05000400/LER-2024-001, Automatic Reactor Trip Due to Main Generator Lock-Out
| ML24204A192 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 07/22/2024 |
| From: | Hoffman D Duke Energy Progress |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA-24-0183 LER 2024-001-00 | |
| Download: ML24204A192 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4002024001R00 - NRC Website | |
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~ ENERGY David S. Hoffman Plant Manager Shearon Harris Nuclear Power Plant 5413 Shearon Harris Road New Hill, NC 27562-9300 10 CFR 50.73 July ~~ 2024 Serial: RA-24-0183 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400/Renewed License No. NPF-63 Subject: Licensee Event Report 2024-001-00 Ladies and Gentlemen:
Duke Energy Progress, LLC, submits the enclosed Licensee Event Report 2024-001-00 in accordance with 10 CFR 50.73(a)(2)(iv)(A) for Shearon Harris Nuclear Power Plant, Unit 1 (HNP). This event had no significance with respect to the health and safety of the public.
There are no regulatory commitments contained within this report.
Please refer any questions regarding this submittal to Mike Hershkowitz at (984) 229-2828.
SincereJ)v{!f-David S. Hoffman Enclosure: Licensee Event Report 2024-001-00 cc:
P. Boguszewski, NRC Senior Resident Inspector, HNP M. Mahoney, NRC Project Manager, HNP NRC Regional Administrator, Region II
Abstract
On May 30, 2024, at 19:49 Eastern Daylight Time, Shearon Harris Nuclear Power Plant, Unit 1, experienced an automatic reactor trip from 100 percent power due to lock-out of the main generator caused by an electrical fault in the non-segmented bus at the 6.9 kV bushing box of Unit Auxiliary Transformer (UAT) 1B. UAT-1B was replaced during the 2024 spring refueling outage. Following the reactor trip, the unit was stabilized in Mode 3 at normal operating temperature and pressure. The reactor trip was not complex, with all systems responding normally post-trip. Local observation identified damage to the UAT-1B Y-side non-segregated bus at the connection to the low side bushing box. The reactor trip was reported on May 30, 2024, under 10 CFR 50.72(b)(2)(iv)(B) as an event or condition that results in actuation of the reactor protection system when the reactor is critical. The event had no impact on the health and safety of the public. A root cause evaluation is in progress to determine the causal factors leading to the electrical fault. Once the evaluation is complete, a supplemental report will be issued containing the causal factors and corrective actions for this event.
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D. Corrective Actions
UAT-1B has been isolated from the onsite electrical system. HNP was synhcronized to the grid at 13:26 on June 1, 2024. Power is aligned to train 'B' electrical loads through SUT-1B. Additional actions will be determined as needed following completion of the root cause evaluation.
E. Safety Analysis
Following the reactor trip and loss of power from UAT-1B, the power supply was automatically fast transferred from UAT-1B to SUT-1B, maintaining the power supply to the associated safety bus. Loads from UAT-1A were also fast transferred to SUT-1A, in accordance with plant design. The automatic reactor trip was not complex, with all safety systems functioning as designed during and following the reactor trip. This reactor trip had no impact on the health and safety of the public.
F. Additional Information
There have been no events at HNP similar to the event documented in this LER in the past three years.
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