05000387/LER-2024-001-01, Main Steam Isolation Valve Leakage Due to Valve Body Seat Wear

Main Steam Isolation Valve Leakage Due to Valve Body Seat Wear

ML24234A326
Person / Time
Site:	Susquehanna
Issue date:	08/21/2024
From:	Casulli E Susquehanna
To:	Office of Nuclear Reactor Regulation
References
PLA-8132 LER 2024-001-01
Download: ML24234A326 (1)

LER-2024-001, Main Steam Isolation Valve Leakage Due to Valve Body Seat Wear

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3872024001R01 - NRC Website

text

Edward Casulli Site Vice President August 21, 2024 Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3795 Fax 570.542.1504 Edward.Casulli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2024-001-01 UNIT 1 LICENSE NO. NPF-14 PLA-8132 TALEN~

ENERGY 10 CFR 50.73 Docket No. 50-387 Atta9hed is Licensee Event Report (LER) 50-387/2024-001-01. The LER supplement reports an event involving inoperability of a Main Steam Line Isolation Valve that was determined to be repmiable 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 Mark Jones, General Manager-* Engineering Acting Site VP for Ed Casulli Attachment: LER 5 0-387/2024-001-01 Copy:

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

NRG FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024)

1. Facility Name 00 050

2. Docket Number 3, Page Susquehanna Steam Electric Station Unit 1 052 00387 1 OF 3

4. Title Main Steam Isolation Valve Leakage Due to Valve Body Seat Wear

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Month Day Year Year Sequential Revision Month Day Year Facility Name Docket Number Number No.

050 03 28 2024 2024 -

001 -

01 8

21 2024 Facility Name Docket Number 052

9. Operating Mode

10. Power Level 5

0

)

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 (HV141F022B) 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. This was due to normal wear on the valve body seat over the previous operating cycle compounded by inherent low margin following prior valve repair in 2022. HV141 F022B was repaired resulting in a total penetration LLRT value of 1,568 seem.

Based on cause, 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 TS. Repairs to the valve resulted in an acceptable as-left LLRT value.

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

CONDITIONS PRIOR TO EVENT

2. DOCKET NUMBER 3, LER NUMBER I

00387 D

NUMBER NO.

I YEAR SEQUENTIAL REV

~-I 001 1-0 Unit 1 - Mode 5, approximately O percent Rated Thermal Power (RTP)

Unit 2 - Mode 1, approximately 100 percent RTP EVENT DESCRIPTION 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. This was due to normal wear on the valve body seat over the previous operating cycle. HV141 F022B was repaired resulting in a total penetration LLRT value of 1,568 seem.

Based on cause, 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 TS.

CAUSE OF EVENT The cause of HV141 F022B LLRT failure was normal wear on the valve body seat over the previous operating cycle compounded by inherent low margin following prior valve repair in 2022.

ANALYSIS/SAFETY SIGNIFICANCE The redundant MSIV (HV141 F028B) 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 TS SR 3.6.1.3.12 limit. In addition, applicable LLRT implementing procedures will be revised to establish a post-repair leak rate alert level to invoke decision making regarding additional repairs.

COMPONENT FAILURE INFORMATION Component Identification - HV141 F022B Component Name - Unit 1 Main Steam Line 'B' Inboard Isolation Valve Valve Manufacturer - Atwood & Morrill Co.

Valve Type - Wye Globe Valve Size - 26" Actuator Manufacturer - Hanna Actuator Type - Tandem Cylinder PREVIOUS OCCURRENCES

2. DOCKET NUMBER

3. LER NUMBER I

00387 I

YEAR I

2024 I -i SEQUENTIAL REV NUMBER NO.

001 1-0 LER 50-387/2022-001-01, Main Steam Isolation Valve Leakage due to Seating Surfaces Wear and Material Deposits, dated August 10, 2022.

LER 50-388/2019-001-01, Main Steam Isolation Valve Leakage, dated July 10, 2019.

LER 50-387/2018-003-01, Main Steam Isolation Valve Leakage Due to Pilot Poppet and Pilot Poppet Seat Wear/Degradation, dated September 05, 2018. Page 3

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