Semantic search
| Entered date | Site | Region | Reactor type | Event description | |
|---|---|---|---|---|---|
| ENS 56789 | 12 October 2023 12:17:00 | Cook | NRC Region 3 | The following information was provided by the licensee via email: Donald C. Cook Nuclear Power Plant completed an internal Part 21 evaluation concerning an issue with an Emergency Diesel Generator (EDG) Digital Reference Unit (DRU) supplied by Engine Systems Incorporated (Appendix B Supplier for Woodward Governors). (On August 8, 2023,) a potential defect was identified (during a surveillance test) concerning a marginal solder joint on the DRU electronic circuit board that can result in a loss of continuity between the termination strip and the electronic board, causing a loss of setpoint output from the DRU to the Electronic Governor, and a subsequent loss of fuel to the EDG and inability to support any load. A formal failure analysis is ongoing at the time of this notification. A written notification will be provided within 30 days. Affected known plants include only Donald C. Cook Nuclear Power Plant Units 1 and 2 at the time of notification. The NRC Resident has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The EDG DRU was replaced after discovery of the potential defect and the EDG is currently operable. | |
| ENS 56216 | 10 November 2022 10:12:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | The following information was provided by the licensee via email: At 0744 EST on November 10, 2022, DC Cook Unit 2 tripped automatically on high-high level of number 23 steam generator (SG). The reason for the high-high level in SG 23 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, 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. 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. |
| ENS 56076 | 28 August 2022 15:41:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | The following information was provided by the licensee via fax or email: On August 28, 2022 at 1348 EDT, DC Cook Unit 1 reactor automatically tripped due to a trip of the #13 Reactor Coolant Pump. 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 1 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 1 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event. Unit 2 remains stable at 100% power / Mode 1. |
| ENS 56046 | 16 August 2022 12:33:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | A licensed employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. |
| ENS 55910 | 24 May 2022 06:49:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | The following information was provided by the licensee via email: On May 24, 2022, at 0414 EDT, while rolling the Unit 1 main turbine during the Unit 1 Cycle 31 refueling outage, the Unit 1 main turbine experienced high vibrations and the main turbine was manually tripped with reactor power at 12 percent. Main turbine vibrations persisted and the reactor was manually tripped, Main Steam Stop Valves were closed, and main condenser vacuum was broken. 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 1 is being supplied by offsite power. All control rods fully inserted. Both Motor Driven Auxiliary Feedwater Pumps started properly. Decay heat is being removed via Steam Generator Power Operated Relief Valves. 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. |
| ENS 55691 | 6 January 2022 11:06:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: On 01/06/22 at 1044 (EST), an Unusual Event was declared due to a Fire Detection Actuation in the Unit 1, auxiliary cable vault (EAL H.U 4.1). No fire was detected. Unit 1 and Unit 2 remain at 100 percent power. The Llcensee notified the NRC Resident Inspector, the state, and local authorities. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).
At 1441 (EST), DC Cook Unit 1 terminated their notification of unusual event. The basis for termination was that the inspection identified no damage to cables or cable trays. The fire protection system is out of service for the auxiliary cable vault with compensatory measures in effect. The licensee has notified the state and local authorities and will notify the NRC Resident Inspector. Notified R3DO (Skokowski), IRD MOC (Grant), NRR EO (Felts), IR (Kennedy)(email), NRR (Veil)(email), R3 DRA (Shuaibi)(email), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). |
| ENS 55322 | 23 June 2021 01:55:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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. |
| ENS 54944 | 12 October 2020 03:46:00 | Cook | NRC Region 3 | At 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. | |
| ENS 54885 | 5 September 2020 02:27:00 | Cook | NRC Region 3 | On 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. | |
| ENS 54729 | 27 May 2020 11:35:00 | Cook | NRC Region 3 | On 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 54687 | 1 May 2020 11:53:00 | Cook | NRC Region 3 | 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.
