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 Start dateReporting criterionTitleEvent descriptionSystemLER
ENS 5532223 June 2021 03:31:0010 CFR 50.72(b)(2)(iv)(B), RPS System ActuationManual Rx Trip Due to Steam Leak in Moisture Separator Re-Heater Crossover PipeOn June 22, 2021, at 2331 EDT, DC Cook Unit 2 Reactor was manually tripped due to a large steam leak in a crossover pipe of the Moisture Separator Re-heater (MSR) to the low pressure turbine. This notification is being made in accordance with 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 eight (8) hour report. The DC Cook Resident NRC Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. All Auxiliary Feedwater Pumps started properly. Decay heat is being removed via the Steam Dump System. 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. Unit 1 was not affected.Reactor Protection System
Auxiliary Feedwater
Control Rod
ENS 5494412 October 2020 04:26:0010 CFR 50.72(b)(2)(iv)(B), RPS System ActuationAutomatic Reactor TripAt 0026 (EDT) on October 12, 2020, D.C. Cook Unit 2 tripped automatically on low-low level of #24 steam generator which occurred after a lowering of main condenser vacuum. The reason for the lowering main condenser vacuum and the reason for the low steam generator #24 level is under investigation. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation as a four (4) hour report. Notification is also being made as an eight (8) hour report under 10 CFR 50.72(b)(3)(iv)(A) due to actuation of the Auxiliary Feedwater System (AFW). The D.C. Cook Resident NRC Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. Auxiliary Feedwater Pumps started as required and are operating properly. Decay heat is being removed via steam generator power operated relief valves (PORVs) due to condenser steam dump unavailability from low main condenser vacuum. All four Reactor Coolant Pumps remain running. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip. D.C. Cook Unit 2 remains stable in Mode 3. No radioactive release is in progress as a result of this event.Steam Generator
Reactor Protection System
Auxiliary Feedwater
Main Condenser
Control Rod
ENS 548855 September 2020 02:42:0010 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS DischargeManual Reactor Trip and Automatic Safety InjectionOn September 4, 2020, DC Cook Unit 2 experienced a lowering Reactor Coolant System (RCS) pressure caused by a failed open Reactor Coolant Pressurizer Spray valve. At approximately 2242 (EDT), a manual Reactor Trip was performed due to the lowering RCS pressure. Following the manual reactor trip, an automatic Safety Injection was actuated due to the lowering RCS pressure. RCS pressure has recovered to normal and is stable. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation, and 10 CFR 50.72(b)(2)(iv)(A), ECCS Discharge to RCS, as a four (4) hour report. Notification is also being made as an 8 hour report under 10 CFR 50.72(b)(3)(iv)(A), Reactor Protection System (RPS), Containment Isolation, Emergency Core Cooling (ECCS), Auxiliary Feedwater System (AFW), and Emergency AC Electrical Power actuations. The DC Cook Resident NRC Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. Aux Feedwater Pumps started as required and are operating properly. All ECCS components operated as required including Containment Isolation. Decay heat is being removed via the Condenser Steam Dumps and ECCS has been secured. Three of four Reactor Coolant Pumps were secured and RCS pressure has recovered to normal pressure and is stable. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip and Safety Injection. DC Cook Unit 2 remains stable in Mode 3. No radioactive release is in progress as a result of this event. Unit 1 was not affected and remains in Mode 1, 100 % power.Reactor Coolant System
Feedwater
Reactor Protection System
Auxiliary Feedwater
Control Rod
ENS 5472927 May 2020 13:12:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Inadvertent Actuation of SirensOn 5/27/20 at approximately 0912 EDT, the Operations Shift Manager was made aware that the Berrien County Sheriff's Department (BCSD) inadvertently actuated the emergency sirens during a planned weekly test. BCSD notified Cook Nuclear Plant that an audible test was initiated instead of a silent test. All Emergency Notification sirens remain in service. No press release is planned by the licensee at this time. 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 546871 May 2020 07:54:0010 CFR 50.72(b)(2)(i), Tech Spec Required ShutdownTechnical Specification Required Shutdown Due to Reactor Coolant System Pressure Boundary Leakage

At 1000 EDT on May 1 2020, Operations commenced a shutdown of DC Cook Unit 2 to comply with LCO 3.4.13, Condition B Reactor Coolant System (RCS) pressure boundary leakage. At 0354 EDT on May 1, 2020, Operations detected an estimated 8 gpm Reactor Coolant System leak. The source of the leak could not be identified and Tech Spec 3.4.13, Condition A was entered for unidentified RCS leakage in excess of the 0.8 gpm limit. At 0745 EDT on May 1, 2020, Unit 2 entered LCO 3.4.13, Condition B when the 4-hour limit to complete the required actions of Condition A could not be met. At 0945 EDT on May 1, 2020, Unit 2 entered LCO 3.4.13, Condition B when the 4-hour limit to complete the required actions of Condition A could not be met. At 0945 EDT on May 1, 2020, inspections inside containment identified the leak as pressure boundary leakage from a pressurizer spray line which also requires entry into LCO 3.4.13, Condition B. At 1059 EDT on May 1, Unit 2 was tripped from 15 percent power. All systems functioned normally. This event is reportable under 10 CFR 50.72(b)(2)(i), the initiation of any nuclear plant shutdown required by the plant's Technical Specifications as a 4-hour report and under 10 CFR 50.72 (b)(3)(ii)(A), degraded condition, as an 8-hour report. The NRC Resident Inspector has been notified.

  • * * PARTIAL RETRACTION ON 5/15/2020 AT 1442 EDT FROM BUD HINCKLEY TO THOMAS HERRITY * * *

The condition identified in EN #54687, pursuant to 10 CFR 50.72 (b)(3)(ii)(a) has been evaluated, and has been determined not to be RCS pressure boundary leakage. As such, the 8-hour report is being retracted, as it is not an event or condition that results in, 'the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.' The leakage was subsequently determined to be from the tell-tale nipple of a pressurizer spray valve, not from the pressurizer spray line piping as previously reported. The Reactor Coolant Pressure Boundary (RCPB) is formed by the valve body, plug, seat, body to bonnet extension, and bonnet of the pressurizer spray valve. Therefore, the leakage is not RCPB leakage. There is no change to the 4-hour report made under 10 CFR 50.72(b)(2)(i), the initiation of any nuclear plant shutdown required by the plant's Technical Specifications. The NRC Resident Inspector was notified of this retraction. Notified R3DO (Stone).

Reactor Coolant System
ENS 5429124 September 2019 13:30:0010 CFR 26.719Fitness-For-Duty ReportOn September 24, 2019, at 0930 EDT, a non-licensed employee contract supervisor had a confirmed positive test result for illegal drugs during a random test. The employee's access to the plant has been denied. The licensee has notified the NRC Resident Inspector.
ENS 5424126 August 2019 14:35:0010 CFR 26.719Fitness for DutyA non-licensed contract employee supervisor had a confirmed positive for an illegal drug during pre-access testing. The employee's access to the plant was denied.
ENS 5417621 July 2019 12:26:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Due Non-Essential Service Water System Degraded ConditionOn July 19, 2019, DC Cook Unit 2 started experiencing degraded performance on the Unit 2 Non-Essential Service Water System (NESW) which affected one (1) NESW pump. On July 21, 2019, a second NESW pump on Unit 2 experienced degradation. On July 21, 2019, DC Cook Unit 2 elected to do a rapid downpower over approximately 40 minutes and perform a Manual Reactor Trip from 17 percent (rated thermal power) to repair the condition before any threshold was exceeded. The manual reactor trip was completed at 0826 EDT on July 21, 2019. This notification is being made in accordance with 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), Reactor Protection System (RPS), as an eight (8) hour report. The DC Cook NRC Resident Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. Aux Feedwater pumps were started as required and are operating properly. Decay heat is being removed via the Steam Generator Power Operated Relief Valves following breaking Main Condenser Vacuum for expedited cooldown of the Main Turbine. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip. DC Cook Unit 2 remains stable in Mode 3. No radioactive release is in progress as a result of this event. Unit 1 was not affected.Steam Generator
Feedwater
Service water
Reactor Protection System
Main Turbine
Main Condenser
ENS 5403630 April 2019 00:29:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to a Spurious Actuation of an Emergency SirenOn 4/29/19, at approximately 2029 EDT, the Operations Shift Manager was made aware that the Berrien County Sheriff's Department (BCSD) had been notified of an Emergency Siren that had spuriously actuated. BCSD was notified by local residents. The affected siren has been disabled and it has been verified that all associated local areas still have coverage from other functional emergency sirens. The cause of the actuation is under investigation at this time. 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 533877 May 2018 07:36:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Rx Trip Due to High-High Level in Moisture Separator Drain TankOn May 7, 2018 at 0336 (EDT), DC Cook Unit 2 Reactor was manually tripped due to a high-high level experienced in the East Moisture Separator Drain Tank (MSDT) of the Moisture Separator Reheater (MSR). This notification is being made in accordance with 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 eight (8) hour report. The NRC Resident Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. All Aux Feedwater Pumps started properly. Decay heat is being removed via the Steam Generator Power Operated Relief Valves following Main Steam Stop Valve closure at 0431 due to a slow RCS (Reactor Coolant System) cooldown. 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.Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
ENS 5334218 April 2018 07:00:0010 CFR 26.719Fitness for Duty - Discovery of Paraphernalia That Could Be Used to Falsify Urine TestOn 4/18/2018, at approximately 0300 EDT, a contract cleaning employee notified her supervisor that she had found an oven mitt and a bottle containing a liquid that was possibly urine. The bottle had a temperature strip and heating element attached to it. These items were found in the trash in a bathroom in the training center located near the bathroom used for Fitness-for-Duty testing. The supervisor notified Security. Security responded and took possession of the objects. The licensee notified the NRC Resident Inspector.
ENS 5333413 April 2018 19:55:0010 CFR 50.72(b)(3)(iv)(A), System ActuationValid Emergency Diesel Generator Start During TestingAt 1555 EDT, the Unit 2 'CD' Emergency Diesel Generator (EDG) automatically started and loaded to 4kV Safeguards bus T21C. Testing was in-progress and the start was unplanned. Unit 2 is currently defueled. Unit 1 remains stable at 100 percent power. The South Spent Fuel Pit Cooling Train lost power due to a load shed. The South Spent Fuel Pit Cooling Pump was restarted on 2 'CD' EDG at 1614 EDT. The North Spent Fuel Pit Cooling Train remained in-service the entire time. There was no observable change in Spent Fuel Pool temperature. This event is reportable under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of an emergency diesel generator, as an eight (8) hour report. The NRC Resident Inspector has been notified.Emergency Diesel Generator
ENS 5323027 February 2018 03:47:0010 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person OffsitePotentially Contaminated Worker Transported to Offsite Medical FacilityAt 2247 Eastern (Standard) Time the Unit 1 Control Room was notified of a personnel injury in the Unit 1 lower containment. Unit 1 is currently in Mode 1 at 100 (percent) (Reactor) Power and the individual was working in lower containment. The individual's injury appears to be Heat Exhaustion. Site emergency medical technicians responded to the scene and the individual was transported to a local medical facility via ambulance. At the time of transport, the individual was considered to be potentially contaminated because complete surveys could not be performed while the individual was immobilized for transfer. The individual and clothing were surveyed at the hospital by a resident Radiation Protection Technician and no contamination was found. This report is being made pursuant to 10 CFR 50.72(b)(3)(xii), 'Any event requiring the transport of a radioactively contaminated person to an offsite medical facility for treatment.' The NRC Resident Inspector has been notified.
ENS 5296713 September 2017 04:47:0010 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).

  • * * UPDATE FROM BUD HINCKLEY TO HOWIE CROUCH AT 0807 EDT ON 9/13/17 * * *

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).

  • * * RETRACTION FROM BUD HINCKLEY TO HOWIE CROUCH AT 1617 EDT ON 9/15/17 * * *

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 5264930 March 2017 07:10:0010 CFR 50.72(a)(1)(i), Emergency Class DeclarationLoss 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.

  • * * UPDATE FROM MAX MILLER TO DONG PARK AT 0821 EDT ON 3/30/2017 * * *

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 525851 March 2017 18:03:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseNotification of Offsite Agencies Due to Sulfuric Acid Leak within the D.C. Cook Protected AreaAt 1303 EDT on March 1, 2017, DC Cook notified the State of Michigan of a sulfuric acid tank leaking over 1,000 gallons of acid into the tank's berm. The leak was identified at approximately 1000 EDT coming from a drain line flange. The berm is designed to contain over 15,000 gallons which is sufficient to collect the known capacity of the tank. Cleanup of the sulfuric acid from the berm is ongoing, with no release to the environment or nearby drains. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies. The NRC Resident Inspector was notified.
ENS 525444 February 2017 01:24:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed ConditionUnanalyzed Condition Due to Unaccounted Loads in Safe Shutdown Analysis

On February 3rd, 2017, during engineering modification reviews of electrical busses for a station switchyard transformer, electrical loads were identified on 4kV breakers that are not accounted for in the current safe shutdown analysis. Further reviews revealed the unanalyzed loads are associated with 26 cables that are routed through multiple fire zones in the Turbine Building and both Unit 1 and Unit 2 4kV rooms that have the potential to be affected from a fire event. Per NFPA 805 requirements, the cables need to be analyzed for overcurrent trip capability to demonstrate that the breakers will isolate a fault for a fire. Hourly Fire Watch tours have been established in the identified fire zones. The public health and safety is not impacted. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. The NRC Resident Inspector was notified. This is a late notification for the 8 hour report.

