Semantic search
| Discovered date | Reporting criterion | Title | Description | LER | |
|---|---|---|---|---|---|
| ENS 57041 | 13 March 2024 10:48:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection (HPCI) Inoperable | The following information was provided by the licensee via email and phone: At 0548 CDT on March 13, 2024, during a planned (high pressure coolant injection) HPCI maintenance window, a condition was identified not associated with the planned maintenance which caused HPCI to be inoperable. Specifically, the HPCI auxiliary oil pump start stop pressure switch could not be adjusted into calibration. Further investigation found that the pressure switch was not mounted as designed. Since HPCI is a single train system, this is a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). The condition was corrected prior to HPCI being declared operable on March 15, 2024. The reason for the delay in the event notification beyond 8 hours from the event time was due to not recognizing the need to report the condition while in a planned HPCI maintenance window. The NRC Senior Resident Inspector has been notified. | |
| ENS 56989 | 22 February 2024 17:03:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Accident Mitigation - High Pressure Coolant Iinjection Declared Inoperable | The following information was provided by the licensee via email: At 1103 CST on February 22, 2024, a potential through-wall steam leak was identified on the high pressure coolant injection (HPCI) steam supply 1-inch drain line. As a result, HPCI was declared inoperable. Since HPCI is a single-train system, this is a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). Reactor core isolation cooling (RCIC) and low pressure emergency core cooling systems (ECCS) remain operable. Additional investigation is in progress. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 56811 | 22 October 2023 16:49:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Momentarily Inoperable | The following information was provided by the licensee via fax and phone: On October 22, 2023, at 1149 CDT, with the reactor at 100 percent core thermal power and steady state conditions, the Cooper Nuclear Station secondary containment differential pressure exceeded the Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.1.1 limit of -0.25 inches water gauge. The condition existed for approximately 80 seconds until the reactor building ventilation system responded to restore differential pressure to normal. Investigations identified a hinged duct access hatch found open. The hatch was closed and latched, and ventilation system parameters were returned to normal. There were no radiological releases associated with this event. Declaring secondary containment inoperable as a result of not meeting TS SR 3.6.4.1.1 is reportable under 10 CFR 50.72(b)(3)(v)(C) and (D) as an event or condition that could have prevented the fulfillment of a safety function needed to control the release of radioactive material and mitigate the consequences of an accident. The NRC Senior Resident Inspector has been informed. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At the time the licensee notified the NRC Headquarters Operations Officer, the cause of the hinged access duct being open had not been determined. This event has been added to the licensee's corrective action program. | |
| ENS 56786 | 10 October 2023 20:53:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification - Spurious Alarm Actuation | The following information was provided by the licensee via fax: On October 10, 2023, at 1553 CDT, Cooper Nuclear Station (CNS) was notified of a spurious actuation of a single alert notification system siren in Nemaha, Nebraska. The CNS Emergency Alert System (EAS) was not activated. The actuation occurred during siren testing conducted at approximately 1545 CDT. No emergency conditions are present at Cooper Nuclear Station. A press release from Nebraska Public Power District is not planned at this time. This condition is reportable under 10CFR 50.72(b)(2)(xi) for any event or situation for which a news release is planned or notification to other government agencies has been or will be made which is related to heightened public or government concern. The NRC Senior Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Offsite notification was to local Nemaha County Emergency Management. | |
| ENS 56509 | 8 May 2023 07:07:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Shutdown Required by Technical Specifications Due to Inoperable Core Spray | The following information was provided by the licensee via fax: At time 0207 CDT, Cooper Nuclear Station (CNS) entered Technical Specification (Limiting Condition for Operation) LCO 3.0.3 due to declaring core spray subsystems A and B inoperable. This declaration was based on an issue with relays installed from the same manufacturing batch. The ability of the relays to function correctly to annunciate loss of logic power was called into question and they were declared inoperable. The plant has initiated actions to repair/replace affected relays. This event is reportable under 10 CFR 50.72(b)(2)(i) as an initiation of any nuclear plant shutdown required by Technical Specifications. In addition, this event Is reportable under 10 CFR 50.72(b)(3)(v) as a condition that could have prevented the fulfillment of a safety function for the core spray systems. NRC Resident Inspector was notified.
The following information was provided by the licensee via email: Technical Specification LCO 3.0.3 was exited at 0805 CDT on May 8, 2023. A reasonable expectation of operability was developed for the core spray subsystems A and B. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Shutdown was initiated and power was reduced approximately 45 percent. Reactor power is currently at 55 percent at the time of notification. Notified R4DO (Werner) via email.
The following information was provided by the licensee via email: CNS is retracting the 8-hour 10 CFR 50.72(b)(3)(v) non-emergency notification, for a condition that could have prevented the fulfillment of a safety function, made on May 8, 2023, at 0207 CDT (EN# 56509). Subsequent evaluation concluded that the core spray subsystems remained operable in accordance with the Technical Specifications Requirements 3.5.1, ECCS - Operating. As a result of the core spray system remaining operable, no loss of safety function occurred. The NRC Senior Resident Inspector has been notified. Notified R4DO (Werner). | |
| ENS 56346 | 9 February 2023 16:06:00 | 10 CFR 26.719, FFD Reporting requirements | Failed Fitness for Duty Test | The following information was provided by the licensee via fax: A licensed operator had a confirmed positive for alcohol during a for-cause fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. | |
| ENS 56278 | 17 December 2022 05:51:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Scram | The following information was provided by the licensee via email: On December 16, 2022 at 2351 CST, with the Unit in Mode 1 at 13 percent power, a manual scram was inserted due to lowering Reactor Pressure Vessel (RPV) pressure, which occurred following an unexpected opening of Main Turbine Bypass Valve 1. All control rods fully inserted. Following actuation of the manual scram, RPV pressure lowered, resulting in an automatic Primary Containment lsolation (PCIS) Group 1 isolation (expected response). The main steam isolation valves and steam line drain valves all closed. The Group 1 (isolation) has been reset allowing RPV pressure control with steam line drains to the main condenser. All systems responded as designed. The plant is stable in Mode 3. Investigation of the bypass valve opening is ongoing. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) RPS Actuation and 50.72(b)(3)(iv)(A) Specified System Actuation. There was no impact on health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified. | |
