05000387/LER-2024-001, Main Steam Isolation Valve Leakage

Main Steam Isolation Valve Leakage

ML24144A278
Person / Time
Site:	Susquehanna
Issue date:	05/23/2024
From:	Casulli E Susquehanna, Talen Energy
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
PLA-8123 LER 2024-001-00
Download: ML24144A278 (1)

LER-2024-001, Main Steam Isolation Valve Leakage

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3872024001R00 - NRC Website

text

May 23, 2024 Edward Casulli Site Vice President Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA I 8603 Tel. 570.542.3795 Fax 570.542. 1504 Edward.Casulli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2024-001-00 UNIT 1 LICENSE NO. NPF-14 PLA-8123 TALEN~

ENERGY 10 CFR 50.73 Docket No. 50-387 Attached is Licensee Event Report (LER) 50-387/2024-001-00. The LER reports an event involving inoperability of a Main Steam Line Isolation Valve that was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.

There were no actual consequences to the health and safety of the public as a result of this event.

This letter contains no new or revised regulatory commitments.

E. Casulli Attachment: LER 50-387/2024-001-00 Copy:

NRC Region I Ms. J. England, NRC Senior Resident Inspector Ms. A. Klett, NRC Project Manager Mr. M. Shields, PA DEP/BRP

Abstract

On March 28, 2024, during Local Leak Rate Testing (LLRT) conducted during the Unit 1 refueling outage, as-found leakage through the inboard Main Steam Isolation Valve (HV141 F0228) was 57,166 standard cubic centimeters per minute (seem) which exceeded the Technical Specification (TS) Surveillance Requirement 3.6.1.3.12 limit of 100 standard cubic feet per hour (scfh)

(47,194 seem) for individual valve leakage. HV141 F022B was repaired resulting in a total penetration LLRT value of 1,568 seem.

There is preliminary indication that the condition existed longer than allowed by TS 3.6.1.3. The condition is being reported in accordance with 10 CFR 50. 73(a)(2)(i)(B) as a condition prohibited by TS.

A cause evaluation is in progress. A supplement will be issued to provide information regarding the cause of the condition and

additional corrective actions

There were no actual consequences to the health and safety of the public as a result of this event.

CONDITIONS PRIOR TO EVENT Unit 1 - Mode 5, zero (0) percent Rated Thermal Power (RTP)

Unit 2 - Mode 1, approximately 100 percent RTP EVENT DESCRIPTION

2. DOCKET NUMBER I

00387 I,,..

I 2024 I-I

3. LER NUMBER SEQUENTIAL NUMBER 001 REV NO.

1-0 On March 28, 2024, during Local Leak Rate Testing (LLRT) conducted during the Unit 1 refueling outage, as-found leakage through the inboard Main Steam Isolation Valve (MSIV) (HV141F022B) [EIIS System/ Component Code: SB/ISV] was 57,166 standard cubic centimeters per minute (seem) which exceeded the Technical Specification Surveillance Requirement (TS SR) 3.6.1.3.12 limit of 100 standard cubic feet per hour (scfh) (47,194 seem) for individual valve leakage. HV141 F022B was repaired resulting in an acceptable as-left penetration LLRT value of 1,568 seem.

Based on preliminary information, there is evidence that the condition existed during the last operating cycle for longer than allowed by TS 3.6.1.3. The condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.

CAUSE OF EVENT The cause of the event is under investigation and will be provided in a supplement to this LER.

ANALYSIS/SAFETY SIGNIFICANCE The redundant MSIV (HV141F028B) in the "B" steam line had an as-found individual leakage value of 4,029 seem, which is below the TS SR 3.6.1.3.12 limit of 100 scfh (47,194 seem). The redundant valve, bounded by engineering evaluation, provides assurance that the dose consequences remain within the regulatory limit of 5 rem Total Effective Dose Equivalent (TEDE) for the control room and 25 rem TEDE for the low population zone and exclusion area boundary. As such, there was no loss of safety function for the redundant valve or the main steam penetration. Accordingly, this event will not be counted as a safety system functional failure in the Reactor Oversight Process Performance Indicators. There were no actual consequences to the health and safety of the public as a result of this event.

CORRECTIVE ACTIONS HV141 F022B was repaired resulting in a leak rate within the TS SR 3.6.1.3.12 limit. Any additional corrective actions will be provided in a supplement to this LER.

PREVIOUS OCCURRENCES Previous occurrences, if any, will be provided in a supplement to this LER. Page 2

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