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). | |
| ENS 54291 | 24 September 2019 15:02:00 | Cook | NRC Region 3 | On 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 54241 | 26 August 2019 16:41:00 | Cook | NRC Region 3 | A 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 54176 | 21 July 2019 12:08:00 | Cook | NRC Region 3 | On 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. | |
| ENS 54036 | 29 April 2019 22:50:00 | Cook | NRC Region 3 | On 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 53387 | 7 May 2018 06:42:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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. |
| ENS 53342 | 18 April 2018 09:29:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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 53334 | 13 April 2018 20:01:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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. |
| ENS 53230 | 27 February 2018 01:15:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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 52967 | 13 September 2017 01:08:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 0047 EDT, the licensee declared a notification of unusual event under emergency action level (EAL) S8 due to actuation of the letdown relief valve which resulted in reactor coolant system leakage to the pressurizer relief tank exceeding 10 gpm. The plant was in mode 3 at the time making preparations to proceed to cold shutdown to support their refueling outage. Operators were in the process of reducing reactor coolant system letdown from 120 gpm to 45 gpm when the letdown system relief valve lifted. The relief discharged to the pressurizer relief tank at approximately 12 gpm. Operators isolated the letdown line which reduced the leakage to approximately 1 gpm. Plant staff is in the process of determining where the 1 gpm leakage is from and evaluating the basis for terminating the unusual event. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email).
At 0800 EDT, the licensee terminated the notification of unusual event. The basis for termination was that the letdown line was isolated which reduced leakage to less than the EAL threshold of 10 gpm. The cause of the letdown relief lifting is still under investigation. The licensee has notified the NRC Resident Inspector and will be notifying the state of Michigan and Berrien County. The licensee has issued a press release to the media concerning this event. Notified R3DO (Riemer), IRD MOC (Stapleton), NRR (Miller), DHS SWO, DHS NICC, FEMA Ops Center, FEMA National Watch Center (email) and Nuclear SSA (email).
The condition reported in Event Notification #52967 pursuant to 10 CFR 50.72(a)(1)(i) has been evaluated, and determined not to have met the threshold for classification as an Unusual Event under Emergency Action Level (EAL) S-8 and is being retracted. During the events of 9/13/17, Control Room staff calculated Reactor Coolant System (RCS) leakage to the Pressurizer Relief Tank (PRT) through the Letdown Relief Valve to be greater than the EAL S-8 threshold of 10 gallons per minute. Subsequent review of trends associated with PRT level increase during the event determined that the RCS leakage to the PRT was less than 10 gallons per minute and therefore did not represent an Unusual Event under EAL S-8. The NRC Resident Inspector was notified of this retraction. Notified R3DO (Riemer). |
| ENS 52649 | 30 March 2017 03:19:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | The Unit 1 DC Cook Nuclear Plant (CNP) Annunciator System failed on Thursday, March 30, 2017 at 0255 (EDT). The failure resulted in a complete loss of all alarm function of the Annunciator System in the Unit 1 Control Room. Unit 2 was unaffected by this failure. At 0310 (EDT), an Unusual Event (UE) was declared due to System Malfunction S-6, Loss of Alarms or Indication, due to an unplanned loss of safety system annunciators and/or indications in the Control Room for greater than 15 minutes. The Unit 1 PPC (Plant Process Computer) and ERDS (Emergency Response Data System) remain functional and available. This notification is being made in accordance with 10 CFR 50.72(a)(1)(i) due to the declaration of an Emergency Classification specified in the licensee's approved Emergency Plan. The licensee has notified the NRC Resident Inspector, the State and local agencies. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.
Unit 1 DC Cook Nuclear Plant Annunciator System has been returned to functional. Unusual Event Classification was terminated at 0817 EDT on 3/30/17. The NRC Resident Inspector will be notified. Notified R3DO (Cameron), NRR EO (Miller), and IRD (Grant). Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail. |
| ENS 52585 | 1 March 2017 15:18:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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 52544 | 8 February 2017 22:19:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 52456 | 22 December 2016 05:45:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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). |
| ENS 52065 | 6 July 2016 01:02:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On July 6, 2016, at 0038 (EDT), DC Cook Unit 2 Reactor was manually tripped and at 0050 (EDT) an Unusual Event (N-7 'Unanticipated Explosion') Emergency Declaration was made due to steam leak and associated damage to the turbine building. In accordance with Emergency Plan procedures, notifications of Berrien County and State of Michigan were completed. The licensee has notified the NRC Senior Resident Inspector. The Unusual Event was terminated at 0207 (EDT). This notification is being made in accordance with 10 CFR 50.72 (a)(1)(i) due to declaration of an emergency class. Original notification to NRC made at 0100 EDT via ENS. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation and 10 CFR 50.72(b)(2)(xi) Offsite Notification, as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. The DC Cook NRC Resident Inspector has been notified. A press release is planned. Unit 2 is being supplied by offsite power. All control rods fully inserted. Decay heat is being removed via Steam Generator PORVs (Power Operated Relief Valve). Preliminary evaluation indicates all plant systems functioned normally following the reactor trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via email. |
| ENS 51859 | 8 April 2016 20:50:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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 51106 | 31 May 2015 16:32:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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).