| ENS 56220 | 13 November 2022 04:19:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Scram | The following information was provided by the licensee email: On November 12, 2022, at 2319 CST, an actuation of the reactor protection system (RPS) initiated a full scram. The plant was in Mode 2, reactor pressure was 149 pounds. The high pressure coolant injection (HPCI) injection valve, HPCI-MOV-MO19, opened and injected cold water into the reactor vessel while HPCI system testing was in progress. The cause is still under investigation. All control rods inserted. Plant is currently in Mode 3 and stable. All systems operated as designed with no Primary Containment Isolation System group isolations. This event is being reported under two event classifications: 50. 72(b)(2)(iv)(B) -- "Any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. 50. 72(b)(3)(iv)(A) -- "Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. The NRC Resident has been informed. | |
| ENS 56174 | 22 October 2022 17:58:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | ECCS Injection While Shutdown | The following information was provided by the licensee via fax: During Mode 5 Refueling operations, while attempting to establish flow through the Fuel Pool Cooling system filter demineralizers, an air operated valve to a radioactive waste tank failed to close automatically. This caused the Fuel Pool Cooling system to pump water from the Skimmer Surge Tanks (SST) to the radioactive liquid waste system. In response to the loss of inventory from the SSTs, the Control Room operating crew started Core Spray Pump A to restore normal operating level In the SST. This prevented the loss of the Fuel Pool Cooling/Alternate Decay Heat Removal system which was the only in service system meeting the safety function of decay heat removal. Core Spray Pump A was used for Injection for less than 3 minutes. This is reportable as a discharge of ECCS into the RCS in response to an event, but not part of a pre-planned sequence under 10 CFR 50.72(b)(2)(iv)(A) and actuation of a specified system under 10 CFR 50.72(b)(3)(Iv)(A). The resident inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Licensee reported approximately 6000-7000 gallons of water was injected into the RCS. The stuck open air operated valve was closed. Proceeding with refueling outage operations. | |
| ENS 56152 | 7 October 2022 05:50:00 | 10 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person Offsite | Potentially Contaminated Individual Transported to Hospital | The following information was provided by the licensee via fax: On 10/7/2022 at 0050 CDT, a potentially contaminated individual was transported off-site via ambulance to a local hospital. Due to the nature of the medical condition, an initial on-site survey for radioactive contamination was not performed prior to transport. Prior to arrival at the hospital, it was confirmed the individual and (the individual's) clothing were not radiologically contaminated. Follow-up surveys performed by radiation technicians identified no radiological contamination of the ambulance and response personnel. This event is being reported per 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 57001 | 27 August 2022 05:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - Service Water Booster Pump Bearing Housing Cover Oil Leak | The following information was provided by the licensee via phone and email: On August 27, 2022, while in Mode 1 at 100 percent power, Nebraska Public Power District (NPPD) Cooper Nuclear Station (CNS) identified a 3 drops per minute (dpm) oil leak from the radial (inboard) bearing housing cover on one of four residual heat removal (RHR) service water booster pumps (SWBP); specifically, SWBP-D. Subsequent analysis determined that the leak was a result of a deviation with the configuration of the labyrinth seal drain path. This deviation was due to an error introduced in a manufacturing drawing used by the vendor for the fabrication of four new replacement pumps. The bearing housing cover is a unique design to CNS for the RHR SWBPs. On March 1, 2024, NPPD completed a substantial safety hazard evaluation and determined that the manufacturing drawing error could cause a substantial safety hazard. The NRC Resident Senior Resident has been notified. This is a non-emergency notification required by 10 CFR 21.21(d)(3)(i). A written notification will be provided within 30 days. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All four SWBPs had a similar housing design. Three of the four pump housings have been replaced. No other nuclear plant is affected due to the housing design being unique to CNS. | |
| ENS 55981 | 7 July 2022 21:01:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of National Warning System Tower | The following information was provided by the licensee via phone and fax: On 7/7/2022, at 0740 CDT, the National Weather Service reported to Cooper Nuclear Station that the NAWAS ((National Warning System)) radio tower near Shubert, Nebraska would neither transmit nor receive. The Shubert Tower transmitter activates the EAS ((Emergency Alert System))/Tone Alert Radios used for public notification. Additional information from the National Weather Service received 7/7/2022 at 1601 (CDT) determined that the Shubert Tower transmitter is non-functional and would not likely be repaired within 24 hours. The backup notification system has been verified to be available throughout this period. This is considered to be a major loss of the Public Prompt Notification System capability. The primary notification system is not expected to be restored to service within 24 hours, and therefore this condition is reportable under 10 CFR 50.72(b)(3)(xiii), since the backup alerting methods do not meet the primary system design objective. The backup notification system is available to use for notifications if needed. The NRC Senior Resident has been informed. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The backup notification system has to be manually activated. | |
| ENS 55907 | 23 May 2022 09:55:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Pressure Exceeded Technical Specification Requirement | The following information was provided by the licensee via email: On May 23, 2022, at 0455 CST, Cooper Nuclear Station experienced a spike in Secondary Containment differential pressure which exceeded the Technical Specifications Surveillance Requirements 3.6.4.1.1 limit of -0.25 inches of water gauge. Secondary Containment differential pressure restored to Technical Specification limits within two minutes and further investigation is ongoing. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10CFR50.72(b)(3)(v)(C) and (D). The NRC Senior Resident Inspector has been informed. | |
| ENS 55715 | 27 January 2022 16:38:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Meteorlogical Data Acquisition System | The Licensee provided the following information via email: On January 27, 2022 at 1038 CST, with Cooper Nuclear Station in Mode 1, 100 percent power, the meteorological tower primary and backup data acquisition system failed, which resulted in a loss of meteorological data to the plant. Information technology personnel investigated and restored the primary system to service. Meteorological data to the plant was restored at 1105 CST on January 27, 2022. This notification Is being made due to a loss of emergency assessment capability In accordance with 10 CFR 50.72(b)(3)(xiii). The NRC Resident Inspector has been Informed.
