05000278/LER-2023-002, Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit

Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit

ML23348A260
Person / Time
Site:	Peach Bottom
Issue date:	12/14/2023
From:	Stiltner R Constellation Energy Corp
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
CCN: 23-97 LER 2023-002-00
Download: ML23348A260 (1)

LER-2023-002, Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2782023002R00 - NRC Website

text

10 CFR 50.73 CCN: 23-97 December 14, 2023 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Unit 3 Subsequent Renewed Facility Operating License No. DPR-56 NRC Docket No. 50-278 Subject:

Licensee Event Report (LER) 2023-002-00 Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit The subject report is being submitted in accordance with 50.73(a)(2)(i)(B) for any operation or condition which was prohibited by the plants Technical Specifications.

There are no commitments contained in this letter. If you have any questions, please contact the Peach Bottom Regulatory Assurance Manager, Mr. Wade Scott at (717) 456-3047.

Respectfully, Ryan C. Stiltner Plant Manager Peach Bottom Atomic Power Station Enclosure cc:

USNRC, Administrator, Region I USNRC, Senior Resident Inspector W. DeHaas, Commonwealth of Pennsylvania S. Seaman, State of Maryland B. Watkins, PSE&G, Financial Controls and Co-Owner Affairs Stiltner, Ryan C Digitally signed by Stiltner, Ryan C

Date: 2023.12.14 12:40:36 -05'00'

Abstract

On October 16, 2023, during performance of a surveillance test while beginning a refueling outage, the stroke times of Main Steam Isolation Valves (MSIVs) exceeded the Technical Specifications limit of five (5) seconds. The apparent causes attributed to two (2) of the MSIVs had the potential to exist during the previous operating cycle. Therefore, the two (2) MSIVs are being reported under 10CFR50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications because the apparent causes had the potential to have existed longer than allowed by Technical Specifications.

The condition was corrected and the valves were returned to satisfactory performance by adjusting the dashpots and exhaust restrictors as needed. There were no safety consequences associated with this condition, as the valve stroke times did not exceed the times considered in the safety analysis.

(See Page 2 for required number of digits/characters for each block)

(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/) Page 3 of 3 The Energy Industry Identification System component function identifier and name of each component or system:

EIIS: Main Steam, SB AO-3-01A-086A, A Main Steam Line Outboard Isolation Valve AO-3-01A-080B, B Main Steam Line Inboard Isolation Valve Manufacturer: Atwood and Morrill Model: 20851-H Safety Consequences The Technical Specification Surveillance Requirement (SR) 3.6.1.3.9 requires the MSIVs to close within 3 to 5 seconds. The Updated Final Safety Analysis Report (UFSAR) conservatively utilizes a maximum valve closure time of 10 seconds for analyses where the loss of reactor coolant inventory is the controlling variable, which provides conservatism between the SR and the analyzed performance. The observed stroke times for the noted MSIVs were no greater than 6.2 seconds. Therefore, the stroke times observed were not outside the bounds of the analyses and the safety function was maintained. There were no actual or potential safety consequences as a result of this event because this issue was identified during testing and the MSIVs closed within their analyzed times.

Since the remaining MSIVs closed satisfactorily, the overall containment isolation function would have been accomplished in 5.1 seconds.

Corrective Actions This condition was corrected by performing follow up stroke timing for each MSIV and making adjustments such as dashpot and exhaust restrictor tuning as required to return the valves to desired performance.

The valve performance has been entered into the Corrective Action Program for further evaluation of the test performance and evaluation methodology.

Previous Similar Events Peach Bottom Unit 3 LER 3-2009-007: An MSIV stroked below the minimum allowable stroke time due to dashpot oil leakage.

Peach Bottom Unit 3 LER 3-1998-003: An MSIV stroked outside the acceptance range.

Peach Bottom Unit 2 LER 2-1983-025: An MSIV stroked above the maximum allowable stroke time due to insufficient flow through the dashpot needle valve.