  • * * RETRACTION PROVIDED BY ERIK LANKHEET TO JEFF ROTTON AT 1522 ON 04/04/2017 * * *

The condition reported in EN# 52544 pursuant to 10 CFR 50.72(b)(3)(ii)(B) has been evaluated, and determined not to be an unanalyzed condition that significantly degraded plant safety and is being retracted. Fire Protection Engineering performed circuit analysis of the discovered loads and determined that the Fire Safety Analysis credited power supply for an established recovery action was lost due to a Turbine Building fire. This was determined to not be a significant impact to plant safety due to the availability of an alternate offsite 4kV power supply that was not impacted by this fire. Emergency Operating Procedures already contain guidance that directs operators to align the 4kV busses to this offsite power circuit and that can be accomplished within the time necessary to perform the recovery action. During periods when this offsite power circuit was removed from service over the past three years, risk was managed using the online risk management process and no additional actions would have been required for its use as the credited power source in the Fire Safety Analysis. The NRC Resident Inspector was notified of this retraction. Notified the R3DO (Skokowski).

ENS 5245622 December 2016 04:00:0010 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentEmergency Diesel Generators Declared Inoperable

With D.C. Cook Unit 1 in Mode 1 and 100 percent power and Unit 2 in Mode 4 during a refueling outage, the following emergency diesel generators (EDGs) were declared inoperable due to a discovered design and manufacturing issue involving some of the diesel fuel pumps/injectors in each of the following EDGs: Unit 1 CD (Train A) EDG, Unit 2 AB (Train B) EDG, and Unit 2 CD (Train A) EDG Due to both Unit 2 EDGs being inoperable, Unit 2 is required to be in Mode 5 by 1300 (EST) on 12/23/16. Unit 1 is required to restore its emergency diesel generator within 14 days (by 2300 (EST) on 1/04/17). In connection with both trains of Unit 2 EDGs being inoperable, this is being reported as an 8-hour report pursuant to 10CFR50.72(b)(3)(v)(D) as loss of safety function in connection with mitigating the consequences of an accident. The NRC Resident Inspector has been informed. Unit 1 maintenance will be prioritized over Unit 2 and Unit 2 will most likely proceed to Mode 5.

  • * * RETRACTION AT 1406 EDT ON 5/22/17 FROM RODNEY PICKARD TO JEFF HERRERA * * *

The condition reported in ENS 52456 pursuant to 10 CFR 50.72(b)(3)(v)(D) has been evaluated, and determined not to be a loss of safety function in connection with mitigating the consequences of an accident, and is being retracted. With D.C. Cook Unit 1 in Mode 1 and 100% power and Unit 2 in Mode 4 during a refueling outage, the following Emergency Diesel Generators (EDGs) were declared inoperable due to a discovered design and manufacturing issue involving some of the diesel fuel pumps/injectors in each of the following EDGs: Unit 1 CD (Train A) EDG, Unit 2 AB (Train B) EDG, and Unit 2 CD (Train A) EDG. Subsequent endurance testing was performed on selected Delivery Valve Holders (DVH), which were the affected components of the diesel fuel pumps/injectors, to evaluate the expected degradation of the DVHs during the EDG mission. This testing determined that the identified design and manufacturing issue would not have prevented the EDGs from performing their intended safety functions. Therefore, all EDGs were OPERABLE and did not result in a loss of safety function in connection with mitigating the consequences of an accident. The NRC Resident Inspector was notified of this retraction. Notified the R3DO (Kunowski).

Emergency Diesel Generator05000316/LER-2016-002
ENS 520656 July 2016 04:38:0010 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 BuildingOn 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
05000316/LER-2016-001
ENS 518598 April 2016 22:20:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Oil Leak in a Switchyard Transformer Oil SystemAt 1657 EDT on April 8, 2016, an oil leak developed from the station's switchyard transformer no. 4. Approximately 25,000 gallons of oil has leaked within the transformer's containment berm. At 1820 EDT on April 8, 2016, DC Cook environmental personnel determined that approximately 2000 gallons of oil had leaked outside of the containment berm onto the ground. None of the oil has made it to any nearby drains. Leak has stopped and cleanup is ongoing. D.C. Cook has notified the State of Michigan and local authorities. The NRC Resident Inspector was notified. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies.
ENS 5110631 May 2015 20:00:0010 CFR 50.72(b)(2)(i), Tech Spec Required ShutdownTechnical Specification Required Shutdown Due to Failure of an Emergency Diesel Generator

At 1600 (EDT) on May 31, 2015, (DC Cook) operations commenced a shutdown of DC Cook Unit 1 to comply with LCO 3.8.1 Condition G, when the 14 day limit to complete Condition B Required Action could not be met. At 0010 (EDT) on May 18, 2015, Unit 1 AB Emergency Diesel Generator was removed from service for planned maintenance. LCO 3.8.1 Condition B was entered which allows 14 days to restore diesel to operable. At 1049 (EDT) on May 21, 2015, Unit 1 AB Emergency Diesel Generator tripped during post maintenance testing due to high bearing temperatures. Subsequent actions to repair and restore the diesel to operable status have been unsuccessful. This event is reportable under 10 CFR 50.72(b)(2)(i), the initiation of any nuclear plant shutdown required by the plant's Technical Specifications, as a four (4) hour report. The DC Cook Sr. Resident NRC Inspector has been notified. Unit 1 is expected to be in Mode 5 by 2030 EDT on June 1, 2015. There is no impact on Unit 2.

  • * * UPDATE FROM CHRIS PEAK TO JOHN SHOEMAKER ON 6/1/15 AT 1704 EDT * * *

This update is to correct the information contained in the block titled 'Power/Mode After'. The power and mode after the event requiring notification (TECHNICAL SPECIFICATION REQUIRED SHUTDOWN DUE TO INABILITY TO RESTORE UNIT 1 AB EDG WITHIN THE COMPLETION TIME PRESCRIBED IN LCO 3.8.1 CONDITION B) was 99% power and mode 1. The licensee has notified the NRC Resident Inspector. D.C. Cook Unit 1 is currently in Mode 3 and conducting a normal cooldown to Mode 4. Notified R3DO (Passehl).

  • * * UPDATE FROM CHRIS PEAK TO HOWIE CROUCH AT 0734 EDT ON 6/2/15 * * *

DC Cook Unit 1 reactor was shut down (Mode 3) at 0231 hours (EDT) June 01, 2015 and achieved Mode 5 at 0410 hours (EDT) June 02, 2015 to comply with LCO 3.8.1 Condition G with all systems operating normally. The licensee has notified the NRC Resident Inspector. Notified R3DO (Passehl).

Emergency Diesel Generator05000315/LER-2015-001
ENS 5100423 April 2015 06:10:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown
Manual Reactor Trip Due to a Secondary Plant TransientOn April 23, 2015 DC Cook Unit 2 Reactor was manually tripped due to an uncontrolled cooldown due to two (2) failed open steam dump valves. The cause of the failure is still under investigation. This event is reportable under 10 CFR 50.72(b)(2)(i) Tech Spec Required Shutdown, as a four (4) hour report; 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 Reactor Protection System (RPS), as an eight (8) hour report. The electrical grid is stable and Unit 2 continues to be supplied by offsite power. All control rods fully inserted. Decay heat is being removed via steam generator Power Operated Relief Valves due to steam dump valves being manually isolated. 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. The DC Cook Resident NRC Inspector has been notified. There is no indication of primary to secondary leakage and there is no impact on Unit 1.Steam Generator
Reactor Protection System
05000316/LER-2015-001
ENS 5082213 February 2015 18:15:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification to Michigan OshaAt 1123 EST on 2/13/2015, an emergency medical report was received in both unit's Control Rooms that an individual was having a personal medical issue outside the protected area. Onsite Emergency Medical personnel were dispatched to the scene. Off-site medical assistance was immediately requested. CPR was administered and the individual was transferred by off-site medical ambulance service to a local hospital. The Operations Shift Manager received confirmation of a fatality at 1315 EST on 2/13/2015. Notification was made to the Michigan Occupational Safety and Health Administration (MIOSHA). Both Units remain at 100% power. This Event Notification is being made due to the fatality and notification to a government agency. The NRC Resident Inspector has been notified. The individual was at the workout facility when this incident occurred.
ENS 5069720 December 2014 17:12:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Oil Leak from Main Turbine Lube Oil System

At 1212 EST on December 12, 2014, D.C. Cook notified the State of Michigan and local authorities of an oil leak from the Unit 2 Main Turbine Lube Oil Cooler to Lake Michigan. Approximately 2000 gallons have leaked into Lake Michigan since October 25, 2014. No visible oil or oil sheen is present on Lake Michigan or the shore line. The leak is currently isolated as of 1030 EST on December 20, 2014. Leak repairs will be made to the cooler prior to placing back in service. The NRC Resident Inspector was notified. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies. Notified DOE, EPA, USDA, HHS, and FEMA.

  • * * UPDATE FROM PERRY GRAHAM TO HOWIE CROUCH AT 1432 EST ON 12/22/14 * * *

The licensee issued a press release about this event this afternoon. Notified R3DO (Dickson).

Main Turbine
ENS 505871 November 2014 06:48:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Dual Unit Manual Reactor Trips Due to Lowering Condenser Vacuum and Degraded Forebay

On November 1, 2014, at 0249 (EDT), DC Cook Unit 1 reactor was manually tripped and at 0248 (EDT) DC Cook Unit 2 was manually tripped due lowering condenser vacuum caused by degraded forebay conditions (observed thick grass and sand). U-1 and U-2 entered Abnormal Operating Procedure for Degraded Forebay on November 1, 2014 at 0153 (EDT). Conditions degraded in U-1 and U-2 until all but 2 screens in each unit were tripped on overload and main condenser vacuum was lowering. U-1 and U-2 met criteria in the Degraded Forebay procedure to remove the units from service and remove all circulating water pumps from service. 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 eight (8) hour report. The electrical grid is stable. Unit 1 and Unit 2 are being supplied by offsite power. All control rods fully inserted in both units. Decay heat is being removed by steam generator PORVs. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip with the exception of U-1 turbine driven auxiliary feed pump. DC Cook Unit 1 and Unit 2 remain stable in Mode 3 while conducting the post trip review. No radioactive release is in progress as a result of this event. Additional information received determined the Unit 1 turbine driven auxiliary feedwater pump tripped for unknown reasons. Feedwater flow to all steam generators was maintained by the U-1 east and west motor driven auxiliary feedwater pumps. U-2 reactor power was lowered from 100 percent to 50 percent over the hour prior to the trip in accordance with the Degraded Forebay Procedure. The DC Cook NRC Resident Inspector has been notified.

  • * * UPDATE PROVIDED BY RICHARD HARRIS TO JEFF ROTTON AT 0945 EDT ON 11/01/2014 * * *

At 0921 EDT, DC Cook issued a press release regarding the event described earlier. The licensee notified the NRC Resident Inspector. Notified R3DO (Lipa)

Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Condenser
ENS 5049828 September 2014 12:30:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Inadvertent Activation of an Emergency SirenOn 9/28/14 at approximately 0830 EDT, the Operations Shift Manager was made aware that the Berrien County Sheriff's 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 notified the NRC Resident Inspector.
ENS 5046216 September 2014 19:19:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notifications and Press Release Regarding Onsite FatalityAt approximately 1420 (EDT) on September 16, 2014, a worker collapsed in an office building inside the protected area. Initial response by on-site responders found the person unresponsive. Subsequent response by off-site medical responders determined the person had died. Licensee was notified of fatality at 1519 (EDT). The fatality was due to an apparent personal medical issue and not work related. The individual was not contaminated. The individual was transported off-site via Medic One, a local ambulance. The NRC Senior Resident Inspector was notified. Plant operation was not impacted by the event. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies. The Licensee plans to make a press release. The licensee also notified Michigan OSHA, and other local authorities.
ENS 5038621 August 2014 06:10:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Suspected Fuel Oil Leak to the Environment

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.

  • * * UPDATE FROM JAMES SHAW TO VINCE KLCO ON 8/22/14 AT 1342 EDT * * *

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).

Emergency Diesel Generator
ENS 5032029 July 2014 14:40:0010 CFR 26.719Fitness for Duty Policy ViolationA non-licensed employee contractor foreman had a confirmed positive test result for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. This notification is being made under 10 CFR 26.719 (b)(2)(ii), significant FFD policy violations or programmatic failures, as a twenty-four (24) hour report. The licensee has notified the NRC Resident Inspector.
ENS 5023830 June 2014 11:30:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessPlanned Maintenance on Technical Support Center Ventilation

At 0730 EDT on Monday, June 30, 2014, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) charcoal filtration system was removed from service for scheduled maintenance. Under certain accident conditions, the TSC may become unavailable due to the inability of the charcoal filtration system 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 and post maintenance testing is scheduled to be completed by 1500 EDT on Monday, June 30. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM JAMES SHAW TO VINCE KLCO AT 1327 EDT ON 6/30/14 * * *

The charcoal filtration system was restored to service at 1245 EDT on 6/30/2014. The licensee will notify the NRC Resident Inspector. Notified the R3DO (McCraw).