The following information was provided by the licensee via fax: This notification is being made to retract event EN 55715 that was reported on January 27, 2022. Based on further investigation, the Emergency Plan and Emergency Plan Implementing Procedures provide acceptable alternative methods for performing emergency assessments that are in addition to the data obtained from the primary and backup meteorological tower information. It was determined that no actual or potential major loss of emergency assessment capability existed per 10 CFR 50.72(b)(3)(xiii). This is consistent with NUREG 1022, Revision 3, Supplement 1 and NEI 13-01, Revision 0. The NRC Resident Inspector has been notified of the retraction. Notified R4DO (O'Keefe) | |
| ENS 55703 | 13 January 2022 14:06:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Spurious Siren Actuation | The following information was provided by the licensee via fax: On 1/13/2022 at 0806 CST, Nebraska Public Power District was notified by Atchison County Missouri of a spurious actuation of (Cooper Nuclear Station) (CNS) Emergency Siren 2113 near Rockport, Missouri from approximately 0800 to 0805 CST. Nebraska Public Power District will issue a press release for this event. The CNS Emergency Alert System (EAS) was not activated. This condition is reportable under 10 CFR 50.72(b)(2)(xi) for any event or situation for which a news release is planned or notification to other government agencies has been or will be made which is related to heightened public or government concern. The NRC Senior Resident Inspector has been informed. | |
| ENS 55098 | 9 February 2021 07:53:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Control Release of Radioactive Material and Accident Mitigation | On February 9, 2021, at 0153 CST, Cooper Nuclear Station experienced a spike in Secondary Containment differential pressure which exceeded the Technical Specifications Surveillance Requirements 3.6.4.1.1 limit of -0.25 inches of water gauge. Secondary Containment differential pressure oscillated coincident with barometric pressure oscillations. Three additional spikes occurred which exceed the Technical Specification limit. The duration of each spike was less than one minute. The last spike occurred at 0232 CST. Secondary Containment differential pressure has restored to Technical Specification limits and further investigation is ongoing. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10CFR50.72(b)(3)(v)(C) and (D), "An event or condition that at the time of discovery could have prevented the fulfillment of the safety function of (Structures, Systems, and Components) SSCs that are needed to control the release of radioactive material and mitigate the consequences of an accident. The NRC Senior Resident Inspector has been informed. | |
| ENS 54976 | 1 November 2020 10:34:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip Due to an Un-Isolable Leak on the Turbine High Pressure Fluid System | On November 1, 2020, at 0534 CST the reactor was manually scrammed due to an un-isolable leak on the Turbine High Pressure Fluid System. Initial power level when the leak was identified was 100 percent. Power was lowered commencing at 0525 in accordance with shutdown procedures. The Reactor Operator scrammed the reactor at 0534 from approximately 75 percent power. Following the scram, Reactor vessel water level lowered to approximately -20 inches on the Wide Range Instruments, and was subsequently recovered to normal post scram range (approximately 36 inches) using the Reactor Feedwater system. Group 2 Isolation occurred due to Reactor vessel level reaching the isolation setpoint (3 inches). The plant is stable in MODE 3 and proceeding to cold shutdown. The Main Condenser remained available throughout the evolution and condenser vacuum is currently being maintained by the Mechanical Vacuum Pumps. Pressure is being controlled using the steam line drains to the main condenser. All control rods fully inserted and there were no complications. All systems responded as designed. The Turbine High Pressure Fluid System has been secured. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) due to RPS Actuation-Critical and 50.72(b)(3)(iv)(A) Valid Specified System Actuation. The licensee has notified the NRC Resident Inspector. | |
| ENS 54690 | 1 May 2020 13:31:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Secondary Containment Access Doors Open Simultaneously | At 0831 CDT, the Main Control Room received a 'Reactor Building 903 ft. Access Both Doors Open' alarm. Investigation found the interlock between the inner and outer doors did not prevent the opening of both doors while personnel were accessing the Reactor Building. The doors were immediately closed. Based on alarm times, both doors were open for less than one second. With both doors open, SR 3.6.4.1.3 was not met and Secondary Containment was declared inoperable. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10 CFR 50.72(b)(3)(v)(c) and (d), 'An event or condition that at the time of discovery could have prevented the fulfillment of the safety function of SSCs that are needed to control the release of radioactive material and mitigate the consequences of an accident.' Secondary Containment was declared operable at 0836 CDT after independently verifying at least one Secondary Containment access door was closed. The NRC Senior Resident Inspector has been informed. | |
| ENS 54425 | 5 December 2019 14:10:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Fire Door Discovered Unlatched | The following was received via email from Cooper Nuclear Station: At 0810 (CST), on 12/5/19, Operations personnel discovered BLDG-DOOR-R209, FIRE DOOR BETWEEN CRITICAL SWITCHGEAR ROOMS F & G, was unlatched. The door was immediately latched upon discovery. Based on door logs, the door separating the two critical switchgear rooms was inadvertently left unlatched for approximately 5 minutes. This door is a Steam Exclusion Boundary (SEB) door. It is required to be closed and latched when the Auxiliary Steam Boiler is in service due to Auxiliary Steam piping passing through Critical Switchgear Room 'G'. If a steam line break was to occur with the door unlatched, steam could render both Critical Switchgear busses inoperable. This is being reported under 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, and 10 CFR 50.72(b)(3)(v), 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 (B) remove residual heat and to (D) mitigate consequences of an accident. There was no impact on the health and safety of the public or plant personnel. The door closes automatically and appeared to have been left unlatched by the last person passing through. The door was tested and latches as required. The licensee notified the NRC Resident Inspector. | |
| ENS 54232 | 19 August 2019 14:39:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Public Prompt Notification System | At 0939 CDT, on 8/19/19, the National Weather Service reported to Cooper Nuclear Station that the National Warning System (NAWAS) Radio would neither transmit nor receive. The system has been intermittently available since then, but never declared fully functional. The backup notification system has been verified to be available throughout this period. Additional information from the National Weather Service received 8/20/19 at 1414 determined that the Shubert Tower transmitter is non-functional and would not be repaired until 8/21/19. The transmission outage is conservatively assumed to have begun at the first notification on 8/19/19 at 0939. The Shubert Tower transmitter activates the (EMERGENCY ALERT SYSTEM) EAS/Tone Alert Radios used for public notification. This is considered to be a major loss of the Public Prompt Notification System capability and is reportable under 10 CFR 50.72(b)(3)(xiii) when the primary notification system is or will be unavailable for greater than 24 hours with the backup system available. The NRC Senior Resident has been informed. | |
| ENS 54099 | 4 June 2019 13:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Issuance of Press Release Due to Spurious Actuation of Emergency Sirens | On 06/04/2019, Nebraska Public Power District will issue a press release concerning the spurious actuation of emergency sirens near Cooper Nuclear Station and Indian Cave State Park. This is a four hour report per 10 CFR 50.72(b)(2)(xi) for any event or situation for which a news release is planned or notification to other government agencies has been or will be made which is related to heightened public or government concern. The cause of the siren actuation is still under investigation. The licensee notified the NRC Resident Inspector.
During this event, State & local government agencies (Nemaha County, Atchison County, Richardson County, and Indian Cave State Park) were contacted regarding the spurious actuation of emergency sirens. This is an update to the original Event Notification # 54099. Notified R4DO (Kellar). | |
| ENS 54049 | 5 May 2019 19:05:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | En Revision Imported Date 5/31/2019 | EN Revision Text: SECONDARY CONTAINMENT DECLARED INOPERABLE DUE TO POTENTIAL EQUIPMENT FAILURE At 1405 CDT, Secondary Containment differential pressure exceeded the Technical Specification limit due to a potential equipment failure. This required entry into (Limiting Condition of Operation) LCO 3.6.4.1 Condition A for Secondary Containment inoperability. An event or condition that could have prevented the fulfillment of a safety function requires an 8 hour report per 10 CFR 50.72(b)(3)(v)(C) for Control of Rad Release. Secondary Containment differential pressure was restored to greater than or equal to 0.25 inches vacuum, water gauge in accordance with plant procedures. Secondary Containment was declared operable at 1600 CDT. The issue has been entered in the Corrective Action Program and investigation of the cause is in progress. The NRC Senior Resident Inspector has been informed of this condition.
