ML24151A026

Final Safety Evaluation Report for NAC International Ums Storage System Certificate of Compliance 1015

ML24151A026
Person / Time
Site:	07201015
Issue date:	06/11/2024
From:	Storage and Transportation Licensing Branch
To:	NAC International
References
Download: ML24151A026 (99)

Text

SAFETY EVALUATION REPORT FOR THE NAC INTERNATIONAL UNIVERSAL MULTI-PURPOSE STORAGE SYSTEM (NAC-UMS SYSTEM)

RENEWAL OF CERTIFICATE OF COMPLIANCE NO. 1015 DOCKET NO. 72-1015 Office of Nuclear Material Safety and Safeguards United States Nuclear Regulatory Commission June 11, 2024

ii CONTENTS INTRODUCTION......................................................................................................................... IV 1

GENERAL INFORMATION................................................................................................. 1-1 1.1 Certificate of Compliance and Certificate of Compliance Holder Information............ 1-1 1.2 Safety Review............................................................................................................ 1-1 1.3 Application Content................................................................................................... 1-2 1.4 Evaluation Findings................................................................................................... 1-2 2

SCOPING EVALUATION.................................................................................................... 2-1 2.1 Scoping and Screening Methodology and Results.................................................... 2-1 2.1.1 Scoping and Screening Process.................................................................... 2-2 2.1.2 Scoping Results............................................................................................. 2-5 2.1.3 Screening of Structures, Systems, and Components Within the Scope of Renewal.......................................................................................... 2-8 2.1.4 Subcomponents Not Within the Scope of Renewal....................................... 2-8 2.2 Evaluation Findings................................................................................................. 2-13 3

AGING MANAGEMENT REVIEW...................................................................................... 3-1 3.1 Review Objective....................................................................................................... 3-1 3.2 Aging Management Review Process......................................................................... 3-1 3.3 Aging Management Review Results: Materials, Service Environments, Aging Effects, and Aging Management Activities................................................................ 3-1 3.3.1 Supplemental Analyses............................................................................... 3-17 3.3.2 Evaluation Findings..................................................................................... 3-21 3.4 Time-Limited Aging Analyses.................................................................................. 3-22 3.4.1 Fatigue of Transportable Storage Canisters and Fuel Baskets................... 3-22 3.4.2 Corrosion Analysis of Vertical Concrete Cask Internal Steel Subcomponents........................................................................................... 3-24 3.4.3 Aging of Neutron Absorber and Neutron Shield Components..................... 3-27 3.4.4 Evaluation Findings..................................................................................... 3-32 3.5 Aging Management Programs................................................................................. 3-33 3.5.1 Aging Management Tollgates...................................................................... 3-68 3.5.2 Evaluation Findings..................................................................................... 3-70 4

CHANGES TO CERTIFICATE OF COMPLIANCE AND TECHNICAL SPECIFICATIONS 4-1 5

CONCLUSION.................................................................................................................... 5-1 6

REFERENCES................................................................................................................... 6-1

iii TABLES Table No.

Page 2.1-1 Major SSCs Within Scope and Not Within Scope of Renewal Review.......................... 2-4 2.1-2 SSC Subcomponents Within the Scope of Renewal Review......................................... 2-8 2.1-3 SSC Subcomponents Not Within the Scope of Renewal Review................................ 2-11 3.3-1 AMREnvironments...................................................................................................... 3-2 3.3-2 AMR ResultsNAC-UMS TSCs.................................................................................... 3-4 3.3-3 AMR ResultsNAC-UMS VCCs................................................................................... 3-7 3.3-4 AMR ResultsNAC-UMS TFRs and Transfer Adapters............................................. 3-12 3.3-5 AMR ResultsNAC-UMS Spent Fuel Assemblies...................................................... 3-14 3.5-1 AMP Review ResultsNAC-UMS Localized Corrosion and SCC of Welded Stainless-Steel TSCs................................................................................................... 3-34 3.5-2 AMP Review ResultsNAC-UMS Internal VCC Metallic Components Monitoring..... 3-40 3.5-3 AMP Review ResultsNAC-UMS External VCC Metallic Components Monitoring.... 3-45 3.5-4 AMP Review ResultsNAC-UMS Reinforced VCC Structures Concrete Monitoring.. 3-50 3.5-5 AMP Review ResultsNAC-UMS TFRs and Transfer Adapters................................. 3-57 3.5-6 AMP Review ResultsNAC-UMS HBU Fuel Monitoring and Assessment................. 3-63

iv ABBREVIATIONS AND ACRONYMS ACI American Concrete Institute AMID Aging Management Institute of Nuclear Power Operations Database AMP aging management program AMR aging management review ANSI American National Standards Institute APS Arizona Public Service ASME American Society of Mechanical Engineers BPV boiler and pressure vessel BWR boiling-water reactor

°C degrees Celsius CFR Code of Federal Regulations CNS Catawba Nuclear Station CoC certificate of compliance DFC damaged fuel can EPRI Electric Power Research Institute

°F degrees Fahrenheit FB fuel basket FSAR final safety analysis report GWd/MTU gigawatt days per metric ton of uranium HAZ heat-affected zones HBU high-burnup HDRP HBU Dry Storage Cask Research and Development Project ISFSI independent spent fuel storage installation ITS important to safety MAPS Managing Aging Processes in Storage MNS McGuire Nuclear Station MPC multi-purpose canister MY Maine Yankee MYAPC Maine Yankee Atomic Power Plant NEI Nuclear Energy Institute NRC U.S. Nuclear Regulatory Commission PH precipitation hardened PWR pressurized-water reactor

v PVNGS Palo Verde Nuclear Generating Station QA quality assurance RAI request for additional information SCC stress corrosion cracking SD shield door SER safety evaluation report SR surveillance requirements SSC structure, system, and component TFR transfer cask TLAA time-limited aging analysis TS technical specifications TSC transportable storage canister UFSAR updated final safety analysis report UMS Universal Multi-purpose Storage VCC vertical concrete cask wt%

weight percent

vi INTRODUCTION By letter dated October 13, 2020, as supplemented on March 3, 2022, March 18, 2022, July 28, 2022, and December 21, 2022, the current certificate of compliance (CoC) holder, NAC International, Inc. (hereafter applicant), applied for renewal of CoC No. 1015 for the Universal Multi-Purpose Storage System (hereafter NAC-UMS System) for an additional 40 years beyond the initial certificate period (the period of extended operation) (NAC International 2020, 2022a, 2022b, 2022c, and 2022e, respectively). This safety evaluation report (SER) generally refers to this application, as supplemented, as the renewal application.

The applicant submitted the renewal application in accordance with the regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) 72.240, Conditions for spent fuel storage cask renewal. Because the applicant submitted its renewal request more than 30 days before the CoC expiration date, under 10 CFR 72.240(b), this application constitutes a timely renewal. The applicant documented the technical bases for renewal of the CoC and proposed actions for managing the potential aging effects of the structures, systems, and components (SSCs) of the dry storage system to ensure that they will maintain their intended functions during the period of extended operation.

Under 10 CFR Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater than Class C Waste, Subpart L, Approval of Spent Fuel Storage Casks, the U.S. Nuclear Regulatory Commission (NRC) approved the NAC-UMS System and issued CoC No. 1015 for 20 years, with effective dates of November 20, 2000 (initial certificate, Amendment No. 0); February 20, 2001 (Amendment No. 1); December 31, 2001 (Amendment No. 2); March 31, 2004 (Amendment No. 3); October 11, 2005 (Amendment No. 4); January 12, 2009 (Amendment No. 5);

January 7, 2019 (Amendment No. 6); July 29, 2019 (Amendments No. 7); October 19, 2021 (Amendment No. 8); and August 29, 2022 (Amendment No. 9). CoC No. 1015 can be used for dry storage of spent nuclear fuel in an independent spent fuel storage installation (ISFSI) at power reactor sites by persons authorized to possess or operate nuclear power reactors under 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, and 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants, under 10 CFR Part 72, Subpart K, General License for Storage of Spent Fuel at Power Reactor Sites.

