05000325/LER-2020-003, Automatic Specified System Actuations Due to Loss of Offsite Power
| ML20265A162 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/21/2020 |
| From: | Krakuszeski J Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RA-20-0268 LER 2020-003-00 | |
| Download: ML20265A162 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3252020003R00 - NRC Website | |
text
September 21, 2020 e..l_~ DUKE
~ ENERGY Serial: RA-20-0268 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Brunswick Steam Electric Plant, Unit No. 1 Renewed Facility Operating License No. DPR-71 Docket No. 50-325 Licensee Event Report 1-2020-003 John A. Krakuszeski Vice President Brunswick Nuclear Plant 8470 River Rd SE Southport, NC 28461 o: 910.832.3698 10 CFR 50.73 In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Duke Energy Progress, LLC, is submitting the enclosed Licensee Event Report (LER). This report fulfills the requirement for a written report within sixty (60) days of a reportable occurrence.
This document contains no regulatory commitments.
Please refer any questions regarding this submittal to Ms. Sabrina Salazar, Manager - Nuclear Support Services, at (910) 832-3207.
Sincerely, John A. Krakuszeski SBY/sby
Enclosure:
Licensee Event Report
U.S. Nuclear Regulatory Commission Page 2 of 2 cc (with enclosure):
Ms. Laura Dudes, NRC Regional Administrator, Region II Mr. Andrew Hon, NRC Project Manager Mr. Gale Smith, NRC Senior Resident Inspector Chair - North Carolina Utilities Commission
Abstract
At 23:02 Eastern Daylight Time on August 3, 2020, with Unit 1 in Mode 1 at approximately 19% power during Hurricane Isaias, a loss of the transformer bus powering the Startup Auxiliary Transformer (SAT) resulted in a Loss of Offsite Power (LOOP). By design, all Main Steam Isolation Valves closed and an automatic reactor scram occurred. All control rods inserted as expected on the scram. At the time of this event the main generator was removed from service due to unrelated generator ground issues and all plant loads were being supplied by the SAT.
By design, the LOOP resulted in automatic actuation of Primary Containment Isolation System (PCIS) Group 1, 2, 3, 6, and 8 isolation valves. In addition, all four emergency diesel generators (EDGs) started, with EDGs 1 and 2 loading to their respective emergency buses per design. Reactor water level reached low level 1 following the scram resulting in automatic actuation of PCIS Groups 2, 6, and 8, by design.
The electrical fault that caused the transformer bus powering the SAT to trip and subsequent LOOP was determined to be a result of storm generated debris.
There was no impact on the health and safety of the public or plant personnel. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) due to valid actuation of the Reactor Protection System, PCIS, and EDGs.
(See Page 3 for required number of digits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
Corrective Actions
Testing on all components that could have caused the electrical fault was completed on August 7, 2020. Resetting and re-energizing the Unit 1 Transformer Bus and placing load on the Unit 1 SAT was completed on August 9, 2020.
Previous Similar Events
No events have occurred within the past three years in which a LOOP has occurred.
Commitments
No regulatory commitments are contained in this report.