05000388/LER-2019-001-01, Main Steam Isolation Valve Leakage
| ML19192A010 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 07/10/2019 |
| From: | Cimorelli K Susquehanna, Talen Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-7799 LER 2019-001-01 | |
| Download: ML19192A010 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3882019001R01 - NRC Website | |
text
JUl 1 0 2019 Kevin Cimorelli Site Vice President U.S. Nuclear Regulatory Commission Attn: Document ControlDesk Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3795 Fax 570.542.1504 Kevin.Cimorelli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2019-001-01 UNIT 2 LICENSE NO. NPF-22 PLA-7799 TALEN~
ENERGY 10 CFR 50.73 Docket No. 50-388 Attached is a supplement to Licensee Event Report (LER) 50-388/2019-001-00. The LER reported 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 regulatory commitments.
Should you have any questions regarding this submittal, please contact Ms. Me lisa Krick, Manager-Nuclear Regulatory Affairs, at (570) 542-1818.
K. Cimorelli Attachment: LER 50-388/2019-001-01 Copy:
NRC Region I Ms. T. E. Hood, NRC Project Manager Ms. L. H. Micewski, NRC Sr. Resident Inspector Mr. M. Shields, PA DEP/BRP Ms. J. C. Tobin, NRC Project Manager
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person Is not required to respond to the information collection.
- 13. Page Susquehanna Steam Electric Station Unit 2 05000388 1 OF 3
- 4. Title Main Steam Isolation Valve Leakage
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year N/A 05000 03 28 2019 2019 001 01 07 !0 2019 Facility Name Docket Number N/A 05000
- 9. Operating Mode JAbstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
During the Susquehanna Unit 2 refueling outage, Local Leak Rate Testing (LLRT) conducted on March 27, 2019 determined combined as-found leakage through the inboard Main Steam Isolation Valve (MSIV)
(HV241 F022D) and the outboard MSIV (HV241 F028D) in the "D" Main Steam Line was 55,425 standard cubic centimeters per minute (seem). Subsequent testing, on March 28, 2019 at approximately 20:30, measured the leakage through HV241 F028D as 47,791 seem, which exceeded the Technical Specification (TS) Surveillance Requirement (SR) 3.6.1.3.12 limit of 100 standard cubic feet per hour (scfh) (47, 194 seem) for individual valve leakage.
Based on cause and history, the condition likely 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.
The direct cause of the LLRT failure was valve seating surface wear/degradation over the 34 years in service. Repairs made to the valve resulted in an acceptable as-left LLRT.
There were no actual safety consequences associated with the condition.
NRC FORM 366 (04-2018)
CONDITIONS PRIOR TO EVENT
Unit 1 - Mode 1, approximately 100 percent Rated Thermal Power Unit 2 - Mode 5, 0 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
EVENT DESCRIPTION
During the Susquehanna Unit 2 refueling outage (19RIO), an LLRT conducted on March 27, 2019 determined combined as-found leakage through the inboard MSIV (HV241F022D) [EIIS System /
Component Code: SB/ISV] and the outboard MSIV (HV241F028D) [EIIS System / Component Code:
SB/ISV] in the D Main Steam Line was 55,425 sccm. Subsequent testing, on March 28, 2019 at approximately 20:30, measured the leakage through HV241F028D as 47,791 sccm, which exceeded the TS SR 3.6.1.3.12 limit of 100 scfh (47,194 sccm) for individual valve leakage.
As-found internal inspections of HV241F028D were performed by the original equipment manufacturer, WEIR Valves and Controls (WEIR) and Continental Field Services (CFS). The inspections identified degradation of the in-body stellite seating surface near the two oclock guide rib and inconsistency in the pilot poppet seating profile. Based on discussions with WEIR and CFS personnel, it is most likely that the degraded condition of the seat was due to a material or fabrication process deficiency that became apparent over the 34 years that the valve was in service.
A seating surface repair was performed during 19RIO. An as-left LLRT was performed, and measured a total penetration leakage value of 28,201 sccm, which is below the TS SR 3.6.1.3.12 limit of 47,194 sccm.
Based on cause and history, the condition likely existed during the last operating cycle for longer than allowed by TS SR 3.6.1.3.12. 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 direct cause of the MSIV HV241F028D LLRT failure was valve seating surface wear/degradation over the 34 years in service. Contributing to the HV241F028D LLRT failure was the latent seat material and/or fabrication deficiency that existed from original production.
ANALYSIS/SAFETY SIGNIFICANCE
The redundant MSIV (HV241F022D) in the D Main Steam Line had an as found individual leakage value of 7634 sccm (approximately 16.2 scfh) which is below the TS SR 3.6.1.3.12 limit of 100 scfh Page 3 of 3 (04-2018)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER Susquehanna Steam Electric Station, Unit 2 05000-388 YEAR SEQUENTIAL NUMBER REV NO.
2019 001 01 (47,194 sccm). As a result, there was no loss of safety function for the redundant valve. Additionally, engineering evaluation of the condition demonstrates 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 (LPZ) and exclusion area boundary (EAB). As such, for the identified condition, there was no loss of safety function for the main steam penetration nor any actual or potential consequences to the health and safety of the public.
CORRECTIVE ACTIONS
Corrective actions included repairs to the valve resulting in an acceptable as-left LLRT.
COMPONENT FAILURE INFORMATION
Component Identification - HV241F028D Component Name - Unit 2 Main Steam Line D Outboard Isolation Valve Valve Manufacturer - Atwood & Morrill (Acquired By Weir Valve)
Valve Type - Wye Globe Valve Size - 26 inch Actuator Manufacturer - Hanna Actuator Type - Tandem Cylinder
PREVIOUS OCCURRENCES
The following are the most recent Susquehanna LERs involving MSIV leakage:
LER 50-387/2018-003-01, Main Steam Isolation Valve Leakage Due to Pilot Poppet and Pilot Poppet Seat Wear/Degradation, dated September 5, 2018 LER 50-387/2012-006-01, "D" Outboard Main Steam Isolation Valve Leakage - 2012, dated August 8, 2013 LER 50-387/2010-004-00, "D" Outboard Main Steam Isolation Valve Leakage - 2010, dated August 8, 2013