The original CoC for the NAC-UMS System included designs for the storage of five classes of transportable storage canisters (TSCs), including three lengths for pressurized-water reactor (PWR) fuel types and two lengths for boiling-water reactor (BWR) fuel types. The system included a TSC provided with integral fuel baskets for the storage of up to 24 PWR and 56 BWR spent nuclear fuel assemblies. Subsequently, the NRC issued nine amendments to the NAC-UMS System CoC.

The licensees application stated the following:

Through the end of 2017 a total of two hundred sixty-four (264) NAC-UMS Systems were loaded with SNF at four Independent Spent Fuel Storage Installations (ISFSls): sixty (60) systems at Maine Yankee Atomic Power Companys (MYAPC) Maine Yankee (MY) ISFSI in Maine; twenty-eight (28) systems at Duke Energy's McGuire Nuclear Station (MNS) in North Carolina; twenty-four (24) systems at Duke Energy's Catawba Nuclear Station (CNS) in

vii South Carolina; and a total of one hundred and fifty-two (152) systems at Arizona Public Service's (APS) Palo Verde Nuclear Generating Station (PVNGS) in Arizona. No additional loading operations were performed after September 1, 2017, and no additional NAC-UMS Systems are planned for loading at the time of this CoC renewal request.

The principal components identified as in-scope SSCs of the NAC-UMS System are as follows:

TSC with PWR or BWR fuel basket (and damaged fuel cans when authorized) vertical concrete casks transfer cask/transfer adapter spent fuel assemblies fuel transfer and auxiliary equipment (e.g., lift yoke, vertical cask transporter, air pads, heavy haul transfer trailer, vacuum drying and helium back-fill system with a helium mass spectrometer leak detector, welding equipment) temperature monitoring equipment ISFSI storage pad ISFSI security equipment In the renewal application, the applicant documented the technical bases for renewal of the CoC and proposed actions for managing potential aging effects on the NAC-UMS System SSCs that are within the scope of CoC renewal to ensure that they will maintain their intended functions during the period of extended operation. The applicant presented general information about the dry storage system design and a scoping evaluation to determine the SSCs within the scope of CoC renewal (the in-scope SSCs) and subject to an aging management review. The applicant further screened the in-scope SSCs to identify and describe the subcomponents that support the intended functions of the in-scope SSCs. For each in-scope SSC subcomponent with an identified aging effect, the applicant proposed an aging management program (AMP) or provided a time-limited aging analysis to give assurance that the SSC will maintain its intended function(s) during the period of extended operation.

The NRC staff reviewed the applicants technical bases for safe operation of the NAC-UMS System for an additional 40 years beyond the current CoC term of 20 years. This SER summarizes the results of the staffs review for compliance with 10 CFR 72.240. In its review of the application and development of the SER, the staff used the guidance in (1) NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, issued June 2016 (NRC, 2016), and (2) NUREG-2214, Revision 0, Managing Aging Processes In Storage (MAPS) Report, issued July 2019 (NRC, 2019b). NUREG-2214 establishes a generic technical basis for the safety review of storage renewal applications, in terms of the evaluation of (1) aging mechanisms and effects that could affect the ability of SSCs to fulfill their safety functions in the period of extended operation (i.e., credible aging mechanisms and effects) and (2) aging management approaches to address credible aging effects, including examples of AMPs that are considered

viii generically acceptable to address the credible aging effects to ensure that the design bases will be maintained in the period of extended operation. The staff evaluated the applicants technical basis for its aging management review and proposed AMPs and compared it to the generic technical basis in NUREG-2214. For this comparison, the staff ensured that the design features, environmental conditions, and operating experience for the NAC-UMS System are bounded by those evaluated in NUREG-2214.

This SER is organized into six sections. Section 1 includes the staffs review of the general information of the dry storage system. Section 2 presents the staffs review of the scoping evaluation performed for determining which SSCs are within the scope of renewal. Section 3 provides the staffs evaluation of the aging management review for the assessment of aging effects and aging management activities for SSCs within the scope of renewal. Section 4 documents the additions and changes to the CoC conditions and technical specifications being made to the initial CoC and associated amendments due to renewal. Section 5 presents the staffs conclusions of the safety review. Section 6 lists the references supporting the staffs review and technical determinations.

1-1 1 GENERAL INFORMATION 1.1 Certificate of Compliance and Certificate of Compliance Holder Information By letter dated October 13, 2020, as supplemented on March 3, 2022, March 18, 2022, July 28, 2022, and December 21, 2022, the current certificate of compliance (CoC) holder, NAC International, Inc. (hereafter applicant), applied for renewal of CoC No. 1015 for the Universal Multi-Purpose Storage System (hereafter NAC-UMS System) for an additional 40 years beyond the initial certificate period (the period of extended operation) (NAC International 2020, 2022a, 2022b, 2022c, and 2022e, respectively). The application is subject to the provisions of Title 10 of the Code of Federal Regulations (10 CFR) Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater than Class C Waste, Subpart K, General License for Storage of Spent Fuel at Power Reactor Sites, and Subpart L, Approval of Spent Fuel Storage Casks.

The applicant requested renewal of the initial NAC-UMS System CoC and Amendments 1 through 9. The U.S. Nuclear Regulatory Commission (NRC) issued the initial CoC (Amendment 0) for the NAC-UMS System on November 20, 2000. Subsequently, the NRC issued nine amendments (1 through 9) to the NAC-UMS System CoC. In its renewal application, NAC described the licensing basis for the NAC-UMS System initial issuance, as well as general descriptions of the changes and reasons for each amendment, including the dates of the applications and associated supplements, the date of issue of the CoC and CoC amendments, and the corresponding updated final safety analysis report (UFSAR) revisions that incorporated the changes. Chapter 1 of the application lists the amendments and describes each amendment along with references. Chapter 2 of the application provides further details on the scope of each amendment.

1.2 Safety Review The objective of this safety review is to determine whether the dry storage system will continue to meet the requirements of 10 CFR Part 72 for an additional 40 years beyond the initial certificate period. The NRC staff safety review is a detailed and in-depth assessment of the technical aspects of the NAC-UMS System renewal application. Pursuant to 10 CFR 72.240(c)(2) and 10 CFR 72.240(c)(3), an application for renewal of a CoC must be accompanied by a safety analysis report that includes (1) time-limited aging analyses (TLAAs) to demonstrate that structures, systems, and components (SSCs) important to safety will continue to perform their intended functions for the requested period of extended operation and (2) a description of the aging management programs (AMPs) for management of issues associated with aging that could adversely affect SSCs important to safety.

The applicant stated that the renewal application includes the information required by 10 CFR 72.240(c), and the application content is based on the guidance provided in NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, issued June 2016 (NRC, 2016). The applicant also referenced NUREG-2214, Managing Aging Processes in Storage (MAPS) Report, issued July 2019 (NRC, 2019); Nuclear Energy Institute (NEI) 14-03, Revision 2, Format, Content and Implementation Guidance for Dry Cask Storage Operations-Based Aging Management, issued December 2016 (NEI, 2016); and other technical references used in support of the renewal application.

1-2 The applicant conducted a scoping evaluation and aging management review (AMR) to identify all SSCs within the scope of the CoC renewal and pertinent aging mechanisms and effects, respectively. The applicant developed AMPs and evaluated TLAAs to ensure that the SSCs identified to be within the scope of renewal will continue to perform their intended functions during the period of extended operation. This safety review documents the staffs evaluation of the applicants scoping evaluation, AMR, and supporting AMPs and TLAAs.

