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| Entered date | Event description | |
|---|---|---|
| ENS 54772 | 10 July 2020 08:28:00 | At 0900 EDT hours on 7/10/2020 Duke Energy will undertake planned maintenance activities on the common Emergency Operations Facility (EOF) for Brunswick, Catawba, Harris, McGuire, Oconee, and Robinson nuclear sites. The work includes performance of upgrades to the emergency AC power system and requires the removal of both normal and emergency power to the facility. The work duration is approximately ten (10) days. If a declared emergency were to occur at Brunswick, the Alternate EOF would be set up in the Catawba Alternate Technical Support Center (TSC) location as described in implementing procedures. The Emergency Response Organization has been notified that the primary EOF will be unavailable during the upgrade project and to report to the alternate location, if activated. This is an eight-hour, non-emergency notification for a loss of emergency assessment capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the work activity affects the functionality of an emergency response facility. The NRC Resident Inspector has been notified. |
| ENS 54603 | 24 March 2020 16:02:00 | At 1205 Eastern Daylight Time (EDT) on March 24, 2020, a Technical Specification-required shutdown was initiated on Unit 1 due to indication of a leak in the drywell. Technical Specification Action 3.4.4.A, Unidentified Reactor Coolant System (RCS) leakage increase not within limit, requires RCS leakage to be reduced to within limits within 8 hours. It was expected that the leakage would not have been reduced to within limits within the required Technical Specification completion time; therefore, this event is being reported in accordance with 10 CFR 50.72(b)(2)(i). Reactor water level reached low level 1 (LL1) following the reactor shutdown. The LL1 signal causes Group 2 (i.e., floor and equipment drain isolation valves), Group 6 (i.e., monitoring and sampling isolation valves), and Group 8 (i.e., shutdown cooling isolation valves) isolations. The LL1 isolations occurred as designed; the Group 8 valves were closed at the time of the event. Due to the valid Primary Containment Isolation System (PCIS) actuation, this event is also being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). Unit 2 is not affected by this event. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 52888 | 4 August 2017 17:25:00 | On August 4, 2017, at 1511 EDT, Unit 1 Secondary Containment was declared inoperable due to a small (i.e., approximately 0.75 inch diameter) hole in Service Water system piping which was found during ultrasonic testing activities. The affected portion of piping penetrates Secondary Containment and flow in the piping creates a vacuum condition; thus bypassing Secondary Containment. The identified hole is being evaluated with respect to its impact on operability of the Service Water system. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(v)(C), as an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. This event did not result in any adverse impact to the health and safety of the public. Initial Safety Significance Evaluation: The initial safety significance of this event is minimal. At the time of discovery, Unit 1 was at 100% steady state conditions. Reactor Building Ventilation was in service in a normal alignment. No abnormal radioactivity conditions existed within Secondary Containment. Corrective Actions: Temporary repair of the affected Unit 1 Service Water piping has been completed. This repair was evaluated by Engineering and it has been determined that the repair meets the requirements to maintain Secondary Containment operable. Unit 1 Secondary Containment operability was restored at 1704 EDT on August 4, 2017. The licensee notified the NRC Resident Inspector.
Based upon further evaluation, Duke Energy is retracting Event Notification 52888. The safety objective of Secondary Containment is to limit the release of radioactivity to the environment after an accident so that the resulting exposures are kept to a practical minimum and are within regulatory limits. A bounding engineering evaluation was performed which demonstrates that potential releases from Secondary Containment could not have resulted in offsite or control room doses exceeding regulatory limits. Furthermore, the condition did not impact Technical Specification operability of Secondary Containment in that the ability of Secondary Containment to maintain the required vacuum was not impacted. Therefore, this condition does not represent an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and is not reportable in accordance with 10 CFR 50.72(b)(3)(v)(C), and the event notification is being retracted. The NRC Senior Resident was notified of this retraction. Notified R2DO (A. Masters). |