05000270/LER-2023-001, Inappropriate Procedural Guidance for Planned Online Maintenance Results in Event or Condition That Could Have Prevented Fulfillment of a Safety Function Licensee
| ML24060A312 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/29/2024 |
| From: | Denise Wilson Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA-24-0072 LER 2023-001-00 | |
| Download: ML24060A312 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 2702023001R00 - 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-24-0072 February 29, 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 2 Docket Number: 50-270 Renewed Operating License: DPR-47
Subject:
Licensee Event Report 270/2023-001, Revision 00 - Inappropriate Procedural Guidance for Planned Online Maintenance Results in Event or Condition that Could Have Prevented Fulfillment of a Safety Function Licensee Event Report 270/2023-001, 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 Laura Boyce, Regulatory Affairs, at (864) 873-6774.
Sincerely, David A. Wilson Manager, Nuclear Support Services Oconee Nuclear Station Enclosure: Licensee Event Report 270-2023-001 Rev.00 dc=com, dc=duke-energy, dc=ent, dc=nam, ou=Accounts, ou=Personal, ou=PNTransitional, cn=DAWilso (252825), email=David.Wilson2@duke-energy.com I attest to the accuracy and integrity of this document.
2024.02.29 18:14:34 -05'00'
RA-24-0072 February 29, 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. Jared Nadel NRC Senior Resident Inspector Oconee Nuclear Station
Abstract
Oconee Nuclear Station Unit 2
00270 4
Inappropriate Procedural Guidance for Planned Online Maintenance Results in Event or Condition that Could Have Prevented Fulfillment of a Safety Function 04 17 2023 2023 001 00 02 29 2024 1
100
Laura Boyce, Senior Nuclear Engineer, Oconee Regulatory Affairs (864) 873-6774 D
Y
On April 17, 2023, Oconee Unit 2 was operating at approximately 100 percent power. Planned maintenance began on the 2A Reactor Building Cooling Unit (RBCU) in the Unit 2 Reactor Building (RB) to clean the heat exchanger tubes. Sequenced steps resulted in a direct pathway from the Unit 2 Reactor Building to the environment through the Low Pressure Service Water (LPSW) return piping for less than one hour. At the completion of the maintenance, valve sequencing again resulted in a direct pathway from the Unit 2 RB to the environment through the LPSW supply and/or return piping for less than eight hours.
Similar events occurred between April 18/19, 2023, for the cleaning of the 2C RBCU and March 2, 2023, for a leak repair on the 2B RBCU. The cause of these events was an error in applicable station procedure guidance which directed entry to TS 3.6.3 Condition C rather than entry to TS 3.6.1 Condition A. An immediate corrective action was taken to place station procedures for isolation of LPSW to the RBCUs on technical hold. Planned corrective actions include development of station procedure revisions to include appropriate TS condition entry guidance and training for licensed operators on application of Containment and Containment Isolation Valve Technical Specifications.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 SAFETY ANALYSIS (CONT'D)
The inoperability of the Unit 2 containment resulting from the 2C RBCU cleaning activities and the 2B RBCU leak repair were also analyzed to determine their risk impact. The configurations entered for the work were equivalent to that of the 2A RBCU cleaning activities. However, the durations of both the isolation and restoration sequences where valve alignments resulted in a direct pathway from the Unit 2 Reactor Building to the environment were less than one hour for the 2C RBCU cleaning and less than three hours for the 2B RBCU leak repair. Because less time was spent in the configurations of interest for the 2C RBCU cleaning activities and the 2B RBCU leak repair than the 2A RBCU cleaning activities, the risk analysis performed for the 2A RBCU cleaning activities bounds the risk associated with 2C RBCU cleaning activities and the 2B RBCU leak repair. Therefore, it can be concluded these events also had a negligible impact to the health and safety of the public.
ADDITIONAL INFORMATION
A review of Duke Energy's Corrective Action Program did not identify any Oconee LERs or additional events in the last three years that involve the same underlying concerns or reasons 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 2 00270 2023 001 00