1.3 Application Content The applicants license renewal application contained the following:

general information scoping evaluation AMRs AMPs TLAAs changes to the CoC No. 1015 UFSAR proposed changes to CoC No. 1015 and technical specifications preapplication inspection report design-basis document review report The applicant also provided UFSAR revisions for all CoC amendments, which incorporated all changes to the NAC-UMS System previously made without prior NRC approval in accordance with 10 CFR 72.48(c) and (d). The UFSAR supplement and changes document provided in appendix C to the application details the changes and additions for the NAC-UMS System. In addition, during the staffs review of the renewal application, the applicant submitted its 2022 biennial update to the UFSAR (ML22318A091) (NAC International 2022d). The staff considered these additional UFSAR revisions in its review of the applicants scoping evaluation and AMR.

1.4 Evaluation Findings

The staff reviewed the general information in the renewal application. The staff performed its review following the guidance in NUREG-1927, Revision 1. Based on its review, the staff determined that the applicant provided sufficient information with adequate details to support the renewal application, with the following findings:

F1.1 The information presented in the renewal application satisfies the requirements of 10 CFR 72.240, Conditions for spent fuel storage cask renewal.

F1.2 The applicant tabulated all supporting information and docketed material incorporated by reference, in compliance with 10 CFR 72.240.

2-1 2 SCOPING EVALUATION As described in NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, issued June 2016 (U.S. Nuclear Regulatory Commission (NRC), 2016), the scoping evaluation identifies the structures, systems, and components (SSCs) requiring an aging management review (AMR). The objective of the scoping evaluation is to identify SSCs meeting one of the following criteria:

(1)

SSCs classified as important to safety (ITS), as they are relied on for one of the following functions:

Maintain the conditions required by the regulations or the certificate of compliance (CoC) to store spent fuel safely.

Prevent damage to the spent fuel during handling and storage.

Provide reasonable assurance that spent fuel can be received, handled, packaged, stored, and retrieved without undue risk to public health and safety.

(2)

SSCs classified as not ITS but, according to the design bases, their failure could prevent fulfillment of an SSC function that is important to safety After determining the scope of SSCs requiring an AMR, the in-scope SSCs are screened to identify and describe the SSC subcomponents that support the intended functions of the in-scope SSCs.

2.1 Scoping and Screening Methodology and Results In Section 2 of the CoC renewal application (NAC International, 2020), the applicant described the scoping and screening evaluation for the Universal Multi-Purpose Storage System (hereafter NAC-UMS System) and provided the following information:

a description of the scoping and screening methodology for determining the SSCs and SSC subcomponents that need to be included in the scope of the renewal review a list of sources of information used for the scoping and screening evaluation descriptions of the SSCs, SSC subcomponents, and their design functions a list of the SSCs and their subcomponents identified to be within and outside the scope of the renewal review and the basis for the scope determination The staff reviewed the applicants description of the scoping and screening process and results for the NAC-UMS System. The following sections discuss the staffs review and findings regarding the applicants scoping and screening evaluation.

2-2 2.1.1 Scoping and Screening Process In Sections 2.2, 2.3, 2.4, and 2.5 of the renewal application, the applicant documented its scoping review of the following licensing and design-basis documents to identify SSCs and subcomponents with design functions meeting either scoping criterion 1 or 2, as defined above:

NAC-UMS System final safety analysis report (FSAR), Docket No. 72-1015, Revisions 0 through 15 FSAR Revision 0, November 2000, Agencywide Documents Access and Management System Accession Nos. ML010180089, ML010170442 (nonpublic),

ML010170385 (nonpublic)

FSAR Revision 1, May 2001, ML011360458, ML011360569, ML011360535, ML011360626, ML011360662, ML011360591, ML020280301, ML020280322, ML011360545 (nonpublic), ML011360565 (non-public), ML011360646 (nonpublic)

FSAR Revision 2, December 2001, ML020250353, ML020250338 (nonpublic)

FSAR Revision 3, March 2004, ML051290397, ML041040369, ML051290403, ML041040397, ML041040050 (nonpublic), ML041040376 (nonpublic)

FSAR Revision 4, November 2004, ML051290405, ML043510070 FSAR Revision 5, October 2005, ML053060314 FSAR Revision 6, November 2006, ML082970749, ML063350398 (nonpublic)

FSAR Revision 7, November 2008, ML110250182, ML083380106 (nonpublic)

FSAR Revision 8, January 2009, ML090370421 (nonpublic)

FSAR Revision 9, November 2010, ML103230363 (nonpublic)

FSAR Revision 10, October 2012, ML12311A149 FSAR Revision 11, November 2016, ML16341B102, ML16337A351, ML16327A394 (nonpublic)

FSAR Revision 12, November 2018, ML18319A102 (nonpublic)

FSAR Revision 13, January 2019, ML19073A165 FSAR Revision 14, July 2019, ML19214A052 FSAR Revision 15, October 2021, ML21301A128 (nonpublic), ML21301A129 (nonpublic)

NRC previously approved the following documents for NAC-UMS System CoC No. 1015, including initial CoC issuance, CoC amendments, and CoC technical

2-3 specifications (TS), as documented in the associated NRC safety evaluation reports (SERs):

CoC No. 1015 initial issue effective date: November 20, 2000, ML003762585, ML003743491, and ML003743508; final NRC SER, ML003743531 CoC No. 1015 Amendment No. 1 effective date: February 20, 2001, ML010440434, ML010260194, and ML010260245; final NRC SER, ML010400311 CoC No. 1015 Amendment No. 2 effective date: December 31, 2001, ML020250569, ML020250588, and ML020250599; final NRC SER, ML020250602 CoC No. 1015 Amendment No. 3 effective date: March 31, 2004, ML040830043, ML040830062, ML040830052, and ML040830054; final NRC SER, ML040830070 CoC No. 1015 Amendment No. 4 effective date: October 11, 2005, ML052860129, ML052860162, ML052860167, and ML052860168; final NRC SER, ML052860175 CoC No. 1015 Amendment No. 5 effective date: January 12, 2009, ML090120418, ML090120439, ML090120459, and ML090120473; final NRC SER, ML090120477 CoC No. 1015 Amendment No. 6 effective date: January 7, 2019, ML18333A237, ML18333A235, ML18333A233, and ML18333A234; final NRC SER, ML18333A236 CoC No. 1015 Amendment No. 7 effective date: July 29, 2019, ML19183A274, ML19183A269, ML19183A270, and ML19183A271; final NRC SER, ML19183A272 Subsequent to the applicants submittal of the CoC renewal application for the NAC-UMS System in October 2020 (NAC International, 2020), the NRC staff completed its review and approval of CoC No. 1015 Amendment 8. The staff confirmed that Amendment 8 does not affect the applicants scoping and screening evaluation for determining the SSCs and SSC subcomponents that need to be included in the scope of the renewal review. NRC approval documents for Amendment 8 are referenced below:

CoC No. 1015 Amendment No. 8 effective date: October 19, 2021, ML21253A238, ML21253A236, and ML21253A237; final NRC SER, ML21253A239 CoC No. 1015 Amendment No. 9 effective date: August 29, 2022, ML22202A022 ML22202A023, and ML22202A024; final NRC SER, ML22202A026 The applicants scoping and screening process identified SSCs and SSC subcomponents as being either scoped into the renewal review under scoping criterion 1 or 2, as described above, or not scoped into the renewal review for items that are not important to safety (i.e., not meeting scoping criterion 1) and that did not meet scoping criterion 2. The staff reviewed the applicants

2-4 description of its scoping and screening process for determining the scope of SSCs and subcomponents requiring an AMR and finds it acceptable because it is consistent with the scoping process described in NUREG-1927, Revision 1, Section 2.4.

2-5 2.1.2 Scoping Results Section 2.3 of the renewal application provides the scoping results for the NAC-UMS System.