ENS 5022324 June 2014 15:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 1100 EDT on Tuesday, June 24, 2014 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 and post maintenance testing is scheduled to be completed by 16:00 EDT on Tuesday, June 24. The licensee has notified the NRC 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.

  • * *UPDATE PROVIDED BY KURT BERAN TO JEFF ROTTON AT 1617 EDT ON 06/24/2014 * * *

At 1615 EDT, TSC ventilation systems were restored to service. The licensee will be notifying the NRC Resident Inspector. Notified R3DO (Lara)

ENS 5018811 June 2014 03:27:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to an Inadvertent Activation of an Emergency SirenOn 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 5014925 May 2014 13:42:0010 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Ventilation Boundary Door Inoperable

At 0942 on May 25, 2014, the Cook Nuclear Plant (CNP) declared both Control Room Emergency Ventilation trains inoperable in accordance with LCO 3.7.10 due to an inoperable Control Room Envelope when a control room boundary door was identified as not latching correctly during a security door check. The latch would not have been able to maintain the door closed during an event resulting in Control Room Pressurization. At this time, Security established a continuous door post and would have been able to maintain the door closed. At 1602 on May 25, 2014, repairs to the control room boundary door latch were completed restoring the Control Room Envelope to Operable. The licensee has notified the NRC Senior Resident Inspector. This notification should have been made within 8 hours of the event in accordance with 10 CFR 50.72 (b)(3)(v)(D) per guidance in section 3.2.7 of NUREG-1022 - Event or Condition that Could Have Prevented Fulfilment of a Safety Function, but was not recognized at that time.

  • * * RETRACTION FROM PERRY GRAHAM TO JOHN SHOEMAKER AT 1443 EDT ON 6/20/14 * * *

The purpose of this report is to retract EN #50149 (May 25, 2014). On June 19, 2014, Cook Nuclear Plant concluded that the EN could be retracted based on the completion of a Maintenance Rule Evaluation (MRE) performed by Systems Engineering. By design, the Control Room Envelope (CRE) pressure boundary is required to be maintained at a positive pressure during all modes of operation and during any irradiated fuel movement. New information contained in the MRE concluded the CRE function was not lost as the control room boundary door remained closed without manual assistance during normal operations. The amount of make-up air during normal operation is similar to the design flow for accident mode (approx. 800 cfm). It was concluded that the sealing integrity was not lost, thus the CRE function was maintained. The CRE would have remained operable and LCO 3.7.10 would not have been entered for the identified condition. The licensee has notified the NRC Senior Resident Inspector. Notified the R3DO (Valos).

Control Room Emergency Ventilation
ENS 5002210 April 2014 09:55:0010 CFR 26.719Fitness for Duty Report Involving a Licensed Employee

A licensed employee violated the site Fitness-for-Duty (FFD) policy. The affected individual will be evaluated under for-cause FFD testing. The employee's plant access has been suspended. The NRC Resident Inspector has been informed.

  • * * UPDATE AT 0100 EDT ON 04/25/14 FROM BUD HINCKLEY TO S. SANDIN * * *

The licensee provided additional clarifying information. The NRC Resident Inspector will be informed. Notified R3DO (Cameron).

ENS 498037 February 2014 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailabiliity of Tsc Ventilation System Due to Scheduled Maintenance

At 03:00 EST on Friday, February 7, 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 and post maintenance testing is scheduled to be completed by 16:00 EST on Friday, February 7. The licensee has notified the NRC 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.

  • * * UPDATE PROVIDED BY BRAD LEWIS TO JEFF ROTTON AT 1605 ON 02/07/2014 * * *

TSC ventilation system was returned to service following successful maintenance and post maintenance testing at 14:30 EST on Friday, February 7, 2014. The licensee has notified the NRC Resident Inspector." Notified R3DO (Orlikowski)

ENS 496871 January 2014 16:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTsc Ventilation System Non-Functional

At 11:00 EST on Wednesday, January 1, 2014, during a scheduled functional test of the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system, the following two dampers failed to properly open when the system was placed in emergency mode (ventilation flow directed through the emergency filtration unit): 12-HV-TSC-SD-5, TSC Ventilation Emergency Flow To & From Air Conditioner 12-HV-TSC-AC-1 Volume Damper 12-HV-TSC-SD-7, TSC Ventilation Emergency Filtration Unit 12-HV-TSC-FIL Inlet Volume Damper The TSC ventilation system is therefore non-functional. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to an emergency response facility being non-functional. Repair activities are in progress for repair of the two dampers. 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. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM DAN KURTH TO CHARLES TEAL AT 0220 EST ON 1/2/14 * * *
After repairs were completed, the TSC was restored to service at 0130 EST on 1/2/14.

The licensee has notified the NRC Resident Inspector.

ENS 4968231 December 2013 15:50:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 1050 EST on Tuesday, December 31, 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 accidents 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 and post maintenance testing is scheduled to be completed by 1600 EST on December 31, 2013. The licensee has notified the NRC 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.

  • * * UPDATE ON 12/31/13 AT 1731 EST FROM BUD HINCKLEY TO DONG PARK * * *

The TSC ventilation system maintenance and testing was completed satisfactorily and the system was restored to service at 1730 EST on 12/31/13. The licensee will notify the NRC Resident Inspector. Notified R3DO (Kunowski)

ENS 4956321 November 2013 01:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessLoss of Emergency Preparedness Capabilities Due to Unit 2 Plant Process Computer Replacement

The Unit 2 DC Cook Nuclear Plant (CNP) Plant Process Computer (PPC) will be removed from service on Wednesday, November 20, 2013 at 2000 (EST) to support planned replacement. The Unit 2 PPC, including the Emergency Response Data System (ERDS), will be unavailable to the NRC Operations Center. Planned replacement also affects the Safety Parameter Display System (SPDS), the Real Time Data Repository (RDR), and PPC data to emergency response facilities at CNP. Safety system annunciators and indications in the control room remain available. The scheduled replacement, returning of equipment to service and post maintenance testing is expected to be completed by 1400 on Sunday, December 22, 2013. Compensatory measures exist within the DC Cook emergency response procedures 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 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).

  • * * UPDATE FROM DAN KURTH TO DONALD NORWOOD AT 1535 EST ON 12/21/2013 * * *

The Unit 2 DC Cook Nuclear Plant (CNP) Plant Process Computer (PPC) has been restored to service as of Saturday, December 21, 2013 at 1046 EST. The Unit 2 PPC, including the Emergency Response Data System (ERDS), Safety Parameter Display System (SPDS), Real Time Data Repository (RDR), and PPC data to the Emergency Response Facilities at CNP have been restored to normal operation. No further compensatory actions required. The licensee has notified the NRC Resident Inspector. Notified R3DO (Riemer).

Emergency Response Data System
Safety Parameter Display System
ENS 4936420 September 2013 02:30:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to an Inadvertent Activation of an Emergency SirenOn 9/19/13 at approximately 2230 EDT, Emergency Siren 602 inadvertently actuated. Berrien County Dispatch was notified by local residents at 2237 EDT. The cause of the actuation is under investigation but believed to be due to rain water intrusion. The siren was subsequently disconnected by a station technician to prevent further erroneous actuation. The siren remains out of service and is the only siren out of service within the 10 mile Emergency Planning Zone (EPZ). There are a total of 70 sirens. This notification is being made under 10 CFR 50.72(b)(2)(xi), Offsite Notification, as a four (4) hour report. The Operations Shift Manager was notified of the actuation on 9/20/13 at 0340 EDT. The licensee has notified the NRC Resident Inspector.
ENS 4928919 August 2013 13:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessLoss of Emergency Preparedness Capabilities Due to Unit 1 Ppc Replacement

The Unit 1 DC Cook Nuclear Plant (CNP) Plant Process Computer (PPC) will be removed from service on Monday, August 19, 2013 at 0900 EDT to support planned replacement. The Unit 1 PPC, including the Emergency Response Data System (ERDS), will be unavailable to the NRC Operations Center. Planned replacement also affects the Safety Parameter Display System (SPDS), the Real Time Data Repository (RDR), and PPC data to Emergency Response Facilities at CNP. Safety system annunciators and indications in the control room remain available. The scheduled replacement, returning of equipment to service and post maintenance testing is expected to be completed by 2000 EDT on Saturday, September 7, 2013. Compensatory measures exist within the DC Cook emergency response procedures 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 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).

  • * * UPDATE AT 1228 EDT ON 10/15/13 FROM BOWMAN TO HUFFMAN * * *

The Unit 1 DC Cook Nuclear Plant (CNP) Plant Process Computer (PPC) was restored to service on Tuesday, October 1, 2013 at 1649 EDT following the planned replacement of the PPC. The Unit 1 PPC is fully functional, including the Emergency Response Data System (ERDS), which is available to the NRC Operations Center. This also restores the Safety Parameter Display System (SPDS), the Real Time Data Repository (RDR), and PPC data to Emergency Response Facilities at CNP. The licensee has notified the NRC Resident Inspector. R3DO (Duncan) notified.

Emergency Response Data System
Safety Parameter Display System
ENS 4922028 July 2013 14:18:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Following Secondary Plant Transient

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.

  • * * UPDATE FROM DEAN BRUCK TO DONALD NORWOOD AT 1753 EDT ON 7/29/13 * * *

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).

Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Condenser
05000316/LER-2013-001
ENS 4919115 July 2013 13:34:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnplanned Loss of Communications Due to Offsite Fiber Optic Cable Damage

At approximately 0934 EDT on Monday, July 15, 2013, the Cook Nuclear Plant (CNP) experienced a loss of capability to transmit Emergency Response Data System (ERDS) information to the Nuclear Regulatory Commission (NRC). Emergency Plan Implementing Procedures provide direction to manually record ERDS data for transmission to the NRC via telephone or fax. Concurrent with the loss of ERDS was a loss of the NRC 'Red Phone' (FTS-2000). The suspected cause of the loss was a damaged fiber optic cable located offsite in Bridgman, Michigan unrelated to CNP. This caused the failure of the internet service provider to CNP. Communications via alternate phone lines and corporate service number remain available and have been tested. CNP has contacted offsite service providers for restoration of service. The estimated time for return to service is 2000 EDT on Monday, July 15, 2013. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of communications capability which includes events that would significantly impair the ability of the licensee to implement the functions of its emergency plans if an emergency were to occur. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE ON 7/15/13 AT 2114 EDT FROM KELLY BAKER TO DONG PARK * * *

At 2050 EDT on Monday, July 15, 2013, DC Cook Operations Department was notified by Information Technology (IT) that the offsite fiber optic cable that was damaged had been repaired. Affected equipment was verified to be working properly, specifically, Emergency Response Data System (ERDS) data is transmitting and the NRC 'Red Phone' is functional. Communication capability has been restored. The licensee has notified the Senior NRC Resident Inspector." Notified R3DO (Hills).

Emergency Response Data System
ENS 491703 July 2013 05:15:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Technical Support Center Ventilation System Due to Scheduled Maintenance

At 0115 EDT on Wednesday, July 3, 2013, 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 and post maintenance testing is scheduled to be completed by 2100 EDT on July 3, 2013. The licensee has notified the NRC 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 CHRIS PEAK TO JOHN SHOEMAKER ON 7/3/13 AT 1540 EDT * * *

The TSC ventilation system maintenance and testing was completed satisfactorily and the system was restored to service at 1430 EDT on 7/3/13. The licensee has notified the NRC Resident Inspector. Notified R3DO (Kunowski)

ENS 4898029 April 2013 13:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTsc Ventilation System Out of Service for Scheduled Maintenance

At 0900 EDT on Monday, April 29, 2013, 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 and post maintenance testing is scheduled to be completed by 1200 EDT on Thursday, May 2, 2013. The licensee has notified the NRC 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.

  • * * UPDATE FROM GREG KANDA TO HOWIE CROUCH ON 5/2/13 AT 1448 EDT * * *

Due to scheduling issues, the restoration of the Technical Support Center (TSC) air conditioning and charcoal filtration systems has been delayed. The TSC ventilation systems are expected to be returned to service by 0000 EDT on Friday, May 3, 2013. The licensee has notified the NRC Resident Inspector. Notified R3DO (Duncan).

  • * * UPDATE FROM DEAN BRUCK TO CHARLES TEAL ON 5/3/13 AT 0515 EDT * * *

The restoration of the Technical Support Center (TSC) air conditioning and charcoal filtration systems has been delayed but is in progress. The TSC ventilation systems are expected to be returned to service by 0600 EDT on Friday, May 3 2013. The licensee will notify the NRC Resident Inspector. Notified R3DO (Duncan).

  • * * UPDATE FROM GREG KANDA TO VINCE KLCO AT 0822 EDT ON MAY 3, 2013 * * *

The Technical Support Center (TSC) air conditioning and charcoal filtration systems were restored at 0818 EDT. The TSC is fully functional. The NRC Resident Inspector has been notified. Notified the R3DO (Duncan).

