ML25119A052
| ML25119A052 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/15/2025 |
| From: | William Orders Plant Licensing Branch IV |
| To: | Heflin A Arizona Public Service Co |
| Orders, William | |
| Shared Package | |
| ML25119A055 | List: |
| References | |
| EPID L-2024-LLA-0116 | |
| Download: ML25119A052 (6) | |
Text
May 15, 2025 Mr. Adam Heflin Executive Vice President/
Chief Nuclear Officer Mail Station 7605 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION UNITS 1, 2, AND 3 REGULATORY AUDIT
SUMMARY
REPORT IN SUPPORT OF LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATIONS 3.5.1 AND 3.5.2 SAFETY INJECTION TANK PRESSURE BANDS AND TO USE GOTHIC CODE (EPID L-2024-LLA-0116)
Dear Mr. Heflin:
By letter dated August 28, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24241A278), Arizona Public Service Company (the licensee) submitted a license amendment request (LAR) for Palo Verde Nuclear Generating Station, Units 1, 2, and 3 (Palo Verde). The proposed amendments would modify Palo Verde Technical Specification (TS) section 3.5.1, Safety Injection Tanks (SITs) - Operating and TS section 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and their associated bases.
Specifically, the proposed TS changes revise Palo Verde Surveillance Requirements 3.5.1.3 and 3.5.2.3 to increase the upper limit of their SIT pressure bands and to list their pressure requirements in units of pounds per square inch absolute as reflected in the Palo Verde safety analyses, with no instrument uncertainties included, instead of the SIT instrument units of pounds per square inch gauge with instrument uncertainties included.
In addition, the proposed changes would include use of the Generation of Thermal Hydraulic Information for Containments (GOTHIC) Code as part of the methodology to perform calculations of the containment pressure and temperature response to various postulated pipe breaks.
To support the review of the LAR, the U.S. Nuclear Regulatory Commission (NRC) staff conducted a virtual regulatory audit using a secure online portal. The audit plan can be located in ADAMS at Accession No.ML25016A345. The audit began on February 4, 2025, followed by two subsequent audit clarification calls described in the attached audit summary report. In accordance with the audit plan, the audit team reviewed documentation and calculations that support the efficient review of the LAR. The audit remained open until April 17, 2025, when it was determined that the LAR supplement dated March 28, 2025 (ML25090A018), contained adequate regulatory and technical information to support a thorough evaluation of the LAR.
The purpose of this letter is to provide the results of the regulatory audit. Documented in the enclosed audit summary are the observations the NRC staff identified during the audit.
Sincerely,
/RA/
William T. Orders, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529, and STN 50-530
Enclosure:
Regulatory Audit Summary cc: Listserv
Enclosure REGULATORY AUDIT
SUMMARY
RELATED TO LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION SECTIONS 3.5.1 AND 3.5.2 SAFETY INJECTION TANK PRESSURE BANDS AND TO USE GOTHIC CODE ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 DOCKET NOS. STN 50-528, STN 50-529, AND STN 50-530
1.0 BACKGROUND
By letter dated August 28, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24241A278), Arizona Public Service Company (APS, the licensee) submitted a license amendment request (LAR) for Palo Verde Nuclear Generating Station, Units 1, 2, and 3 (Palo Verde). The proposed amendments would modify Palo Verde Technical Specification (TS) section 3.5.1, Safety Injection Tanks (SITs) - Operating and TS section 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and their associated bases.
Specifically, the proposed TS changes would revise Palo Verde Surveillance Requirements 3.5.1.3 and 3.5.2.3 to increase the upper limit of their SIT pressure bands and to list their pressure requirements in units of pounds per square inch absolute as reflected in the Palo Verde safety analyses, with no instrument uncertainties included, instead of the SIT instrument units of pounds per square inch gauge with instrument uncertainties included.
In addition, the proposed changes would include use of the Generation of Thermal Hydraulic Information for Containments (GOTHIC) Code as part of the methodology to perform calculations of the containment pressure and temperature response to various postulated pipe breaks.
