05000331/LER-2020-001, Notice of Unusual Event and Unit Trip Due to Loss of Offsite Power Due to High Winds
| ML20258A229 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 09/11/2020 |
| From: | Dean Curtland NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-20-0076 LER 2020-001-00 | |
| Download: ML20258A229 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iii) |
| 3312020001R00 - NRC Website | |
text
September 11, 2020 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Duane Arnold Energy Center Docket 50-331 Renewed Op. License No. DPR-49 Licensee Event Report 2020-001 NEXTeraM ENERGY~
DUANE ARNOLD NG-20-0076 10 CFR 50.73 Please find attached the subject report submitted in accordance with 10 CFR 50.73. This letter makes no new commitments or changes to any existing
commitments
Dean Curtland Site Director, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC cc:
Administrator, Region Ill, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324
NRC FORM 366 (04-201 8)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
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- 1. Facility Name Duane Arnold Energy Center
- 4. Title
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
Duane Arnold Energy Center 05000-331 YEAR 2020
- 3. LER NUMBER SEQUENTIAL NUMBER
- - 001 Operators were quickly able to establish pressure control initially via Steam Line Drains and RCIC and establish a cooldown rate.
Both recirculating pumps tripped when power was lost to their associated non-safety related electrical busses. The operators followed procedures for cooldown with no forced circulation in the core. When Shutdown Cooling was placed in service, forced circulation was re-established which resulted in exceeding the bottom head cooldown limits of 100 degrees per hour. This was anticipated and could not be avoided.
This event did not result in a Safety System Functional Failure.
Ill.
Cause of Event
The cause of the LOOP was an extremely severe storm (called a Derecho) with heavy rains and very high winds. Wind speeds exceeded 80 mph for over 20 minutes with peaks on site at greater than 100 mph. The National Weather Service later estimated wind speeds were likely near 130 mph. These winds resulted in all 6 off site power sources (4 - 161 kV and 2 - 345 kV) coming into the DAEC switchyard being damaged or downed. A separate offsite 69 kV line which feeds non-essential plant loads was also damaged.
IV.
Corrective Actions
REV NO.
- - 00 The high winds experienced on August 10, 2020 were not considered a beyond design basis event. The systems and components responded as designed and the overall peak wind speeds were within the Design Basis Tornado. The damage observed coincides with the amount of damage expected for the event. Given this event was outside the control of the station staff and that all components worked as designed, no additional corrective actions beyond repair/recovery efforts related to the wind storm are needed.
V.
Additional Information
Previous Similar Occurrences:
A review of NextEra Energy Duane Arnold LERs from the previous 5 years identified the following event:
LER 2018-004 - Automatic Reactor Scram due to Feedwater Regulating Valve Failure LER 2019-001 - Automatic Reactor Scram due to Loss of Feedwater Page 3 of 4 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3D
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR Duane Arnold Energy Center 05000-331 2020 EllS System and Component Codes:
EB - Medium-Voltage Power System
Reporting Requirements
This activity is being reported pursuant to the requirements of 10 CFR 50.73(a)(2)(iv)(A) and 50.73(a)(2)(iii). SEQUENTIAL NUMBER
- - 001 REV NO.
- - 00 Page 4 of 4