The scoping results identify the major SSCs that the applicant determined to be within the scope of renewal review and not within the scope of renewal review. SER table 2.1-1 lists scoping results for the major SSCs; it identifies the scoping criterion met by the in-scope SSCs; and it identifies the scoping criteria not met by the out-of-scope SSCs.

Table 2.1-1 Major SSCs Within Scope and Not Within Scope of Renewal Review SSC Criterion 1 Criterion 2 In-Scope Transportable Storage Canister Yes N/A Yes Vertical Concrete Cask Yes N/A Yes Transfer Cask Yes N/A Yes Transfer Adapter Yes N/A Yes Spent Nuclear Fuel Assemblies Yes N/A Yes Fuel Transfer Auxiliary Operating Equipment No No No Temperature Monitoring Equipment No No No ISFSI Storage Pad No*

No No*

ISFSI Security Equipment No No No

• The applicant stated that the independent spent fuel storage installation (ISFSI) storage pad is not an ITS component within the scope of the CoC renewal; however, general licensees may have designated their ISFSI storage pads as ITS. Table 2.3-1 of the application labeled the scoping result for the ISFSI storage pad as yes (in scope) to address those site-specific cases.

The staff reviewed the scoping results to determine whether the applicant accurately identified the in-scope SSCs based on the scoping criteria described above and whether the applicants determination of the out-of-scope SSCs accurately reflect the design bases of the NAC-UMS System. The discussion below addresses the staffs review of the applicants basis for determining that the out-of-scope SSCs listed in SER table 2.1-1 may be excluded from the scope of the renewal review.

The applicant stated that the fuel transfer auxiliary operating equipment is not part of the NAC-UMS System, as approved by the NRC under CoC No. 1015, and is not described in detail in the NAC-UMS System FSAR. The equipment includes the lifting yoke, air-pallets, heavy haul trailer, vertical cask transporter, vacuum drying system, welding equipment, weld inspection equipment, drain pump equipment, temperature monitoring equipment, helium leak detection equipment, and similar equipment used in the operation of the ISFSI. The applicant also stated that the failure of these components would not affect the safety functions of any ITS SSC for the NAC-UMS System. Therefore, the applicant concluded that this equipment is not within the scope of renewal review.

2-6 The staff reviewed the CoC and confirmed that the fuel transfer auxiliary operating equipment components are not listed as components of the NAC-UMS System. In addition, the staff reviewed the design bases of the system, as described in the FSAR, and did not identify any means by which the failure of the subject equipment would affect the functions of an ITS SSC.

Regarding the equipment to lift and transfer the vertical concrete cask (VCC), the staff noted that table A.5-1 and section B3.5 of the NAC-UMS TS include requirements to ensure that a drop of the VCC (which could be caused by failure of one or more of the lifting components) would not affect the safety functions of any ITS SSC because VCC lifts are to be performed within the analyzed limits. Therefore, based on review of the applicants design-basis documentation, the staff finds the applicants determination that the fuel transfer auxiliary operating equipment is not within the scope of renewal review to be acceptable.

Heat removal is a safety function of the VCC, which can be assessed by monitoring the temperature difference between the inlet and outlet vents, either manually or with temperature monitoring equipment. The applicant stated that the VCC temperature monitoring equipment is one method authorized to verify the continued operability of the VCC heat removal system, although it is not part of the NRC-approved design bases under the CoC. As such, the FSAR does not describe the temperature monitoring equipment in detail. The applicant noted that, as an alternative to the use of VCC temperature monitoring equipment, manual temperature measurements or a visual inspection of the inlet and outlet screens may be performed on a 24 -hour frequency to verify that the inlet and outlet screens are not obstructed such that passive cooling air flow is maintained through the VCC. The applicant also stated that the failure of the VCC temperature monitoring equipment would not prevent the VCC from maintaining the stored fuel cladding and NAC-UMS System components within the allowable temperature limits for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to allow corrective actions to be taken to reestablish operability of the VCC heat removal system. Therefore, the applicant concluded that the VCC temperature monitoring equipment is not within the scope of the renewal review.

The staff reviewed the design bases of the NAC-UMS System, as described in the FSAR, and verified that the VCC temperature monitoring equipment is not identified as an ITS SSC. The staff also noted that the FSAR describes the temperature monitoring equipment as optional.

The staff verified that a failure of the VCC temperature monitoring equipment would not affect the safety function of any ITS SSC since, in the event that the passive VCC heat removal system is declared inoperable, the NAC-UMS System TS limiting conditions for operation require that general licensees take action to ensure required heat removal to prevent exceeding short-term temperature limits and restore the VCC heat removal system to operable status. To ensure operability of the passive VCC heat removal system, the TS include a surveillance requirement (SR) to verify, every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, that the difference between the ISFSI ambient temperature and the average outlet air temperature is within the specified limits, although use of the online temperature monitoring equipment is not required to meet this SR. As an alternative to these temperature difference measurements, the staff noted that later NAC-UMS System TS (Amendment Nos. 4, 5, 6, 7, and 8) also include the option in the SRs to visually verify that all four air inlet and outlet vent screens are unobstructed as a basis for determining that the passive VCC heat removal system is operable. The staff noted the earlier NAC-UMS System TS do not include this SR option as a means for determining that the VCC heat removal system is operable; however, the TS limiting conditions for operation and action statements provide the needed requirements for ensuring the required heat removal, including performing the temperature difference measurements that are specified in the SR. Further, the staff noted that section 2.4.3 of NUREG-1927, Revision 1, states that instrumentation and other active components or systems (i.e., not passive or long-lived SSCs, but subject to a change in configuration or replacement based on a qualified life or service time period) may be excluded

2-7 from the scope of renewal, provided that they do not meet either of the scoping criteria discussed above. Therefore, the staff finds the applicants determination that the VCC temperature monitoring equipment is not within the scope of renewal review to be acceptable.

The applicant stated that the ISFSI storage pad is not part of the NAC-UMS System, as approved by the NRC under CoC No. 1015. The ISFSI storage page provides free-standing support of the loaded transportable storage canisters (TSCs) and VCCs. The FSAR includes generic physical properties for the ISFSI storage pad that are used for the evaluation of the design-basis VCC drop accident and the beyond-design-basis VCC tip-over accident. The applicant noted that the FSAR and CoC authorize the evaluation of the ISFSI storage pad on a site-specific basis as part of the evaluation in Title 10 of the Code of Federal Regulations (10 CFR) 72.212, Conditions of general license issued under 10 CFR 72.210. The applicant noted that the ISFSI storage pad meets scoping criterion 1 if it is classified as an ITS SSC by general licensees. The applicant identified that the ISFSI storage pad is not with the scope of CoC renewal review for the NAC-UMS System. However, if general licensees classify the pad as ITS, the regulations require aging management of the ISFSI storage pad to be addressed in a site-specific inspection program by general licensees using the NAC-UMS System.

The staff reviewed the FSAR and CoC and confirmed that the ISFSI storage pad is not included as an ITS SSC for the NAC-UMS System. The CoC lists only the TSC, VCC, transfer cask (TFR), and the transfer adapter as SSCs for the NAC-UMS System. While a failure of the ISFSI storage pad could potentially have an adverse impact on the safety function performance of the NAC-UMS SSCs (e.g., during VCC drop and tip-over accident conditions), the FSAR provides for this potential adverse impact to be evaluated by general licensees on a site-specific basis, and accordingly, any inspections needed for ISFSI storage pad aging management are to be performed on a site-specific basis by general licensees. Therefore, the staff finds the applicants determination that the ISFSI storage pad is not within the scope of the NAC-UMS System CoC renewal review to be acceptable.

