Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 53496 | 9 July 2018 05:00:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | At approximately 1334 CDT on 7/9/18, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of less than 3 seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. Secondary Containment was immediately restored to operable by closing the airlock doors. Subsequently, the airlock interlock was verified to operate correctly. This event is being reported pursuant of 10 CFR 50.72(b)(3)(v)(C). The Senior NRC Resident Inspector has been notified. | Secondary containment | |
| ENS 52511 | 26 January 2017 09:00:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Containment Valves Failed Surveillance Testing | On January 25, 2017, at 1800 CST, during planned surveillance testing, the Drywell Vent Line Inboard Isolation valve, CV-4302, was found to exceed its valve leakage limits and was declared inoperable. After completion of repairs to CV-4302, post maintenance testing showed that the Drywell Vent Line Outboard Isolation valve, CV-4303, was exceeding its valve leakage limits, and therefore, was declared inoperable at 0300 CST on January 26, 2017. This resulted in a containment penetration flow path not within purge valve leakage limits and is reportable in accordance with 10 CFR 50.72(b)(3)(v)(C). Repairs were completed on CV-4303 and both containment valves were declared operable at 1007 CST on January 26, 2017. Secondary Containment was operable at all times. The NRC Resident Inspector has been informed. | Secondary containment | 05000331/LER-2017-001 |
| ENS 52053 | 29 June 2016 14:40:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | At 0940 CDT on 6/29/2016, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of less than 5 seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. Secondary Containment was immediately restored to operable by closing the airlock doors. The airlock interlock was repaired and verified to operate correctly. This event is being reported pursuant of 10 CFR 50.72(b)(3)(v)(C). The Senior Resident Inspector has been notified. | Secondary containment | 05000331/LER-2016-001 |
| ENS 52022 | 19 June 2016 20:33:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | At 1533 CDT on 06/19/2016, while performing Tech Spec Secondary Containment Airlock verification testing, both doors of a Secondary Containment Airlock were reported to be open simultaneously. The identified condition caused Secondary Containment to be considered inoperable. Upon discovery, immediate action was taken to close the doors restoring Secondary Containment. Airlock doors were under control of plant personnel throughout the event. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The licensee informed the NRC Resident Inspector. | Secondary containment | 05000331/LER-2016-001 |
| ENS 51353 | 27 August 2015 12:52:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | At 0752 CDT on 8/27/2015, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of approximately five seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. The airlock interlock was verified to operate correctly, and Secondary Containment has been restored to an operable status. The licensee has notified the NRC Resident Inspector. | Secondary containment | 05000331/LER-2015-004 |
| ENS 50989 | 16 April 2015 18:20:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Secondary Containment Airlock Doors Open Simultaneously | At 1320 CDT, on April 16, 2015, both doors of a Secondary Containment Airlock were reported to be open. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. Upon discovery, immediate action was taken to close the doors. The doors were open concurrently for a momentary amount of time. The action to close the door allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. The notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. The licensee is investigating how the electrical interlock failed to prevent this occurrence. | Secondary containment | 05000331/LER-2015-003 |
| ENS 50914 | 21 March 2015 05:30:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Secondary Containment Doors Opened Simultaneously | At 0030 CDT, on March 21, 2015, both doors of a Secondary Containment Airlock were opened concurrently by two separate individuals. The doors being open at the same time caused a failure to meet SR (Surveillance Requirement) 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO (Technical Specification Limiting Condition for Operation) 3.6.4.1. Upon discovery, immediate action was taken to close the doors. The doors were open concurrently for a momentary amount of time. The action to close the door allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. | Secondary containment | 05000331/LER-2015-001 |
| ENS 50560 | 23 October 2014 06:07:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable Due to Both Airlock Doors Open Simultaneously | At 0107 CDT on October 23rd, 2014, both doors in one of the Secondary Containment airlocks were momentarily open concurrently. This occurred during vessel drain down following refueling activities, an Operation with the Potential to Drain the Reactor Vessel (OPDRV), which required Secondary Containment to be operable. The doors being open at the same time resulted in the momentary inoperability of Secondary Containment. One of the doors was immediately closed, and Secondary Containment was restored to an operable status. The station (Duane Arnold) has now completed the OPDRV associated with vessel drain down, and Secondary Containment is no longer required to be operable. The Resident Inspector has been notified.