ENS 4896424 April 2013 18:11:0010 CFR 50.72(b)(3)(iv)(A), System ActuationValid Actuation of an Emergency Diesel Generator Due to a Loss of Train a Reserve Feed to the SiteOn 4/24/13 at 1411 EDT, a fault occurred on the Unit 1 101 CD Reserve Auxiliary Transformer causing the 12 CD 34kV Reserve Feed Breaker to open resulting in a loss of Train A Reserve Feed to Unit 1 and Unit 2. The cause of the fault is still under investigation. Unit 2 remains stable in 100% power. Unit 2 entered LCO 3.8.1, AC Source - Operating, Condition A, one required offsite circuit inoperable Restore Unit 2 reserve feed to operable status within 72 hours. Unit 1 is currently in a refueling outage and offline. Unit 1 CD Emergency Diesel Generator (EDG) automatically started and loaded as expected. North Spent Fuel Pit Cooling Train lost power due to a load shed, which resulted in a 2 degree Fahrenheit rise in the Spent Fuel Pool Temperature. The North Spent Fuel Pit Cooling Pump was restarted on 1 CD EDG at 1447 EDT. South Spent Fuel Pool Cooling Train remained in-service the entire time. The licensee has notified the NRC Resident Inspector.Emergency Diesel Generator05000315/LER-2013-002
ENS 4894519 April 2013 03:12:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseInadvertent Activation of an Emergency SirenOn 4/18/13 at 2312 EDT, Emergency Siren 955 inadvertently actuated for approximately 5 minutes. The cause of the actuation is under investigation but believed to be due to rain water intrusion. The siren stopped on its own, and was subsequently disconnected by the siren vendor to prevent further erroneous actuation. The siren remains out service and is the only siren out of service within the 10 mile Emergency Planning Zone (EPZ). There are a total of 70 sirens. The siren is located in a state park not currently inhabited by campers; due to the siren location and time of activation the impact on the surrounding population was minimal. The event was therefore determined to not be reportable. A subsequent review of the event, considering communications made between Cook Nuclear Plant and the Berrien County 911 Dispatch Center, as well as recent industry operating experience of similar events, was performed; its conclusion was to conservatively make a report under 10 CFR 50.72(b)(2)(xi). The licensee has notified the NRC Resident Inspector.
ENS 4892214 April 2013 18:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 1400 EDT on Sunday, April 14, 2013, 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 and post maintenance testing is scheduled to be completed by 1400 EDT on Wednesday, April 17, 2013. The licensee has notified the NRC 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.

  • * * UPDATE FROM GREGORY KANDA TO CHARLES TEAL AT 1456 EDT ON 4/17/13 * * *

The Technical Support Center (TSC) air conditioning and filtration systems have been returned to service following maintenance. The TSC is fully functional. The NRC Resident Inspector has been notified. Notified R3DO (Orth).

ENS 4886831 March 2013 08:14:0010 CFR 50.72(b)(3)(ii)(A), Seriously DegradedRcs Flow Instrument Line Through Wall Weld DefectOn 3/31/13 at 0414 EDT, dye penetrant testing identified a 10mm long relevant linear indication on a 3/4 inch RCS flow instrument line weld, between the RCS loop piping and the instrument isolation valve. This constitutes a weld defect in the primary coolant system that cannot be found acceptable per ASME Section XI. This section of piping is unisolable from the Reactor Coolant System. There is no evidence of active leakage currently or during the previous operating cycle, however, based on the dye penetrant testing this is considered a through wall leak. This event notification is being made in accordance with 10CFR50.72(b)(3)(ii)(A), as a condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded. Unit 1 is currently in a scheduled refueling outage in Mode 5 making preparations to transition to Mode 6. The plant is evaluating the appropriate repair method for this condition. The condition will be corrected during the current refueling outage. Unit 2 is in Mode 1 at 100% power and is unaffected by this condition. The NRC Resident Inspector has been notified.Reactor Coolant System05000315/LER-2013-001
ENS 4874712 February 2013 20:30:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseNotification of Offsite Agencies Due to Discovery of Potential Human Remains

At 1530 EST on February 12, 2013, bones were discovered in the debris removal baskets in the Screen House at the Cook Nuclear Plant. These bones have the potential to be human remains. Local law enforcement agencies have been notified and the remains were removed by law enforcement personnel. The NRC Senior Resident Inspector was notified. Plant operations was not impacted by the event. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies and potential for media involvement related to the discovery.

  • * * UPDATE FROM GREG KANDA TO CHARLES TEAL ON 2/15/13 AT 1045 EST * * *

After analysis by the Berrien County Sheriff's Department, it was determined that the bones discovered in the debris removal baskets in the screenhouse at the Cook Nuclear Plant on February 12, 2013 at 1530 EST were not of human origin, but most likely from a deer or other animal. The licensee has notified the NRC Resident Inspector. Notified the R3DO (Pelke).

ENS 487317 February 2013 22:35:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Related to Death of Contractor OnsiteAt 1620 EST on 2/7/2013 an emergency medical report was received in Unit 1 Control Room that an individual was reported to have collapsed and was lying unconscious outside of the protected area. Fire protection and Emergency Medical personnel were dispatched to the scene. The individual was unresponsive, without a pulse and not breathing. Off-site medical assistance was immediately requested. CPR was commenced and continued until transfer of the individual to off-site medical ambulance service Medic 1. An Automatic External Defibrillator (AED) was used once, as allowed by the AED. Confirmation of the fatality was received at 1735 EST on 2/7/2013. The individual was pronounced dead at 1712 EST on 2/7/2013. Both Units remain at 100% power. This Event notification is being made due to the onsite fatality. The NRC Resident Inspector has been notified.
ENS 486453 January 2013 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0300 EST on Thursday, January 3, 2013, the DC 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 and post maintenance testing is scheduled to be completed by 2200 EST on January 3, 2013. The licensee has notified the NRC 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.

  • * * UPDATE FROM GREGORY KANDA TO S. SANDIN ON 1/3/13 AT 2202 EST * * *

The TSC ventilation system maintenance and testing was completed satisfactorily and the system was restored to service at 2115 EST on 1/3/13. The licensee has notified the NRC Resident Inspector. Notified R3DO (Skokowski).

ENS 4850413 November 2012 14:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessPartial Loss of Emergency Assessment During Planned Modifications

Cook Nuclear Power Plant will begin a cyber security modification of Unit 1 and Unit 2 Plant Process Computers (PPCs) and associated network infrastructure on Tuesday, November 13, 2012 at 0900 EST. This includes the Emergency Response Data System (ERDS) communication with the NRC Operations Center. The entire PPC for each unit will be out of service and unavailable for approximately 6 hours. During that time, the PPC satellite display systems in the Control Rooms, TSC and EOF will be unavailable. After approximately 9 hours, the ERDS will be restored to service along with the satellite display systems in the Control Rooms, TSC and EOF. Compensatory measures exist within the DC Cook Emergency Response procedures to provide plant data in the event of an actual Emergency to the NRC Operations Center until the ERDS can be returned to service. Unavailability of the ERDS and Control Room, TSC and EOF data is being reported in accordance with 10 CFR 50.72(b)(3)(xiii) as a major loss of emergency assessment capability. The NRC Resident Inspector has been notified. A follow-up ENS communication will be made when both units ERDS are fully restored to service. Unit 1 and Unit 2 PPC availability is expected to be restored on Tuesday, November 13, 2012 at 1500 EST. ERDS communication with the NRC Operations Center is expected to be restored on November 13, 2012 at 1800 EST.

  • * * UPDATE FROM BRADDOCK LEWIS TO HOWIE CROUCH @ 1559 EST ON 11/13/12 * * *

The licensee notified the Operations Center that the PPC work was delayed and, as a consequence, ERDS restoration will be delayed. Work on the PPC continues. The licensee has notified the NRC Resident Inspector. Notified R3DO (Giessner) and ERDS Group (via email).

  • * * UPDATE AT 1908 EST ON 11/13/12 FROM GREG KANDA TO MARK ABRAMOVITZ * * *

ERDS was declared operable at 1815 EST. The licensee notified the NRC Resident Inspector. Notified R3DO (Giessner) and ERDS Group (via email).

Emergency Response Data System
ENS 4812019 July 2012 19:30:0010 CFR 50.72(b)(2)(i), Tech Spec Required ShutdownTech Spec Required Shutdown Due to Inability to Restore Main Steam Isolation Automatic Actuation Logic and Actuation Relays within the Required TimeAt 1530 on July 19, 2012, operators commenced shutdown of DC Cook Unit 1 to comply with LCO 3.3.2, Condition I when the 6 hour time limit to complete Condition C Required Action could not be completed. At 0734 on July 19, 2012, operators identified that power had been lost to two of four Steam Generator Stop Valve Dump Valves (Dump Valves) on one of the two trains. DC Cook entered LCO 3.3.2 Condition B for Function 4a, manual initiation: 'restore required channel or train to operable within 48 hours.' DC Cook also entered LCO 3.3.2 Condition C for Function 4b, automatic actuation logic and actuation relays: 'restore required channel or train to operable within 6 hours.' Power was restored to one Dump Valve which was then declared operable at 1030. Efforts continue to restore power to the remaining Dump Valve. Enforcement Discretion was verbally granted by the Nuclear Regulatory Commission at 1736 on July 19, 2012 to begin at 1934 and end at 1934 on July 20, 2012. Upon receiving the Enforcement Discretion, the power reduction was stopped at 1738 at 50% power. This event is reportable under 10CFR50.72(b)(2)(i), 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications,' as a four (4) hour report. The DC Cook Sr. Resident NRC Inspector has been notified.Steam Generator
ENS 480602 July 2012 06:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 02:00 EDT on Monday, July 2, 2012, 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 and post maintenance testing is scheduled to be completed by 15:00 EDT on Monday, July 2, 2012. The licensee has notified the NRC 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.

  • * * UPDATE FROM BEN HUFFMAN TO DONG PARK AT 1727 EDT ON 7/2/12 * * *

The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1725 EDT on 7/2/12. The licensee will notify the NRC Resident Inspector.

Notified R3DO (Daley).

ENS 478811 May 2012 03:28:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip Due to Main Turbine TripOn 30 April, 2012, at 2328 (EDT), DC Cook Unit 2 Reactor automatically tripped due to a trip of the main turbine. The cause of the main turbine trip is still under investigation. 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 Generator PORVs to atmosphere. 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 releases were experienced as a result of this event. 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 eight (8) hour report. The DC Cook Resident NRC Inspector has been notified. The licensee stated that the trip was uncomplicated and the reactor is stable in mode 3 at no load temperature and pressure. The unit is on steam generator atmospheric relief valves because the secondary steam load on the plant was causing too much of a cool down. There is no primary to secondary steam generator leakage for the unit. The trip had no impact on Unit 1 which continues to operate at full power.Steam Generator
Reactor Protection System
Auxiliary Feedwater
Main Turbine
ENS 4786426 April 2012 02:46:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseNotification to Offsite Agencies Due to Oil SpillAt 2246 EDT on April 25, 2012, D.C. Cook notified the State of Michigan and local authorities of an oil spill from the Unit 2 (Main Generator) Seal Oil system at 2110 EDT which resulted in a portion of this oil entering the absorption pond, which is in the owner controlled area. An oil sheen is present on the absorption pond which has a surface area of approximately 2 acres (87,000 square feet) and it is estimated that five to ten gallons of oil are on the absorption pond. The NRC Resident Inspector was notified. The licensee has contained the oil leak and clean up efforts are ongoing.
ENS 478013 April 2012 12:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnit 2 Plant Process Computer Out-Of-Service for Planned Maintenance

The Unit 2 DC Cook Nuclear Plant (CNP) Plant Process Computer (PPC) will be removed from service on Tuesday, April 3, 2012 at 0800 EDT to support scheduled maintenance. This will cause the entire Unit 2 PPC, including the ERDS (Emergency Response Data System) to be unavailable to the NRC Operations Center. The planned maintenance also affects the Safety Parameter Display System (SPDS), the Real Time Data Repository (RDR), and PPC data to Emergency Response Facilities at CNP. The scheduled maintenance, returning of equipment to service, and post maintenance testing is expected to be completed by 0000 EDT on Wednesday, April 4, 2012. Compensatory measures exist within the DC Cook Emergency Response procedures 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, offsite communications capability (e.g. significant portion of control room indication, Emergency Notification System, or offsite notification system).

  • * * UPDATE FROM BRAD LEWIS TO CHARLES TEAL ON 4/3/12 AT 1536 EDT * * *

At time 1500 EDT, the Plant Process Computer and ERDS system has been restored to service. The licensee has notified the NRC Resident Inspector. Notified R3DO (Dickson).

Safety Parameter Display System
ENS 477941 April 2012 08:26:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0445 EDT on Sunday, April 1, 2012, 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 and post maintenance testing is scheduled to be completed by 1900 EDT on Sunday, April 1, 2012. The licensee has notified the NRC 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.

* * * UPDATE FROM DEAN BRUCK TO PETE SNYDER ON 4/1/12 AT 1633 EDT * * * 

The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1620 EDT on 4/1/12. The licensee will notify the NRC Resident Inspector. Notified R3DO (Dickson).

ENS 475663 January 2012 09:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Technical Support Center Ventilation Due to Scheduled Maintenance

At 0400 EST on Tuesday, January 3, 2012, 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 1500 EST on Tuesday, January 3, 2012. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM BEN HUFFMAN TO DONALD NORWOOD AT 1645 EST ON 1/3/12 * * *

The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1644 EST on 1/3/12. The licensee notified the NRC Resident Inspector. Notified R3DO (Valos).