The applicant stated that the ISFSI security equipment (e.g., ISFSI security fences and gates, lighting, communications, monitoring equipment) is not part of the NAC-UMS System approved by the NRC and is not described in the FSAR. The applicant stated that existing plant programs and procedures ensure that ISFSI security equipment requirements are satisfied in accordance with 10 CFR Part 73, Physical Protection of Plants and Materials. Further, the applicant stated that failure of the ISFSI security equipment would not prevent fulfillment of any SSC safety functions for the NAC-UMS System.

The staff reviewed the FSAR and CoC and confirmed that the ISFSI security equipment is not included as an ITS SSC in the NAC-UMS System. The staff also verified that a failure of the ISFSI security equipment would not affect the safety function of any ITS SSC for the NAC-UMS System. As a result, NUREG-1927, Revision 1, specifically excludes ISFSI security equipment from the scope of renewal review. Therefore, based on review of the applicants design-basis documentation, and consistent with the review guidance in NUREG-1927, Revision 1, the staff finds the applicants determination, that the ISFSI security equipment is not within the scope of the renewal review, to be acceptable. Notwithstanding this finding, the staff notes that 10 CFR 73.55, Requirements for physical protection of licensed activities in nuclear power reactors against radiological sabotage, includes requirements for ISFSI security equipment to be adequately maintained by general licensees at all times, irrespective of whether the general licensees operation of the NAC-UMS System is during the initial storage term or the period of extended operation. However, since the security equipment requirements are not associated

2-8 with maintaining safety function performance for ITS SSCs of the NAC-UMS System, they are not included in the scope of the renewal review.

Based on the foregoing review of the applicants scoping process and scoping results for the NAC-UMS System, the staff determined that the applicant has identified the major in-scope SSCs in a manner consistent with NUREG-1927, Revision 1. The staff also determined that the applicants identification of the out-of-scope SSCs accurately reflect the design bases of the NAC-UMS System. Therefore, the staff finds the applicants scoping results to be acceptable.

The applicant screened the major in-scope SSCs to identify and describe the SSC subcomponents that support the SSCs intended safety functions. SER section 2.1.3 addresses the staffs review of the applicants screening evaluation to determine SSC subcomponents that are within the scope of the renewal review. SER section 2.1.4 addresses the staffs review of the applicants screening evaluation to determine SSC subcomponents that are not within the scope of the renewal review.

2.1.3 Screening of Structures, Systems, and Components Within the Scope of Renewal Using the scoping results discussed in section 2.3 of the renewal application for the NAC-UMS System, the applicant screened the major SSCs that are within the scope of renewal to identify their subcomponents that are within the scope of renewal review. The in-scope SSCs include the TSC, VCC, TFR, transfer adapter, and spent nuclear fuel assemblies, all of which were determined to be within the scope of renewal under criterion 1. SER table 2.1-2 tabulates the subcomponents of these SSCs that the applicant determined to be within the scope of renewal based on the screening review. The applicant noted that the screened-in SSC subcomponents require an AMR.

The staff reviewed the applicants screening of the in-scope SSCs to identify SSC subcomponents within the scope of renewal review. The staffs review considered the intended function of the subcomponents, their safety classification, the basis for their inclusion in the scope of renewal review, and design-basis information in the NAC-UMS System FSAR. Based on its review, the staff determined that the applicant screened the in-scope SSCs in a manner consistent with NUREG-1927, Revision 1. Therefore, the staff finds the screening results for determining the in-scope SSC subcomponents to be acceptable.

2.1.4 Subcomponents Not Within the Scope of Renewal The applicant screened in-scope SSCs to identify any SSC subcomponents that do not support the intended safety functions of the in-scope SSCs and thus do not need to be included within the scope of renewal review. SER table 2.1-3 tabulates the SSC subcomponents that are not within the scope of renewal review and thus not subject to an AMR.

The staff reviewed the applicants screening of the in-scope SSCs to determine the out-of-scope SSC subcomponents. The staffs review considered the intended function of the subcomponents, their safety classification, the basis for their exclusion from the scope of renewal review, and design-basis information in the NAC-UMS System FSAR. It should be noted that the scope of renewal review includes all of the subcomponents of the spent fuel assemblies. Therefore, SER table 2.1-3 does not list any spent fuel assembly subcomponents.

Based on its review, the staff determined that the applicant screened the in-scope SSCs to identify out-of-scope SSC subcomponents in a manner consistent with NUREG-1927, Revision

2-9

1. Therefore, the staff finds the screening results for determining the out-of-scope SSC subcomponents to be acceptable.

Table 2.1-2 SSC Subcomponents Within the Scope of Renewal Review Transportable Storage Canister Shell Bottom Shield lid Structural lid Port cover Shield lid support ring Spacer ring Boiling-water reactor (BWR) basket flat washer BWR bottom fuel basket (FB) plate/disk BWR bottom FB weldment pad BWR bottom FB weldment support pad BWR top FB plate/disk BWR top FB weldment ring BWR top FB weldment support plate BWR top FB weldment baffle BWR FB support disk Spacer (2)*

Top nut (2)

Tie rods (2)

Top spacer (2)

Split spacer (2)

BWR FB heat transfer disk BWR fuel tube Neutron absorber (3)

Cladding (3)

Tube flange (3)

BWR oversize fuel tube Pressurized-water reactor (PWR) fuel tube PWR bottom FB plate/disk PWR bottom FB weldment center support plate PWR bottom FB weldment support plate PWR bottom FB weldment plate PWR top FB plate/disk PWR top FB weldment ring PWR top FB weldment support plate PWR top FB weldment center support plate PWR top FB weldment baffle PWR FB support disk PWR FB heat transfer disk PWR basket flat washer Damaged fuel can (DFC) collar DFC lid plate Wiper Lid bottom Filter screen Backing screen Bottom plate Side plate DFC tube body Lift tee Support ring Dowel pin (Item No. 16)

• The numerical identifiers at the end of some the above SSCs indicate that there are multiple occurrences of this item in FSAR table 2.3-1.

2-10 Table 2.1-2 SSC Subcomponents Within the Scope of Renewal Review (cont.)

Vertical Concrete Cask VCC liner shell Top flange Support ring Base weldment inlet cover Base weldment shield ring Base weldment bottom Inlet side Inlet top Stand plate Baffle weldment baseplate Nelson stud Outlet bottom Outlet top Outlet shield plate Outlet side Outlet back Baffle Screen tab Supplemental shield pipe/tube/bar Alternate baffle weldment cover Rebar/threaded rebar Concrete shell Vent screen Screen strips Lifting lug Anchor base plate Supplemental cover Nut Washer (Item No. 45)

Spacer plate Retainer plate Screen Alternate screen VCC lid Shield plug plate Neutron shield retaining ring Neutron shield Neutron shield cover plate Lifting boss Center boss Lid bolt Cover Removeable supplemental shield side plate Supplemental shield pipe/tube/bar Transfer Cask/Transfer Adapter Bottom plate TFR inner shell TFR outer shell Trunnion Neutron shield Top plate (Item No. 15)

Shield door rail Door lock bolt (2)*

Retaining ring Support plate Shield door (SD) bottom plate A SD bottom plate B SD neutron shield boundary plate SD neutron shield cover plate A SD neutron shield cover plate B Gamma shield block Retaining ring bolt Connector TFR extension TFR extension bolts Shielding ring Wear strip Lock pin Transfer adapter

• The numerical identifiers at the end of some the above SSCs indicate that there are multiple occurrences of this item in FSAR table 2.3-1.

2-11 Table 2.1-2 SSC Subcomponents Within the Scope of Renewal Review (cont.)