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). |
| ENS 51004 | 23 April 2015 05:25:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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. |
| ENS 50822 | 13 February 2015 15:55:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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 50697 | 20 December 2014 13:39:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
The licensee issued a press release about this event this afternoon. Notified R3DO (Dickson). |
| ENS 50587 | 1 November 2014 05:03:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
At 0921 EDT, DC Cook issued a press release regarding the event described earlier. The licensee notified the NRC Resident Inspector. Notified R3DO (Lipa) |
| ENS 50498 | 28 September 2014 10:55:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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 50462 | 16 September 2014 16:34:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 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 50386 | 21 August 2014 04:03:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | At 0210 EDT on August 21, 2014, D.C. Cook made notifications to the State of Michigan, local authorities and the National Response Center due to a suspected release of approximately 8,700 gallons of diesel fuel oil to the environment. The level in the buried fuel oil storage tank for the Train B Emergency Diesel Generator was found to be approximately 8,700 gallons less than measurements taken within the last 24 hours. The tank is located within the plant protected area. At this time the suspected fuel oil plume has not left the site. The NRC Resident Inspector was notified. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) and NUREG 1022 section 3.2.12, due to notification of offsite agencies.
An event investigation determined that no spill occurred. The discrepancy in level was due to maintenance activities that caused an error in level indication. No actual loss of inventory from the fuel oil storage tank occurred. Offsite agencies have been notified that this spill event is being retracted (to the State and Offsite agencies). The NRC Resident Inspector was notified. Notified the R3DO (Passehl). |
| ENS 50320 | 30 July 2014 08:16:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | A 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 50238 | 30 June 2014 07:50:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 50223 | 24 June 2014 10:37:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
At 1615 EDT, TSC ventilation systems were restored to service. The licensee will be notifying the NRC Resident Inspector. Notified R3DO (Lara) |
| ENS 50188 | 11 June 2014 01:23:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 6/10/14 at approximately 2327 EDT, the Operations Shift Manager was made aware that the Berrien County Sheriffs Department (BCSD) had been notified of an Emergency Siren that had actuated. BCSD was notified by local residents. BCSD reset the emergency siren and a local police officer verified the siren was no longer actuating. The cause of the actuation is under investigation at this time. The siren remains in service pending further investigation. There are a total of 70 sirens and all remain functional. This notification is being made under 10 CFR 50.72(b)(2)(xi), Offsite Notification, as a four (4) hour report. The licensee has notified the NRC Resident Inspector. |
| ENS 50149 | 29 May 2014 14:10:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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). |
| ENS 50022 | 10 April 2014 14:33:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
The licensee provided additional clarifying information. The NRC Resident Inspector will be informed. Notified R3DO (Cameron). |
| ENS 49803 | 7 February 2014 03:04:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 49687 | 1 January 2014 15:21:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 49682 | 31 December 2013 10:50:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 49563 | 20 November 2013 17:04:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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).
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). |
| ENS 49364 | 20 September 2013 05:42:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On 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 49289 | 19 August 2013 08:46:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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).
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. |
| ENS 49220 | 28 July 2013 13:43:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | On July 28, 2013, at 1018 EDT, DC Cook Unit 2 Reactor was manually tripped due to lowering steam generator level caused by an automatic trip of the west main feed pump. The west main feed pump tripped on low suction pressure resulting from a secondary plant transient. The cause of the secondary transient is still under investigation. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation, as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an (8) hour report. The DC Cook Sr. Resident NRC Inspector has been notified. The electrical grid is stable and Unit 2 is being supplied by offsite power. All control rods fully inserted. Decay heat is being removed via steam dumps to the main condenser. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the post trip review. No radioactive release is in progress as a result of this event. There was no affect on Unit 1.
Additional information received determined the Turbine Driven Auxiliary Feedwater Pump discharge valve to Steam Generator #2 did not position, as required, following the reactor trip. The affected discharge valve opened as expected during pump start. The valve closed instead of throttling to the intermediate position upon subsequent high flow demand. Feedwater flow to Steam Generator #2 was maintained by the East Motor Driven Auxiliary Feedwater Pump. The NRC Resident Inspector has been notified of this update. Notified R3DO (Orth). |
| ENS 49191 | 15 July 2013 16:10:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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). |
| ENS 49170 | 3 July 2013 01:15:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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 48980 | 29 April 2013 08:41:00 | Cook | NRC Region 3 | Westinghouse PWR 4-Loop | 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.
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).
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).
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). |