CNS (Cooper Nuclear Station) is retracting the 8-hour notification made for event 54049 which occurred on May 5, 2019 at 1405 CDT. Subsequent evaluation determined that no equipment failure occurred. In addition, there were no procedure inadequacies or human performance issues identified. The indications observed were expected and part of a pre-planned evolution which included entry into a planned LCO for the Secondary Containment. The NRC Resident Inspector has been notified. Notified the R4DO (Kozal). | |
| ENS 53941 | 16 March 2019 16:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Tone Alert Radio Transmission Tower | At approximately 1100 CDT on March 15, 2019, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was not functioning due to evacuating their office in Omaha as a result of local flooding. This affects the tone alert radios used to notify the public in event of an emergency condition. Loss of function of this tower is reportable at 1100 CDT on March 16, 2019, when the tower could not be restored within 24 hours of the loss. This condition is reportable under 10 CFR 50.72(b)(3)(xiii). A backup notification method is available and will be utilized for notifications if needed. A return to service time for the Shubert tower is not currently available. The NRC Senior Resident Inspector has been informed. | |
| ENS 53934 | 15 March 2019 10:46:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | En Revision Imported Date 3/25/2019 | EN Revision Text: UNUSUAL EVENT DECLARED DUE TO HIGH RIVER LEVEL At 0546 CDT, Cooper Nuclear Station declared an Unusual Event due to the Missouri River level reaching 899.05 feet above mean sea level (MSL), which is above the Emergency Action Level (EAL) HU 1.5 elevation of 899 feet above MSL. The river is expected to crest above 901 feet above MSL within the next day, and remain above 899 feet above MSL for the next several days. Declaration of an Unusual Event is a 1 hour report, and is reportable under 10 CFR 50.72.a.1.1. Actions are in progress in accordance with site flooding procedure, including strategic placement of barriers at building entrances and important facilities. There is no major plant equipment out of service at this time. Personnel access to the site is not presently impeded and emergency evacuation routes remain available. A press release is planned for this event, which is a four hour report, reportable under 10 CFR 50.72.b.2.11. If the Missouri River were to reach 901.5 feet above MSL, Cooper would initiate a unit shutdown in accordance with their procedures. If the Missouri River were to rise greater than 902 feet above MSL, Cooper will declare an Alert. The licensee notified the NRC Resident Inspector. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
The licensee terminated the Unusual Event at 1601 CDT due to lowering Missouri River water levels. River water level is currently at 896.0 feet MSL and lowering. A press release will be issued to inform the public of Cooper Nuclear Station's exit from the Notification of Unusual Event regarding high Missouri River level. The initial entry into the Notification of Unusual Event occurred on 03/15/2019 and was exited on 03/24/2019 at 1601 CDT. The press release is reportable per 10 CFR 50.72(b)(2)(xi). The licensee notified the NRC Resident Inspector. Notified R4DO (O'Keefe), NRR EO (Miller), IRD MOC (Gott), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). | |
| ENS 53809 | 29 December 2018 06:00:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notice of Unusual Event Due to Toxic Gas and Fire | At 0904 CST, on December 29, 2018, Cooper declared a Notice of Unusual Event under emergency action level HU 3.1. The emergency declaration was due to a toxic gas asphyxiant as a result of a fire. The fire is contained and the fire brigade continues to extinguishing the fire. Offsite support has not been requested. The licensee notified the NRC Resident Inspector. Additionally, State and Local government agencies were also notified. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
At 1544 CST, on December 29, 2018, Cooper terminated the Notice of Unusual Event under emergency action level HU 3.1. The fire was verified to be extinguished and the flammable material was removed. The plant remained at 100% power for the duration of the event. The licensee issued a press release regarding the event at 1202 CST, on December 29, 2018. The license notified the NRC Resident Inspector. Notified R4DO (Taylor), NRR EO (Groom), IRD MOC (Gott), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). | |
| ENS 53668 | 15 October 2018 05:00:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness-For-Duty Test Positive for Licensed Employee | In accordance with 10 CFR 26.719(b)(2)(ii), this notification reports a licensed Reactor Operator tested positive for alcohol during a random fitness for duty test. The employee's access to the plant has been suspended. The NRC Senior Resident Inspector has been notified. | |
| ENS 53776 | 13 October 2018 05:00:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of Invalid Specified System Actuation | This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a Primary Containment Isolation System (PCIS) Group 1 for Main Steam Isolation Valves (MSIVs), Group 3 for Reactor Water Cleanup (RWCU), Group 6 for Secondary Containment isolation, Group 7 for Reactor Water Sampling, Diesel Generator, Reactor Core Isolation Cooling (RCIC) System logic, and Residual Heat Removal (RHR) logic. Group 1, Group 6, Diesel Generator actuation, RCIC actuation and RHR actuation are within scope of 10 CFR 50.73(a)(2)(iv). Group 3 and Group 7 are not within scope as they affect only one system. Cooper Nuclear Station (CNS) was shut down in Mode 5 at the time of the event with the reactor cavity flooded. On October 13, 2018, at 0028 Central Daylight Time, CNS received full PCIS Groups 1, 3, and 6, and a half Group 7 on the Division 1 side. The MSIVs and RWCU isolation valves were already closed for maintenance. The Secondary Containment isolated. Control Room Emergency Filter and the Standby Gas Treatment Systems initiated. The inboard Reactor Water Sample valve isolated. Diesel Generator #1 started but was not required to connect to the critical bus. Reactor Core Isolation Cooling System logic actuated with no expected response due to being isolated for shutdown conditions. Division 1 RHR pump logic actuated. Division 1 RHR system was operating in shutdown cooling mode. The actuation caused the Division 1 RHR outboard injection and heat exchanger bypass valves to open. Shutdown cooling was unaffected and remained in service throughout the event. The plant systems responded as expected with no Emergency Core Cooling System injection. At the time of the event, an in-service inspection of welds inside the reactor vessel was taking place using a robot scanner that uses two vortex thrusters to hold the robot to the vessel wall. The robot inadvertently passed over an instrument penetration, drawing suction on the process leg, resulting in low reactor water level indications and the subsequent invalid Level 1 and 2 system actuations. Actual reactor vessel water level remained steady at cavity flooded conditions. The NRC Resident Inspector has been notified of this event. | |
| ENS 53650 | 5 October 2018 05:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Emergency Filter System Inoperable | On 10/5/2018, at 2219 CDT, the Control Room Emergency Filter (CREF) System was determined to be inoperable during a required condition of applicability due to being aligned to a Division 2 power source with its associated emergency power supply (Diesel Generator #2) removed from service earlier in the day. The power supply alignment was not identified at the time Diesel Generator #2 was removed from service (Diesel Generator #2 was rendered inoperable on 10/5/2018 at 1728 CDT). Movement of lately irradiated fuel assemblies in the Secondary Containment was in progress at the time of discovery of this condition. This condition represents an unplanned loss of safety function for a single train system during its specified condition of applicability. Movement of irradiated fuel was suspended until the power supplies to CREFs could be realigned to Division 1 which was completed at 0004 CDT on 10/6/2018. This represents a condition that could have prevented the fulfillment of the safety function of CREFs needed to mitigate the consequences of a fuel handling accident. The NRC Resident Inspector has been notified. | |
| ENS 53646 | 5 October 2018 05:00:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | En Revision Imported Date 10/25/2018 | EN Revision Text: MAIN STEAM ISOLATION VALVES EXCEEDED PRIMARY CONTAINMENT LOCAL LEAK RATE ACCEPTANCE CRITERIA At 0520 (CDT), on October 05, 2018, it was discovered that a Primary Containment local leak rate test performed on Main Steam Isolation Valves (MSIV) exceeded its acceptance criteria. During Mode 1, 2, and 3, Surveillance Requirement 3.6.1.3.10 requires MSIV leakage for a single MSIV line to be less than or equal to 106 standard cubic feet per hour (scfh) when tested at 29 psig and Surveillance Requirement 3.6.1.3.12 requires the combined leakage rate for all MSIV leakage paths to be less than or equal to 212 scfh when tested at 29 psig. As-found for the 'C' MSIV line leakage results were unquantifiable and gave a (minimum) path value greeter than 160 scfh. This leakage rate lead to Surveillance Requirement 3.6.1.3.10 and 3.6.1.3.12 limits to be exceeded. This event is being reported as a condition of the nuclear power plant, including its principal safety barriers, being seriously degraded per 10 CFR 50.72(b)(3)(ii)(A) since the Primary Containment Isolation Valves leakage limits for MSIVs were exceeded. The NRC Resident Inspector has been notified.