Spent Fuel Assemblies Fuel rod cladding Guide tubes (PWR) or water channels (BWR)

Spacer grids Lower and upper end fittings Fuel channel (BWR)

Poison rod assemblies (PWR)

2-12 Table 2.1-3 SSC Subcomponents Not Within the Scope of Renewal Review Transportable Storage Canister Location lug Paint (alignment mark) on TSC shell Drain tube nipple Drain tube Seal (2)

Nipple Key Paint (alignment mark) on structural lid Shield lid plug Structural lid plug Dowel pin (Item No. 24)

BWR drain tube sleeve Spacer shim PWR drain tube sleeve Lid guide Vertical Concrete Cask Jack base Jack gusset Jack screw Jack nut Jack jam nut Lifting nut Dowel pin Primer and coating for liner, pedestal, and baseplate assemblies Flat washer Screen screw Concrete anchor Screw Name plate Screen bolt Washer (Item No. 41)

Primer and coating for lift lugs/anchors Primer and paint for VCC lid Primer and coating for shield plug Washer (Item No. 14)

Seal tape Security seal Seal wire Tab Coating (Item No. 3)

Shims Transfer Cask/Transfer Adapter Trunnion cap Spent fuel pool coating system Lead wool Paint Nameplate Scuff plate Fill/drain line plate Fill/drain line pipe Dowel pin Door plug Lift plate A Lift plate B TFR door stop bottom plate Top plate (Item No. 2)

Back plate Handle Attachment screw

2-13

2.2 Evaluation Findings

The NRC staff reviewed the scoping and screening evaluation provided in the renewal application for the NAC-UMS System. The staff performed its review by following the guidance in NUREG-1927, Revision 1. Based on its review, the staff finds the following:

F2.1 The applicant has identified all ITS SSCs and all SSCs whose failure could prevent an SSC from fulfilling its safety function, in accordance with the requirements of 10 CFR 72.3, Definitions, and 10 CFR 72.236, Specific requirements for spent fuel storage cask approval and fabrication.

F2.2 The applicants justification for SSCs determined not to be within the scope of the renewal is adequate and acceptable.

3-1 3 AGING MANAGEMENT REVIEW 3.1 Review Objective The objective of the staffs evaluation of the applicants aging management review (AMR) is to determine whether the applicant has adequately reviewed applicable materials and environments, addressed credible aging mechanisms and effects, and proposed adequate aging management activities for in-scope structures, systems, and components (SSCs). The AMR identifies aging mechanisms and effects that could adversely affect the ability of the SSCs and associated subcomponents to perform their intended functions during the period of extended operation.

3.2 Aging Management Review Process Following the scoping review, the applicant described its AMR process as consisting of the following steps:

(1)

Identify materials of construction.

(2)

Identify operating environments.

(3)

Identify aging mechanisms and effects requiring aging management.

(4)

Determine the activities required to manage the effects of aging.

The applicant identified the materials of construction and operating environments for each SSC and associated subcomponent within the scope of renewal. The applicant then determined the aging effects and associated aging mechanisms that could cause degradation resulting in a loss of intended function. Finally, for each aging effect requiring management, the applicant determined the required aging management activitieseither a time-limited aging analysis (TLAA) or an aging management program (AMP)to ensure that the intended function of the SSC would be maintained during the period of extended operation.

The staff reviewed the applicants AMR process and finds it acceptable because the process is consistent with the methodology in NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, issued June 2016 (NRC, 2016), and is adequate for identifying credible aging effects for the SSCs within the scope of the renewal review.

3.3 Aging Management Review Results: Materials, Service Environments, Aging Effects, and Aging Management Activities The staff evaluated the applicants technical basis for its AMR by comparing it to the generic technical basis in NUREG-2214, Managing Aging Processes in Storage (MAPS) Report, issued July 2019 (NRC, 2019b). In this evaluation, the staff of the U.S. Nuclear Regulatory Commission (NRC) verified that the design features, environmental conditions, and operating experience for the Universal Multi-Purpose Storage System (hereafter, NAC-UMS System) are bounded by those evaluated in NUREG-2214.

The applicant defined the SSC service environments in section 3.1.2.2 of the renewal application. Table 3.3--1 of this safety evaluation report (SER) summarizes these environments and compares them to the environments evaluated in NUREG--2214. The staff considered this

3-2 comparison in its determination of whether the environments in NUREG--2214 are applicable to the applicants AMR for the NAC--UMS System.

Table 3.3-1 AMREnvironments Environment Specified in the Renewal Application Description of Environment from the Renewal Application Equivalent Environment(s)

Specified in NUREG-2214 Helium Environment inside of the TSC is vacuum dried and backfilled with inert helium gas and has very low levels of oxygen and moisture.

Helium Fully encased steel Environment applies to materials that are fully embedded or encased within steel or fully lined by steel, thereby preventing the ingress of water or contaminants.

This environment also includes small free volumes that exist between components that are sealed from replenishment by outside air.

Embedded in metal Fully encased or lined in metal Sheltered Environment includes ambient air but not sunlight, rain, or wind exposure. The ambient air may contain moisture and salinity.

Sheltered Embedded concrete Environment applies to steel components that are embedded inside concrete.

Embedded in concrete Airoutdoor Environment for exterior surfaces that are exposed to all weather-related effects, including sunlight, wind, rain, snow, ice (with potential for salts), and with temperature ranges equivalent to the site ambient temperature ranges.

Airoutdoor Airindoor/outdoor Environment for components that are typically housed indoors, except for periodic outdoor exposure during transfer operations. The typical environment may be a building, outdoor storage container, or other protective covering.

In the AMR, the applicant conservatively evaluated these components as being normally exposed to outdoor air.

Airoutdoor (Includes the indoor/outdoor air environment described by the applicant.)

Tables 3.2-1, 3.2-2, 3.2-3, and 3.2-4 of the renewal application provide the AMR results for the NAC-UMS transportable storage container (TSC) and fuel baskets, vertical concrete cask (VCC), transfer cask (TFR) and transfer adapters, and spent fuel assemblies, respectively. SER tables 3.3-2 through 3.3-5 summarize the results of the applicants AMR for these SSCs and identify the applicants disposition of each potential aging effect for SSC subcomponent

3-3 materials within the scope of renewal. These tables identify whether the applicants conclusion on the credibility of each aging effect is consistent with the generic technical bases and conclusions discussed in NUREG-2214. The tables also identify the applicants disposition of the aging effect, in terms of whether (1) an aging management activity (i.e., AMP or TLAA) is, or is not, needed to address the aging effect or (2) there is a separate technical basis or supporting analysis that justifies either that an aging effect is not credible or that an aging management activity is not needed for the aging effect.

For SSC subcomponent materials within the scope of renewal, the staff reviewed the applicants AMR resultsspecifically, the materials, environments, aging mechanisms, aging effects, credibility of aging effects, and disposition of aging effects to determine the need for aging management activitiesfor consistency with the corresponding AMR results in NUREG-2214. If the staff was able to verify that the applicants AMR results are consistent with the corresponding AMR results in NUREG-2214, the staff determined that the AMR results are acceptable, and this SER includes no additional discussion of the AMR results. SER section 3.3.1, which follows the tabulated summary of the applicants AMR results in SER tables 3.3-2 through 3.3-5, addresses the review of the applicants conclusions on aging mechanisms and effects for which the staff was not able to verify consistency with NUREG-2214 or for which it considered an additional explanation to be warranted.

