05000482/LER-2025-003, Loss of Voltage on ESF Bus Results in Automatic Actuation of Emergency Diesel Generator
| ML25351A150 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  (NPF-042) |
| Issue date: | 12/17/2025 |
| From: | Carlson E Wolf Creek |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 001279 LER 2025-003-00 | |
| Download: ML25351A150 (0) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4822025003R00 - NRC Website | |
text
P.O. Box 411 l Burlington, KS 66839 l 620-364-8831 Eric D. Carlson Plant Manager December 17, 2025 001279 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Docket No. 50-482: License Event Report (LER) 2025-003-00, Loss of Voltage on ESF Bus Results in Automatic Actuation of Emergency Diesel Generator Commissioners and Staff:
The enclosed Licensee Event Report (LER) 2025-003-00 is being submitted pursuant 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in a valid actuation of one of the emergency diesel generators at Wolf Creek Generating Station.
This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-8831 extension 4570, or Dustin Hamman at (620) 364-4204.
Sincerely, Eric D. Carlson EDC/jkt
Enclosure:
LER 2025-003-00 cc:
A. N. Agrawal (NRC), w/e S. S. Lee (NRC), w/e J. D. Monninger (NRC), w/e Senior Resident Inspector (NRC), w/e WC Licensing Correspondence, w/e - WO 25-001279
Abstract
Wolf Creek Generating Station (WCGS)
00482 3
Loss of Voltage on ESF Bus Results in Automatic Actuation of Emergency Diesel Generator 11 5
2025 2025 003 00 12 17 25 Mode 5 0%
Jason Knust, Lead Licensing Engineer 620-364-8831
At 1003 Central Standard Time (CST), with the unit in Mode 5 at 0% power, an actuation of the 'A' Emergency Diesel Generator (EDG) occurred when energizing main transformers from the switchyard for post-installation soak. The energization was coordinated with transmission system operators using approved procedures. However, grid conditions external to the substation allowed the voltage to drop below the NB01 bus undervoltage relay setpoint.
The EDG automatically started as designed and picked up the loads on the NB01 bus. All safety systems responded as designed. Substation parameters immediately recovered to normal values and all systems were restored to standby conditions. This event is being submitted pursuant 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in a valid actuation of one of the emergency diesel generators at Wolf Creek Generating Station.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 BASIS FOR REPORTABILITY The 'A' EDG automatically actuated during the energization of the Main Transformers from the switchyard as part of the post-installation soak process. This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) due to the valid actuation of the 'A' EDG. In addition, the valid actuation of the 'A' EDG was also reported on 11/5/2025 as an 8-hour non emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) (ENS#58026).
CAUSE
The event was caused by insufficient base loading to support the power requirements for energizing the main transformers.
CORRECTIVE ACTIONS
Immediate actions included restoring the offsite source to energize NB01. As a corrective action to be taken, Evergy Transmission will complete a grid study to develop appropriate parameters and acceptable ranges prior to energizing the main transformers on backfeed in the future.
SAFETY SIGNIFICANCE
There were no safety consequences as a result of the 'A' EDG actuation. The EDG automatically started as designed and picked up the loads on the NB01 bus. All safety systems responded as designed. Substation parameters immediately recovered to normal values, and all systems were restored to standby conditions.
OPERATING EXPERIENCE/PREVIOUS EVENTS No similar events were identified at WCGS within the last three years.
3 3
Wolf Creek Generating Station (WCGS) 00482 25 003 00