CNS (Cooper Nuclear Station) is retracting the 8-hour non-emergency notification made on October 5, 2018 at 0520 CDT (EN# 53646). Subsequent evaluation concluded that overall as-found 'C' MSIV leakage rate was not at a level that exceeded the surveillance requirement 3.6.1.3.10 and 3.6.1.3.12 limits and thus the Primary Containment Isolation Valve leakage rate limits for the MSIVs were not exceeded. The NRC Senior Resident Inspector has been notified. Notified the R4DO (Drake). | |
| ENS 53476 | 26 June 2018 05:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | En Revision Imported Date 8/14/2018 | EN Revision Text: CONTROL ROOM EMERGENCY FILTRATION SYSTEM DECLARED INOPERABLE On June 26, 2018, at 1630 CDT, the Control Room Emergency Filtration System (CREFS) was declared inoperable when Main Control Room Supply Fan SF-C-1B was discovered to have elevated vibrations that brought into question the ability to meet its mission time. CREFS is a single train safety system. Per 10 CFR 50.72(b)(3)(v)(D), an 8 hour report is required due to the fact that at the time of discovery this condition could have prevented the fulfillment of a safety function of an SSC (System Structure or Component) that is required to mitigate the consequences of an accident. The licensee has notified the NRC Senior Resident Inspector.
The following retraction was received from Cooper Nuclear Station (CNS) via facsimile and phone call: CNS is retracting the 8-hour non-emergency notification made on June 26, 2018 at 1630 CDT (EN# 53476). Subsequent evaluation concluded that overall vibration levels were not at a level that would impact the ability of the Main Control Room Supply Fan SF-C-18 to perform its safety function for its required mission time and the CREFS therefore, was operable. The NRC Senior Resident Inspector has been notified. Notified the R4DO (Deese). | |
| ENS 53416 | 22 May 2018 14:00:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Unplanned Public Notification During a Drill | On 05/22/2018, Cooper Nuclear Station (CNS) was conducting an Emergency Response Organization (ERO) drill which included state and local involvement. At approximately 09:00 CST Nebraska Emergency Management Agency (NEMA) inadvertently broadcasted CNS' declaration of a Notice of Unusual Event for the drill over the public scanner. This resulted in various members of the public or news media inquiring about the perceived event or posting erroneous information via Twitter, television news outlets, newspapers, and radio stations. These news outlets have been informed that CNS was conducting a drill and do not intend to release any stories regarding this event. There is no evidence of a formal news release at this time. However, due to the uncontrolled source of the information, the determination was made to make this report. This unplanned media event is a 4 hour report, in accordance with 10CFR50.72(b)(2)(xi). This event is not significant with respect to the health and safety of the public. The licensee notified the NRC Resident Inspector. | |
| ENS 53261 | 14 March 2018 22:11:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Notification Tone Alert Radio System | At approximately 1711 CDT on 14 MAR 2018, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was not functioning. This affects the tone alert radios used to notify the public in event of an emergency condition. This condition is reportable under 10CFR50.72(b)(3)(xiii). A backup notification method is available and will be utilized for notifications if needed. The local telephone company is providing troubleshooting and repair services. A return to service time for the Shubert tower is not currently available. The NRC Senior Resident Inspector has been informed. The issue was identified during periodic maintenance. The licensee notified all counties within the 10 mile Emergency Planning Zone.