3-4 Table 3.3-2 AMR ResultsNAC-UMS TSCs Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Stainless steel Helium Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Creep (canister internals)

Change in dimensions No Yes AMP/TLAA not necessary Fatigue Cracking Yes Yes TLAA (See SER section 3.4.1)

Thermal aging (17-4 precipitation-hardened stainless)

Loss of fracture toughness/loss of ductility Yes Yes TLAA (See SER section 3.4.3)

Thermal aging (austenitic stainless)

Loss of fracture toughness/loss of ductility No Yes AMP/TLAA not necessary Stress relaxation Loss of preload No Yes AMP/TLAA not necessary Sheltered Pitting and crevice corrosion Loss of material (precursor to stress corrosion cracking (SCC))

Yes Yes TSC Localized Corrosion and SCC AMP Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Fatigue Cracking Yes Yes TLAA (See SER section 3.4.1)

Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Fully encased Pitting and crevice corrosion Loss of material (precursor to SCC)

No Yes AMP/TLAA not necessary Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Fatigue Cracking Yes Yes TLAA (See SER section 3.4.1)

3-5 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Stainless steel Fully encased Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Stainless steel (welded)1 Helium Thermal aging Loss of fracture toughness/loss of ductility No Yes AMP/TLAA not necessary Sheltered SCC Cracking Yes Yes TSC Localized Corrosion and SCC AMP Fully encased SCC Cracking No Yes AMP/TLAA not necessary Steel Helium General corrosion Loss of material No Yes AMP/TLAA not necessary Fatigue Cracking Yes Yes TLAA (See SER section 3.4.1)

Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Creep Change in dimensions No Yes AMP/TLAA not necessary Thermal aging Loss of fracture toughness/loss of ductility No Yes AMP/TLAA not necessary Aluminum Helium General corrosion Loss of material No Yes AMP/TLAA not necessary Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Creep Change in dimensions No Yes2 AMP/TLAA not necessary Thermal aging Loss of strength No Yes2 AMP/TLAA not necessary

3-6 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Neutron Absorber (Boral)

Helium Boron depletion Loss of criticality control Yes Yes TLAA (See SER section 3.4.3)

General corrosion Loss of material No Yes AMP/TLAA not necessary Thermal aging Loss of strength No Yes AMP/TLAA not necessary Wet corrosion and blistering Change in dimensions No Yes AMP/TLAA not necessary Creep Change in dimensions No Yes AMP/TLAA not necessary Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material No Yes AMP/TLAA not necessary 1 The aging management line items listed for stainless steel (welded) are considered for stainless-steel welds, including the weld heat-affected zone, in addition to the items listed for stainless-steel base metal components. This convention is consistent with that in NUREG-2214.

2 The applicant concluded that creep and thermal aging are not credible for the aluminum heat transfer discs in a helium environment since they do not bear any load beyond their own weight. The staff verified that this conclusion is consistent with NUREG-2214 for nonstructural aluminum components.

3-7 Table 3.3-3 AMR ResultsNAC-UMS VCCs Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Steel Sheltered General corrosion Loss of material Yes Yes TLAA (See SER section 3.4.2) and Internal VCC Metallic Components Monitoring AMP Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material Yes Yes TLAA and Internal VCC Metallic Components Monitoring AMP Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material No No AMP/TLAA not necessary Embedded (concrete)

General corrosion Loss of material Yes Yes TLAA Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material Yes Yes TLAA Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Corrosion of reinforcing steel rebar Loss of concrete/

steel bond Yes Yes1 TLAA Loss of material Yes Yes1 TLAA Cracking Yes Yes1 TLAA

3-8 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Steel Embedded (concrete)

Corrosion of reinforcing steel rebar Loss of strength Yes Yes1 TLAA Airoutdoor General corrosion Loss of material Yes Yes External VCC Metallic Components Monitoring AMP Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material Yes Yes External VCC Metallic Components Monitoring AMP Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Stress relaxation Loss of preload No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material Yes Yes External VCC Metallic Components Monitoring AMP (See SER section 3.5)

Concrete Airoutdoor Reaction with aggregates Cracking Yes Yes Reinforced VCC Structures AMP Loss of strength Yes Yes Reinforced VCC Structures AMP Salt scaling Loss of material (spalling, scaling)

Yes Yes Reinforced VCC Structures AMP Creep Cracking No Yes AMP/TLAA not necessary Dehydration at high temperatures Cracking No Yes AMP/TLAA not necessary

3-9 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Concrete Airoutdoor Dehydration at high temperatures Loss of strength No Yes AMP/TLAA not necessary Delayed ettringite formation Loss of material (spalling, scaling)

No Yes AMP/TLAA not necessary Loss of strength No Yes AMP/TLAA not necessary Cracking No Yes AMP/TLAA not necessary Fatigue Cracking No Yes AMP/TLAA not necessary Aggressive chemical attack Cracking Yes Yes Reinforced VCC Structures AMP Loss of strength Yes Yes Reinforced VCC Structures AMP Loss of material (spalling, scaling)

Yes Yes Reinforced VCC Structures AMP Freeze-thaw (above the freeze line)

Cracking Yes Yes Reinforced VCC Structures AMP Loss of material (spalling, scaling)

Yes Yes Reinforced VCC Structures AMP Radiation damage Cracking No Yes AMP/TLAA not necessary Loss of strength No Yes AMP/TLAA not necessary Shrinkage Cracking No Yes AMP/TLAA not necessary Leaching of calcium hydroxide Loss of strength Yes Yes Reinforced VCC Structures AMP

3-10 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Concrete Airoutdoor Leaching of calcium hydroxide Increase in porosity and permeability Yes Yes Reinforced VCC Structures AMP Reduction of concrete pH (reduction of corrosion resistance)

Yes Yes Reinforced VCC Structures AMP Stainless steel Airoutdoor Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material No Yes AMP/TLAA not necessary Radiation embrittlement Cracking No Yes AMP/TLAA not necessary SCC Cracking No Yes AMP/TLAA not necessary Stress relaxation Loss of preload No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material Yes Yes External VCC Metallic Components Monitoring AMP Sheltered Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material No Yes AMP/TLAA not necessary Radiation embrittlement Cracking No Yes AMP/TLAA not necessary SCC Cracking No Yes AMP/TLAA not necessary

3-11 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Neutron shield (NS-3/NS-4-FR)

Fully encased (steel)

Radiation embrittlement Cracking Yes Yes TLAA (See SER section 3.4.3)

Thermal aging Loss of shielding effectiveness Yes Yes TLAA (See SER section 3.4.3)

Boron depletion (NS-4-FR)2 Loss of shielding effectiveness Yes Yes TLAA (See SER section 3.4.3) 1 Although the applicant stated that corrosion of the reinforcing steel in the VCC concrete is addressed by a TLAA, and the applicant included an evaluation of projected corrosion of embedded steel in concrete as part of its TLAA, the staff determined that the applicants Reinforced VCC Structures AMP includes inspections for this aging effect that are consistent with NUREG-2214 for adequately managing this aging effect.

2 The staff verified that the applicants analysis of boron depletion was appropriately limited to the NS-4-FR material because the presence of boron was not credited in any design-basis analysis of NS-3 shielding material. See Section 4.3.2 of NAC Calculation No. 30013-5001, Aging Analyses for MPC/UMS Neutron Absorber and Neutron Shield Components (Storage/Transfer), provided in appendix B to the renewal application.

3-12 Table 3.3-4 AMR ResultsNAC-UMS TFRs and Transfer Adapters Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Steel Airoutdoor General corrosion Loss of material Yes Yes TFRs and Adapters AMP Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material Yes Yes TFRs and Adapters AMP Radiation embrittlement Cracking No Yes AMP/TLAA not necessary Galvanic corrosion (retaining ring and shield door rails)

Loss of material Yes Yes TFRs and Adapters AMP Wear (trunnion, shield door rails)

Loss of material Yes Yes TFRs and Adapters AMP Fully encased None identified None identified No Yes AMP/TLAA not necessary Neutron shield (NS-4-FR)

Fully encased (steel)

Radiation embrittlement Cracking Yes Yes TLAA (See SER section 3.4.3)

Thermal aging Loss of shielding effectiveness Yes Yes TLAA (See SER section 3.4.3)

Boron depletion Loss of shielding effectiveness Yes Yes TLAA (See SER section 3.4.3)

Stainless steel (austenitic and ferritic)

Airoutdoor Microbiologically influenced corrosion Loss of material No Yes AMP/TLAA not necessary Pitting and crevice corrosion Loss of material No Yes AMP/TLAA not necessary Radiation embrittlement Cracking No Yes AMP/TLAA not necessary

