally required monitoring of TSC radiological conditions. Charcoal filter maintenance is scheduled to complete at 1300 on Wednesday, June 25, 2008. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss an emergency response facility. Notified R3DO (Lipa).
The planned maintenance and testing was completed. The TSC Ventilation system was returned to service at 2045 EDT on 06/26/08. The licensee notified the NRC Senior Resident Inspector. Notified R3DO (Lipa). |
| ENS 44171 | 26 April 2008 05:11:00 | On April 25, 2008, DC Cook Unit 1 was in Mode 4 heating up the RCS after a refueling outage. Personnel were performing a containment walkdown, with the RCS at 1000 psig, looking for leakage. Wisps of steam were seen coming from a 3/4 inch RCS flow instrument line weld, between the RCS loop piping and the instrument isolation valve. The leakage is less than 0.1 gpm. The leakage can not be isolated from the RCS and has been declared to be RCS Pressure Boundary Leakage. Entry into the RCS Operational Leakage Technical Specification, 3.4.13, was made at 2210 on April 25, 2008. This Technical Specification requires being in Mode 5 within 36 hours. The plant is cooling down and depressurizing as required by Technical Specifications. The plant is currently evaluating the appropriate repair method for this condition. The licensee notified the NRC Resident Inspector. |
| ENS 40660 | 9 April 2004 01:47:00 | On April 8, 2004, at about 2215, Cook Unit 2 experienced a feedwater flow transient resulting in oscillating flows to Nr. 22, 23, & 24 steam generators. At 2216, the high level turbine trip setpoint was reached in Nr. 24 steam generator resulting in (a) main turbine trip signal. The main turbine trip signal caused a turbine trip resulting in an RPS (Reactor Protection System) actuation (reactor trip). At the time of the RPS actuation, Cook Unit 2 was at about 50 percent power and lowering power to facilitate turbine control maintenance. The cause of (the) feedwater transient is unknown and under investigation at this time. Following the RPS actuation, the Auxiliary Feedwater System automatically started on low-low Steam Generator levels. This constituted a valid unplanned actuation of the Engineered Safeguards Feature (ESF). Operators stabilized the Plant using Condenser Steam Dumps and Auxiliary Feedwater. Unit 2 is currently in Mode 3 with Reactor Coolant System conditions stable at normal operating temperature and pressure. No other ESF systems actuated. During the response to the RPS actuation by the operating crew, it was noted that the Main generator output breaker remained closed requiring a manual trip signal to open the output breakers. Another condition identified was a leak from a crack in the side of the 'C' South condenser near the condensate booster pumps' recirculation line inlet. The operating crew removed the condensate booster pumps from service to stop condenser hotwell outleakage; the main condenser remains in service. The causes for the above items are unknown and (are) under investigation at this time. All control rods fully inserted into the core in response to the automatic reactor trip and heat sink is currently been maintained using Auxiliary Feedwater Pumps and the Main Steam Dumps. Except as noted, all other systems functioned as required. The licensee notified the NRC Resident Inspector. |