Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 54690 | 1 May 2020 15:34:00 | 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 16:03:00 | 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 54049 | 5 May 2019 20:41:00 | 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 53476 | 26 June 2018 23:29:00 | 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 52771 | 26 May 2017 12:11:00 | 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. |
| ENS 52768 | 23 May 2017 15:57:00 | 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 50854 | 28 February 2015 01:20:00 | Cooper Nuclear Station became aware of the installation of two 12,000 gallon anhydrous ammonia tanks approximately 1.5 miles from the site. This amount of anhydrous ammonia at that distance exceeds the control room habitability hazardous chemical analysis previously evaluated for the nuclear station. The control room staff has been informed of the condition and have reviewed the appropriate abnormal procedures for actions to take in the case of a leak. This potentially represents an unanalyzed condition that significantly degrades plant safety and is reportable under 10 CFR 50.72(b)(3)(ii)(B). The licensee has notified the NRC Resident Inspector.
Subsequently it was determined that the Control Room Habitability Analysis that was performed in response to the NRC's post-TMI requirements bounds the identified condition. This analysis includes the potential of a toxic chemical leak from a 725-ton tank on a river barge carrying anhydrous ammonia. The volume of chemical, and distance from the control room, included in the post-TMI habitability analysis bounds the conditions found with the newly constructed anhydrous ammonia tanks. The licensee notified the NRC Resident Inspector. Notified the R4DO (Farnholtz). |
| ENS 44671 | 20 November 2008 18:24:00 | On 20 Nov 08 at 1230, the Control Room Emergency Filtration System (CREFS) was declared inoperable due to a report that a non-running Control Room supply fan discharge damper was found partially open. Per the System Operating Procedure, the idle fan's discharge damper must be fully closed to assure operability. With the damper not closed, reasonable assurance that CREFS would fulfill its safety function could not be established. With the Idle Control Room supply fan discharge damper not in the closed position, some portion of the air discharged from the operating Control Room supply fan will go backwards through the idle supply fan to the suction side of both supply fans. The CREFS fan discharges to the Control Room supply fan suctions. With CREFS in this as-found line-up, there is no assurance that the flow through CREFS is high enough to meet the design requirements assumed in control room occupant dose calculations. The Control Room supply fans and discharge dampers are required support features for CREFS at CNS. This is a single train system and 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 licensee notified the NRC Resident Inspector. The damper was returned to a fully closed position at the time of discovery, and CREFS was returned to operable status.
This notification is being made to retract Event Notification EN# 44671 which reported a loss of safety function due to the unplanned inoperability of the Control Room Emergency Filtration (CREF) system. The CREF system was declared inoperable due to the non-running control room supply fan discharge damper found partially open on November 20, 2008. Cooper Nuclear Station has determined through further evaluation that while the CREF system was procedurally required to be declared inoperable, the ability of the CREF system to perform its safety function was not lost. Testing was performed on December 19, 2008, with the non-running control room supply fan discharge damper aligned in the as-found condition (~25% open) of November 20, 2008 and again tested with the damper aligned to 50% open. Technical Specifications surveillance flow requirements were met in both tests. Using the results of the test and inspection of the discharge damper it has been concluded that during the ten days the damper was out of position, the CREF system was still capable of performing its safety function and satisfying Technical Specifications requirements. Notified R4DO (Werner). |
| ENS 43856 | 20 December 2007 14:50:00 | This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) as an event that resulted 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.) At 0700 on 12/20/07, one of the five T-1 data lines to the Emergency Offsite Facility (EOF) was discovered to be out of service. This caused a loss of Safety Parameter Display System capability, the FTS 2001 system, Alternate Intercom system, and Low Band base radio (the primary Downwind Survey team radio) at the EOF. Computer terminals remained functional for calculating CNS Dose. All other Emergency Response Facilities were unaffected. At 0826, the T-1 line was restored by repairing a line repeater. At 0948, all EOF equipment affected by the T-1 line were satisfactorily tested and verified to be operational. The NRC Resident Inspector was notified of the loss and restoration of the T-1 line. |