ML22031A098
| ML22031A098 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/28/2022 |
| From: | Aaronscooke N Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML22031A098 (4) | |
Text
WEB-BASED PROPOSED ALTERNATIVE SUBMISSION 10 CFR 50.55a(z)(2)
Submission Date: January 28, 2022 Submitted By: Nawaporn AaronsCooke Document Sensitivity: Non-Sensitive Licensee: Arizona Public Service Company Plant Unit(s) and Docket No(s): Palo Verde 2 (05000529)
Licensee
Contact:
Matthew S. Cox, Licensing Section Leader Matthew.Cox@aps.com (623) 393-5753 Project
Title:
Relief Request 69 - Unit 2, Extension Request for Relief from Containment Tendon Inspections Proposed Alternative Number or Identifier:
Relief Request 69 Request Type:
Inservice Inspection (ISI) or Inservice Testing (IST)
Inservice Inpection (ISI)
Requested Completion Date:
February 08, 2022 Brief Description of Proposed Alternative APS is proposing a one-time, 4-month extension, of the current 12-month extension provided by RR-66, to permit completion of final test report of the examinations that are in progress.
Proposed Duration of Alternative (in terms of ISI/IST Program Interval with Start and End Dates):
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.Second Interval IWL: August 1, 2011, to July 31, 2021, which was extended for Unit 2 to February 8, 2022, by Relief Request 66 [Agencywide Documents Access and Management System (ADAMS) Accession No. ML21089A010].
Applicable ASME Code Requirements IWL-2420 Unbonded Post-Tensioning Systems, states:(a) Unbonded post-tensioning systems shall be examined in accordance with IWL-2520 at 1, 3, and 5 years following the completion of the containment Structural Integrity Test and every 5 years thereafter.(c) The 10-year and subsequent examinations shall commence not more than 1 year prior to the specified dates and shall be completed not more than 1 year after such dates. If plant operating conditions are such that examination of portions of the post-tensioning system cannot be completed within this stated time interval, examination of those portions may be deferred until the next regularly scheduled plant outage, Reference 1.APS is currently in the subsequent examinations period, as the specified date (i.e., the anniversary date) for the 35th surveillance year is February 8, 2020. The Unit 2 PVNGS deadline for the completion of the inspection was February 8, 2021. Relief Request 66 allowed for a one-time 12-month extension of Containment Post-Tensioning System Inspection for Unit 2, 35th year Tendon Surveillance from February 8, 2021, to February 8, 2022. IWL-2421 Sites with Multiple Plants, states, For sites with multiple plants, the examination requirements, for the concrete containments may be modified if the containments utilize the same prestressing system and are essentially identical in design, if post-tensioning operations for each subsequent containment constructed at the site were completed
not more than 2 years apart, and if the containments are similarly exposed to or protected from the outside environment, Reference 1.PVNGS is a multiple unit site. All three units utilize the same pre-stressing system, are essentially identical in design, and are similarly exposed to the outside environment. The post-tensioning operation for each subsequent containment structure was completed within two years of each other. Because the conditions of IWL-2421(a) are met the PVNGS Unit 2 surveillances are scheduled in compliance with IWL-2421(b)(2). This means all examinations required by IWL-2500 shall be performed at 1, 5, and 15 years and every 10 years thereafter. Only the examination required by IWL-2524 and IWL-2525 need to be performed at 3 and 10 years and every 10 years thereafter.
Applicable American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPV Code), or ASME Operation and Maintenanceof Nuclear Power Plants (OM Code), Edition and Addenda American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section XI, 2007 Edition through the 2008 Addenda, Rules for Inservice Inspection of Nuclear Power Plant Components Current ISI or IST Program Interval Number and Start/End Dates Second Interval IWL: August 1, 2011, to July 31, 2021, which was extended for Unit 2 to February 8, 2022, by Relief Request 66 (ADAMS Accession number ML21089A010).
Applicable ASME Code Components and/or System Description Examination Category L-B; Unbonded Post-Tensioning Systems
Reason for Request
Relief is requested pursuant to 10 CFR 50.55a(z)(2) - Hardship without a compensating increase in quality and safety, Reference 2.
