ML22034A013
| ML22034A013 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/02/2022 |
| From: | Siva Lingam NRC/NRR/DORL/LPL4 |
| To: | Cox M Arizona Public Service Co |
| References | |
| L-2022-LLR-0011 | |
| Download: ML22034A013 (5) | |
Text
From: Lingam, Siva Sent: Wednesday, February 2, 2022 4:26 PM To: Matthew.Cox@aps.com Cc: Dixon-Herrity, Jennifer; Colaccino, Joseph; Ma, John; Carl.Stephenson@aps.com; Nawaporn.AaronsCooke@aps.com; Boris.Bolf@aps.com; Sarah.Kane@aps.com; Dacia.Dallago@aps.com
Subject:
Palo Verde, Unit 2 - Verbal Approval of RR-69 to Extend Containment Tendon Inspection from 2/8/22 to 6/8/22 (EPID L-2022-LLR-0011)
By teleconference call on February 2, 2022, the U.S. Nuclear Regulatory Commission (NRC) staff provided verbal authorization to Arizona Public Service Company (APS, the licensee) for the subject relief request (RR) for Palo Verde Nuclear Generating Station, Unit 2 (Palo Verde, Unit 2) based on the following explanation.
Participants:
NRC APS Joseph Colaccino Boris Bolf Jennifer Dixon-Herrity Matthew Cox Siva Lingam Dacia Dallago John Ma Sarah Kane Christine King Mark Meyer Jordan Nuss Carl Stephenson Carlos Valenzuela
VERBAL AUTHORIZATION BY THE OFFICE NUCLEAR REGULATION 10 CFR 50.55a REQUEST TO DEFER ASME CODE INSERVICE INSPECTION OF CONTAINMENT TENDON INSPECTION DUE TO PANDEMIC (COVID -19)
PALO VERDE NUCLEAR GENERATING STATION, UNIT 2 ARIZONA PUBLIC SERVICE COMPANY RELIEF REQUEST NO. RR-69 DOCKET NO. 50-529 FEBRUARY 2, 2022
Technical Evaluation read by Joseph Colaccino, Chief of the Structural, Civil, and Geotechnical Engineering Branch (ESEB), Office of Nuclear Reactor Regulation
By electronic submittal dated January 28, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22031A098), Arizona Public Service Company (APS, the licensee) submitted a COVID 19 relief request (RR) RR-69 to extend containment tendon inspection at Palo Verde Nuclear Generating Station, Unit 2 (Palo Verde, Unit 2) for one time from February 8, 2022 to June 8, 2022 (i.e., 4 months), in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(z)(2), Hardship without a compensating increase in quality and safety. Specifically, pursuant to 10 CFR 50.55a(z)(2), the licensee requested U.S. Nuclear Regulatory Commission (NRC) approval of RR-69 regarding the interval between containment tendon inspections as specified per paragraph IWL 2420 of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),
Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, Subsection IWL, Requirements for Class CC [Concrete Containment] Concrete Components of Light-Water Cooled Plants, required by 10 CFR 50.55a, Codes and standards.
On April 2, 2021, the NRC approved RR-66 extending the containment tendon inspection from February 8, 2021 to February 8, 2022 (ADAMS Accession No. ML21089A010) for the licensees submittal on November 5, 2020 (ADAMS Accession No. ML20315A156).
In the licensees previous submittal dated November 5, 2020, the licensee stated that a regression analysis of the lift-off was performed for the license renewal application. The NRC staffs review of this analysis demonstrated that the average prestress in tendons should remain above the applicable minimum required values for at least 60 years of operation and that all tendons should, therefore, maintain their design basis function for the extended period of operation. The material condition of other components (e.g., concrete, bearing surfaces, grease, button heads, etc.) showed only minor degradation in few areas; none indicating a need for significant corrective action. The licensee also stated that the following results of the 25th and 30th Year tendon surveillances performed on Palo Verde, Unit 2 confirmed that the functional integrity of the selected post-tensioning system met the applicable code requirements:
- The chemical tests of the in-service grease were all within required specifications for moisture content and soluble ions.
- All inspected tendon ends were found with no evidence of free water and were acceptable per subparagraph IWL-3221.3(e).
- Soluble ion concentrations and moisture contents were within acceptable limits for all inspected tendons, per subparagraph IWL-3221.4.
- Some of the button heads were cracked, but did not meet the rejection criteria; therefore, they were acceptable.
- All inspected tendon anchorage components were found with an acceptable corrosion level of A or B, which were acceptable per subparagraph IWL-3221.3. No cracks were identified in the anchor heads.
- All cracks observed within the 24-inch perimeter of the concrete surrounding each inspected bearing plate were less than 0.01 inch in width, per subparagraph IWL-3221.3(d).
- All tendon grease caps were properly installed to their respective tendon ends, and all tendon grease caps were refilled with grease to acceptable levels, per subparagraph IWL-3221.4.
In the licensees submittal dated November 5, 2020, the licensee further stated that the following results of the 25th tendon surveillances performed on Palo Verde, Unit 2 confirmed that the functional integrity of the selected post-tensioning system met the applicable code requirements (these were not completed for the 30th year surveillance):
- All as-found tendon lift-off forces exceeded the prescribed lower limit value.
- The hydraulic jacks used for tendon lift-offs were calibrated before and after the surveillance period and were found to be within an acceptable variation of +/- 1.5 percent.
