ML24297A621

Request for Additional Information Relief Request (RR) No. 72: Re-Submittal of RR-39/ASME Code X1 IWC-3420, IWA-3300

ML24297A621
Person / Time
Site:	Palo Verde
Issue date:	10/22/2024
From:	William Orders Plant Licensing Branch IV
To:	Dilorenzo M Arizona Public Service Co
Orders, William
References
EPID L-2024-LLR-0051
Download: ML24297A621 (1)

Text

From: William Orders To: Michael.Dilorenzo@aps.com Cc: John Tsao Bcc: William Orders

Subject:

REQUEST FOR ADDITIONAL INFORMATION Re: RELIEF REQUEST (RR) NO. 72:

Date: Tuesday, October 22, 2024 12:54:00 PM Attachments: RAI-10368-R1-FINAL 102224.docx

V/r Bill From: William Orders

To: Michael.Dilorenzo@aps.com

Subject:

REQUEST FOR ADDITIONAL INFORMATION Re: RELIEF REQUEST (RR) NO. 72:

RE-SUBMITTAL OF RR-39/ASME CODE X1 IWC-3420, IWA-3300

Date: October 22, 2024

Mr. Dilorenzo, By letter dated July 31, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24213A329), Arizona Public Service Company (APS or the licensee) requests Nuclear Regulatory Commission (NRC) staff approval of Relief Request Number 72 from the flaw characterization requirements of American Society of Mechanical Engineers (ASME) Code,Section XI, paragraphs IWC-3420 and IWA-3300. Pursuant to 10 CFR 50.55a(z)(1), licensees may request authorization to implement alternative methodologies that deviate from regulatory requirements provided they achieve an acceptable level of quality and safety.

The NRC staff requests the attached additional information (RAI) to complete its review of the proposed relief request.

Please advise me if you request a confirmation call to address these items or provide a response to these questions within 30 days of this e-mail communication.

A publicly available version of this communication will be placed in ADAMS, the NRCs official document repository system. Please contact me if you have any questions concerning this request.

William T. Orders Senior Project Manager Plant Licensing Branch 4 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Phone: (301) 415-3329 Willam.Orders@nrc.gov

1 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST (RR) NO. 72: RE-SUBMITTAL OF RR-39/ASME CODE X1 IWC-3420, IWA-3300 ARIZONA PUBLIC SERVICE COMPANY PALO VERDE, UNIT 1 DOCKET NO. 05000528 ISSUE DATE: 10/22/2024

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Background===

By letter dated July 31, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24213A329), Arizona Public Service Company (APS or the licensee) requests Nuclear Regulatory Commission (NRC) staff approval of Relief Request Number 72 from the flaw characterization requirements of American Society of Mechanical Engineers (ASME) Code,Section XI, paragraphs IWC-3420 and IWA-3300. Pursuant to 10 CFR 50.55a(z)(1), licensees may request authorization to implement alternative methodologies that deviate from regulatory requirements provided they achieve an acceptable level of quality and safety.

The NRC staff requests the following additional information (RAI) to complete its review of the proposed relief request.

Regulatory Basis The ASME Code,Section XI, 2013 Edition, requires that the flaw or flaws associated with the nitrogen gas leak be identified and repaired so that the leak is stopped, and the level of quality and safety is restored to the design requirements.

The ASME Code,Section XI, Subarticle IWA-3300 and Paragraph IWC-3420, are applicable to any flaws discovered during inservice inspection (lSI) of a Class 2 component. Specifically, as stated in the licensee's submittal:

• IWC-3420, Characterization, states that each detected flaw or group of flaws shall be characterized by the rules of IWA-3300 to establish the dimensions of the flaw(s). These dimensions shall be used in conjunction with the acceptance standards of IWC-3500.

• I WA-3300, Flaw Characterization, states that flaws detected by inservice examinations shall be sized by the bounding rectangle or square for the purpose of description and dimensioning.

The provisions in 10 CFR 50.55a(z)(1) allow alternatives to the ASME Code,Section XI requirements when the licensee can demonstrate that either (1) the proposed alternatives would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Question 1

RAI-1

Issue Section I of Relief Request No. 72 states that the affected ASME Code Item is C2.20 for the safety injection tank nozzles.Section II of the relief request states that the code of record for the fourth inservice inspection is the 2013 Edition of the ASME Code,Section XI. The NRC staff notes that the 2013 Edition of the ASME Code,Section XI, Table IWC-2500- 1, Examination Category C-B, does not provide inspection provisions for Examination Item number C2.20.

Rather, Examination Item number C2.20 includes subcategories of C2.21, Nozzle-to-Shell (Nozzle-to-Head or Nozzle-to-Nozzle) Weld and C2.22, Nozzle Inside Radius Section.

Examination Items C2.21 and C2.22 do contain inspection requirements. It seems to the NRC

2 staff that if the subject safety injection tank vent nozzle is classified as Item number C2.20, the subject vent nozzle would be inspected in accordance with Item number C2.21 and/or C2.22.

The NRC staff recognizes that the relief request proposes not to perform inspection of the original partial penetration weld of the vent nozzle at the inside diameter of the safety injection tank. However, the NRC staff seeks information regarding the inspection of the new pressure boundary weld at the outside diameter of the safety injection tank.

Request

• Identify which Inspection Item (C2.21 or C2.22) under the ASME Code,Section XI, Table IWC-2500-1, Examination Category C-B, Inspection Item C2.20 establishes the inspection requirements for the new pressure boundary weld at the subject safety injection tank vent nozzle during the 5 th and 6 th ISI interval.

• Discuss whether inspections were performed on the new pressure boundary weld (at the outside diameter of the safety injection tank) at the vent nozzle since 2008. If affirmative, provide inspection performed and results. If not, provide the basis that this new pressure boundary weld was not inspected.

Question 2

RAI-2

Issue Second paragraph of the Background in the relief request states that On Thursday, June 5, 2008, Palo Verde Nuclear Generating Station (PVNGS) declared the Unit 1 SIT 1A inoperable when a small leak was identified at the annulus between the tank and the vent line during the performance of a leak test The NRC staff notes that the ASME Code,Section XI, Table IWC-2500- 1, Examination Category C-H, Item No. C7.10 requires a system leakage test each inspection period. Also, the NRC staff seeks information on defense-in-depth measures to ensure structural integrity of the repaired subject safety injection tank vent nozzle.

Request (a) Discuss whether a system leakage test is performed on the subject vent nozzle every inspection period in accordance with the ASME Code,Section XI, Category C-H, Item No.

C7.10.

(b) Discuss whether there are sensor(s) that could detect the nitrogen leak at the safety injection tank vent nozzle and provide signals to the control room to notify the operator(s). If such sensor(s) does not exist, discuss any method that could detect potential leak.

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