This is a follow up notification to update the status of the Shubert radio transmission tower that was reported to be out of service on March 14th per EN53261. The tower was restored to service and determined to be functional at 0759 (CDT) on March 19th, 2018. The licensee notified the NRC Resident Inspector. Notified R4DO (Groom). | |
| ENS 53253 | 10 March 2018 13:09:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection System Declared Inoperable | HPCI (High Pressure Coolant Injection) was removed from service (unplanned) on 3/10/2018 at time 0709 (CST) by closing HPCI-MO-15, STEAM SUPPLY INBOARD ISOLATION. The inboard steam supply isolation valve is inside Primary Containment. The steam supply valve was closed in an effort to isolate (unidentified) leakage to Primary Containment from a suspected packing leak from HPCI-MO-15. After closing the HPCI-MO-15, Reactor Coolant System Leakage parameters returned to within Technical Specification (TS) LCO (Limiting Condition of Operations) 3.4.4 limits. Entered into Technical Specification LCO 3.5.1 Condition C - HPCI System Inoperable. Required Actions for Condition 'C' are to verify by administrative means RCIC (Reactor Core Isolation Cooling) System is operable within 1 hour and restore HPCI System to operable status within 14 days. RCIC was verified operable by administrative means concurrent with declaration of HPCI inoperable. Normal plant shutdown activities are being planned (for 03/11/2018 at 1200 CDT) to support entry into Primary Containment to initiate any necessary repairs. HPCI is a single train safety system. This report is submitted as a condition that at time of discovery could prevent the fulfillment of the safety function of an SSC (System, Structure, or Component) needed to mitigate the consequences of an accident. This condition has been entered into the CNS (Cooper Nuclear Station) Corrective Action Program. CR-CNS-2018-01346 LCO 3.4.4 was entered during unplanned maintenance of the HPCI system. When the HPCI-MO-15 was cycled from closed to open, unidentified leakage in the containment increased above 2 gallons per minute (gpm) in less than a 24 hour period. Also, total unidentified leakage exceeded 5 gpm. The licensee closed the HPCI-MO-15 valve resulting in a decrease in unidentified leakage below TS shutdown limit. The NRC Resident Inspector was notified. | |
| ENS 53133 | 20 December 2017 21:59:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Emergency Alert System Out of Service | During review of the documentation for the 11/16/17 outage of the NOAA/NWS (National Oceanographic and Atmospheric Administration/National Weather Service) tower, it was identified that there was also record of a trouble ticket being issued on 11/19/17 for the NOAA/NWS tower. Further discussions with the National Weather Service determined that the tower did experience an outage on 11/19/17 which affected the ability to activate EAS (Emergency Alert System)/Tone Alert Radios. Final determination that the EAS/Tone Alert Radios were affected during this outage was made at 1559 (CST), which was the time that the National Weather Service sent the e-mail to the EP (Emergency Planning) Manager and EP Offsite Coordinator with notification that activation of the EAS/Tone Alert Radios was affected during the outage. This is considered to be a major loss of the Public Prompt Notification System capability, and is reportable under 10CFR 50.72(b)(3)(xiii). The transmission outage was on 11/19/2017 0853 until 1100 but CNS (Cooper Nuclear Station) was not notified until 1559 on 12/20/2017. The NRC Senior Resident has been informed | |
| ENS 53128 | 19 December 2017 19:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Diesel Generators (Dgs) Declared Inoperable Due to a Common Issue | During regular power operations at 100% power, DG#1 and DG#2 were declared inoperable due to a common issue associated with indicating lights and the associated sockets installed in various control and auxiliary circuits for both DG's. The indicating lights in question are incandescent 120V AC style 120MB bulbs in a socket with a 550 ohm resistor. Style 120MB light bulbs have a failure mechanism where the bulb can cause a short circuit rather than the more common open circuit that is expected when an incandescent bulb filament fails. Cooper originally believed that the socket's integral resistor was sufficient to protect the circuit. In testing performed by an outside laboratory and confirmed on-site using warehouse stock, it was determined that the integral resistor may not have the power dissipation capability to protect the circuit ln which the light and socket are installed if a bulb fails in short circuit. This condition resulted in both DG's being declared inoperable at 1340 (CST) due to a loss of reasonable expectation that they would meet their safety function required action to start, load and run to support loads required to mitigate the consequences of an accident. This is a loss of safety function under 10CFR 50.72(b)(3)(v)(D) subject to an 8 hour report. As a result of both DG's being inoperable, the Control Room Emergency Filtration System is also inoperable. This is also a loss of safety function subject to an 8 hour report for the same criterion. The Senior Resident has been notified.
CNS is retracting the 8-hour non-emergency notification made on December 19, 2017 at 1340 CST (EN# 53128). Subsequent evaluation concluded a postulated lamp short circuit failure in any of the affected circuits would not impact the ability of the Diesel Generators to perform their safety function and therefore, were operable. With DG operability not affected, the Control Room Emergency Filtration System also remained operable. The NRC Resident Inspector has been notified. Notified the R4DO (Werner). | |
| ENS 53074 | 16 November 2017 02:07:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Public Prompt Notification System Capability | At 0008 CST on 11/16/2017, Cooper Nuclear Station (CNS) was notified by Omaha Weather that the NOAA broadcast and the Shubert radio tower for this area is off. This affects the tone alert radios used to notify the public in event of an emergency condition. This is considered to be a major loss of the Public Prompt Notification System capability, and is reportable under 10CFR50.72(b)(3)(xiii). The transmission outage actually began at 2007 (CST), 11/15/2017, but CNS was not notified until 0008 (CST), 11/16/2017. Backup notification methods remained available throughout the period. At time 0447 CST on 11/16/2017, Cooper Nuclear Station was notified that the NOAA broadcast and Shubert radio transmission tower was returned to service. Nemaha County, NE, Richardson County, NE, and Atchison County, MO authorities within the 10 mile EPZ were notified by Cooper Nuclear Station of the condition and the effect on the tone alert radios at 0642 (CST), 11/16/2017. This is reportable under 10CFR50.72(b)(2)(xi) as a 4 hour report. The NRC Senior Resident has been informed. | |
| ENS 53069 | 14 November 2017 17:18:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Hydrogen Line Leak | At 1118 CST on 11/14/17, Cooper Nuclear Generating Station declared an Unusual Event due to a hydrogen leak on a main generator purge line. The leak was reported to be caused by Maintenance cutting into a one inch line. The total size of the leak is unknown, however, it is estimated to be depressurizing in the main generator at approximately 1lb per hour. The current pressure is 52 to 53 lbs. pressure and is stable. The operations staff have entered their abnormal procedure and are taking actions to isolate the leak. Operators have isolated the source of hydrogen and have opened the exterior roll up doors to increase the airflow and minimize the concentration of hydrogen in the area. The area has been evacuated and hot work has been stopped. The NRC Resident Inspector has been notified. Notified DHS, FEMA, NICC and NNSA (via email).
On 11/14/2017, Nebraska Public Power District will issue a press release concerning the declaration of a Notification of Unusual Event (EN#53069) declared today at 1118 (CST) for a small hydrogen leak in the turbine building. This is a four hour report per 10CFR50.72(b)(2)(xi) for any event or situation for which a news release is planned or notification to other government agencies has been or will be made which is related to heightened public or government concern. Notified the R4DO (Kozal).
At 1744 CST the licensee exited from the Unusual Event. The leak was patched under a temporary repair. The patch was tested to verify the leak has stopped. The NRC Resident Inspector was notified. Notified the R4DO (Kozal), IRDMOC (Gott), NRR EO (Miller), DHS, FEMA, NICC and NNSA (via email). | |
| ENS 53022 | 18 October 2017 07:09:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Declared Inoperable | Eight hour report due to HPCl (High Pressure Coolant Injection) inoperability. HPCl valve operability testing was performed on October 18, 2017. Following satisfactory completion of opening stroke timing, the control switch for HPCI-MOV-MO19, HPCI Injection Valve, was taken to close. The valve indicates that it moved to an intermediate position, but it has not indicated that it has fully closed. This resulted in the valve being declared inoperable. This valve is normally closed and automatically opens on a HPCI initiation signal. HPCl was previously declared inoperable at time 0136 (CDT) on October 18 for surveillance testing. Entry was made into Tech Spec LCO 3.5.1 Condition C - HPCI System Inoperable at that time. Required Actions for Condition C are to verify by administrative means RCIC System is operable within 1 hour and restore HPCI System to operable status within 14 days. RClC was verified operable by administrative means concurrent with declaration of HPCI inoperable. Troubleshooting activities for HPCI are being planned. HPCI is a single train safety system. This report is submitted as a condition that at time of discovery could prevent the fulfillment of the safety function of an SSC (structures, systems, and components) needed to mitigate the consequences of an accident. This condition has been entered into the CNS Corrective Action Program. The licensee notified the NRC Resident Inspector.
