05000287/LER-2024-001, Procedure Deficiency Results in Inadvertent Automatic Feedwater Isolation and Automatic Emergency Feedwater Actuation
| ML24215A408 | |
| Person / Time | |
|---|---|
| Site: | Oconee  (DPR-055) |
| Issue date: | 08/02/2024 |
| From: | Denise Wilson Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA-24-0207 LER 2024-001-00 | |
| Download: ML24215A408 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2872024001R00 - NRC Website | |
text
David A. Wilson Manager, Nuclear Support Services Oconee Nuclear Station Duke Energy ON01SC l 7800 Rochester Hwy Seneca, SC 29672 o. 864.873.3451 f: 864.873.5791 David.Wilson2@duke-energy.com RA-24-0207 August 2, 2024 10 CFR 50.73 Attn: Document Control Desk U. S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2746 Duke Energy Carolinas, LLC Oconee Nuclear Station Unit 3 Docket Number: 50-287 Renewed Operating License: DPR-55
Subject:
Licensee Event Report 287/2024-001, Revision 00 - Procedure Deficiency Results in Inadvertent Automatic Feedwater Isolation and Automatic Emergency Feedwater Actuation Licensee Event Report 287/2024-001, Revision 00, is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
There are no regulatory commitments associated with this LER.
If there are questions, or further information is needed, contact David Wilson, Nuclear Support Services Manager, at (864) 873-3451.
Sincerely, David A. Wilson Manager, Nuclear Support Services Oconee Nuclear Station Enclosure: Licensee Event Report 287-2024-001 Rev.00
RA-24-0207 August 2, 2024 Page 2 cc (w/Enclosure):
Ms. Laura Dudes, Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. Shawn Williams, Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-08B1A Rockville, MD 20852-2738 Mr. Nick Smalley NRC Senior Resident Inspector Oconee Nuclear Station
Abstract
At 00:51 Eastern Daylight Time on 6/3/2024, with Oconee Nuclear Station Unit 3 in Mode 3 at 0 percent power, an actuation of the emergency feedwater system (EFW) occurred as main steam (MS) pressure was being lowered as part of reactor coolant system cooldown for a planned shutdown. MS pressure was lowered below the actuation setpoint for the Automatic Feedwater Isolation System (AFIS) prior to bypassing AFIS, resulting in trip of the operating main feedwater pump and subsequent auto-start of the 3A and 3B motor driven EFW pumps on low steam generator level circuit. All systems operated as designed, no equipment failures occurred or contributed to the event, and there was no release of radioactive material to the environment. The cause of the event was a change to the unit shutdown procedure that did not include appropriate barriers to consistently prevent an inadvertent AFIS actuation. An additional cause for the event was inadequate oversight of operator monitoring of MS pressure and bypass of AFIS. Corrective actions include revising unit shutdown procedures to ensure barriers to AFIS actuation and improvements to operator and oversight training.
This event was reported to the NRC on 6/3/2024 (Event Notification 57159), as an 8-hour notification under 10 CFR 50.72(b)(3)
(iv)(A) - Specified System Actuation (EFW) and is also reportable under 10 CFR 50.73(a)(2)(iv)(A) as an EFW system actuation.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
SAFETY ANALYSIS
AFIS and EFW responded as expected to actual low MS pressures and an actual low SG level signal, respectively. All safety systems operated as designed and no equipment failures occurred or contributed to the event. There was not a significant change in plant parameters since the reactor had already entered Mode 3 in the process of a normal plant shutdown and the event did not result in any releases to the environment. Additional defense-in-depth to maintain safe shutdown was available from EFW cross connects from Units 1 and 2, SSF ASW, and PSW, and portable FLEX equipment. No Emergency Core Cooling System (ECCS) [BP, BQ] or other automatic safety system actuations occurred in response to this event. A post-event review found no procedural or human performance issues with the operator response to the event. There were no maintenance or other safety significant activities being conducted on any of the defense-in-depth plant systems or equipment at the time of the event. It has been determined this event had a negligible impact on nuclear safety.
ADDITIONAL INFORMATION
A review of Duke Energys Corrective Action Program did not identify any Oconee LERs or events in the last three years that involved the same causes as this event.
This event is considered INPO IRIS Reportable. There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.
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Oconee Nuclear Station Unit 3 00287 2024 001 00