Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 56989 | 22 February 2024 20:02:00 | 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 56278 | 17 December 2022 04:03:00 | 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 55715 | 27 January 2022 15:07:00 | 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 55098 | 9 February 2021 10:35:00 | 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 53022 | 18 October 2017 05:27:00 | 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 03:31:00 | 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. |
| ENS 52327 | 28 October 2016 17:14:00 | 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. |
| ENS 52279 | 4 October 2016 18:16:00 | 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 51886 | 27 April 2016 01:17:00 | At 1736 (CDT) on 26 April 2016, a licensed operator performing a control room panel walkdown noted the green standby light for the HPCI (High Pressure Coolant Injection) Auxiliary Oil Pump (AOP) was not illuminated. The bulb was replaced and the replacement bulb did not illuminate. A non-licensed operator (NLO) was dispatched to the local 250VDC starter rack. The NLO discovered the green standby light on the 250VDC starter rack had failed. An attempt was made to start the AOP with the control switch. The pump did not start. The AOP is required to start in order to open the steam admission valves for the HPCI turbine. HPCI was declared inoperable at time 1754 (CDT) on 26 April 2016. Tech Spec LCO Conditions were entered and required actions completed. HPCI is a single train system. This report is submitted as a condition that at time of discovery could prevent the fulfillment of the safety function of an SSC (Structure, System, and Component) needed to mitigate the consequences of an accident. A similar condition was discovered on 25 April 2016 (see NRC Event #51882). Corrective maintenance was performed and HPCI was declared operable following satisfactory completion of post work testing of the AOP. Initial investigation indicates that the fault which occurred on 26 April is not the same as that which occurred 25 April. Investigation is on going. The licensee has notified the NRC Resident Inspector. |
| ENS 51882 | 26 April 2016 01:54:00 | 8-hour report due to HPCI inoperability. At approximately 2109 (CDT) on 04/25/16, a licensed operator performing a control room panel walkdown noted the green light for HPCI Auxiliary Oil Pump (AOP) was not illuminated. The bulb was replaced and the replacement bulb did not illuminate. A non-licensed operator was dispatched to the local 250VDC starter rack. Both the green and red power indicating lights on the starter rack were found extinguished. An attempt was made to start the AOP with the control switch. The pump did not start. The AOP is required to start in order to open the steam admission valves for the HPCI turbine. HPCI was declared inoperable at time 2117 (CDT), resulting in entry into Tech Spec LCO 3.5.1 Condition C - HPCI System Inoperable. 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. RCIC was verified operable by administrative means concurrent with HPCl declaration. Troubleshooting activities for HPCI are being planned. HPCI is a single train 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. The licensee informed the NRC Resident Inspector. |