The U.S. Nuclear Regulatory Commission (NRC) staff conducted a virtual regulatory audit in accordance with the Office of Nuclear Reactor Regulation (NRR) Office Instruction LIC 111, Revision 1, Regulatory Audits, dated October 31, 2019 (ML19226A274). A regulatory audit is a planned license or regulation-related activity that includes the examination and evaluation of primarily non-docketed information. A regulatory audit is conducted with the intent to gain understanding, to verify information, and/or to identify information that will require docketing to support the basis of a licensing or regulatory decision. Performing a regulatory audit of the licensees information is expected to assist the NRC staff in efficiently conducting its review or to gain insights on the licensees processes or procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket.
During the regulatory audit, the NRC staff reviewed documents, responses to audit questions, and held discussions with members of APS. The purpose of the audit was to gain an understanding of the information needed to support the NRC staffs licensing decision regarding the LAR and to develop requests for additional information, if needed.
2.0 AUDIT ACTIVITIES AND OBSERVATIONS 2.1 Virtual Audit The audit was conducted by the NRC staff consistent with the regulatory audit plan dated January 21, 2025 (ML25016A345). The NRC staff provided a list of documents needed in the audit plan along with audit questions. The licensee uploaded the requested documents to a secure electronic portal and provided access to the NRC audit team. The NRC staff reviewed the documents made available by the licensee in an electronic reading room. The audit was conducted beginning on February 4, 2025, continuing in subsequent clarification calls as described below The following documents were made available for the NRC staffs review on a web-based portal throughout the duration of the audit period.
Item #
Audit Item 1
Engineering Evaluation ENG WO: 24-06661-033 2
Engineering Evaluation ENG WO:24-06661-034 3
13-NC-ZC-0232, Loss of Coolant Accident Pressure and Temperature Containment Analysis for Limiting Case, Revision 13 4
80DP-0CC02, Control of Non-Process Software and Data, Revision 23 5
93DP-0LC07-01, 10 CFR 50.59 [Title 10 of the Code of Federal Regulations (10 CFR) Section 50.59] and 72.48 Administrative Guideline, Revision 12 6
N001-0205-00317, Evaluation of a SIT Maximum Pressure Increase on the Palo Verde Nuclear Generating Station Units 1, 2, and 3 LBLOCA [Large Break Loss-of-Coolant Accident] Analysis of Record - CVERMLOCACNAA000001, Revision 0 The audit was conducted virtually beginning on February 4, 2025, and during subsequent audit clarification calls March 6, 2025, and March 19, 2025. The clarification call conducted on March 6, 2025, was to ensure that the licensee understood the requested documentation that was to be placed on the portal. The clarification call conducted on March 19, 2025, was to discuss the rationale for the NRC staffs request for proprietary information.
At the conclusion of the audit activities, the NRC staff requested that the licensees responses to selected questions from the audit be transmitted in a LAR supplement, which was provided by letter dated March 28, 2025 (ML25090A018). The audit was maintained open until the LAR supplement was determined to contain adequate information to allow the NRC staff to support a thorough evaluation of the LAR. The audit was terminated on April 16, 2025, during routine communication between the Palo Verde project manager and the licensee.
3.0 RESULTS OF THE AUDIT The NRC staff did not make any regulatory decisions regarding the LAR during the audit. At the completion of the audit, the NRC staff reviewed the proposed responses to the audit questions provided in the audit supplement dated March 28, 2025. After reviewing the supplemental information, the NRC staff did not identify the need for additional information.
4.0 AUDIT PARTICIPANTS NRC Participants from NRR Ahsan Salman Jo Ambrosini, William Orders Licensee Participants Michael DiLorenzo William Hutchins Carl Stephenson Autumn Schuelka Francisco Diaz Gallegos Maria Groshner Thomas Remick Nawaporn Aaronscooke David Medek Jill Anderson Nicholas Doyle Michael Hooshmand Austin Kee Katherine Gil
Package: ML25119A055 Audit Summary: ML25119A052 Audit Plan: ML25016A345
- concurrence by eConcurrence OFFICE NRR/DORL/LPL4/PM*
NRR/DORL/LPL4/LA* NRR/DORL/LPL4/PM* NRR/DSS/SNSB/BC*
NAME WOrders PBlechman WOrders DMurdock DATE 4/29/2025 5/1/2025 5/1/2025 5/6/2025 OFFICE NRR/DORL/LPL4/BC*
NRR/DORL/LPL4/PM*
NAME TNakanishi WOrders DATE 5/6/2025 5/15/2025