  • * * UPDATE AT 0546 EST ON 1/4/12 FROM ESSIG TO HUFFMAN * * *

UNAVAILABILITY OF TSC VENTILATION SYSTEM DUE TO DAMPER FAILURE This is an update to EN #47566. At 2300 EST on Tuesday, January 3, 2012, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration system volume damper 12-HV-TSC-SD-6, TSC Ventilation Normal Flow to and from Air Conditioner HV-TSC-AC-1 Volume Damper, did not reposition during surveillance 12-OHP-5030-028-007 TSC Ventilation Filtration System Functional Test. When the damper position was checked, damper remained open with system in Emergency mode. Per 12-OHP-5030-028-007, if any damper fails to reposition, the ventilation unit is considered non-functional. 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 had previously been performed to clean, inspect, and lubricate linkages associated with this damper on 1-3-2012. That work was completed at approximately 1700 EST on 1-3-2012. Following discovery, maintenance was contacted and discovered the linkage was loose for 12-HV-TSC-SD-6. Maintenance adjusted the linkage and damper was retested satisfactory at 0311 EST on 1-4-2012. TSC functionality has been restored. The licensee has notified the NRC 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. R3DO (Valos) notified.

ENS 4747725 November 2011 10:23:0010 CFR 50.72(b)(3)(iv)(A), System ActuationAux Feedwater Pump Start After Main Feedwater Pump TripAt 0522 EST on November 25, 2011, operators manually started all Auxiliary Feedwater (AFW) pumps in response to a manual trip of the Unit 1 East Main Feedwater Pump due to bearing failure. Operators were responding to increasing vibrations on the East Main Feedwater Pump and reducing turbine load when the East Main Feedwater Pump was manually tripped (at approximately 90% power) due to high vibrations. Operators entered the abnormal operating procedure for Loss of One Main Feedwater Pump, which directs starting all three AFW pumps. Plant power was stabilized at approximately 58%. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10CFR50.72(b)(3)(iv)(A) due to the valid actuation of the AFW system in response to equipment failure.Feedwater
Auxiliary Feedwater
05000315/LER-2011-002
ENS 473174 October 2011 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0400 EDT on Tuesday, October 4, 2011, 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 1500 EDT on Tuesday, October 4, 2011. The licensee has notified the NRC 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.

  • * * UPDATE FROM BUD HINCKLEY TO JOE O'HARA ON 10/04/11 AT 1443 * * *

The TSC ventilation system maintenance began at 0504 EDT on 10/04/11 and the system was restored to service at 1430 EDT on 10/04/11. The NRC Resident Inspector has been notified. Notified R3DO(Phillips)

ENS 472477 September 2011 12:54:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip Following Main Turbine Trip from 100% PowerOn Sept 7, 2011, at 0854, DC Cook Unit 1 reactor automatically tripped due to a trip of the main turbine. The cause of the main turbine trip 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 eight (8) hour report. The DC Cook Sr. Resident NRC Inspector has been notified. The electrical grid is stable and Unit 1 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 1 remains stable in Mode 3 while conducting the post trip review.Reactor Protection System
Auxiliary Feedwater
Main Turbine
Main Condenser
05000315/LER-2011-001
ENS 4719423 August 2011 18:24:0010 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.

  • * * UPDATE FROM SCOTT BURNS TO HOWIE CROUCH AT 1543 EDT ON 8/23/11 * * *

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.

  • * * UPDATE FROM SCOTT BURNS TO ERIC SIMPSON AT 1859 EDT ON 8/23/11 * * *

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 4704011 July 2011 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0400 EDT on Monday, July 11, 2011, 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 2000 EDT on Monday, July 11, 2011. The licensee has notified the NRC 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.

  • * * UPDATE FROM DAN KURTH TO JOE O'HARA AT 2151 ON 7/11/11 * * *

TSC ventilation system maintenance was completed satisfactorily and the system restored to service at 1800 EDT on 7/11/11. The NRC Resident Inspector will be notified. Notified R3DO(Bloomer)

ENS 470256 July 2011 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0400 EDT on Wednesday, July 6, 2011, 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 1600 EDT on Wednesday, July 6, 2011. The licensee has notified the NRC 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.

* * * UPDATE FROM DEAN BRUCK TO PETE SNYDER ON 7/7/11 AT 1056 EDT * * * 

The TSC ventilation system maintenance was completed satisfactorily and the system restored to service at 1500 EDT on 7/6/11. The licensee notified the NRC Resident Inspector.

ENS 467316 April 2011 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center Ventilation System Out of Service Due to Planned Maintenance

At 0400 EDT on Wednesday, April 6, 2011, 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 1600 EDT on Wednesday, April 6, 2011. The licensee has notified the NRC 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 DONG PARK ON 4/6/11 AT 1514 EDT * * *

The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1455 EDT. Notified R3DO (Daley).

ENS 465204 January 2011 13:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0800 EST on Tuesday, January 4, 2011, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems were 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 1600 EST on Tuesday, January 4, 2011. The licensee has notified the NRC 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,

  • * * UPDATE FROM BUD HINCKLEY TO DONALD NORWOOD AT 1709 EST ON 01/04/2011 * * *

The TSC ventilation system maintenance was completed satisfactorily and the system was restored to service at 1705 EST. The licensee will notify the NRC Resident Inspector. Notified the R3DO (Lipa) via e-mail.

ENS 4647714 December 2010 02:19:0010 CFR 50.72(b)(3)(iv)(A), System ActuationManual Actuation of Auxiliary Feedwater System in Response to Loss of One Main Feedwater PumpAt 2119 EST on December 13, 2010, operators manually started all Auxiliary Feedwater (AFW) pumps in response to a loss of the Unit 1 East Main Feedwater Pump. Operators were responding to decreasing condenser vacuum on the East Main Feedwater Pump and reducing turbine load when the East Main Feedwater Pump was manually tripped at approximately 21 inches of vacuum Hg. Operators entered the abnormal operating procedure for Loss of One Main Feedwater Pump, which directs starting all three AFW pumps. Plant power was stabilized at approximately 49%. The licensee will be notifying the NRC Senior Resident Inspector. This notification is being made in accordance with 10CFR50.72(b)(3)(iv)(A) due to the valid actuation of the AFW system in response to equipment failure. No maintenance was in progress, and the cause of the decreasing condenser vacuum in the MFP was due to debris in the traveling water screen.Feedwater
Auxiliary Feedwater
05000315/LER-2010-003
ENS 4633918 October 2010 14:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Emergency Response Data System (Erds) for Scheduled Maintenance

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.

  • * * UPDATE FROM DEAN BRUCK TO JOE O'HARA AT 1518 EDT ON 10/18/10 * * *

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).

Emergency Response Data System
Safety Parameter Display System
ENS 463106 October 2010 11:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

At 0700 on Wednesday, October 6, 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 1600 on Wednesday, October 6, 2010. The licensee has notified the NRC 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.

  • * * UPDATE AT 1738 ON 10/6/2010 FROM BRADDOCK LEWIS TO BILL HUFFMAN * * *

TSC ventilation was returned to service at 1645 EDT. The licensee notified the NRC Resident Inspector. Notified the R3DO (Passehl).

ENS 463116 October 2010 04:08:0010 CFR 50.72(b)(3)(iv)(A), System ActuationValid Actuation of Auxiliary Feedwater System in Response to Valid Steam Generator Low-Low Level SignalsAt 0008 on Wednesday, October 6, 2010, Cook Nuclear Plant (CNP) Unit 2 had a Valid Automatic Actuation of the Unit 2 Turbine Driven Auxiliary Feedwater Pump. Cook Nuclear Plant Unit 2 Reactor had been manually tripped at 0001 from 14% power per normal operating procedures in preparation for the Unit 2 refueling outage. Following the reactor trip, water level in steam generators 23 and 24 lowered to 21% causing an automatic start of the Unit 2 Turbine Driven Auxiliary Feedwater Pump. Manual operator actions were in progress to restore steam generator water levels at the time of the actuation. The Turbine Driven Auxiliary Feedwater Pump operated normally to provide auxiliary feedwater flow to all four Unit 2 steam generators, and steam generator levels were restored to normal post trip values. Prior to the trip of Unit 2 reactor, the Unit 2 East and West Motor Driven Auxiliary Feedwater Pumps were manually started per procedure, as part of the pre-planned reactor trip, to control steam generator water levels. The cause of the low steam generator levels is still under investigation. The licensee has notified the NRC Resident Inspector.Steam Generator
Auxiliary Feedwater
05000316/LER-2010-001
ENS 462348 September 2010 11:47:0010 CFR 50.72(b)(2)(xi), Notification to Government Agency or News ReleaseOffsite Notification Due to Body Discovered in the Owner Controlled AreaAt 0747 hours on September 8, 2010, a body was discovered on the beach along the Owner Controlled Area at the Cook Nuclear Plant. Local law enforcement agencies have been notified. It is expected that a press release will be issued from local law enforcement. The NRC Senior Resident Inspector was notified. Plant operation was not impacted by the event. The fatality did not occur on site. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) due to notification of offsite agencies and expected media involvement related to the discovery. Although unconfirmed, the licensee believes that the body belongs to a person that went missing on the lake last week. The licensee notified Lake Township, Berrien County Sheriffs Office, Federal Bureau of Investigation and the U.S. Coast Guard. Either Berrien County or Lake Township will be issuing a press release.
ENS 4608913 July 2010 12:10:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System Due to Scheduled Maintenance

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 4603723 June 2010 18:28:0010 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.

  • * * UPDATE AT 1645 EDT ON 06/23/10 FROM JAMES SHAW TO S. SANDIN * * *

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).

  • * * UPDATE AT 2017 EDT ON 6/23/2010 FROM TIMOTHY WICE TO MARK ABRAMOVITZ * * *

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 458932 May 2010 12:58:0010 CFR 50.72(b)(3)(iv)(A), System ActuationManual Actuation of Auxiliary Feedwater System in Response to Loss of One Main Feedwater PumpAt 0858 (EDT) on Sunday, May 2, 2010, operators manually started all Auxiliary Feedwater (AFW) pumps in response to a loss of the East Main Feedwater Pump (EMFP). Operators were responding to high bearing temperatures on the EMFP, and had entered the Rapid Power Reduction Procedure, when they received EMFP Hi and Hi-Hi vibration alarms and reports of oil leaking from the EMFP. Operators entered the procedure for Loss of One Main Feed Pump, which directs starting the AFW pumps, and removed the EMFP from service. The plant was stabilized at approximately 49% power. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10CFR50.72(b)(3)(iv)(A) due to the valid actuation of the AFW system in response to equipment failure.Feedwater
Auxiliary Feedwater
05000315/LER-2010-002
ENS 4583112 April 2010 08:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessScheduled Maintenance on the Technical Support Center Ventilation System

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.

  • * * UPDATE FROM SCOTT SCHNEIDER TO CHARLES TEAL AT 1545 EDT ON 4/12/2010 * * *

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 4569815 February 2010 14:30:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Emergency Response Data System (Erds) Due to Plant Process Computer (Ppc) Scheduled Maintenance

At 0930 on Monday, February 15, 2010, the Cook Nuclear Plant (CNP) Unit 2 Plant Process Computer will be removed from service for scheduled maintenance for data backup and preventative maintenance which will take ERDS out of service to the NRC Operations Center. The scheduled maintenance will affect the Safety Parameter Display System (SPDS) and the Real Time Data Repository (RDR), 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 notified the NRC Resident Inspector 2/15/2010 at 8:45 a.m. This notification is being made in accordance with NUREG 1022 Revision 2 for CFR 50.72 (b)(3)(xiii) due 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). The unit is expected to be maintained at 100% during the maintenance evolution. PPC trending and indication and rod position monitor will be out of service (OOS) while the PPC is OOS.

  • * * UPDATE FROM BRAD LEWIS TO DONALD NORWOOD AT 1205 EST ON 2/15/2010 * * *

The DC Cook U-2 Plant Process Computer was returned to service and a fully operable and available status at 1144 EST on 2/15/2010. The licensee notified the NRC Resident Inspector. Notified R3DO (Peterson) via E-mail.

Emergency Response Data System
Safety Parameter Display System
ENS 4565325 January 2010 14:30:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessEmergency Response Data System Unavailable Due to Plant Process Computer Maintenance

At 0930 on Monday, January 25, 2010, the Cook Nuclear Plant (CNP) Unit 1 Plant Process Computer (PPC) will be removed from service for scheduled maintenance which will take the Emergency Response Data System (ERDS) out of service. The scheduled maintenance is planned from 0930 hours EST until 1530 hours EST. Personnel will be performing computer system backups and maintenance. Compensatory measures exist within the CNP Emergency Response procedure to provide plant data via the Emergency Notification System 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 NUREG 1022 Revision 2 for 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).

  • * * UPDATE FROM RICH KRESS TO JOE O'HARA AT 1207 EST ON 1/25/10 * * *

The Unit 1 Plant Process Computer and the Emergency Response Data System (ERDS) were returned to functional Status at 11:35 on Monday, January 25, 2010. This follow up notification is being made to provide closure from the initial notification under 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). The NRC Resident Inspector has been notified. Notified R3DO(Lipa)

Emergency Response Data System
ENS 4562012 January 2010 09:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System and Charcoal Filter for Scheduled Maintenance

The Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system air conditioning and filtration systems are scheduled to be removed from service for scheduled preventive maintenance at 0400 on January 12, 2010. 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 air conditioning and filtration systems are scheduled to be restored to service by 1400 on Tuesday January 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 unavailability of an emergency response facility.