CNS is retracting the 8-hour non-emergency notification made on October 18, 2017 at 0209 CDT (EN# 53022). Subsequent evaluation concluded HPCI-MOV-MO19 was still capable of performing its safety function with the failed torque switch identified during troubleshooting and would have supported the operability of the HPCI system. HPCI-MOV-MO19 only has a safety function to open to support HPCI safety function. The failed torque switch only affects the close function of the valve; therefore the HPCI system remained fully capable of performing its required safety function and was operable with the identified condition. The NRC Resident Inspector has been notified. Notified R4DO (Haire). | |
| ENS 52813 | 20 June 2017 02:15:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Primary Containment Declared Inoperable Due to Failure of Drywell to Suppression Chamber Vacuum Breaker to Fully Close | This report is being made pursuant to 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.' At time 2115 CDT on June 19, 2017, one torus to drywell vacuum breaker failed to indicate that it was closed after being cycled for surveillance testing. The vacuum breaker had been cycled open and then closed to satisfy SR 3.6.1.8.2 - Perform a functional test of each required vacuum breaker. Failure of the vacuum breaker to indicate closed after the control switch was taken to the closed position represents a failure to satisfy SR 3.6.1.8.2 and SR 3.6.1.8.1 - Verify each vacuum breaker is closed. Primary containment is allowed to have a bypass area between the drywell and suppression chamber less than or equivalent to a one inch diameter hole. The are of bypass was indeterminate while the vacuum breaker did not indicate fully closed. Primary containment was declared inoperable during the time the vacuum breaker did not indicate fully closed. The vacuum breaker control switch was subsequently cycled open and closed one additional time. At time 2311 CDT, the vacuum breaker indicated fully closed. At that time, primary containment was declared operable. Currently, all twelve Drywell to Suppression Chamber vacuum relief valves are closed and in the normal line-up. The NRC Senior Resident Inspector has been notified. | 05000298/LER-2017-004 |
| ENS 52771 | 26 May 2017 08:21:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Emergency Filtration System Inoperable | On May 26, 2017 at 0321 (CDT), Control Room staff questioned air flow and differential pressure in the Main Control Room. The CREFS (control room emergency filtration system) booster fan discharges to the Control Room supply fan suctions. With supply fan flows questionable, reasonable assurance that CREFS would fulfill its safety function could not be established. Engineering confirmed CREFS system flow rate by testing and determined the actual flow was 802 cfm, below the required flow of 810 cfm. Based on this information, CREFS was declared inoperable. CREFS is a single train system. Per 10CFR50.72(b)(3)(v)(D), an 8-hour report is required due to the fact that, at the time of discovery, this condition could have prevented the fulfillment of the safety function of an SSC that is required to mitigate the consequences of an accident. The NRC Senior Resident Inspector will be informed. CREFS being out of service places the plant in a 7-day LCO shutdown action statement. | 05000298/LER-2017-003 |
| ENS 52768 | 23 May 2017 13:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Meteorological Tower Primary and Backup Communication Equipment | This notification is being made due to a loss of emergency assessment capability in accordance with 10 CFR50.72(b)(3)(xiii). On (May, 23, 2017) at 0830 (CDT), the meteorological tower primary and backup communication equipment failed, which resulted in a loss of meteorological data to the plant. Information technology and communications personnel investigated and restored the primary system to service. Meteorological data to the plant was restored at 0925 on (May 23, 2017). The NRC Senior Resident Inspector has been informed. | |
| ENS 52765 | 19 May 2017 13:05:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Nonfunctional Radio Transmission Tower Affects Tone Alert Radios | At approximately 0805 CDT on 05/19/2017, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was not functioning. This affects the tone alert radios used to notify the public in event of an emergency condition. This is considered to be a major loss of the Public Prompt Notification System capability, and is reportable under 10CFR50.72(b)(3)(xiii). Nemaha County, NE, Richardson County, NE, and Atchison County, MO authorities within the 10 mile EPZ (Emergency Planning Zone) were notified by Cooper Nuclear Station of the condition and the affect on the tone alert radios. The first county was notified at 0834 CDT and the last was notified at 0836 CDT. Backup notification method will be utilized. Notification of other government agencies makes this condition reportable under 10CFR50.72(b)(2)(xi). At time 1007 CDT on 5/19/2017, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was returned to service. The NRC Senior Resident (Inspector) has been informed. | |
| ENS 52416 | 8 December 2016 04:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Fan Switch Mis-Positioned | At 2240 (CST), December 16, 2016, it was identified that HV-SW-(SF-C-1A)(CS), control switch for supply fan SF-C-1A for HV-FAN-(SF-C-1A), main control room A/C unit supply fan had been inadvertently been placed to OFF, leaving no supply fan running as required to maintain CREFS (Control Room Emergency Filtration System) operable. This was discovered following the performance of 6.1HV.302 Essential Control Building Ventilation Functional Test (DIV 1). It is estimated that the control switch was placed in OFF at approximately 2220 during preparation of 6.1HV.302 per S.O.P. 2.2.38. Time of discovery was 2240. This resulted in an unplanned LCO entry for the CREFS. CREFS was subsequently declared inoperable and LCO 3.7.4 Condition A was entered, with required action A.1 to restore CREFS to operable status within 7 days. The switch was restored to its required position at 2247 and CREFS was subsequently declared operable and the referenced LCO was exited. CR-CNS-2016-08744 was written to document the unplanned inoperability." The NRC Resident Inspector has been notified. | |
| ENS 52327 | 28 October 2016 14:24:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | Shutdown Cooling System Declared Inoperable | At 0851 (EDT) on October 28, 2016, Division 1 RHR was started in shutdown cooling (SDC) mode of operation. Prior to starting the RHR system, the Alternate Decay Heat Removal (ADHR) system was maintaining RPV and Spent Fuel Pool temperature. At 0924 on October 28, 2016, RHR (pump A) tripped due to RHR-MOV-17 (SDC suction valve) closing. This is considered to be an event or condition that could have prevented fulfillment of a safety function, and is reportable under 10 CFR 50.72(b)(3)(v)(B). RHR SDC subsystem A was declared inoperable. CNS (Cooper Nuclear Station) entered LCO 3.9.7, Condition A - Required Action A.1: Verify an alternate method of decay heat removal is available within 1 hour and once per 24 hours thereafter; Condition C - Required Action C.1: Verify reactor coolant circulation by an alternate method within 1 hour from discovery of no reactor coolant circulation and once per 12 hours thereafter, and Required Action C.2: Monitor reactor coolant temperature hourly. All LCO conditions specified have been met. ADHR remained in service throughout the event and the plant remained aligned for natural circulation. Spent fuel pool weir temperature monitoring was commenced to verify natural circulation. No increase in RPV (reactor pressure vessel) temperature has been observed. There was no impact to plant operations. Initial investigation indicates that installation of PCIS relay K27 during a maintenance activity physically agitated the adjacent relay, K30, which actuated and caused RHR-MOV-17 to close. The NRC Resident Inspectors have been informed. | 05000298/LER-2016-007 |
