05000389/LER-2024-002-01, Safety Injection Tank Vent Through Wall Leakage

Safety Injection Tank Vent Through Wall Leakage

ML24194A149
Person / Time
Site:	Saint Lucie
Issue date:	07/11/2024
From:	Rasmus P Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2024-117 LER 2024-002-01
Download: ML24194A149 (1)

LER-2024-002, Safety Injection Tank Vent Through Wall Leakage

Event date:
Report date:
3892024002R01 - NRC Website

text

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July 11, 2024 L-2024-117 10 CFR 50.73

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Re: St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 2024-02-01 Date of Event: January 3, 2024

Safety Injection Tank Vent Through Wall Leakage

The attached Licensee Event Report, 2024-02-01, is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Should you have any questions regarding this submission, please contact Mr. Kenneth Mack, Fleet Licensing Manager, at 561-904-3635.

This letter contains no new or modified regulatory commitments.

Sincerely,

Paul Rasmus General Manager - Regulatory Affairs - Nuclear Fleet Florida Power & Light Company

Attachment

cc: St. Lucie NRC Senior Resident Inspector St. Lucie Station NRC Program Manager

Florida Pow er & Li ght Comp any

6501 S. Oc ean Driv e, Jen se n Beach, FL 3 4957

Abstract

This LER revision supersedes LER 2024-02-00 in its entirety.

On January 3, 2024, while in Mode 3, it was determined that the Reactor Coolant Pressure Boundary (RCPB) had a through wall flaw with Safety Injection Tank (SIT) leakage. The leakage was coming from the welded connection of a vent valve for SIT 2A2 outlet valve piping segment Sl-227. The cause of the leak was microcracks in weld material from a December 16, 2023, repair.

This leak resulted in the Unit being in a Degraded Condition. There were no Systems, Structures, or Components that were inoperable at the start of the event that contributed to the event. This event is being reported pursuant of 10 CFR 50.73(a)(2)

(ii)(A), Degraded Condition.

Description of Event

On January 3, 2024, while in Mode 3, it was determined that the Reactor Coolant Pressure Boundary (RCPB) had a through wall flaw with Safety Injection Tank (SIT) leakage. The leakage was coming from the welded connection of a vent valve for SIT 2A2 outlet valve piping segment Sl-227. This leak resulted in the Unit being in a Degraded Condition. There were no Systems, Structures, or Components that were inoperable at the start of the event that contributed to the event.

Cause of Event

The leak was caused by microcracks in weld material from a December 16, 2023, repair. These microcracks occurred during solidificat ion of the weld material.

Safety Significance :

This event did not prevent any safety systems from performing their safety related functions based on the minimal amount of leakage identified.

This Licensee Event Report is being reported pursuant of 10 CFR 50.73(a)(2)(ii)(A), Degraded Condition.

This event did not result in a Safety System Functional Failure.

Corrective Act ions:

Repairs to Sl-227 were completed on January 5, 2024.

Sim ilar Events:

A review of events over the past 5 years identified one previous event that involved a similar underlying cause of the event reported under this Licensee Event Report. This event is documented in LER 2024-01, Sa fety Injection Tank Vent Line Through Wall Leakage, dated February 13, 2024. The cause of that event was stresses resulting fatigue crack initiation and propagation.

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