Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 51353 | 27 August 2015 14:10:00 | 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. |
| ENS 50560 | 23 October 2014 09:48:00 | 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). . |
| ENS 50243 | 30 June 2014 17:55:00 | This is a one hour report for the discovery of a condition that briefly met the emergency action level (EAL) for an Unusual Event but did not warrant declaration of an emergency classification. A detailed review of the conditions that existed during a thunderstorm that took place today revealed that the backup 50 meter wind speed briefly indicated 95.5 mph, which exceeds the HU 1.3 criteria of 95 mph. The primary 50 meter wind speed indicator did not exceed 89 mph. Operators in the control room did not observe wind speed exceed 80 mph on SPDS. This event is a one hour report based on the guidance in NUREG-1022 for a condition that met an emergency plan EAL and the basis for the emergency classification no longer existed at the time of discovery." The NRC Resident Inspector has been informed. |
| ENS 49747 | 21 January 2014 05:48:00 | On 1/20/14 at 2230 CST, an interruption in the control power to the TSC diesel generator was discovered. Investigation revealed a blown fuse supplying the TSC diesel generator control panel. The blown fuse has resulted in the TSC diesel generator starting batteries depleting. The fuse has since been replaced, and the TSC diesel generator starting batteries are currently recharging. The TSC diesel generator remains non-functional until the starting batteries are charged. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to the unplanned loss of the backup power supply to the Emergency Response Facility (ERF). The NRC Resident Inspector has been informed. An update notification will be made when the TSC diesel generator has been restored to fully functional status.
At 1400 CST, the licensee restored the TSC emergency diesel generator to functional status. The NRC Resident Inspector was notified by the licensee. Notified R3DO (Valos). |
| ENS 49092 | 6 June 2013 09:27:00 | A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) has removed the emergency power supply to the TSC from service as of 0900 EDT. If a loss of the normal power supply to the TSC were to occur during this period, the TSC would be rendered non-functional. The repair to the power supply is expected to last 6 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore the emergency power supply to service. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC emergency power supply has been restored to normal operation. The licensee has notified the NRC Resident Inspector.
The TSC diesel generator has been returned to functional status. The NRC Resident Inspector has been notified R3DO (Lipa) has been notified. |
| ENS 45603 | 2 January 2010 04:12:00 | This report is being made under 10CFR50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in Paragraph (b)(3)(iv)(B) of this section' due to an auto start of the 'A' Standby Diesel Generator. The auto start of the 'A' Standby Diesel Generator occurred on a valid bus undervoltage condition caused by a momentary fault on the 161 kV Vinton line. Switchyard inspection revealed a failed 161 kV line arrestor (on) one of the phases of the Vinton line. The 'A' Standby Diesel Generator supply breaker was not required to close onto its respective essential bus as it remained powered from its normal power supply, 1X003 Start-up Transformer, during and after the event. Offsite power remained fully operable during and following the event. The 'A' Standby Diesel Generator has been returned to the standby/readiness condition. As designed, the 'A' Emergency Service Water systems auto started when the 'A' Standby Diesel Generator started. The Emergency Service Water systems have been returned to the standby/readiness condition. The 'B' Well Water Pump tripped as a result of the electrical transient. The 'A' Well Water pump and 'B' Emergency Service Water pump were manually started by operators in accordance with Abnormal Operating Procedure 408, Well Water System Abnormal Operation. The in-service Reactor Water Cleanup pump tripped which removed RWCU from service. The RWCU system has been returned to service. The in-service Spent Fuel Pool Cooling pump tripped as a result of the electrical transient. Spent Fuel Pool Cooling has been returned to service. Spent fuel pool temperature rose 0.7 (degrees) F while the pump was out of service. All ECCS systems were available before the event and have remained available following the event. The licensee is not in any Technical Specification LCO's as a result of this event. The in-service Spent Fuel Pool Cooling pump was OOS for approximately 58 minutes. The NRC Resident Inspector has been notified. |