05000389/LER-2024-001, Safety Injection Tank Vent Through Wall Leakage

Safety Injection Tank Vent Through Wall Leakage

ML24044A167
Person / Time
Site:	Saint Lucie
Issue date:	02/13/2024
From:	Strand D Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2024-017 LER 2024-001-00
Download: ML24044A167 (1)

LER-2024-001, Safety Injection Tank Vent Through Wall Leakage

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
3892024001R00 - NRC Website

text

February 13, 2024 L-2024-017 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: 2024-01-00 Date of Event: December 15, 2023

Safety Injection Tank Vent Through Wall Leakage

The attached Licensee Event Report, 2024-01, 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.

Diann S rand General anager, Regulatory Affairs Florida Power & Light Company

Attachment

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

Florida Power & Light Company

6501 S. Ocean Drive, Jensen Beach, FL 34957

Abstract

On December 15, 2023, 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 stresses resulting in fatigue crack initiation and propagation.

This leak resulted in the Unit being in a Degraded Condition. There were no Systems, Structures, or Components inoperable 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 December 15, 2023, 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 inoperable that were inoperable at the start of the event that contributed to the event.

Cause of Event

The cause of the leak was stresses resulting in fatigue crack initiation and propagation. These stresses were related to internal pressure within the piping, bending stresses related to the vent valve weight and its mounting arrangement, and system vibration.

Safety Significance

This event d id 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 Actions

Repairs to Sl-227 were completed on December 16, 2023.

Similar Events

A review of events over the past 5 years did not identify any previous events that involved the same underlying cause of the event reported under this Licensee Event Report.