05000280/LER-2024-001, Troubleshooting Initiated Unknown Turbine Trip Feature in Control System
| ML24212A077 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/30/2024 |
| From: | Denise Wilson Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-230 LER 2024-001-00 | |
| Download: ML24212A077 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2802024001R00 - NRC Website | |
text
July 30, 2024 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001
Dear Sir or Madam:
10CFR50.73 Virginia Electric and Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 Serial No.:
24-230 SPS:
MMT Docket No.: 50-280 License No.: DPR-32 Pursuant to 1 0CFR50. 73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to Surry Power Station Unit 1.
Report No. 50-280 I 2024-001-00 This report has been reviewed by the Station Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee.
Enclosure Commitment contained in this letter: None
- 1, /2_
David H. Wilson Site Vice President Surry Power Station cc:
U.S. Nuclear Regulatory Commission, Region II Marquis One Tower, Suite 1200 245 Peachtree Center Ave., NE Atlanta, GA 30303-1257 NRC Senior Resident Inspector Surry Power Station
Abstract
Surry Power Station, Unit 1
00280 3
Troubleshooting Initiated Unknown Turbine Trip Feature in Control System 06 02 2024 2024 001 00 07 30 2024 N
013
David H. Wilson, Site Vice President (757) 365-2001 B
JJ DCC E232 Y
On June 2, 2024, at 1708 hours0.0198 days <br />0.474 hours <br />0.00282 weeks <br />6.49894e-4 months <br /> with Unit 1 at 13% power, Unit 1 experienced an automatic reactor trip due to a turbine trip.
Upon synchronizing Unit 1 turbine generator to the grid, the Turbine Control System (TCS) did not transition to load control as expected. TCS troubleshooting identified that the Breaker Cycling Test mode was active, inhibiting the control system response to breakers being closed. While disabling Breaker Cycling Test mode, the breaker status points were taken off scan. This action initiated an unexpected turbine trip and automatic reactor trip. The turbine trip initiation was caused by a flawed TCS trip logic design. The flawed trip logic rendered a Remote IO failure indication on the TCS Remote IO Failure Trip where no failure existed.
The TCS was returned to a normal configuration for turbine startup, an extent of condition review of the Ovation System for additional unrecognized trips was performed, and TCS indicators and controls were updated in station operating procedures. The health and safety of the public were not affected by this event.
This report is being submitted pursuant to 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in the automatic actuation of the Reactor Protection System.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
5.0 Additional Corrective Actions
Corrective Actions to Address Contributing Causes (CACC) were developed to address procedural review requirements (electronic and non-electronic), specific guidance requirements when developing digital design changes (to include software functionality), training analysis for troubleshooting procedure, revise guidance for Owners Review tracking of open items to resolution, and adding supervisory review requirements for Owners Review in guidance document.
6.0 Actions to Prevent Recurrence Correct flawed identified TCS trip logic for both Unit 1 and Unit 2 Turbine Control Systems.
7.0 Similar Events
No similar events have been noted at Surry.
8.0 Additional Information
The health and safety of the public were not affected by this event. There was no impact to Unit 2.
3 3
Surry Power Station, Unit 1 00280 2024 001 00