  • * * UPDATE FROM BEN HUFFMAN TO HOWIE CROUCH @ 1420 EST ON 01/12/10 * * *

The TSC ventilation system and charcoal filter were returned to functional status at 1418 EST on Tuesday, January 12, 2010. This follow up notification is being made to provide closure of the initial notification under 10 CFR 50.72 (b)(3)(xiii). The licensee has notified the NRC Resident Inspector. Notified R3DO (Lipa).

ENS 4545422 October 2009 04:01:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center Out of Service for Ventilation System and Charcoal Filter Maintenance

At 0001 on Thursday, October 22, 2009, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system air conditioning and filtration systems will be removed from service for a scheduled maintenance activity. The Motor Control Center providing electrical power to several TSC ventilation components will be de-energized to facilitate replacement of the U1 CD Emergency Diesel Generator room ventilation supply fan starter (1-88X-DGS-2). 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 availability is scheduled to be restored at 0800 on Thursday, October 22, 2009. The licensee has notified the NRC Resident Inspector. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the unavailability of an emergency response facility.

  • * * UPDATE AT 1008 ON 10/22/2009 FROM DAN KURTH TO MARK ABRAMOVITZ * * *

The TSC ventilation was restored to service at 0937 EDT. The licensee will notify the NRC Resident Inspector. Notified the R3DO (Kozak).

Emergency Diesel Generator
ENS 4542913 October 2009 11:44:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center Unavailable Due to Planned Maintenance

At 0744 (EDT) on Tuesday, October 13, 2009, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems were 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 at 1500 (EDT) on Tuesday, October 13, 2009. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an emergency response facility. The licensee notified the NRC Senior Resident Inspector.

  • * * UPDATE FROM BUD HINCKLEY TO DONALD NORWOOD AT 1336 EDT ON 10/13/09 * * *

The CNP TSC ventilation system was returned to functional status following scheduled maintenance at 1333 (EDT) on Tuesday, October 13, 2009. This follow-up notification is being made to provide closure from the initial notification under 10CFR50.72.(b)(3)(xiii) due to the loss of an emergency response facility. The licensee has notified the NRC Senior Resident Inspector of the return to service of the TSC Ventilation System. Notified R3DO (Eric Duncan)

ENS 4536118 September 2009 14:30:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed ConditionInoperability of Both Edg'S Due to Valve Found Out of Position

At 02:00 on Friday, September 18, 2009, the Unit 2 AB Emergency Diesel Generator (EDG) Air Jet Assist Control Air Shutoff valve, which is required to be open, was discovered closed. At 10:30 on Friday, September 18, 2009, it was determined that with the valve closed, the EDG Air Jet Assist may not be able to support the EDG fast speed start to meet the EDG's Operability requirements. This condition renders the Unit 2 AB EDG inoperable. The valve was repositioned and verified open at 02:15 on Friday, September 18, 2009, restoring the EDG to operable status. Similar valves were verified to be in the correct position on all other EDGs in both Units. The Unit 2 AB Emergency Diesel Generator Air Jet Assist Control Air Shutoff valve was last confirmed open on July 21, 2009. The time the valve became closed is not known. Since July 21, 2009, there have been 3 periods of inoperability for Unit 2 CD EDG, the redundant Emergency Diesel Generator. During each of these periods, both of the Unit 2 EDGs are assumed to be inoperable. The periods are as follows: August 10, 2009 at 09:31 until August 10, 2009 at 23:00 August 11, 2009 at 07:30 until August 11, 2009 at 23:16 September 9, 2009 al 00:02 until September 9, 2009 at 04:40 This notification is being made in accordance with 10 CFR 50.72 (b)(3)(ii)(B) due to the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. The licensee has notified the NRC Senior Resident Inspector.

  • * * RETRACTION ON 10/01/2009 AT 1634 EDT FROM JAMES SHAW TO DONALD NORWOOD * * *

At 02:00 on Friday, September 18, 2009, the Unit 2 AB Emergency Diesel Generator (EDG) Air Jet Assist Control Air Shutoff valve, which is required to be open, was discovered closed. At 10:30 on Friday, September 18, 2009, it was determined that with the valve closed, the EDG Air Jet Assist may not be able to support the EDG fast speed start to meet the EDG's Operability requirements. This condition renders the Unit 2 AB EDG inoperable. The valve was repositioned and verified open at 02:15 on Friday, September 18, 2009, restoring the EDG to operable status. Since the last time the Turbocharger Air Jet Assist Control Air Shutoff valve was confirmed open, July 21, 2009, there were three periods where the redundant EDG was inoperable for planned maintenance and surveillance testing. During each of these periods, both of the Unit 2 EDGs are assumed to be inoperable. As such, Cook Nuclear Plant (CNP) submitted Event Notification 45361 in accordance with 10CFR50.72(b)(3)(ii)(B) due to the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. On September 25, 2009, CNP conducted two EDG fast speed starts, one with the Turbocharger Air Jet Assist Control Air Shutoff valve closed, and one with the valve open. Based on a review of the data collected and observed performance of the EDG, the determination has been made that having the Turbocharger Air Jet Assist Control Air valve closed does not adversely impact operability of an EDG. The circumstances discussed in the notification did not result in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. The licensee has notified the NRC Resident Inspector. Notified R3DO (Lara).

Emergency Diesel Generator
ENS 4531131 August 2009 11:21:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTsc Potentially Out of Service

At 0721 on Monday, August 31, 2009, a portion of the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system and Technical Support Center (TSC) air conditioning system was removed from service for maintenance on the electrical power supply Motor Control Center (MCC). The MCC being removed supports 3 of the 4 air conditioning units for the Technical Support Center, as well as the filtration system. The remaining air conditioning unit which is not supported by the MCC will remain in service. Under certain accident conditions the TSC may become unavailable due to the inability of the ventilation 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 2100 on Monday, August 31, 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 of an emergency response facility.

  • * * UPDATE AT 2147 EDT ON 8/31/09 FROM BRUCK TO HUFFMAN * * *

The TSC ventilation system air conditioning was returned to functional status at 21:37 on Monday, August 31, 2009. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility. The licensee has notified the NRC Resident Inspector. R3DO (Lipa) notified.

ENS 4522826 July 2009 19:06:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Due to a Reactor Coolant Pump Seal MalfunctionAt 1506 on Sunday, July 26, 2009, the Cook Nuclear Plant (CNP) Unit 2 reactor was manually tripped after the control room staff concluded that the #22 Reactor Coolant Pump (RCP) needed to be promptly secured due to a RCP seal malfunction as indicated by lowering #1 seal leakoff flows and rising #1 seal return and pump radial bearing temperature. This requires a 4-hour report under 10CFR50.72(b)(2)(iv)(B). Both motor-driven Auxiliary Feedwater pumps automatically started due to the reactor trip and trip of both Main Feedwater Pumps. The Turbine-Driven Auxiliary Feedwater Pump (TDAFP) started automatically due to low-low water levels in at least two steam generators, which is expected for a reactor trip from approximately full power. The automatic actuation of the reactor protection system and the TDAFP require an 8-hour report under 10CFR50.72(b)(3)(iv)(A). All systems functioned as expected after the trip, and no major components were out of service at the time except for the Moisture Separator Reheaters which were not in service since the beginning of the current power cycle. The licensee has notified the NRC Senior Resident Inspector. All control rods fully inserted as required. Electrical system is in normal post-trip lineup. Plant cooldown is via Condenser Steam Dumps using Auxiliary Feedwater pumps. Plant cooldown will continue to Mode 5 (cold shutdown).Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
ENS 451856 July 2009 11:12:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System and Charcoal Filter for Scheduled Maintenance

At 0712 on Monday, July 6, 2009, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system air conditioning and filtration systems were removed from service for scheduled preventive maintenance. 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 Monday, July 6, 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.

  • * * UPDATE FROM JAMES SHAW TO JOE O'HARA AT 1640 EDT ON 07/06/09 * * *

The TSC Ventilation System and Charcoal Filter have been returned to functional status at 1517 EDT on Monday, July 6, 2009. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility. The licensee has notified the NRC Senior Resident Inspector - Jay Lennartz. Notified the R3DO(Passehl).

ENS 4499215 April 2009 08:15:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System and Charcoal Filter During Scheduled Maintenance

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.

  • * * UPDATE FROM DEAN BRUCK TO JOHN KNOKE AT 1352 ON 4/15/09 * * *

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 4476513 January 2009 14:07:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center Unavailable Due to Scheduled Hvac Maintenance

At 0907 on Tuesday, January 13, 2009, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems were 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. Ventilation system maintenance is scheduled to complete at 1500 on Tuesday, January 13, 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 of an emergency response facility.

* * * UPDATE FROM SCOTT SCHNEIDER TO PETE SNYDER AT 1534 ON 1/13/09 * * * 

The TSC ventilation system air conditioning was returned to functional status at 1532 on Tuesday, January 13, 2009. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility. The licensee notified the NRC Resident Inspector." Notified R3DO (Passehl).

ENS 4457016 October 2008 15:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessPartial Unavailability of Tsc Ventilation Air Conditioning System for Scheduled Maintenance

At 1100 on Thursday, October 16, 2008, a portion of the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system air conditioning was removed from service for maintenance on the Non-Essential Service Water System (NESW). The NESW system supports 3 of the 4 air conditioning units for the Technical Support Center. The filtration system will remain available, and an air conditioning unit which is not supported by NESW will remain in service. Under certain accident conditions the TSC may become unavailable due to the inability of the ventilation 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 1800 on Thursday, October 16, 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.

* * * UPDATE ON 10/17/08 AT 0526 FROM BEN HUFFMAN TO PETE SNYDER * * * 

The TSC ventilation system air conditioning was returned to functional status at 0525 on Friday, October 17, 2008. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility. The licensee notified the NRC Resident Inspector. Notified R3DO (Phillips).

Service water
ENS 445426 October 2008 08:45:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Tsc Ventilation System and Charcoal Filter for Scheduled Maintenance

At 0445 on Monday, October 6, 2008, 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 16:00 on Monday, October 6,2008. 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.

  • * * UPDATE AT 1630 EDT ON 10/06/08 FROM TOD KASPAR TO HOWIE CROUCH * * *

The TSC Ventilation System and Charcoal Filter was returned to functional status at 14:35 on Monday, October 6, 2008. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility. The licensee has notified the NRC Resident Inspector. Notified R3DO (Lara).

ENS 4450721 September 2008 00:18:0010 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.

  • * * UPDATE AT 0005 EDT ON 09/21/08 FROM BRADDOCK LEWIS TO V. KLCO * * *

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).

  • * * UPDATE PROVIDED BY PAUL LEONARD TO JASON KOZAL AT 0414 ON 09/21/08 * * *

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
ENS 443907 August 2008 16:15:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Technical Support Center

At 1215 EDT on Thursday, August 7, 2008, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) ventilation system charcoal filter was removed from service for scheduled preventive maintenance on one of the TSC air conditioning systems. The charcoal bed filtration system is also out of service in support of the maintenance on the air conditioning 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. Air conditioning system maintenance is scheduled to complete at 1515 EDT on Thursday, August 7, 2008. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss an emergency response facility. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM BRAD LEWIS TO JOHN KNOKE AT 1657 EDT ON 08/07/08 * * *

The TSC air conditioning system was returned to functional status at 16:25 on Thursday, August 7, 2008. This follow up notification is being made to provide closure from the initial notification under 10 CFR 50.72 (b)(3)(xiii) due to the loss an emergency response facility. The licensee has notified the NRC Resident Inspector. Notified R3DO (David Hills)

ENS 4436525 July 2008 13:17:0010 CFR 26.719Positive Random Fitness for Duty TestA 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. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector. This event is being reported pursuant to 10 CFR 26.719 (b)(2)(ii).
ENS 4432427 June 2008 19:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessProcedure Change Initiated to Support Tsc Habitability Dose CalculationAt 1500 on Friday, June 27, 2008, upon review of a calculation performed to demonstrate the TSC habitability requirements; a determination was made that a procedure change was required to support the assumptions in the calculation. The identified procedure change was effective at 1800 on June 27, 2008. Based on implementation of the procedure change, the TSC is now considered functional, but degraded. This issue has been entered into the Corrective Action Program. 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.
ENS 4431123 June 2008 07:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessLoss of Emergency Response Capability - Tsc Is Unavailable

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.

  • * * UPDATE AT 1455EDT ON 06/24/08 FROM SCOTT SCHNEIDER TO S. SANDIN * * *

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).

