ML24285A256

License Renewal - Alloy 600 Management Program Plan Response to Request for Additional Information

ML24285A256
Person / Time
Site:	Palo Verde
Issue date:	10/11/2024
From:	Horton T Arizona Public Service Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
102-08874-TAH/MDD
Download: ML24285A256 (1)

Text

10 CFR 54

Todd A. Horton Senior Vice President Regulatory & Oversight

Palo Verde Nuclear Generating Station 102-08874-TAH/MDD P.O. Box 52034 October 11, 2024 Phoenix, AZ 85072 Mail Station 7605 U.S. Nuclear Regulatory Commission Tel: 623.393.6418

ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Renewed Operating License Number NPF-41, NPF-51, and NPF-74 License Renewal - Alloy 600 Management Program Plan Response to Request for Additional Information

By letter dated February 22, 2024 (ADAMS Accession No. ML24053A397), Arizona Public Service Company (APS) submitted the Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2 and 3, Alloy 600 Management Program Plan to the U.S. Nuclear Regulatory Commission (NRC) for review in compliance with license renewal Commitment 23 of Table 19.5-1 of the PVNGS Updated Final Safety Analysis Report (UFSAR). In Section 6.4, RCS [reactor coolant system] Dissimilar Metal Butt-Welds, Table 3 of the submittal provides the current inspection requirements for dissimilar metal welds.

By NRC correspondence dated September 11, 2024 (ADAMS Accession No. ML24257A101), the NRC staff requested confirmation of two items regarding the Alloy 600 Management Program Plan. The enclosure to this letter provides the APS response, as requested.

No new commitments are being made to the NRC by this letter.

Should you need further information regarding this letter, please contact Michael D.

DiLorenzo, Department Leader Nuclear Regulatory Affairs - Licensing at (623) 393-3495.

Sincerely,

TAH/MDD/cr

Enclosure:

Palo Verde Nuclear Generating Station Units 1, 2 and 3 Alloy 600 Management Program Plan - Response to Request for Additional Information cc: J. D. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS L. N. Merker NRC Senior Resident Inspector for PVNGS B. D. Goretzki Arizona Department of Health Services - Bureau of Radiation Control

A member of the STARS Alliance, LLC

Callaway Diablo Canyon Palo Verde Wolf Creek ENCLOSURE

Palo Verde Nuclear Generating Station Units 1, 2 and 3 Alloy 600 Management Program Plan - Response to Request for Additional Information Enclosure Palo Verde Nuclear Generating Station Units 1, 2 and 3 Alloy 600 Management Program Plan -

Response to Request for Additional Information

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Background===

By letter dated February 22, 2024 (ADAMS Accession No. ML24053A397), Arizona Public Service Company (APS) submitted the Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2 and 3, Alloy 600 Management Program Plan to the U.S. Nuclear Regulatory Commission (NRC) for review in compliance with license renewal Commitment 23 of Table 19.5-1 of the PVNGS Updated Final Safety Analysis Report (UFSAR). In Section 6.4, RCS [reactor coolant system] Dissimilar Metal Butt-Welds, Table 3 of the submittal provides the current inspection requirements for dissimilar metal welds.

By NRC correspondence dated September 11, 2024 (ADAMS Accession No. ML24257A101), the NRC staff requested confirmation of two items regarding the Alloy 600 Management Program Plan. This enclosure provides the NRC request followed by the APS response.

Confirmatory Item 1:

The licensee identified several of the PVNGS Units 1, 2 & 3, ASME Code Class 1 dissimilar metal (DM) butt welds were mitigated by the full structural weld overlay (FSWOL). These FSWOL welds are required to be inspected in accordance with ASME Code N-770-5, Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation Activities,Section XI, as mandated by 10 CFR 50.55a(g)(6)(ii)(F), Augmented ISI requirements: Examination requirements for Class 1 piping and nozzle dissimilar metal butt welds.

Note 10 of ASME Code N-770-5 states, in part, Those welds not included in the 25 percent sample shall be examined prior to the end of the mitigation evaluation period if the plant is to be operated beyond that time.

Confirm that the licensee has reviewed the design basis for each of these FSWOL welds for the period of extended operation to verify the reinspection frequency in accordance with Note 10 of ASME Code Case N-770-5 are incorporated into the Alloy 600 Management Program Plan.

APS Response:

Yes, each FSWOL weld has been reviewed and inspection frequencies are in alignment with the design basis of record. Updated crack growth analysis reports for weld overlays are in process and are referenced in the Alloy 600 Management Program Plan as described in Section 6.4 (References 8.25 & 8.26 of the Program Plan).

1 of 2 Enclosure Palo Verde Nuclear Generating Station Units 1, 2 and 3 Alloy 600 Management Program Plan -

Response to Request for Additional Information

Confirmatory Item 2:

Due to industry operating experience (OE), Electric Power Research Institute (EPRI)

Technical Report 3002012244, Revision 3, Nondestructive Evaluation: Guideline for Conducting Ultrasonic Examinations of Dissimilar Metal Welds, dated February 2018, provides enhanced guidance and Nuclear Energy Institute (NEI) 03-08, Guideline for the Management of Materials Issues requirements and recommendations for the examinations of DM welds.

Confirm that the licensee has reviewed EPRI Technical Report 3002012244, Revision 3, and incorporated the enhanced guidance requirements and recommendations in accordance with NEI 03-08 in the Alloy 600 Management Program Plan for DM weld examinations.

APS Response:

Yes, EPRI Technical Report 3002012244, Revision 3, has been reviewed and the guidance is administered in the PVNGS procedure 73DP-9XI08, Conduct of Dissimilar Metal Weld Ultrasonic Examinations, mentioned in Section 2 of the Alloy 600 Management Program Plan.

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