05000287/LER-2023-002, Passive Containment Isolation Device Inoperability Results in Operation or Condition Prohibited by Technical Specifications
| ML24060A311 | |
| Person / Time | |
|---|---|
| Site: | Oconee  (DPR-055) |
| Issue date: | 02/29/2024 |
| From: | Denise Wilson Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA-24-0071 LER 2023-002-00 | |
| Download: ML24060A311 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 2872023002R00 - 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-24-0071 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 3 Docket Number: 50-287 Renewed Operating License: DPR-55
Subject:
Licensee Event Report 287/2023-002, Revision 00 - Passive Containment Isolation Device Inoperability Results in Operation or Condition Prohibited by Technical Specifications Licensee Event Report 287/2023-002, 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 287-2023-002 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 18:12:09 -05'00'
RA-24-0071 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 3
00287 4
Passive Containment Isolation Device Inoperability Results in Operation or Condition Prohibited by Technical Specifications 06 23 2023 2023 002 00 02 29 2024 1
100
Laura Boyce, Senior Nuclear Engineer, Oconee Regulatory Affairs (864) 873-6774 B
KG PSP X000 Y
On June 22, 2023, Oconee Unit 3 was operating at approximately 100 percent power. At approximately 22:50 Eastern Daylight Time (EDT), an unexpected increase in Unit 3 Reactor Building Normal Sump (RBNS) input rate was identified. The source of the Unit 3 RBNS input was identified at approximately 21:45 EDT on June 24, 2023, as a 3/4-inch instrument line broken upstream of normally closed instrument valve 3LPS-IV-0081. The direct cause is associated with the physical failure of a short section of 3/4 inch carbon steel instrument piping due to internal corrosion of the carbon steel piping at a carbon steel (CS) to stainless steel (SS) weld. The most probable cause of the failure was a deficiency in either the design scope or implementation of a 1998 Engineering Change; resulting in small segments of small-bore CS instrument piping not being replaced with SS as intended.
Immediate corrective actions included: replacing piping configuration at 3LPS-IV-0081 to resolve the leak and performing an extent of condition (EOC) review to identify additional small-bore instrument piping locations with CS to SS welds. Planned corrective actions include installation of alternate piping configurations for components with CS to SS welds identified during EOC review and revision of design documentation to reflect existing stainless steel pipe configurations.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 CORRECTIVE ACTIONS (CONT'D)
Planned:
- 1. For Unit 3 components with CS to SS welds identified during the EOC review, install alternate piping configurations at identified components during Spring 2024 Unit 3 Refueling Outage.
- 2. Complete EOC walkdowns for areas that are inaccessible at power at the next available opportunity (Spring 2024 Unit 3 Refueling Outage and Fall 2024 Unit 1 Refueling Outage)
- 3. Revise design documentation to reflect existing stainless steel pipe configurations.
SAFETY ANALYSIS
The Unit 3 LPSW leak resulting in the requirements of TS 3.6.3 not being met was evaluated for its risk impact. It was determined the condition had a negligible impact to public health and safety. The applicable risk metric is LERF as the condition resulted in failing to satisfy the requirements established in TS 3.6.3 pertaining to operability of the containment isolation devices. A leak rate more than allowable overall containment leakage limits existed for a period of approximately 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br />. An accident occurring during this limited window of time is very unlikely. Additionally, throughout the duration of the event the ability to isolate containment was maintained. Penetrations 21 and 22 affected by the condition were capable of being isolated via closure of valves 3LPSW-6 and 3LPSW-15. Both valves close automatically on ES signal.
Therefore, it has been concluded this event 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 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 3 00287 2023 002 00