05000528/LER-2025-003, Specified System Actuation Due to Loss of Power (Lop)/Load Shed (LS) Signal
| ML25156A358 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/05/2025 |
| From: | Spina J Arizona Power Services |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-08956-JLS/TR LER 2025-003-00 | |
| Download: ML25156A358 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 5282025003R00 - NRC Website | |
text
10 CFR 50.73 A member of the STARS Alliance, LLC Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek Jennifer L. Spina Vice President Nuclear Regulatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7602 Tel: 623.393.4621 102-08956-JLS/TR June 5, 2025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Palo Verde Nuclear Generating Station (PVNGS) Unit 1 Docket No. STN 50-528 / Renewed License No. NPF-41 Licensee Event Report 2025-003-00 Enclosed, please find the Licensee Event Report (LER) 50-528/2025-003-00 that has been prepared and submitted pursuant to 10 CFR 50.73. This LER reports an event in which Unit 1 had a Specified System Actuation due to an invalid Loss of Power (LOP)/Load Shed (LS) signal which resulted in a valid LOP to the Train A Class 1E 4.16 kilovolt (kV) bus.
In accordance with 10 CFR 50.4, copies of this LER are being forwarded to the Nuclear Regulatory Commission (NRC) Regional Office, NRC Region IV, and the Senior Resident Inspector.
No new commitments are being made to the NRC by this letter.
Should you need further information regarding this submittal, please contact Matthew S. Cox, Department Leader, Nuclear Regulatory Affairs, at (623) 393-5753.
Sincerely, JLS/TR/cr Enclosure: Unit 1 Licensee Event Report 2025-003-00 cc:
J. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS A. Tran NRC Acting Senior Resident Inspector for PVNGS Spina, Jennifer (Z08962)
Digitally signed by Spina, Jennifer (Z08962)
Date: 2025.06.05 11:50:41 -07'00'
ENCLOSURE Unit 1 Licensee Event Report 2025-003-00
Abstract
Palo Verde Nuclear Generating Station (PVNGS) Unit 1
00528 4
Unit 1 Specified System Actuation due to Loss of Power (LOP)/Load Shed (LS) Signal 04 08 2025 2025 003 00 06 05 2025 Defueled 0
Matthew S. Cox, Department Leader, Nuclear Regulatory Affairs (623) 393-5753
On April 8, 2025, at 1924 Mountain Standard Time (MST), while Operations was re-energizing the Unit 1 Train A Balance of Plant Engineered Safety Features Actuation System (BOP-ESFAS) following pre-planned refueling outage maintenance, an invalid Loss of Power (LOP)/Load Shed (LS) signal actuated. This resulted in a valid LOP to the Unit 1 Train A Class 1E 4.16 kilovolt (kV) bus. Operators restored power to Train A Class 1E 4.16 kV bus with the Train A Emergency Diesel Generator (EDG) at 1934 MST.
The direct cause of this event was that the Repetitive Task (RT) to install cross train jumpers and lift leads for the load shed relays to support de-energizing the Train A BOP-ESFAS was not performed. Corrective Actions include briefings with Operations and maintenance personnel to reinforce effective communication and supervisory oversight in accordance with station procedures as well as procedure and design modification implementation enhancements. Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
7. CORRECTIVE ACTIONS
Development of briefings to reinforce effective communication and supervisory oversight in accordance with station procedures for Operations and maintenance personnel.
Revise Operations procedure for de-energizing BOP-ESFAS to enhance verbiage and to add a new step to confirm the action was completed prior to proceeding in the procedure sequence.
Review of the BOP-ESFAS modification implementation activities to identify any gaps in required work activities.
8. PREVIOUS SIMILAR EVENTS
On April 27, 2024, Unit 3 Train B EDG inadvertently started when the handswitch was taken to REMOTE as part of clearance restoration activities. The automatic start of the EDG was caused by a LOP signal that had not been reset after the de-energization of Train B BOP-ESFAS. The cause of this event was an error trap in the De-Energization of BOP-ESFAS procedure.
Although both of these events resulted from utilizing the De-Energization of BOP-ESFAS procedure, the corrective actions from the previous LER (50-530/2024-002-00) event would not have prevented the event which is the subject of this LER.
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Palo Verde Nuclear Generating Station (PVNGS) Unit 1 00528 2025 003 00