| ENS 52436 | 28 October 2016 07:39:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Isolation Valves | This telephone notification is being made in lieu of a Licensee Event Report in accordance with 10CFR50.73(a)(1) to notify the NRC of on invalid actuation of a group isolation, reportable under 10CFR50.73(a)(2)(iv)(A). On October 28, at 0139 Central Daylight Time, electricians were removing a test jack from a terminal on a primary containment isolation system relay due to the test jack being installed on the wrong relay. During removal of the test jack, a neutral wire came out of the terminal causing multiple relay actuations resulting in a half Group 2 isolation signal on the Division 2 side. Because of the plant being in Mode 5, refueling, the only isolation valves that closed because of the invalid isolation signal were the Division 2 isolation valves associated with the drywell ventilation monitor and the drywell floor and equipment sumps. The specific train and system actuated was the Primary Containment Isolation System (PCIS) Division 2 portion of the Group 2 isolation circuit (i.e. half group isolation). This was a partial actuation affecting only half of the logic and causing isolation of two systems. Based on the inadvertent actuation of the affected PCIS relays, the system isolated and functioned as expected. The isolation signal was reset at 0230 and the affected systems restored to service. The licensee notified the NRC Resident Inspector. | |
| ENS 52315 | 24 October 2016 00:08:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Emergency Ventilation Fan Inoperable Due to Elevated Vibration | At 1908 CDT on 10/23/16, elevated vibration readings were identified on Cooper Nuclear Station (CNS), Control Room Emergency Filter System (CREFS) supply fan A. Vibration readings were evaluated by Engineering and were determined to be indicative of bearing failure on supply fan A. The Control Room declared CREFS inoperable and entered LCO 3.7.4, Condition A, which requires restoration of CREFS to operable status in 7 days. Repair activities have been initiated for this condition. The plant is currently in Mode 5, with refueling activities and OPDRVs (Operation with Potential to Drain Reactor Vessel) in progress. CNS is not currently in the mode of applicability for a USAR defined accident. This condition is being conservatively reported under 10 CFR 50.72(b)(3)(v)(D) as a single train safety system that is required to be OPERABLE during situations under which significant radioactive releases can be postulated. The NRC Resident Inspector has been notified. | 05000298/LER-2016-006 |
| ENS 52279 | 4 October 2016 20:30:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Cooper Nuclear Station Loss of Tone Alert Radios | At 1530 CDT on I0/4/20l6, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was not functioning. This affects the tone alert radios used to notify the public in the event of an emergency condition. This is considered to be a major loss of the Public Prompt Notification System capability, and is reportable under 10CFR50.72(b)(3)(xiii). Nemaha County, NE, Richardson County, NE, and Atchison County, MO authorities within the 10 mile EPZ (Emergency Planning Zone) were notified by Cooper Nuclear Station of the condition and the effect on the tone alert radios. The first county was notified at 1540 CDT and the last was notified at 1550 CDT. A backup notification method will be utilized. Notification of other government agencies makes this condition reportable under 10CFR50.72(b)(2)(xi). Estimated return to service time is unknown. The cause of failure is unknown. The NRC Senior Resident Inspector has been informed. | |
| ENS 52262 | 25 September 2016 14:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Cooper Nuclear Station Loss of Tone Alert Radios | At 0915 CDT on 9/25/2016, Cooper Nuclear Station was notified by the National Weather Service that the Shubert radio transmission tower was not functioning. This affects the tone alert radios used to notify the public in the event of an emergency condition. This is considered to be a major loss of the public prompt notification system capability and is reportable under 10 CFR 50.72(b)(3)(xiii). Nemaha, NE, Richardson, NE, and Atchison, MO county authorities within the 10 mile EPZ were notified by Cooper Nuclear Station of the condition and the effect on the tone alert radios and will utilize the backup notification method making this condition reportable under 10 CFR 50.72(b)(2)(xi) for notification of other government agencies. Estimated return to service time is unknown. The cause of the failure is unknown. The NRC Senior Resident Inspector has been notified of this condition. | |
| ENS 52261 | 25 September 2016 06:03:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Actuation of Group 1 Isolation Signal | At 0103 CDT a Group 1 Isolation signal was received on Main Steam Line (MSL) A High Flow while attempting to un-isolate MSL A. During plant cooldown for refueling outage, all inboard MSIV's were closed to minimize steam flow to control cooldown rate. With all inboard MSIV's closed and all outboard MSIV's open, MSL drains in-service, and reactor pressure at approximately 330 psig, an attempt was made to un-isolate MSL A by opening A inboard MSIV. This resulted in a MSL high flow signal on MSL A as the valve was being opened, resulting in a Group I Isolation and closure of all MSIV's and MSL Drain Valves. Pressure was equalized to less than 200 psid across MSIV A prior to attempting to open the valve in accordance with plant procedures. All valves actuated as expected and the cause of the event is under investigation. There are no indications of a leak. The Group I Isolation has been reset. The licensee notified the NRC Resident Inspector. | |
| ENS 52221 | 3 September 2016 12:10:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Seismic Event Alarm | At 0710 CDT, Cooper Nuclear Station declared a Notification of Unusual Event under EAL HU1.1 due to the station seismic event alarm registering a response to an earthquake (epicenter near Pawnee, OK). The reactor was not affected by the earthquake and remains at 93 percent power. The licensee is performing walkdowns of structures and equipment to verify that the site is unaffected. Notified the DHS SWO, FEMA Ops Center, DHS NICC, FEMA National Watch Center (E-mail) and Nuclear SSA (E-mail).
At 1547 CDT, Cooper Nuclear Station terminated the Notice of Unusual Event. All inspections and walkdowns of the plant have been completed. No damage or injuries were reported. The seismic event caused no impact to the plant. The Licensee has notified the NRC Resident Inspector. Notified R1DO (Warnick), NRR EO (Miller), IRDMOC (Stapleton), DHS SWO, FEMA Ops Center, DHS NICC, FEMA National Watch Center (E-mail) and Nuclear SSA (E-mail). |