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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 52888 | 4 August 2017 19:11:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable Due to Opening in Service Water Piping | 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). | Secondary containment Service water Reactor Building Ventilation | |
| ENS 50046 | 20 April 2014 06:15:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Due to Opening in Reactor Building Roof Drain Piping | Due to openings found in degraded roof drain piping, Brunswick Nuclear Power Plant Unit 2 secondary containment was declared inoperable at 0215 (EDT) on 04/20/2014. During operator rounds the Reactor Building Aux Operator noted rainwater coming out of a roof drain line into the Reactor building. Upon further investigation a rusted area 2 foot by 2 inches was found on the pipe. Several through wall holes were found in this rusted area and the remainder of the rusted area was allowing water to weep through. The openings resulting from the through wall holes and rusted area exceeded the allowable openings in secondary containment, and this would have challenged secondary containment from performing its safety function. This event did not result in any adverse impact to the health and safety of the public. This is a non-emergency notification. INITIAL SAFETY SIGNIFICANCE EVALUATION: At the time that is was discovered that Unit 2 Secondary Containment was inoperable. Unit 2 was at 100% steady state conditions. Reactor building ventilation was in service in a normal alignment. The Unit 2 reactor building differential pressure was normal during the entire time secondary containment was inoperable. At no time was there a release of radioactive material from Unit 2 secondary containment. CORRECTIVE ACTIONS: The Unit 2 reactor building roof drain line has had a temporary repair applied. This repair has been evaluated by the Engineering department with site procedures and meets the requirements to maintain Secondary Containment operable. Unit 2 Secondary Containment operability was restored at 04/20/2014 0600 (EDT). The licensee notified the NRC Resident Inspector. | Secondary containment Reactor Building Ventilation | |
| ENS 49921 | 17 March 2014 11:50:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Airlock Door Interlock Malfunction | At 0750 EDT on March 17, 2014, Operations determined that both the inner and outer secondary containment airlock doors, on the 20 foot elevation of the Unit 1 reactor building, had been simultaneously opened for approximately 10 seconds. This event occurred while an employee was exiting secondary containment immediately after another employee had previously entered. Upon recognition of the condition, the employees took action to secure both doors. The cause of this event was malfunction of the secondary containment airlock door interlock. This condition is being reported in accordance with 10CFR50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. With both doors open, Surveillance Requirement 3.6.4.1.3 of Technical Specification 3.6.4.1, Secondary Containment, was not met, rendering secondary containment inoperable. At the time at the time of the condition, Unit 1 was engaged in Operations with the Potential to Drain the Reactor Vessel (OPDRV) and was crediting Secondary Containment as Operable. This event did not result in any adverse impact to the health and safety of the public. The safety significance of this is minimal. Secondary containment was only inoperable for approximately 10 seconds. This event did not result in any adverse impact to the health and safety of the public. The door interlock investigation (is) in progress. Doorwatches with communications have been stationed on either side of the Unit 1 and Unit 2 20 foot reactor building air lock doors. All other secondary containment access doors on both Reactor Building have been controlled as emergency exit only. Installation of temporary video surveillance system (is) being pursued until long term corrective action can be established per the corrective action program. The NRC Senior Resident has been notified. | Secondary containment | |
| ENS 49910 | 13 March 2014 13:37:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Apparent Secondary Containment Airlock Door Interlock Malfunction | At 0937 EDT on March 13, 2014, Operations determined that both the inner and outer secondary containment airlock doors, on the 50 foot elevation of the reactor building, had been simultaneously opened for approximately one minute. This event occurred while an employee was exiting secondary containment at the same time when an employee was attempting to enter secondary containment. Upon recognition of the condition, the employees took action to secure both doors. The apparent cause of this event was malfunction of the secondary containment airlock door interlock. However, upon investigation no failures of the interlock could be identified. The interlock was satisfactorily tested multiple times following the event. This condition is being reported in accordance with 10CFR50.72(b)(3)(v)(c), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. With both doors open, Surveillance Requirement 3.6.4.1.3 of Technical Specification 3.6.4.1, Secondary Containment, was not met, rendering secondary containment inoperable. At the time at the time of the condition, Unit 1 was engaged in Operations with the Potential to Drain the Reactor Vessel (OPDRV) and was crediting Secondary Containment as Operable. This event did not result in any adverse impact to the health and safety of the public. The safety significance of this is minimal. Secondary containment was only inoperable for approximately one minute. This event did not result in any adverse impact to the health and safety of the public. The door interlock was investigated and tested multiple times with no abnormalities noted. The NRC Senior Resident has been notified. The licensee is establishing a door watch as a compensatory measure. | Secondary containment | 05000325/LER-2014-003 |
| ENS 49880 | 6 March 2014 21:05:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Airlock Door Interlock Malfunction | At 1605 EST on March 6, 2014, Operations determined that both the inner and outer secondary containment airlock doors, on the 50 foot elevation of the reactor building, had been simultaneously opened for approximately one minute on March 5, 2013. This event occurred while an employee was exiting secondary containment. The inner door failed to latch and opened as the employee was opening the outer door. Upon recognition of the condition the employee took action to secure both doors. The cause of this event was malfunction of the secondary containment airlock door interlock. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. With both doors open, Surveillance Requirement 3.6.4.1.3 of Technical Specification 3.6.4.1, Secondary Containment, was not met, rendering secondary containment inoperable. Repairs to the secondary containment airlock door interlock have been completed. This event did not result in any adverse impact to the health and safety of the public. The NRC Senior Resident Inspector has been notified. | Secondary containment | 05000324/LER-2014-001 |