05000395/LER-2024-001, (Vcsns), Unit 1, Automatic Actuation of B Emergency Diesel Generator
| ML24108A143 | |
| Person / Time | |
|---|---|
| Site: | Summer  (NPF-012) |
| Issue date: | 04/17/2024 |
| From: | Ryan Justice Dominion Energy South Carolina |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-167 LER 2024-001-00 | |
| Download: ML24108A143 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3952024001R00 - NRC Website | |
text
Dominion Energy South Carolina V. C. Summer Nuclear Station Bradham Boulevard & Highway 215, Jenkinsville, SC 29065 Mailing Address:
P.O. Box 88, Jenkinsville, SC 29065 Dominion Energy.com April 17, 2024 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 i; Dominion
- iiiiii" Energy Serial No.
- 24-167 VCS-LIC/JB RO Docket No. 50-395 License No. NPF-12 DOMINION ENERGY SOUTH CAROLINA, INC. (DESC)
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 LICENSEE EVENT REPORT 2024-001-00 AUTOMATIC ACTUATION OF 'B' EMERGENCY DIESEL GENERA TOR Dominion Energy South Carolina, Inc. hereby submits Licensee Event Report (LER) 2024-001-00, for VCSNS. This report provides details concerning the automatic actuation of 'B' Emergency Diesel Generator (EOG) on February 19, 2024, and is submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A).
Should you have any questions, please call Mr. Michael Moore at (803) 345-4752.
Sincerely, Rob rt. Justice Site Vice President V.C. Summer Nuclear Station Enclosure Commitments contained in this letter: None cc:
G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II G. Miller - NRC Project Mgr.
NRC Resident Inspector J. N. Bassett - INPO Marsh USA, Inc.
Abstract
On February 19, 2024, at approximately 0236 EDT, V.C. Summer Nuclear Station (VCSNS) experienced an automatic actuation of the 'B' Emergency Diesel Generator (EDG). The actuation was caused by the 1 DB Normal incoming breaker opening due to an intermittent undervoltage control circuit connection on the associated fuse holder. All plant equipment and systems responded as expected. 'B' Train electrical loads were transferred back to the 1DB Normal power supply at 1700 EDT that same day, following the repair of the fuse holder connection. Reactor power remained at 100% throughout the event.
This event is being reported in accordance with 10 CFR 50. 73(a)(2)(iv)(A).
1.0 DESCRIPTION OF THE EVENT
- 2. DOCKET NUMBER
- 3. LER NUMBER I
395 D
NUMBER NO.
I YEAR SEQUENTIAL REV
~-I 001 1-0 On February 19, 2024, at approximately 0236 EST, the 'B' EOG automatically started as designed when the undervoltage signal was received due to the loss of control power to the undervoltage relays. The undervoltage signal opened the normal incoming breaker and started the 'B' EOG, which powered the 1 DB Bus.
The unit remained in mode 1 at 100% power throughout the event. The 'B' Emergency Feedwater Pump started as part of the normal ESF loading sequence and ran for approximately one minute until it was secured by Operations. All other plant equipment and systems also responded as expected.
Prior to the event, the 'A' EOG was tagged out for scheduled work and entered Technical Specification (TS) 3.8.1.1.b.
With the 'A' EOG tagged out and the 1 DB Normal incoming breaker open, the station entered TS 3.8.1.1.c. The 'A' EOG was restored, aligned for autostart and declared OPERABLE at 1344 EST exiting TS 3.8.1.1.c and transitioned to TS 3.8.1.1.a. The station repaired the control power fuse, returned 1 DB to normal feed, realigned 'B' EOG for autostart, and exited TS 3.8.1.1.a at 1700 EST.
Due to the automatic actuation of 'B' EOG and the EFW system, this event is being reported in accordance with 10 CFR
- 50. 73(a)(2)(iv)(A).
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
With the loss of 1 DB Normal offsite power and unavailable 'A' EOG, the station's remaining credited power supplies consisted of 'B' EOG and both offsite site power sources to bus 1 DA. The Parr Alternate AC power supply was also available. During this event, the 'B' EOG carried the 1 DB Bus as designed.
3.0CAUSEOFTHEEVENT The troubleshooting inspection identified poor contact between the contact clips on the fuse cover and base of the fuse holder. A Level of Effort Evaluation (LEE) determined the likely cause of the poor contact between the contact clips is age related degradation.
4.0 IMMEDIATE CORRECTIVE ACTIONS
The faulty fuse holder was repaired, which allowed 'B' Train loads to be transfered to 1 DB Normal offsite power supply.
5.0 ADDITIONAL CORRECTIVE ACTIONS
In addition to performing an evaluation to further understand the cause, the following actions were developed:
- 1. Perform an extent of condition replacement for the control power fuse holder in XSW1 DA 10.
- 2. Review the maintenance strategies for the control power fuse holder in XSW1 DA, XSW1 DB, XSW1 EA, XSW1 EB, XSW1A, XSW1 B, and XSW1 C.
6.0 ACTIONS TO PREVENT RECURRENCE I
- 2. DOCKET NUMBER
- 3. LER NUMBER I
YEAR SEQUENTIAL REV I 2024 I NUMBER NO.
395
- - I I -0 001 The station is revising EMP-405.018-7.2kV Switchgear Preventive Maintenance and STP-506.004-7.2kV Emergency Bus Undervoltage Unit Calibration to incorporate G.E. SAL 322.1 additional instructions for inspections of fuse holders, application of contact grease for proper fuse holder engagement, and other potential corrections as required.
7.0 SIMILAR EVENTS
No similar events were identified within the last three years.
8.0 MANUFACTURER & MODEL (OR OTHER IDENTIFICATION)
G.E. Fuse Holder 30A Part# 0673D0515-421-04
9.0 ADDITIONAL INFORMATION
None Page 3
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