Relief Request (RR) 66 was requested (ADAMS Accession No. ML20315A156) and approved based upon the U.S. Federal Government having made a COVID-19 declaration of emergency pursuant to the Stafford Act on March 13, 2020. In response to the COVID-19 Pandemic and to comply with CDC guidance, APS established the Pandemic Plan.
Specifically, RR-66 was a one-time 12-month extension of Containment Post-Tensioning System Inspection for Unit 2, 35th year Tendon Surveillance from February 8, 2021, to February 8, 2022. NRC verbal approval of RR-66 was dated November 19, 2020, and written approval was dated April 2, 2021 (ADAMS Accession number ML21089A010).
This RR-69 requests a 4-month extension, of the current 12-month extension provided by RR-66, to permit completion of final test report of the containment tendon examinations.
Full Description of Proposed Alternative Pursuant to 10 CFR 50.55a(z)(2), APS hereby requests NRC approval of RR-69 regarding a one-time, 4-month extension, of the current 12-month extension provided by RR-66 for the interval between containment tendon inspections as specified per Paragraph IWL-2420 of the ASME BPV Code,Section XI, Subsection IWL, Reference 1. Relief is requested on the basis that compliance with the Code-specified inspection interval during the COVID-19 pandemic would result in hardship without a compensating increase in the level of quality and safety.
APS has 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.
Unfortunately, due to tooling parts and material manufacturing at the other facilities, there were delays in vendor completion of work at other sites, which delayed mobilization at PVNGS until January 2022.
The majority of the inspection work is expected to be completed by the deadline of 2/8/22; 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 components are ASME Class CC.
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.
Description of Basis for Use The purpose of the Containment Post-Tensioning System Inspection is to assess the structural performance of the containment post-tensioning system and the containment building concrete shell on an ongoing basis, up through and including the plant's period of extended operation. All prior Containment Post-Tensioning System Inspection surveillances have been completed successfully with no abnormal degradation of the containment post-tensioning system identified.
A regression analysis of the lift-off was performed for license renewal application. This analysis demonstrated that the average prestress in tendons should remain above the applicable minimum required values (MRVs) for at least 60 years of operation and that all tendons should, therefore, maintain their design basis function for the extended period of operation, Reference 3.
The Concrete Containment Tendon Prestress Program demonstrated that average prestress in both the vertical tendon group and the horizontal cylinder and horizontal dome tendon subgroups should remain above the applicable MRVs for at least 60 years of operation. Therefore, all tendons should maintain their design basis function for the extended period of operation. The material condition of other components (e.g., concrete, bearing surfaces, grease, uttonheads, etc.) showed only minor degradation in a few areas; none indicating a need for significant corrective action, Reference 3.
Describe Hardship or Unusual Difficulty APS has 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. Unfortunately, due to tooling parts and material manufacturing at the other facilities, there were delays in vendor completion of work at other sites, which delayed mobilization at PVNGS until January 2022. The majority of the inspection work is expected to be completed by the deadline of 2/8/22; 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.
Any Additional Information (submission attachments listed here)
Docket Number 05000529 License Number NPF-51 See also detailed technical basis provided with RR-66. Relief Request 66 (ADAMS Accession No. ML20315A156) and NRC verbal approval dated November 19, 2020 (ML20325A039), and written approval dated April 2, 2021 (ADAMS Accession number ML21089A010).
Technical Specification Section 5.5.6, Pre-Stressed Concrete Containment Tendon Surveillance Program states: The Tendon Surveillance Program, inspection frequencies, and acceptance criteria shall be in accordance with ASME Code Section XI, Subsection IWL of the ASME Boiler and Pressure Vessel Code and applicable addenda as required by 10 CFR 50.55a, except where an exemption or relief has been authorized by the NRC.
Precedents PVNGS Relief Request 66 (ADAMS Accession number ML21089A010).
References
- 1. American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI, 2007 Edition through 2008 Addenda
- 2. 10 CFR 50.55a, Code and standards, June 3, 2020
- 3. Safety Evaluation Report - Related to the License Renewal of Palo Verde Nuclear Generating Station, Unit 1, 2, and 3, ADAMS Accession No. ML11095A011