PNO-III-20-002, Notice of Unusual Event and Unplanned Shutdown Greater than 72 Hours Due to Loss of Offsite Power from Severe Weather Event
| ML20227A083 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 08/14/2020 |
| From: | April Nguyen, Robert Ruiz NRC/RGN-III/DRP/B1, NRC/RGN-III/DRP/B2 |
| To: | |
| References | |
| PNO-III-20-002 | |
| Download: ML20227A083 (2) | |
PRELIMINARY NOTIFICATION August 14, 2020 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-20-002 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. Some of the information may not yet be fully verified or evaluated and is essentially all that is known by the Region III staff on this date.
Facility Licensee Emergency Classification Duane Arnold Energy Center __X _ Notification of Unusual Event (entered 8/10/20, exited 8/11/20)
NextEra Energy, Inc. Alert Palo, IA Site Area Emergency Docket No: 50-331 General Emergency Not Applicable
SUBJECT:
NOTICE OF UNUSUAL EVENT AND UNPLANNED SHUTDOWN GREATER THAN 72 HOURS DUE TO LOSS OF OFFSITE POWER FROM SEVERE WEATHER EVENT On August 10, 2020, at approximately 12:45 p.m. (all times CDT), severe thunderstorms and high winds approached the Duane Arnold Energy Center (DAEC) and caused an offsite power grid perturbation, which led to an automatic start of both DAEC Emergency Diesel Generators (EDGs). The plant was operating at the time.
At 12:49 p.m., the severe weather damaged the offsite power lines resulting in a loss of offsite power to the plant, leading to an automatic reactor shutdown. All rods inserted and cooling was addressed via the Reactor Core Isolation Cooling (RCIC) system. With the EDGs already running, onsite essential equipment was automatically powered and maintained without issue. Plant safety parameters remained stable throughout the event.
At 12:58 p.m., the licensee declared a Notice of Unusual Event due to the loss of offsite power. No injuries occurred onsite and there was no impact on public health or safety.
On August 11, 2020, at 1:35 p.m., one source of offsite power was restored to the DAEC essential buses and the EDGs were placed in standby. Later that day, at 4:00 p.m., DAEC exited the Unusual Event. The reactor was safely cooled down and remains shutdown.
The licensee continues working to restore all offsite power lines to the site and assess potential damage from the storm.
The NRC Senior Resident Inspector responded to the site and verified that required safety functions were maintained. Additional NRC inspectors from Region 3 assisted in response and are continuing to monitor licensee actions to restore offsite power, independently assess any issues caused by the storms, and review the licensees actions in response to the weather event.
This preliminary notification is issued for information only.
The State of Iowa has been notified.
The information presented herein has been discussed with the licensee and is current as of 09:00 a.m. on August 14, 2020.
ADAMS Accession Number: ML20227A083 Contacts: A. Nguyen R. Ruiz (630) 829-9587 (630) 829-9732 April.Nguyen@nrc.gov Robert.Ruiz@nrc.gov