05000325/LER-2020-004, (Bsep), Unit 1, Setpoint Drift in Main Steam Line Safety Relief Valves Results in Three Valves Inoperable
| ML20274A324 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/29/2020 |
| From: | Krakuszeski J Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RA-20-0269 LER 2020-004-00 | |
| Download: ML20274A324 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3252020004R00 - NRC Website | |
text
September 29, 2020
£ ~ DUKE
~ ENERGY Serial: RA-20-0269 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Brunswick Steam Electric Plant, Unit No. 1 Renewed Facility Operating License No. DPR-71 Docket No. 50-325 Licensee Event Report 1-2020-004 John A. Krakuszeski Vice President Brunswick Nuclear Plant 8470 River Rd SE Southport, NC 28461 o: 910.832.3698 10 CFR 50.73 In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Duke Energy Progress, LLC, is submitting the enclosed Licensee Event Report (LER). This report fulfills the requirement for a written report within sixty (60) days of a reportable occurrence.
This document contains no regulatory commitments.
Please refer any questions regarding this submittal to Ms. Sabrina Salazar, Manager - Nuclear Support Services, at (910) 832-3207.
Sincerely, John A. Krakuszeski SBY/sby
Enclosure:
Licensee Event Report
U.S. Nuclear Regulatory Commission Page 2 of 2 cc (with enclosure):
Ms. Laura Dudes, NRC Regional Administrator, Region II Mr. Andrew Hon, NRC Project Manager Mr. Gale Smith, NRC Senior Resident Inspector Chair - North Carolina Utilities Commission
Abstract
On August 12, 2020, BSEP received test results for the eleven main steam line safety relief valves (SRVs) removed from Unit 1 during the spring 2020 refuel outage (RFO). Three of the eleven valves were found to have as found pilot valve lift setpoints outside the +/-3 percent tolerance required by Technical Specification (TS) 3.4.3, which requires ten of the eleven installed SRVs to be operable.
Since less than ten SRVs were operable, this event is being reported per 10 CFR 50.73(a)(2)(i)(B) as operation prohibited by the plants TS. At the time the test results were received, Unit 1 was shutdown for an unrelated maintenance outage.
The direct cause of the out of tolerance as-found lift setpoints was corrosion bonding of the SRV pilot discs to the pilot seats. The root cause of the corrosion bonding was inadequate procedures in place when these valves were refurbished and installed in the 2018 RFO. Subsequent to the 2018 installation of these SRVs, as a result of the Root Cause Evaluation associated with LER 1-2018-003, dated August 9, 2018 (i.e., ADAMS Accession Number ML18221A552), corrective actions were completed revising the associated procedures to prevent this condition from recurring.
All eleven of the SRV pilot valves were replaced with certified spares before Unit 1 startup from the spring 2020 RFO. These spares were rebuilt utilizing the revised procedures.
(See Page 3 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/)
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Corrective Actions
Subsequent to the 2018 installation of these SRVs, as a result of the Root Cause Evaluation (RCE) associated with LER 1-2018-003, dated August 9, 2018 (i.e., ADAMS Accession Number ML18221A552), corrective actions were completed revising the associated procedures to add the necessary guidance to ensure consistent surface preparation and proper quality checks of surface condition prior to platinum coating, to prevent this condition from recurring. All eleven of the SRV pilot valves were replaced with certified spares before Unit 1 startup from the spring 2020 refueling outage. The certified spares were rebuilt utilizing the revised procedures.
In addition to the aforementioned completed corrective actions, BSEP currently plans to pursue a license amendment request to adopt Technical Specification Task Force (TSTF) 576, following its approval by the NRC, to align TS 3.4.3 with the safety function of the SRVs vs. the currently prescribed +/-3 percent setpoint tolerance.
Previous Similar Events
A review of LERs for the past three years identified the following previous similar event associated with SRVs with as-found lift setpoints outside of TS allowable limits.
LER 1-2018-003, dated August 9, 2018, reported Unit 1 operation prohibited by TSs due to two of the eleven valves found with lift setpoints of their pilot valves outside the +/-3 percent tolerance required by TS 3.4.3.
The direct cause of this event was corrosion bonding. The root cause was attributed to the procedures lacking sufficient detail to ensure consistent surface preparation and proper quality checks of surface condition prior to platinum coating.
Commitments
No regulatory commitments are contained in this report.