- All test wires removed and tested were found to have acceptable corrosion levels of A, diameter values within the acceptable range, and acceptably high ultimate stress, yield stress, and elongation percent values, per subparagraph IWL-3221.2.
- All de-tensioned tendons were re-tensioned to acceptable forces and had acceptable elongations, per subparagraph IWL-2523.3.
The licensee also stated in its submittal dated November 5, 2020, that (1) a visual examination of the Unit 2 Concrete Containments exterior surface was completed in August of 2017, (2) no conditions were identified which would require structural repair or more frequent examinations, and (3) the condition of the exterior concrete surface was deemed acceptable, per
[subparagraph] IWL-3211.
Based on the NRC staffs evaluation of the information provided by the licensee, the NRC staff finds that (1) reasonable assurance of adequate protection based on the operating experience that the average prestress in tendons should remain above the applicable minimum required values for at least 60 years of operation, (2) the 2017 visual examination of the Unit 2 concrete containments exterior surface indicated no structural problems or needed more frequent examinations, and (3) all the surveillance data met the ASME Code,Section XI, Subsection IWL, as required by 10 CFR 50.55a.
In the licensees submittal dated January 28, 2022, the licensee stated that it had made good faith efforts to complete the Unit 2 containment tendon examinations by the February 8, 2022, due date. Examinations were originally scheduled to start in November 2021. However, due to the delay of vendor completion of work at other sites, which delayed the mobilization at Palo Verde, Unit 2 until January 2022. The majority of the inspection work is expected to be completed by the deadline of February 8, 2022; however, further COVID-19 impacts have been experienced, with examiners being ill or isolated due to close contact. Initial inspections are targeted by February 8, 2022, with the final vendor report targeted for March 2022, and final APS acceptance in April 2022. The proposed timeline provides contingency or margin in the schedule to ensure completion of the final report and closure of the surveillance package, to support containment operability. The duration of the proposed alternative would extend from the current February 8, 2022, deadline for completing the Unit 2, 35th year IWL Containment Post-Tensioning System Inspection until June 8, 2022.
The NRC staff reviewed the licensees RR-69, and it concludes that the licensees hardship justification is acceptable because all prior Containment Post-Tensioning System Inspection surveillances have been completed successfully with no abnormal degradation of the containment post-tensioning system and their analysis results indicated that the average prestress in tendons should remain above the applicable minimum required values well beyond the proposed 4-month extension.
Authorization read by Jennifer Dixon-Herrity, Chief of the Plant Licensing Branch IV, Office of Nuclear Reactor Regulation
As Chief of the Plant Licensing Branch IV, Office of Nuclear Reactor Regulation, I agree with the conclusion of the Structural, Civil, and Geotechnical Engineering Branch.
The NRC staff concludes that the proposed relief for Palo Verde, Unit 2 will provide reasonable assurance of adequate safety to extend containment tendon inspection by an additional 4 months, based on 10 CFR 50.55a(z)(2). The NRC staff finds that complying with the requirement of the due date of February 8, 2022, to submit the APSs final report to the NRC would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2).
Therefore, the NRC authorizes the use of the proposed alternative at Palo Verde, Unit 2, to extend from the current February 8, 2022, deadline for performing the Unit 2, 35th year IWL Containment Post-Tensioning System Inspection until June 8, 2022.
All other requirements in ASME Code,Section XI for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
This verbal authorization does not preclude the NRC staff from asking additional clarification questions regarding the proposed relief while subsequently preparing the written safety evaluation.
Siva P. Lingam U.S. Nuclear Regulatory Commission Project Manager Palo Verde Nuclear Generating Station, Units 1, 2, and 3 Grand Gulf Nuclear Station Entergy Fleet Location: O-9E22; Mail Stop: O-9E03 Telephone: 301-415-1564 E-mail address: Siva.Lingam@nrc.gov
Hearing Identifier: NRR_DRMA Email Number: 1505
Mail Envelope Properties (SJ0PR09MB61096A7A137765E88D276FB9F6279)
Subject:
Palo Verde, Unit 2 - Verbal Approval of RR-69 to Extend Containment Tendon Inspection from 2/8/22 to 6/8/22 (EPID L-2022-LLR-0011)
Sent Date: 2/2/2022 4:26:01 PM Received Date: 2/2/2022 4:25:00 PM From: Lingam, Siva
Created By: Siva.Lingam@nrc.gov
Recipients:
"Dixon-Herrity, Jennifer" <Jennifer.Dixon-Herrity@nrc.gov>
Tracking Status: None "Colaccino, Joseph" <Joseph.Colaccino@nrc.gov>
Tracking Status: None "Ma, John" <John.Ma@nrc.gov>
Tracking Status: None "Carl.Stephenson@aps.com" <Carl.Stephenson@aps.com>
Tracking Status: None "Nawaporn.AaronsCooke@aps.com" <Nawaporn.AaronsCooke@aps.com>
Tracking Status: None "Boris.Bolf@aps.com" <Boris.Bolf@aps.com>
Tracking Status: None "Sarah.Kane@aps.com" <Sarah.Kane@aps.com>
Tracking Status: None "Dacia.Dallago@aps.com" <Dacia.Dallago@aps.com>
Tracking Status: None "Matthew.Cox@aps.com" <Matthew.Cox@aps.com>
Tracking Status: None
Post Office: SJ0PR09MB6109.namprd09.prod.outlook.com
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