05000382/LER-2025-004, Station Air Leak in Control Room Envelope Results in a Condition That Could Have Prevented Fulfilment of a Safety Function
| ML25357A159 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 12/23/2025 |
| From: | Twarog J Entergy Operations |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| W3F1-2025-0057 LER 2025-004-00 | |
| Download: ML25357A159 (0) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3822025004R00 - NRC Website | |
text
John Twarog Manager Regulatory &
Emergency Planning 504-739-6747 Entergy Operations, Inc., 17265 River Road, Killona, LA 70057 W3F1-2025-0057 10 CFR 50.73 December 23, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Licensee Event Report 50-382/2025-004-00, Station Air Leak in Control Room Envelope Resulting in a Condition That Could Have Prevented Fulfillment of a Safety Function Waterford Steam Electric Station, Unit 3 NRC Docket No. 50-382 Renewed Facility Operating License No. NPF-38 Entergy Operations, Inc. (Entergy) submits the enclosed Licensee Event Report (LER) 50-382/2025-004-00 for Waterford Steam Electric Station, Unit 3 (WF3). The event reported herein is reportable in accordance with 10 CFR 50.73(a)(2)(v)(D), event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to "(D) mitigate the consequences of an accident."
This letter contains no new commitments.
Should you have any questions concerning this issue, please contact me at 504-739-6747.
Respectfully, John Twarog JRT/jst
- ) entergy
W3F1-2025-0057 Page 2 of 3 Enclosure: LER 50-382/2025-004-00 cc:
NRC Region IV Regional Administrator NRC Senior Resident Inspector Waterford Steam Electric Station, Unit 3 NRC Project Manager Waterford Steam Electric Station, Unit 3 Louisiana Department of Environmental Quality
Enclosure W3F1-2025-0057 Licensee Event Report 50-382/2025-004-00
Abstract
On October 26, 2025, at 0040 CDT, Waterford Steam Electric Station, Unit 3 (WF3) was operating at approximately 93% reactor power when the operating crew discovered an air leak on Station Air (SA) piping in the 46 foot elevation Control Room Envelope (CRE) Hallway Area. The hairline crack was initially 3" to 4" long located on one side of a nearby piping support. The hairline crack eventually propagated to roughly twice the original size and traveled to the opposite side of the support. The operating crew declared the CRE inoperable and entered Technical Specification (TS) 3.7.6.1.
TS 3.7.6.1 Action b was satisfied by closing manual valves SA-502 and SA-514, isolating the section of piping that developed the crack. The SA leak was isolated at 0120 CDT on October 26, 2025. The piping section was replaced on October 31, 2025. The pipe failure is attributed to age, stress corrosion cracking and a corrosive element present.
This event is reportable pursuant to 10 CFR 50. 73(a)(2)(v)(D), event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to "(D) mitigate the consequences of an accident," due to the control room envelope being inoperable.
Event Description
050 052
- 2. DOCKET NUMBER
- 3. LER NUMBER I
00382 NUMBER NO.
I YEAR SEQUENTIAL REV a-I 004 1-0 On October 26, 2025, at 0040 CDT, Waterford Steam Electric Station, Unit 3 (WF3) was operating at approximately 93%
reactor [RCT] power when the operating crew discovered an air leak on Station Air (SA) piping [PSP] (7SA2-29) in the 46 foot elevation Control Room Envelope [VI] (CRE) Hallway Area. The hairline crack was initially 3" to 4" long located on one side of a nearby piping support. [SPT] The hairline crack eventually propagated to roughly twice the original size and traveled to the opposite side of the support. The operating crew declared the CRE inoperable and entered Technical Specification (TS) 3.7.6.1. Event Notification (EN 58007) was made on October 26, 2025 at 0829 CDT for 10 CFR 50.72 (b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to "(D) mitigate the consequences of an accident," due to the control room envelope being inoperable.
TS 3.7.6.1 states, "Two control room emergency air filtration trains (S-8) shall be OPERABLE. (Note 1)
ACTION:
b. With one or more control room emergency air filtration [FLT] trains inoperable due to inoperable control room envelope boundary in MODES 1, 2, 3, or 4, then perform the following:
- 1. Immediately initiate action to implement mitigating actions; and
- 2. Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, verify mitigating actions ensure control room envelope occupant exposures to radiological, chemical, and smoke hazards will not exceed limits; and
- 3. Within 90 days, restore the control room envelope boundary to OPERABLE status."
TS 3.7.6.1 Action b.1 was satisfied by closing manual valves [ISV] SA-502 and SA-514, isolating the section of piping that developed the crack. TS 3.7.6.1 was exited upon repairs to the piping on October 31, 2025.
Event Cause
The investigation identified the direct cause of the pipe failure was due to stress corrosion cracking. 7SA2-29 is a non-safety, non-seismic 2" red brass pipe. The average lifespan of red brass pipe is 40 to 80 years depending on operating conditions. The pipe was 40 years old and within the end of its expected lifespan. The crack started on one side of the U-bolt support and propagated towards the support, eventually making its way to the other side. The weight of the brass pipe length caused a downward force on the pipe length between U-Bolt supports. When the piping was replaced, the maintenance staff noted that there was a small amount of water present within the pipe, which could have attributed to corrosion. The downward stresses, aging of piping, and corrosion resulted in a thru-wall crack propagating along the pipe near the support.
Safety Assessment
There were no radiological, environmental, or industrial impacts associated with this event. The health and safety of the public and site personnel were not impacted during this event. The SA header pressure remained constant throughout the duration of the leak. Instrument Air (IA) header pressure was never affected.
Corrective Actions
Completed:
7SA2-29 pipe section was replaced on October 31, 2025, under WO 54334852 Planned:
Replace all red brass piping within Control Room Envelope associated with Station Air and Instrument Air
Previous Occurrences
None NOTE: Energy Industry Identification System (EIIS) codes are identified in the text as [XX]. Page 2
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