ML26034C112
| ML26034C112 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  (NPF-041) |
| Issue date: | 01/30/2026 |
| From: | Spina J Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-09037-JLS/MDD | |
| Download: ML26034C112 (0) | |
Text
10 CFR 50.55a A member of the STARS Alliance, LLC Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek Jennifer Spina Vice President Nuclear Regulatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7602 Tel: 623.393.4621 102-09037-JLS/MDD January , 2026 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Renewed Operating License No. NPF-41 Relief Request 74 Supplemental Clarification Letter Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, Codes and Standards, paragraph (z)(1), Arizona Public Service Company (APS) requested Nuclear Regulatory Commission (NRC) staff authorization of Relief Request 74, to defer the in-service inspection (ISI) examinations for certain steam generator (SG) welds and pressurizer (PZR) welds from the current American Society of Mechanical Engineers (ASME) Code,Section XI ISI interval requirement. The regulation in 10 CFR 50.55a(z)(1) requires APS to demonstrate that the proposed alternative provides an acceptable level of quality and safety.
By letter dated September 4, 2025 Agencywide Documents Access and Management System (ADAMS) Accession No. ML25247A295, APS submitted DrequesWIRU15&
DXWKRUL]DWLRQof proposed ISI alternative Relief Request 74 for PVNGS, Units 1, 2, and 3, in accordance with 10CFR, Section 50.55a(z)(1).
During a call with the NRC staff on January 8, 2026, VXPPDUL]HGLQ$'$06$FFHVVLRQ1R
0/$15&UHTXHVWHGFODULILFDWLRQVWRWKHVXEPLWWDO:
Page 12 of the enclosure states -
From Attachment 2, the minimum coverage for the steam generators (SGs) at the three Palo Verde units is associated with an examination performed on an Item No.
B2.31 component at Unit 3, which had an inspection coverage of 59.5%.
Page 15 of the enclosure, and Section 3.4 of Attachment 4 to the enclosure contain similar information regarding the Item No. B2.31 component at Palo Verde Unit 3.
However, Table 2-6 of Attachment 2 Examination History indicates that the examination coverage for the Item No. B2.31 component at Palo Verde Unit 3 is 96.5% for the third and fourth 10-year ISI interval.
Its not clear to staff which examination coverage (i.e., 59.5% or 96.5%) identified in the submittal, if either, is accurate for the replacement steam generators at Palo Verde Unit 3. Additionally, its not clear if there are additional discrepancies associated with the accuracy of the examination coverage of the subject SG and
102-09037-JLS/MDD ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Relief Request 74 - Supplemental Clarification Letter Page 2 pressurizer components in the licensees submittal. Accurate information is necessary for the staff to determine if the licensees plant-specific conditions are adequately encompassed by the probabilistic fracture mechanics analyses that support the technical basis of this proposed alternative.
NRC Item:
Clarify the examination coverage for the B2.31 components in the SGs for Palo Verde Unit 3.
APS Response:
The volumetric coverage applicable to the third interval examination of the Unit 3, item number B2.31, weld 3-108 is 96.5%. The 96.5% examination took place in 2018. An examination crediting 59.5% coverage took place in 2013 on the same circumferential weld joint and was the basis for the submittal discussion on page 15 of the Enclosure. More examinations were performed and reviewed than provided on Tables 2-1 through 2-6 with the 59.5% examination of Unit 3 weld 3-108 not listed on Table 2-6. The use of 59.5% minimum coverage for the steam generator components is conservative and the later examination credited at 96.5% does not impact the conclusions of relief request 74.
NRC Item:
Verify the examination coverages for the pressurizer and steam generator welds for all three units in the submittal are accurate.
APS Response:
An additional review was performed of examination percentages reported in Tables 2-1 through 2-6. During this review, no volumetric discrepancies were noted.
APS makes no new commitments to the NRC by this letter.
Should you need further information regarding this letter, please contact Michael. D.
DiLorenzo, Licensing Department Leader, at (623) 393-3495.
Sincerely, JS/MDD/cr
Enclosure:
cc:
J. D. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS E. R. Lantz Senior Resident Inspector for PVNGS Spina, Jennifer (Z08962)
Digitally signed by Spina, Jennifer (Z08962)
Date: 2026.01.30 10:19:35 -08'00'