ML24114A281

Request for Additional Information (RAI-10150-R1)

ML24114A281
Person / Time
Site:	Palo Verde
Issue date:	04/19/2024
From:	William Orders Plant Licensing Branch IV
To:	Dilorenzo M Arizona Public Service Co
Orders, William
References
EPID L-2023-LRO-0052
Download: ML24114A281 (3)

Text

From: WilliamOrders Sent: Friday,April19,2024 To: Michael.Dilorenzo@aps.com

Subject:

FormalIssuanceof2ndRoundRAIsforPaloVerdeNuclearGeneratingStation (PVNGS)Units1,2,and3proposedmethodtomanageenvironmentally assistedfatigue(EAF)forthepressurizersurgelineduringtheperiodof extendedoperation.

Attachments: SecondRoundRAI.docx(RAI10150R1)

Mr. Dilorenzo,

By letter dated July 26, 2023 [Agencywide Documents Access and Management System (ADAMS) Accession Number ML23207A248], Arizona Public Service Company (APS) submitted a proposed method to manage environmentally assisted fatigue (EAF) for the pressurizer surge line during the period of extended operation, as committed during license renewal, for Nuclear Regulatory Commission (NRC) approval for Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3.

The NRC staff requested additional information to complete their review with regard to the proposed submittal. A clarifying phone call was held between NRC staff and APS on November 30, 2023, to discuss the additional information needed. The APS response to the request for additional information was provided in the enclosure to a January 12, 2024 (APS) letter [Agencywide Do cuments Access and Management System (ADAMS) Accession Number ML24012A245].

The NRC staff has reviewed the information submitted and needs additional information to complete its review and approval of the licensees submittal. Theis request for additional information (RAI) is attached to this email. and are released formally with a 30-day response period (May 20, 2024) requested.

William Orders (301) 415-3329 REQUEST FOR ADDITIONAL INFORMATION No. 020 (RAI-10150-R1)

BY THE OFFICE OF NUCLEAR REACTOR REGULATION PALO VERDE NUCLEAR GENERATING STATION Units 1, 2, and 3 DOCKET NO. STN 50-528, 50-529, and 50-530 RENEWED OPERATING LICENSE NUMBER NPF-41, NPF-51, AND NPR-74 LICENSE RENEWAL PRESSURIZER SURGE LINE INSPECTION ISSUE DATE: April 19, 2024

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Background===

By letter dated JULY 26, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23207A248), as supplemented on January 12, 2024 (ADAMS Accession No. ML24012A245), Arizona Public Service Company (APS or the licensee) requested approval for the Pressurizer Surge Line Inspection Program to manage the aging effect of environmentally assisted cracking (EAF) in the pressurizer surge line at Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2 and 3. The aging management program is based on a flaw tolerance evaluation in accordance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, Non-mandatory Appendix L, Operating Plant Fatigue Assessment. The program includes periodic inspections for aging management.

APS submitted the proposed method to manage environmentally assisted fatigue for pressurizer surge line in accordance with the requirements of Title 10 Code of Federal Regulations (10 CFR) Part 54, Requirements for Renewal of Operating License for Nuclear Power Plant, The NRC staff has reviewed the information in the Appendix L flaw tolerance evaluation and determined that additional information is required to complete its review.

Regulatory Basis

10CFR 54.21(c) states each license renewal application must contain an evaluation of time-limited aging analyses. Pressurizer surge line aging effect of fatigue is a time-limited aging analysis. 10CFR 54.21(c)(1)(iii) states that the applicant shall demonstrate that:

The effects of aging on the intended function(s) will be adequately managed for the period of extended operation.

APS proposed Pressurizer Sur ge Line Inspection Program to manage the aging effect of environmentally assisted cracking (EAF) in the pressurizer surge line at Palo Verde Nuclear Generating Station (PVNGS). The aging management inspection program is based on a flaw tolerance evaluation in accordance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, Non-mandatory Appendix L, Operating Plant Fatigue Assessment.

Issue

APS performed crack growth evaluation using ASME Section XI Code Case (CC) N-809-1. This crack growth law includes a parameter ST that accounts for temperature effects. APS states that the temperature for fatigue crack growth rate is taken as the average temperature of each transient. In EMIB-RAI-2, the staff asked APS to provide the technical basis for using average temperature for crack growth evaluation.

highest fatigue usage, and axial flaws of the surge line welds, which have shorter assumed lengths.

Requested Information

Please provide the technical basis for using the average temperature for locations other than the circumferential weld cracks.