ML23296A016

October 20, 2023 Presubmittal Meeting Presentation - 1R24 Pressurizer Nozzle Repair - RR-70 (EPID: L?2023?LLR-0057)

ML23296A016
Person / Time
Site:	Palo Verde
Issue date:	10/20/2023
From:	Arizona Public Service Co
To:	Division of Operating Reactor Licensing
References
EPID: L?2023?LLR-0057
Download: ML23296A016 (1)

Text

Pre-Submittal Meeting - 1R24 Pressurizer Nozzle Repair - RR-70 October 20, 2023

Agenda

• Introduction

• Background

• Pressurizer Leak Identification

• Nozzle Design History

• Pressurizer Nozzle Repair

• Code Requirements

• Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

• Schedule 2

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Background===

• Boric acid walkdowns (Code Case N-722-1) in Unit 1 outage identified boric acid leak in pressurizer thermowell nozzle

• Three pinhole leaks identified in nozzle weld

• Design history of the pressurizer thermowell was preemptively repaired in 1992

• Weld material is Alloy 82 3

Pressurizer Leak Identification Overview of the area 119 4

Pressurizer Leak Identification Visual inspection, confirmed boron with isotopic analysis PT exam identified three pin holes 119 5

Nozzle Design History (Pre 1992)

Nozzle - Alloy 600 Weld - Alloy 82/182 6

Nozzle Design History (Post 1992) 7

Pressurizer Nozzle Repair

• Remove existing Alloy 82 weld pad and Alloy 690 nozzle

• Roll expand Alloy 690 outer sleeve in penetration bore

• Perform surface examination on outer surface of pressurizer shell in preparation for new weld pad

• Deposit Alloy 52M weld pad in accordance with Code Case N-638-10

• Perform examination of final bore and J-groove weld prep

• Replacement Alloy 690 nozzle installation and welding

• Perform progressive surface examination of nozzle weld 8

Pressurizer Nozzle Repair 9

Code Requirements ASME Code,Section XI, 2013 Edition IWB-3522: Pressure retaining material leakage requires corrective action per IWA-5250 and acceptance per IWB-3142 Flaw Removal

• Corrective actions per IWA-5250, and IWA-4000 repair/replacement activities will eliminate the pressure boundary leakage by installation of the Alloy 52M welds and Alloy 690 nozzle

• Flaw removal required per IWA-4412/4420 10

Code Requirements ASME Code,Section XI, 2013 Edition Flaw Evaluation

• IWB-3142.1(b) states A component whose visual examination detects the relevant conditions described in the standards of Table IWB-3410-1 shall be unacceptable for continued service, unless such components are accepted by supplemental evaluation, accepted by corrective measures, or accepted by analytical evaluation.

• IWB-3420 states, Each detected flaw or group of flaws shall be characterized by the rules of IWA-3300 to establish the dimensions of the flaws.

• IWA-3300 Flaws detected by inservice examinations shall be sized 11

Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

Flaw Removal and Flaw Evaluation

• As an alternative to flaw removal of the internal J-groove weld, to meet the applicable acceptance standards per IWA-4412/4420, assumed flaws in the original internal J-groove weld and autogenous weld will remain in place

• As an alternative to performing the nondestructive examination (NDE) required to characterize a flaw under IWB-3420, analyze a maximum postulated flaw that bounds the range of flaw sizes that could exist in the original internal J-groove weld 12

Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

Welding

• In lieu of NB-4620 post weld heat treatment requirements, install Alloy 52M welded pad in accordance with ASME Case N-638-10, ambient temperature gas tungsten arc weld (GTAW) temper bead technique

• An alternative is proposed to N-638-10, Paragraph 4(a)(2), that requires the first three tempering layers are in place for 48-hour prior to performing NDE, APS proposes to perform the NDE after completion of the weld repair 13

Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

Basis for Alternatives

• A review of previous analyses has been performed and confirmed that the As Left J-Groove Weld Analysis is acceptable for at least one operating cycle

• White paper supporting elimination of 48-hour hold in Code Case N-888-1

• Potential loose parts assessment summarized in Relief Request

• Corrosion analysis to be provided 14

Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

Duration of Proposed Alternative

• Relief is requested for the duration of the Unit 1 Cycle 25 which concludes Spring of 2025

• Separate relief request to be submitted for continued use of the nozzle repair for the life of the plant prior to the end of the cycle 15

Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1)

Precedents - Flaw Evaluation and 48-Hour Hold

• NRC approval via verbal authorization on November 6, 2020 (ML20314A028) for Peach Bottom Atomic Power Station, Unit 2. Safety Evaluation April 23, 2021 (ML21110A680)

• NRC verbal authorization on April 15, 2012, for Quad Cities, Unit 2 (ML12107A472). Safety Evaluation January 30, 2013 (ML13016A454)

• NRC approval via a verbal authorization on May 17, 2017, for Limerick, Unit 2 (ML17137A307). Safety Evaluation August 14, 2017 (ML17208A090)

• NRC verbal authorization on May 9, 2023 (ML23129A312) for Beaver Valley, Unit 2 (ML23118A381) and Letter from David Gudger (Constellation Energy Generation) to NRC dated March 24, 2023, ADAMS Accession No. ML23083B991 16

Schedule

• Proposed submittal date for RR-70

- October 23, 2023

• Requested verbal authorization target date

- October 27, 2023

• Proposed submittal date for final one-cycle flaw analytical evaluation, evaluation of repair, and corrosion evaluation days after the end of the Unit 1 outage 17

Questions