  • * * UPDATE PROVIDED BY DEAN BRUCK TO JASON KOZAL AT 1846 ON 6/27/08 * * *

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 4429212 June 2008 17:45:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessUnavailability of Emergency Operations FacilityAt 1345 on Thursday, June 12, 2008, the Cook Nuclear Plant (CNP) Buchanan Office Building was conservatively evacuated due to the presence of a solvent vapor in the building. The Buchanan Office Building houses both the Emergency Operations Facility (EOF) and Joint Information Center (JIC). The Buchanan Office Building has been ventilated and has been verified inhabitable by Safety and Health personnel. The Emergency Operations Facility and Joint Information Center access was restored at 1530 on Thursday, June 12, 2008. Further investigation concluded that the concentration of the solvent vapor was never at a level that would have mandated evacuation. This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss of offsite response capability. The licensee notified the NRC Resident Inspector.
ENS 4417126 April 2008 02:10:0010 CFR 50.72(b)(3)(ii)(A), Seriously DegradedNon-Isolable Rcs Boundary Leakage from Instrument LineOn 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.05000315/LER-2008-004
ENS 4414718 April 2008 10:02:0010 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.

  • * * UPDATE AT 0910 EDT ON 04/18/08 FROM CHRIS KELLEY TO S. SANDIN * * *

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).

  • * * UPDATE AT 0958 EDT ON 04/18/08 FROM BRAD LEWIS TO S. SANDIN * * *

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).

  • * * UPDATE AT 1203 EDT ON 4/18/08 FROM TIMMOTHY WICE TO JASON KOZAL * * *

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).

  • * * UPDATE AT 1616 EDT ON 4/18/08 FROM FRANK BAKER TO JASON KOZAL * * *

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 4414114 April 2008 16:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessLoss of Siren Alert Notification System Due to System ModificationsOn April 14, 2008 during activities being performed by a Berrien County (BC) vendor associated with relocation of the BC 911 Dispatch Center, a microwave line was wired in parallel with the transceiver used to activate the Alert and Notification System (ANS) sirens. Following completion of the installation of the parallel microwave circuit, station personnel were informed and a poll was conducted at approximately 1633 hours on April 14, 2008, to verify no loss of capability of the ANS. This poll was unsuccessful. Immediate corrective actions included removal of the parallel microwave circuit and performance of an additional siren poll. The subsequent siren poll was completed successfully at approximately 1739 hours on April 14, 2008. A silent testing performed at 1000 hours on April 15, 2008, confirmed that all sirens are operational. An investigation has been initiated to evaluate the exact nature of the intended change, and to examine the processes used to control activities that may impact ANS operation. The ANS may not have been available on April 14, 2008, from approximately 1200 hours when the parallel circuit was installed, until the configuration was restored and successfully polled at 1739 hours. The licensee has notified the NRC Resident Inspector. They are working with Berrien County during the investigation.
ENS 441227 April 2008 08:30:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center May Become Uninhabitable Due to Scheduled Maintenance

At 04:30 hours on Monday, April 7, 2008, the Cook Nuclear Plant (CNP) removed the Technical Support Center (TSC) Heating Ventilation Air Conditioning (HVAC) System from service for planned maintenance. The TSC HVAC system will remain out of service for a period of approximately three days. 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. This notification is being made in accordance with NUREG 1022 as a potential unavailability of an emergency response facility in accordance with 10 CFR 50.72 (b)(3)(xiii). The licensee notified the NRC Resident Inspector. The licensee will supplement this notification upon returning the TSC HVAC system to normal operational status.

  • * * UPDATE PROVIDED AT 1329 ON 04/07/08 BY RICHARD HACKMAN TO JEFF ROTTON * * *

The following information was provided by the licensee to RETRACT the event: Upon additional evaluation CNP determined that the planned maintenance reported above was limited in scope and did not remove the entire TSC HVAC system from service. The planned maintenance resulted in two of three fully redundant air chillers (air conditioners) being removed from service for maintenance. The third chiller and the TSC HVAC system is operable and remains in service. Therefore, the CNP TSC has been maintained in a configuration that ensures habitability. The NRC Resident Inspector has been notified of the retraction. Notified R3DO (Skokowski).

HVAC
ENS 4408119 March 2008 17:40:0010 CFR 26.73Fitness for Duty - Non-Licensed SupervisorA non licensed supervisor had a confirmed positive for illegal drugs during a pre-access fitness-for-duty test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector.
ENS 439677 February 2008 00:20:0010 CFR 50.72(b)(3)(ii)(B), Unanalyzed ConditionTrain "a" 250 Vdc Cable Passes Through Train "B" Switchgear RoomOn February 6, 2008 at 1920 hours, Cook Nuclear Plant Engineering personnel identified an unanalyzed condition that has the potential to degrade plant safety. Specifically, a cable routing error in the original design for safety related Train 'A' 250 VDC was discovered. A short section of Train 'A' 250 VDC was found to pass through the Train 'B' 4kV switchgear room. This routing was discovered to exist in both units. The routing of the cabling presents the possibility that a fire could disable the remote control to both 4kV switchgear trains. Local inspection identified no additional or supplementary fire barrier such as fire retardant wrapping. Compensatory measures (fire watch) have been established. In accordance with 10 CFR 50.72(b)(3)(ii) this condition is reportable as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. The licensee notified the NRC Resident Inspector.
ENS 439562 February 2008 10:30:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Manual Reactor Trip Due to High Turbine VibrationsThe DC Cook Unit 1 Reactor was manually tripped from 93% power due to high vibrations on main turbine bearings #5 and 6. This event is reportable under 10CFR50.72(b)(2)(iv)(B), RPS actuation, as a four (4) hour report and under 10CFR50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 1 remains stable in Mode 3 while conducting the post Trip Review. No radioactive release is in progress as a result of this event. The DC Cook Resident NRC Inspector was notified 02/02/08 at approximately 0535 EST. The electrical grid is stable and Unit 1 is being supplied by offsite power. Unit 2 is not affected. All control rods fully inserted. Decay heat is being removed via steam dumps to the main condenser.Auxiliary Feedwater
Main Turbine
Main Condenser
ENS 4393525 January 2008 18:00:0010 CFR 50.72(b)(3)(xiii), Loss of Emergency PreparednessTechnical Support Center May Become UninhabitableAt approximately 1300 hours Eastern Standard Time on Friday, January 25, 2008, the Cook Nuclear Plant (CNP) determined that under certain accident conditions, the Technical Support Center (TSC) may become uninhabitable due to the inability to switch to the emergency ventilation mode. 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. Parts are available and repairs are expected to be completed during the current shift. This event is reportable as specified in NUREG 1022 as a loss of an emergency response facility in accordance with 10 CFR 50.72 (b)(3)(xiii). The licensee notified the NRC Resident Inspector.
ENS 436843 October 2007 10:36:0010 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person OffsiteContaminated Worker Transported to Offsite Medical FacilityAt 0540 Eastern Daylight Time (EDT) the Unit 2 Control Room was notified of a personnel injury in the Unit 2 containment. Unit 2 is currently in a refueling outage and the individual was working in upper containment in support of the reactor vessel closure head replacement project. The individual injuries are apparently the result of being struck when a rigging clevis (not under load) dropped from an elevated position. Site emergency medical technicians responded to the scene and the individual was transported to a local medical facility (Lakeland Hospital, St. Joseph, MI) via ambulance at 0636 EDT. At the time of transport, the individual was considered to be potentially contaminated because complete surveys could not be performed while the individual was immobilized for transfer. Subsequently, after arrival at the hospital, radiation protection personnel verified the presence of low levels of contamination on outer contamination clothing and transport material. These materials are being returned to plant in accordance with DOT guidelines. This report is being made pursuant to 10 CFR 50.72(b(3)(xii), 'Any event requiring the transport of a radioactively contaminated person to an offsite medical facility for treatment.' The NRC Resident Inspector has been notified.
ENS 4360528 August 2007 17:54:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip After Digital Feedwater System FailureAt 13:54 on 8/28/07, DC Cook Unit 1 experienced an automatic reactor trip due to low steam generator water level coincident with low feedwater flow on #11 steam generator. The cause was a malfunction of the Main Feedwater Pump Digital Control System, which remains under investigation. This requires a 4-hour report under 10CFR50.72(b)(2)(iv)(B). Both Motor-Driven Auxiliary Feedwater Pumps automatically started due to the reactor trip. The Turbine-Driven Auxiliary Feedwater Pump (TDAFP) started automatically due to low-low water levels in at least two steam generators, which is expected for a reactor trip from 100% power. The automatic actuation of the reactor protection system and the TDAFP start require an 8-hour report under 10CFR50.72(b)(3)(iv)(A). All systems functioned as expected after the trip, and no major components were out of service at the time of the trip. This is a non-complicated trip. The NRC resident has been notified. The reactor tripped at 15% steam generator level and then level went off scale low as expected. All control rods fully inserted. No primary or secondary safeties or relief valves lifted with the exception of a feed heater relief valve. The plant is feeding steam generators with the motor driven auxiliary feed water pumps and dumping decay heat to the main condenser. The plant is in the normal shutdown electrical lineup.Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Condenser
ENS 4357216 August 2007 17:32:0010 CFR 26.73Fitness for Duty - Non-Licensed SupervisorA 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. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector.
ENS 4296925 September 2006 14:34:0010 CFR 50.73(a)(1), Submit an LERInvalid System Actuation - Partial Phase a Containment IsolationThis 60-day telephone notification is being made under the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation partial containment Phase A isolation affecting more than one system. On 09/25/2006 at approximately 1034 hours, while in MODE 6, 'Refueling Operations' with no core alterations in progress, a partial Containment Phase 'A' Isolation occurred without a valid initiating signal from the Train 'A' Solid State Protection System. All components responded as designed and Operations verified stable conditions in accordance with plant operating procedures. The following components were actuated: 1-XCR-100, Containment Air Supply Header No. 2 Containment Isolation Valve, 1-XCR-102, Control Air Supply Header No. 1 Containment Isolation Valve, 1-VCR-11, Glycol to Air Handling Units, 1-VCR-21, Glycol from Air Handling Units, 1-DCR-600, Containment Sumps to Dirty Waste Hold-up Tank Containment Isolation Valve, 1-DCR-610, Ice Condenser Fans Cooler Units Drain to WDS Containment Isolation Valve, 1-CCR-455, CCW to Reactor Support Coolers Containment Isolation Valve, 1-QCR-919, Demin Water to Containment Isolation Valve, 1-QRV-51, Pressurizer Auxiliary Spray Line from CVCS Isolation Valve, 1-QRV-61, Alternate Charging Line to Cold Leg 1 Isolation Valve, 1-QRV-62, Normal Charging Line to Cold Leg 4 Isolation Valve. All components responded as expected. The remaining Phase 'A' components did not actuate because they had been previously removed from service. This event was caused by an intermittent electrical connection at Universal Logic Card A313 receptacle and a failed A213 card. The inadequate receptacle spring tension on the A313 card has been corrected, and the failed A213 card has been replaced. There were no safety consequences or impacts on the health and safety of the public. The event has been entered into the Donald C. Cook Nuclear Plant's corrective action program. The NRC Senior Resident was notified of this report, time 1220, 11/7/06.
ENS 4273930 July 2006 11:30:0010 CFR 50.72(b)(2)(i), Tech Spec Required ShutdownTechnical Specification Shutdown for High Containment Air TemperatureOn July 30, 2006, at 0730, a plant shutdown was initiated in accordance with Technical Specification (TS) Action 3.6.5.B.1. This action requires that the unit be placed in Mode 3 within six hours if containment air temperature is not restored to within limits during the previous eight hours. On July 29, 2006, at 2026 TS Action 3.6.5.A was entered due to containment lower compartment average air temperature exceeding the TS Limiting Condition for Operation 3.6.5.B limit of 120 degrees Fahrenheit. Efforts to reduce the containment temperature during the eight hour completion time of Action 3.6.5.A were unsuccessful. In accordance with normal plant operating procedures, the unit shutdown was completed by initiating a manual reactor trip from 16.5% Reactor Power following a controlled plant shutdown on July 20, 2006, at 1014. All safety systems and plant equipment used in the shutdown functioned as designed. All rods inserted fully without incident. No PORV/safety valves lifted. Decay heat is being removed with AFW. Unit 2 containment air temperature is 117 degrees Fahrenheit. The licensee notified the NRC Resident Inspector.
ENS 4253629 April 2006 14:56:00Other Unspec ReqmntDiscovery of After-The- Fact Emergency Condition - Unusual Event Due to Rcs Lineup

D.C. Cook Unit 2 was in Mode 4 and heating up after Unit 2 Cycle 16 refueling outage when 2-IMO-340 (East RHR pump to Charging Pump Suction Header) was throttled open. RHR suction was aligned to Loop 2 Hot Leg with wide range RCS pressure at 337 psig and RCS average temperature 280 degrees Fahrenheit. Charging header safety valve 2-SV-56 lifted with a setting of 220 psig and relieved to the Pressurizer Relief Tank (PRT) between 10:56:00 and 10:58:30. 2-IMO-340 was then closed. Approximately, 120 gallons of reactor coolant were directed to the PRT during the approximate 2.5 minutes, resulting in a flow rate of approximately 48 gpm, greater than the 25 gallon per minute identified leak rate limit for an Unusual Event (10 CFR 50.72(a)(1)(i)). Time of discovery for leakage quantity and reportability was 13:21 on 4/29/06. Therefore, for approximately 2.5 minutes, D.C. Cook Unit 2 met the conditions for an Unusual Event. However, this fact was discovered after leakage was stopped. Unit 2 is stable in Mode 4 at 340 degrees Fahrenheit and 405 psig RCS pressure. An Unusual Event was NOT declared, but the conditions for an Unusual Event were met under Emergency Condition Criteria S-8 between 10:56:00 and 10:58:30 on 4/29/06. This ENS notification is being made within one hour of the discovery of the undeclared event. The licensee will notify the NRC Resident Inspector.

