ML21082A433

Completion of License Renewal Commitment No. 11, Aging Management of Environmentally-Assisted Fatigue

ML21082A433
Person / Time
Site:	Mcguire, McGuire
Issue date:	03/30/2021
From:	Klos L Plant Licensing Branch II
To:	Teresa Ray Duke Energy Carolinas
Klos L
References
EPID L-2020-LRO-0085
Download: ML21082A433 (4)

Text

March 30, 2021 Mr. Tom Ray Site Vice President Duke Energy Carolinas, LLC McGuire Nuclear Station 12700 Hagers Ferry Road Huntersville, NC 28078-8985

SUBJECT:

WILLIAM B. MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 - COMPLETION OF LICENSE RENEWAL COMMITMENT NO. 11, AGING MANAGEMENT OF ENVIRONMENTALLY-ASSISTED FATIGUE (EPID L-2020-LRO-0085)

Dear Mr. Ray:

By letter dated May 17, 2020 (Agency Documents Access and Management System (ADAMS)

Accession No. ML20157A077), Duke Energy Carolinas, LLC (the licensee, Duke Energy),

submitted a document to the U.S. Nuclear Regulatory Commission (NRC) which proposed Duke Energys inspection plan for License Renewal Commitment (LRC) No. 11 (ADAMS Accession No. ML030850237, NUREG-1772, Appendix D). Specifically, the letter documents Duke Energys proposed use of flaw tolerance evaluations and inspections of the pressurizer surge line nozzles and safety injection nozzle welds for McGuire Nuclear Station, Units 1 and 2 to address LRC No. 11 and environmentally-assisted fatigue (EAF) aging management program.

The NRC staff reviewed the submittal and finds that the licensees EAF aging management program, for LRC No. 11 is acceptable.

The NRC staffs review is found in the enclosure of this letter.

If you have any questions, please contact me at (301) 415-3867 or via email at John.Klos@nrc.gov.

Sincerely,

/RA/

John Klos, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370 cc: Listserv

NRC STAFF TECHNICAL REVIEW LICENSE RENEWAL COMMITMENT NO. 11, ENVIRONMENTALLY-ASSISTED FATIGUE AGING MANAGEMENT PROGRAM DUKE ENERGY CAROLINAS, LLC MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-369 AND 50-370 By letter dated May 17, 2020(Agency Documents Access and Management System (ADAMS),

Accession No. ML20157A077), Duke Energy submitted a letter, which documented Duke Energys proposal to meet License Renewal Commitment (LRC) No. 11, by providing an environmentally-assisted fatigue (EAF) aging management program for the pressurizer surge line and safety injection nozzle welds.

Duke Energys submittal stated that the licensee is committed to addressing EAF effects on several fatigue-sensitive locations during the McGuire Nuclear Station (MNS) period of extended operation (PEO). Duke Energy also stated that it determined that the critical locations of concern for fatigue environmentally-adjusted cumulative usage factor (CUFen) for the MNS, during the PEO are the Hot Leg Surge Nozzle, and Safety Injection Nozzle welds. The licensee also stated that the calculated CUFen values for these locations were determined to exceed the American Society of Mechanical Engineers Boiler & Pressure Vessel (ASME) Code,Section III allowable cumulative usage factor (CUF) of 1.0 during the PEO and would, therefore, be subject to future inspection.

Flow Tolerance Evaluation and Staff Finding The licensees letter detailed plant-specific, fatigue flaw tolerance evaluation results for the pressurizer surge line and safety injection nozzle welds. The staff finds the flaw tolerance evaluation the licensee used as the basis for the inspection interval acceptable, because the licensee performed the evaluations for the subject welds using the 2013 Edition of ASME Code,Section XI, Appendix L, Operating Plant Fatigue Assessment. For reference purposes it is noted that the 2013 Edition of ASME Code,Section XI is endorsed by reference in Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, and includes Nonmandatory Appendix L without any conditions. Additionally, Appendix L, Subarticle L-1100 states that this Appendix is applicable only in the absence of any flaw at the location of concern, which is larger than allowed by the applicable acceptance standard referenced in ASME Code,Section XI, Table IWB-3410-1.

Pressurizer surge line inspections The licensees flow tolerance evaluation stated that for the pressurizer surge line, the most bounding location was the hot leg nozzle weld where a postulated flaw reached the allowable flaw depth in approximately 11 years of service. The licensee also stated that the plant-specific, pressurizer surge line inspection program will consist of periodic volumetric examinations that will be performed once per interval (not to exceed 10 years) for pressurizer nozzle-to-pipe welds and the hot leg surge nozzle welds for MNS (total of two welds per unit).

Safety injection line inspections The results of the flaw tolerance evaluations indicate that for the safety injection line -- with a postulated surface-connected flaw -- both axial and circumferential flaws remained acceptable for 60 years of operation. The licensee also stated that the plant-specific, safety injection nozzle weld inspection program will consist of periodic volumetric examinations that will be performed once per interval (not to exceed 10 years) for each of the injection line cold leg nozzle welds for MNS (total of four welds per unit).

Staff finding on inspection program For the applicable pressure surge and safety injection line welds, the staff reviewed the proposed inspection program and independently confirmed that it includes volumetric examinations which provide; (a) an effective method of inspection for the detection of flaws due to fatigue, and (b) reasonable assurance of adequate safety, because when unacceptable flaws are detected, replacement, or repair can be implemented such that the intended function and structural integrity of the piping system will be maintained for MNS during its PEO.

Therefore, the staff finds that the licensees proposed EAF aging management inspection program is acceptable.

The NRC staff also noted that the subject welds for MNS were most recently examined using volumetric examinations with satisfactory results in 2017 and 2018.

EAF aging management program Lastly, the staff also noted that the proposed inspection program implements the ten elements criteria for a comprehensive aging management program which is was found acceptable to the staff per NUREG-1801, Generic Aging Lessons Learned (GALL) Report.

Based on the above review, the staff finds that the licensees proposed EAF aging management program and LRC No. 11 is acceptable.

Docket Nos.: 50-369 and 50-370 Primary reviewer: Roger Kalikian

ML21082A433 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME JKlos KGoldstein MMarkley (EMiller for) JKlos DATE 03/22/2021 03/24/2021 03/25/2021 03/29/2021