The purpose of this notification is to retract a previous report made on 10/23/2014, at 0948 (EDT) (EN 50560). Notification of the event to the NRC was initially made as a result of an event where both doors in one of the Secondary Containment airlocks were momentarily open concurrently. This occurred during vessel drain down following refueling activities, an Operation with the Potential to Drain the Reactor Vessel (OPDRV), which required Secondary Containment to be operable. The doors being open at the same time resulted in the momentary inoperability of Secondary Containment. One of the doors was immediately closed, and Secondary Containment was restored to an operable status. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the doors in question were not mechanically degraded such that they were incapable of being closed. A momentary condition of having both secondary containment airlock doors open for a matter of seconds is not an event or condition that could have prevented the fulfillment of a safety. Furthermore, the conduct of OPDRVs during a momentary opening of both secondary containment doors that is immediately rectified does not constitute a condition prohibited by TS. Therefore, this event is not considered a Safety System Functional Failure or a Condition Prohibited by TS and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified the R3DO (McCraw). . | Secondary containment | |
| ENS 50375 | 15 August 2014 17:18:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Standby Gas Treatment System Inoperable | On 8/15/2014 at 1218 CDT, the 'B' Standby Gas Treatment (SBGT) System was undergoing its monthly surveillance testing. With the 'B' fan running, as part of the surveillance, the 'A' Standby Gas Treatment Mode Select Switch was taken to Manual. This renders the 'A' SBGT subsystem inoperable. Almost simultaneously the 'B' fan Flow Indicating Controller went blank and flashed an error message although indicated flow through the 'B' train remained at 4073 SCFM. Based on the indication seen on 'B' controller, regardless of flow, the 'B' SBGT subsystem was also declared inoperable. In accordance with the surveillance the 'A' SBGT mode switch was placed back in the AUTO position on 8/15/2014 at 1220 CDT, restoring that train to operability. The 'B' SBGT was still considered inoperable based on its flow indicating controller being blank and flashing an error message. For a period of two minutes both SBGT subsystems were considered inoperable which is a condition that could have prevented the fulfillment of the safety function of SBGT system to control the release of radioactive material. This is considered a 8-hour reportable event per 50.72(b)(3)(v)(C) 'Any event or condition that at the time discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.' During the 2 minutes that 'A' SBGT was in Manual, the 'B' SBGT train maintained 4073 scfm train flow which is at the required flow rate per STP 3.6.4.3-01B. In addition, the 'A' train could have been initiated manually at any time during that 2 minutes by the operator who was stationed at the panel performing the surveillance. The licensee notified the NRC Resident Inspector.
The purpose of this notification is to retract a previous report made on 08/15/2014 at 1802 (EDT) (EN 50375). Notification of the event to the NRC was initially made as a result of declaring both trains of the Standby Gas Treatment (SBGT) System inoperable. Specifically, during performance of planned surveillance testing required by Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.3.2, with the 'B' train of SBGT running as part of the testing, the 'A' SBGT train's mode switch was taken to manual. This action renders the 'A' train inoperable. Simultaneously with this action, the 'B' SBGT Flow Indicator Controller went blank and flashed an error message. This resulted in the 'B' train being declared inoperable. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that TS SR 3.6.4.3.2 contains a note that states, 'When a SBGT subsystem is placed in an inoperable status solely for the performance of VFTP testing required by this Surveillance on the other subsystem, entry into associated Conditions and Required Actions may be delayed for up to 1 hour.' The 'A' SBGT train mode switch was in manual for approximately 2 minutes; therefore, entry into the associated conditions and actions was not required. Therefore, this event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified R3DO (Dickson) | Standby Gas Treatment System | |
| ENS 50153 | 30 May 2014 12:59:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Airlock Inoperable for 10 Seconds | At 0759, on May 30, 2014, both doors in one of the Secondary Containment Airlocks were open concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered INOPERABLE per TS LCO 3.6.1.4. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to OPERABLE status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. The cause of this event was a misaligned door magnet. | Secondary containment | 05000331/LER-2014-003 |
| ENS 49838 | 18 February 2014 15:44:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Momentary Loss of Secondary Containment | At 0944 CST, on February 18, 2014, both doors in the Secondary Containment Airlock were opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.1.4.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.1.4. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. | Secondary containment | 05000331/LER-2014-002 |
| ENS 49657 | 18 December 2013 14:30:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Doors in Secondary Containment Airlock Opened Concurrently | At 0830 CST on December 18, 2013, both doors in the Secondary Containment Airlock were opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. | Secondary containment | 05000331/LER-2013-006 |
| ENS 48212 | 20 August 2012 20:20:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Rwcu System Isolation Differential Flow - High Function Inoperable | On 8-20-2012 during scheduled surveillance testing, the Reactor Water Cleanup (RWCU) System Isolation Differential Flow - High function was discovered to be inoperable at 1520 CDT. The high differential flow signal is provided to detect a break in the RWCU system when area or differential temperature would not provide detection (i.e. cold leg break). This instrumentation provides isolation signals to both inboard and outboard isolation valves and its loss is being reported pursuant to 10CFR50.72(b)(3)(v)(C). The NRC Resident Inspector was notified.
Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the RWCU Differential Flow High instrument loop was, at all times, capable of performing its TS function. Specifically an engineering analysis of the impact of the instrument as-found and as-left values on the overall instrument loop setting was performed. The analysis determined that the instrument in question was set at a value which would have isolated the RWCU Primary Containment Isolation Valves prior to reaching the Technical Specification (TS) allowable value and therefore the instrument loop remained capable at all times of performing its TS function. This event is not considered a Safety System Functional Failure or a Condition Prohibited by TS and is not reportable to the NRC as a Licensee Event Report (LER) per 10CFR50.73. The NRC Senior Resident Inspector has been notified. Notified the R3DO (Lipa). | Primary containment Reactor Water Cleanup | |
| ENS 47709 | 29 February 2012 18:22:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Isolation Dampers Fail to Close During Quarterly Surveillance | On 2/29/2012 at 0905 (CST) during scheduled surveillance testing it was discovered that Secondary Containment isolation damper 1VAD017B3 would not fully isolate. 1VAD017B3 was declared inoperable per Technical Specification 3.6.4.2 Condition A and an 8 hour action statement to isolate the affected flowpath via a closed and deactivated damper was entered. While performing subsequent actions to isolate the companion isolation damper, 1VAD017A3, it was found on 2/29/2012 at 1222 (CST) that this damper also failed to fully isolate. This left both Secondary Containment isolation dampers in the same flowpath unable to isolate, and Technical Specification 3.6.4.2 Condition B was entered with a 4 hours action statement to isolate the affected flowpath. This condition is reported under 50.72(b)(3)(v)(C), any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of the structures or systems that are needed to control the release of radioactive material. Further actions to isolate the flowpath were successful and both 4 hour and 8 hour Technical Specification action statements were completed within the required time. The licensee informed the NRC Resident Inspector. | Secondary containment | |
| ENS 41785 | 20 June 2005 08:08:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Standby Gas Treatment Trains Briefly Inoperable During Testing | During the performance of the monthly 10-hour run testing of the 'B' Standby Gas Treatment (SBGT) train it was discovered that the flow-indicating controller was not controlling flow at the required setpoint. The 'B' SBGT train was declared inoperable at 0308 on 20 June 2005. As part of the testing, the 'A' SBGT train Mode Select switch was in Manual with the inlet damper closed rendering the 'A' SBGT train inoperable. During the short period of time (approximately 4 minutes) between the discovery of the 'B' SBGT controller failure and the return of the 'A' SBGT train to an operable condition, both SBGT trains were inoperable which is a condition that could prevent the fulfillment of the safety function of the SBGT system to control the release of radioactive material. This is an 8-hour reportable event per 50.72(b)(3)(v)(C). The 'A' SBGT train was restored to operable status at 0312 when its inlet damper was reopened and its Mode Select switch was returned to AUTO per the surveillance test. The licensee will inform the NRC Resident Inspector. | 05000331/LER-2005-002 |