  • * * RETRACTION ON 4/30/06 AT 1419 EDT FROM D. TURINETTI TO J. MACKINNON * * *

EN# 42536 reported that D.C. Cook Unit 2 satisfied the conditions for entry into an Unusual Event under Emergency Condition Criteria S-B, identified RCS leakage exceeding 25 GPM. This was identified after system alignment had been restored, ending the event, and was reported as an after the fact declaration that the conditions for an Unusual Event had been satisfied, but not declared. Subsequent review of this event has determined that the conditions for Emergency Condition Criteria S-B were not satisfied in that no identified RCS leakage occurred during this event. The diversion of 120 gallons of CVCS (Chemical Volume and Control System) inventory was the result of plant alignment by Operations personnel which was immediately recognized and terminated. Plant systems and components functioned as designed to terminate this event. The licensee will notify the NRC Resident Inspector. Notified R3DO (H. Peterson).

ENS 4253127 April 2006 06:07:0010 CFR 50.72(b)(3)(iv)(A), System ActuationLow Pressure Steam Line Pressure Safety Injection Signal Inadvertently InitiatedOn 4/27/06 at 02:00, with D.C. Cook Unit 2 in Mode 5 and the Control Rod Drive System de-energized under clearance and incapable of withdrawal, Instrumentation and Controls Technicians were beginning Instrumentation Channel Operational Test and Trip Actuating Device Operational Tests. The block for Main Steam Line Low Pressure Safety Injection was inadvertently removed. This allowed the existing low steam generator pressure (0 psig) and low RCS temperature (186 degrees F) to initiate a Low Steam Line Pressure Safety Injection and a Steam Line Isolation signal. At 02:07 Unit 2 had a Main Steam Line Low Pressure Safety Injection signal on both Trains. The following components automatically started: Unit 2 West Centrifugal Charging Pump (on minimum flow recirc path with injection path isolated for LTOP -- no injection to RCS) Unit 2 South Safety Injection Pump (on minimum flow recirc path with injection path isolated for LTOP - no injection to RCS) Unit 2 East Residual Heat Removal Pump Unit 2 East Component Cooling Water Pump Unit 2 CD Emergency Diesel Generator Both Trains of Unit 2 Control Room Pressurization Both Trains of Unit 2 Phase A Containment Isolation signal Both Trains of Unit 2 Containment Ventilation Isolation. Both Trains of Unit 1 Control Room Pressurization Fans Unit 1 West Essential Service Water Pump All available equipment actuated as expected for this condition. (The Unit 2 Boron Injection Tank was isolated under clearance for LTOP. The Unit 2 East Centrifugal Charging Pump, Unit 2 West Residual Heat Removal Pump, and Unit 2 West Component Cooling Water Pump were already running. The Unit 2 AB Emergency Diesel Generator was under a clearance for maintenance. The Unit 2 North Safety Injection Pump was under an administrative clearance for LTOP. The Unit 1 East Essential Service Water Pump was already running.) After diagnosing the event, operators manually blocked the Steam Line Isolation and manually reset Safety Injection signals for both trains. Components were returned to normal status for plant conditions. The licensee notified the NRC Resident Inspector.Steam Generator
Service water
Emergency Diesel Generator
Residual Heat Removal
ENS 421258 November 2005 08:58:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Trip Due to Reactor Coolant Pump Bus UndervoltageAt 03:58 on 11-08-05, D.C. Cook Unit 2 experienced an automatic, reactor trip due to Reactor Coolant Pump Bus Undervoltage. The cause of the reactor trip its under investigation. This requires a 4-hour report under 10CFR50.72(b)(2)(iv)(B). All four reactor coolant pumps have remained running. The Unit 2 Turbine Driven Auxiliary Feedwater Rump (TDAFP) started automatically due to low-low levels in at least two steam generators which is expected for a reactor trip from 100% power. The 'B' train Emergency Diesel Generator (2AB EDG) automatically started and loaded "B" train emergency bus T21A. These automatic actuations of the reactor protection system, TDAFP start, and 2A13 EDG start require an 8-hour report under I OCFR50.72(b)(3)(iv)(A). 'B' train emergency bus T21B was declared inoperable after it failed to be energized automatically on the start of the 2AB EDG. The cause of this failure is under investigation. The 'A' train Emergency Diesel Generator (2CD EDG) had been inoperable for scheduled maintenance during the time of the event. It was restored to operable status at 06:06. All control rods fully inserted. Steam generators are discharging steam to the main condenser using steam dumps. The licensee notified the NRC Resident Inspector.Steam Generator
Reactor Protection System
Emergency Diesel Generator
Auxiliary Feedwater
Main Condenser
ENS 4163926 April 2005 04:02:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip with Afw ActuationThe DC Cook Unit 1 Reactor automatically tripped during normal plant startup preparations to synchronize the Main Generator with the offsite electrical GRID. Indicated Reactor power at the time of trip was 8 % power and stable. Preliminary review indicates the trip was caused by an Intermediate Range high flux reactor trip signal. The Intermediate Range High Flux Reactor trip occurred below the Reactor Protection System actuation setpoint. This is a one-out-of-two logic and the trip is active below interlock Permissive P-10 (10% reactor power). The cause of the Reactor Trip is under investigation. This event is reportable under 10CFR50.72(b)(2)(iv)(B), RPS actuation, as a four (4) hour report and under 10CFR50,72(b)(3)(iv)(A), Specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 1 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event. The DC Cook Senior Resident NRC Inspector was notified 04/26/05 at approximately 00:30 (hrs. EDT). The electrical grid is stable and Unit 1 is being supplied by offsite power. Unit 2 is not affected. All control rods fully inserted. Decay heat is being removed via steam dumps to the main condenser.Reactor Protection System
Auxiliary Feedwater
Main Condenser
ENS 4147910 March 2005 16:00:0010 CFR 26.73Contractor Supervisor Found Positive for Illegal Drugs During a Pre-Access Drug TestA contractor supervisor was determined to have been under the influence of an illegal drug during a pre-access drug test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The NRC Resident Inspector was notified of this event by the licensee.
ENS 4133814 January 2005 15:00:0010 CFR 26.73Fitness for DutyA non-licensed employee was determined to be under the influence of illegal drugs during a random test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector.
ENS 4123330 November 2004 12:49:0010 CFR 26.73Fitness for Duty ReportA licensed employee was determined to be under the influence of alcohol during a random test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee informed the NRC resident operator.
ENS 4119412 November 2004 16:18:0010 CFR 26.73Fitness for DutyA non-licensed contract supervisor tested positive for drugs during a followup test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector.
ENS 4111111 October 2004 04:20:0010 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentContainment Ventilation Isolation System Inoperable During Fuel MovementThe following information was obtained from the licensee via facsimile: In accordance with 10 CFR 50.72(b)(3)(v)(D) ('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 mitigate the consequences of an accident'), D.C. Cook Unit 2 is making an 8-hour non-emergency report. At 00:20 (EDT) on 10-11-2004, it was discovered that neither train of the Containment Ventilation Isolation System would have automatically isolated containment purge on a high radiation signal within the containment. Also, a manual Phase A containment isolation actuation would not have isolated containment purge. At all times, containment purge could have been isolated using individual control switches from the Unit 2 Control Room. D.C. Cook Unit 2 Technical Specification 3.9.9 requires during core alterations or movement of irradiated fuel within the Containment that the Containment Purge and Exhaust Isolation System be operable. Technical Specification 3.9.4.c requires during core alterations or movement of irradiated fuel within the containment that each containment penetration providing direct access from the containment atmosphere to the outside atmosphere be closed by an isolation valve, blind flange, manual valve, or equivalent, OR be capable of being closed by an operable automatic Containment Purge and Exhaust isolation valve. Technical Specification 3.0.4 requires when a Limited Condition of Operation is not met, entry into an operational mode or other specified condition in the applicability shall be made only in specified conditions. Core alterations and movement of irradiated fuel assemblies began at 14:41 on 10-09-2004, approximately 71 minutes after the Containment Ventilation Isolation System had been made inoperable. At approximately 13:30 on 10-09-2004, breaker 2-CRID-1-7 (Reactor Protection and Safeguards Actuation Cabinet RPS-A Input Channel I & All RPS A Output) and 2-GRID-4-8 (Reactor Protection & Safeguards Actuation Cabinet RPS-B Input Channel IV & ALL RPS B) were opened and tagged as part of a clearance. This prevented the automatic actuation of both trains of the Containment Ventilation Isolation System and prevented a manual phase A containment isolation from isolating containment purge. Thereafter, at 14:41 on 10-09-04, fuel movement commenced from the reactor vessel to the Spent Fuel Pit. At 23:25 on 10-10-2004, breakers 2-CRID-1-7 and 2-CRID-4-8 were re-closed. At 0020 on 10-11-2004, it was discovered that during the time from approximately 13:30 on 10-09-2004 to 23:25 on 10-10-2004, the Containment Ventilation isolation system had been inoperable. D.C. Cook Unit 2 is currently stable in Mode 6 during the Unit 2 Cycle 15 refueling outage with core offload to the Spent Fuel Pit in progress. The licensee has notified the NRC Resident Inspector.
ENS 4071629 April 2004 19:57:00Other Unspec ReqmntIdentified Leakage Limit Exceeded for 5 Minute Period Due to Lifted Letdown Line Safety ValveD.C. Cook Unit 2 was performing post-maintenance testing on a solenoid valve associated with a letdown orifice valve and realigning letdown flowpath when safety valve 2-SV-51 (Regenerative Heat Exchanger Letdown Outlet Safety Valve) lifted on 4/29/04 at 15:57 EDT, relieving 323 gallons of water to the Pressurizer Relief Tank over a five (5) minute period before letdown was isolated. Average leak rate was approximately 65 gallons per minute, greater than the 25 gallon per minute identified leak rate limit for an Unusual Event (10CFR50.72(a)(1)(i)). This was a rapidly concluded event of a five (5) minute duration. Time of discovery for leakage quantity and reportability was 17:10 on 4/29/04. Therefore, for a five (5) minute period, D.C. Cook Unit 2 met the conditions for an Unusual Event. However, this fact was discovered after leakage was stopped. Unit 2 is stable at approximately 100% reactor thermal power with the excess letdown system in service. An Unusual Event was NOT declared, but the conditions for an Unusual Event were met between 15:57 and 16:02 on 4/29/04. This ENS notification is being made within one hour of the discovery of the undeclared event. The licensee notified the NRC Resident Inspector.
ENS 406609 April 2004 02:16:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip Due to a Feedwater Flow TransientOn 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.Steam Generator
Reactor Coolant System
Feedwater
Auxiliary Feedwater
Main Condenser
05000316/LER-2004-002
ENS 4062229 March 2004 19:04:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Automatic Reactor Trip During Reactor Trip Bypass Breaker Manipulation TestOn March 29, 2004 at 1404 hours (EST), Unit 2 received an automatic actuation of the Reactor Protection (RPS). The RPS actuation occurred when the train B Reactor Trip Bypass Breaker was manipulated during the conduct of the Solid State Protection System (SSPS). Testing the Bypass Breaker had been racked in and closed, but correct indication was not received earlier during the test. The decision was made to restore from the testing and the Bypass Breaker was being racked out when the actuation occurred. The Unit was at full power with all system in normal alignment. Initial indication is that the actuation signal was a Power Range Rate Trip. The RPS actuation is believed to be related to the manipulation of the Bypass Breaker. Cause is under investigation. 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. No other ESF systems actuated. All other Plant systems responded normally. All control rods fully inserted into the core. The Plant is currently stable in Mode 3, and Steam Generator levels are being maintained using the Auxiliary Feedwater System. The Licensee notified the NRC Resident Inspector.Steam Generator
Auxiliary Feedwater
05000316/LER-2004-001
ENS 4041930 December 2003 18:30:0010 CFR 50.72(b)(2)(iv)(B), RPS System Actuation
10 CFR 50.72(b)(3)(iv)(A), System Actuation
Reactor Tripped from 100% Power Due to Low Steam GeneratorCook unit 2 automatically tripped from 100% power due to low steam generator level coincident with feed flow less than steam flow. The cause of this condition is under investigation, but it is suspected that unplanned closure of the steam generator 2 & 3 feedwater isolation valves led to the initiating signal. It is believed that the feedwater isolation valve closure originated from an abnormality in the Control Room Instrument Distribution(CRID) 120VAC power system. Technicians were landing leads on a Residual Heat Removal (RHR) System flow transmitter which was fed from the suspected CRID supply at the time of the event. An arc was observed during the lead landing procedure. The main generator also required a manual trip signal by control room operators due to sticking of the main stop valve which is also being investigated. All other systems responded as expected. All rods fully inserted, no ECCS actuation occurred, and no relief valves lifted. The unit is stable in mode 3 with aux feedwater providing heat sink supply. The NRC Resident Inspector has been informed.Steam Generator
Feedwater
Residual Heat Removal
05000316/LER-2003-005
ENS 4040219 December 2003 23:44:0010 CFR 50.72(a)(1)(i), Emergency Class DeclarationUnusual 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.

  • * * UPDATE AT 2020 ON 12/19/03 FROM KEPPLER TO THOMAS * * *

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.