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| Entered date | Event description | |
|---|---|---|
| ENS 55756 | 24 February 2022 14:35:00 | The following information was provided by the licensee via email: This 60-day optional telephone notification is being made in lieu of an LER (Licensee Event Report) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 1316 Eastern Standard Time (EST) on January 4, 2022, during performance of isolation logic periodic testing associated with Primary Containment Isolation System Groups 2 and 6, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring (CAC/CAM) and Post Accident Sampling (PASS) isolation valves) occurred. This resulted in a Division I CAC isolation signal, a full CAM isolation, and a full PASS isolation. Reactor Building Ventilation isolated and Standby Gas Treatment started per design. No manipulations associated with the isolation or reset logic were ongoing at the time. Troubleshooting determined that the Group 6 isolation signal resulted from a high resistance contact on a relay associated with the main stack radiation high-high isolation logic. This condition interrupted electrical continuity and prevented the Group 6 logic from resetting. Following cleaning of the relay contacts, the isolation logic remained in the reset state. The main stack radiation monitor is a shared component that sends isolation signals to Unit 1 and Unit 2. It was verified that the radiation monitor was not in trip electrically and there were no Unit 2 actuations. Therefore, the actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. As a result, this event has been determined to be an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified. |
| ENS 55191 | 14 April 2021 13:00:00 | This 60-day optional telephone notification is being made in lieu of an LER submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). At approximately 1507 EDT on February 17, 2021, during performance of isolation logic periodic testing associated with Primary Containment Isolation System Groups 2 and 6, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring and Post Accident Sampling isolation valves) occurred. The Group 6 isolation signal resulted from the reactor building ventilation radiation monitor `B' Channel exceeding the setpoint value. This condition likely resulted from the radiation monitor electronics being impacted by humidity levels, which exceeded the instrument design requirements that developed in the area over time as a result of the Unit 2 reactor building ventilation being secured per the test procedure. The `A' Channel, located in the same plenum, remained steady and below the setpoint value through the entire event. This, along with readings made by a Radiation Protection Technician, confirmed that there was no actual high radiation condition in the reactor building exhaust. Upon returning Unit 2 reactor building ventilation to service, the `B' Channel readings returned to be consistent with the `A' Channel. The PCIVs functioned successfully and the actuation was complete. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified. |
| ENS 54322 | 10 October 2019 12:14:00 | At 1122 EDT, on October 10, 2019, Duke Energy initiated voluntary notification of North Carolina State and local officials per the guidance in Nuclear Energy Institute (NEI) 07-07, 'Industry Groundwater Protection Initiative - Final Guidance Document,' due to release of tritiated water in excess of 100 gallons. On October 8, 2019, at approximately 1300 EDT, Brunswick plant personnel drilling as part of an ongoing site project, damaged a storm drain discharge line. The resulting leak was isolated and water around the impacted area was sampled for gamma emitters and tritium. No gamma emitters were detected. The tritium concentration was below the Environmental Protection Agency (EPA) drinking water limit of 20,000 pCi/L. The leak has been stopped and excavation and repair efforts are in progress. This notification is being made solely as a four-hour, non-emergency notification for a notification of other government agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 53911 | 5 March 2019 12:46:00 | At 05:35 Eastern Standard Time (EST) on March 5, 2019, with Unit 2 in Mode 5 at 0% power, an actuation of the Primary Containment Isolation System occurred during hydrolazing of the reactor water level variable leg instrumentation line nozzle N011B in the reactor cavity. The hydrolazing activity caused low reactor water level to be sensed on Division II of the shutdown range level instrumentation. Per design, the low level 1 signal resulted in 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. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Primary Containment Isolation System. There was no impact on the health and safety of the public or plant personnel. The Group 8 was reset and shutdown cooling was restored at approximately 05:45 EST. The safety significance of this event was minimal. Although there was a brief interruption of the shutdown cooling, the Residual Heat Removal (RHR) shutdown cooling system operation was restored in approximately 10 minutes without extensive troubleshooting or maintenance, and remained operable. The RHR shutdown cooling system is not credited in any Updated Final Safety Analysis Report Chapter 6 or 15 accidents or transients. The NRC Resident Inspector has been notified. |