3-13 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Stainless steel (austenitic and ferritic)

Airoutdoor SCC Cracking No Yes AMP/TLAA not necessary Stress relaxation Loss of preload No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material Yes Yes TFRs and Adapters AMP Wear (wear strip)

Loss of material Yes Yes TFRs and Adapters AMP Lead Fully encased None identified None identified No Yes AMP/TLAA not necessary

3-14 Table 3.3-5 AMR ResultsNAC-UMS Spent Fuel Assemblies Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Zirconium-based alloys (fuel rod cladding)

Helium Oxidation Loss of load bearing capacity No Yes AMP/TLAA not necessary Pitting corrosion Loss of material No Yes AMP/TLAA not necessary Galvanic corrosion Loss of material No Yes AMP/TLAA not necessary SCC Cracking No Yes AMP/TLAA not necessary Hydride-induced embrittlement Loss of ductility No Yes AMP/TLAA not necessary Delayed hydride cracking (high-burnup fuel)

Cracking No Yes AMP/TLAA not necessary Hydride reorientation (high-burnup fuel)

Cladding breach/

structural failure Yes Yes High-Burnup Fuel Monitoring and Assessment AMP Thermal creep (high-burnup fuel)

Changes in dimensions Yes Yes High-Burnup Fuel Monitoring and Assessment AMP Low-temperature creep (high-burnup fuel)

Changes in dimensions No Yes AMP/TLAA not necessary Radiation embrittlement Loss of strength No Yes AMP/TLAA not necessary Fatigue Cracking No Yes AMP/TLAA not necessary Mechanical overload (high-burnup fuel)

Cracking No Yes AMP/TLAA not necessary

3-15 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Zirconium-based alloys (guide tubes, water channels, spacer grids, fuel channels)

Helium Creep Changes in dimensions No Yes AMP/TLAA not necessary Hydriding Changes in dimensions No Yes AMP/TLAA not necessary Radiation embrittlement Loss of strength No Yes AMP/TLAA not necessary Fatigue Cracking No Yes AMP/TLAA not necessary General corrosion Loss of material No Yes AMP/TLAA not necessary Inconel Helium Creep Changes in dimensions No Yes AMP/TLAA not necessary General corrosion Loss of material No Yes AMP/TLAA not necessary SCC Cracking No Yes AMP/TLAA not necessary Radiation embrittlement Loss of strength No Yes AMP/TLAA not necessary Fatigue Cracking No Yes AMP/TLAA not necessary Stainless steel Helium Creep Changes in dimensions No Yes AMP/TLAA not necessary General corrosion Loss of material No Yes AMP/TLAA not necessary SCC Cracking No Yes AMP/TLAA not necessary Radiation embrittlement Loss of strength No Yes AMP/TLAA not necessary

3-16 Material Environment Aging Mechanism Aging Effect Applicant Defined as Credible Consistent with Conclusion of NUREG-2214 Disposition Stainless steel Helium Fatigue Cracking No Yes AMP/TLAA not necessary

3-17 3.3.1 Supplemental Analyses The following SER sections document the staffs review of those AMR results for which it was not able to verify consistency with NUREG-2214 and for which it considered additional explanation or revisions of the AMR results, or both, to be warranted.

3.3.1.1 Thermal Aging of Precipitation-Hardened Martensitic Stainless-Steel Transportable Storage Canister Items In table 3.2-1 of the original renewal application, the applicant stated that thermal aging of the Type 17-4 precipitation-hardened (PH) martensitic stainless-steel fuel basket support discs is not a credible aging mechanism. In section 3.2.1.2.8 of the renewal application, the applicant stated that the maximum long-term service temperature of the support discs is about 316 degrees Celsius (°C) (601 degrees Fahrenheit (°F)), which is below the 343°C (650°F) maximum allowable service temperature specified in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section II, Part D. As a result, the applicant concluded that reduction in fracture toughness due to thermal aging is not a credible aging effect and mechanism.

NUREG-2214 states that applicants should provide an analysis on a case-specific basis to demonstrate that 17-4 PH martensitic stainless-steel fuel basket components do not undergo unacceptable reductions in fracture toughness due to thermal aging. NUREG-2214 cites studies recommending a component-specific evaluation of material and service conditions for 17-4 PH martensitic stainless-steel items that are in service at operating temperatures between 243°C (470°F) and 316°C (600°F). NUREG-2214 also states that above 316°C (600°F), the use of 17-4 PH martensitic stainless steel in any condition is not recommended.

Considering the above guidance in NUREG-2214, the staff noted that the original application did not provide a sufficient evaluation of the reduction in fracture toughness due to thermal aging for the 17-4 PH martensitic stainless-steel fuel basket support discs. Therefore, the staff issued a request for additional information (RAI) on December 21, 2021 (NRC, 2021b), asking, in RAI 3-2, that the applicant provide a technical justification to support the conclusion that thermal aging resulting in loss of fracture toughness is not a credible aging mechanism for the 17-4 PH martensitic stainless-steel fuel basket support discs during the 60-year extended storage period.

In its response to the RAI (NAC International, 2022a), the applicant stated that it evaluated the applicable service conditions for the 17-4 PH martensitic stainless-steel fuel basket support disks, including initial heat treatment condition, service temperature, operating environment, and stress level. The applicant provided information to demonstrate that thermal aging will not compromise the safety function of the 17-4 PH martensitic stainless-steel support disks, based on the recommended criteria from the thermal aging studies referenced in NUREG-2214. The staff noted that the applicants evaluation considered the material specification and initial heat treatment, service temperature and service environment, operating conditions, and stress level, all of which affect thermal aging behavior and the associated impact on fracture toughness and structural performance for 17-4 PH martensitic stainless-steel components. The applicant evaluated these data to determine the likely impact on the structural safety function of the fuel basket support discs during the period of extended storage. The applicant determined that the 17-4 PH martensitic stainless-steel support discs are in a service environment where some portion of them can be exposed to service temperatures between 243°C (470°F) and 316°C (600°F), which could potentially result in some thermal embrittlement based on the studies cited

3-18 in NUREG-2214. However, the applicant noted that the component failures described in the thermal aging studies cited in NUREG-2214 are associated with combined conditions of high operating stresses, dynamic or cyclic loads, and elevated operating temperatures. The applicant compared the service conditions, material properties, heat treatment, and operating stresses analyzed in the NUREG-2214-cited studies with those that are applicable to the NAC-UMS fuel basket support discs. Based on its comparison, the applicant determined that any reduction in fracture toughness due to thermal aging of the fuel basket support discs will not adversely impact the structural safety function of the support discs because of the following characteristics and conditions:

The support disks have been heat treated to an optimum condition to minimize the susceptibility of the material to thermal embrittlement. The applicant specified that the heat treatment condition for the support discs is considered optimal for this structural application based on the thermal aging studies for 17-4 PH martensitic stainless steel referenced in NUREG-2214.

For the design-basis heat load, the thermal analysis shows that only a limited portion at the center of the discs is subjected to temperatures above 243°C (470°F) (the lower bound threshold for thermal aging susceptibility for 17-4 PH martensitic stainless-steel components), and the average temperature for the support discs is below 204°C (400°F) for normal conditions of storage. The design-basis heat load does not credit the decay of the radioactive heat source during the 20-year initial licensed storage period or the 40-year period of extended operation.

The 17-4 PH martensitic stainless-steel support disks are maintained in the inert helium operating environment and subjected to a small static inertial load corresponding to their self-weight only during normal storage conditions.

The applicant determined that the maximum stress intensity resulting from the small static load is only a small fraction of the allowable stress intensity based on the requirements of the 1995 Edition of the ASME BPV Code,Section III, Subsection NG, Core Support Structures (ASME, 1995). Therefore, the applicant determined that any thermal aging effect would have negligible impact on the structural safety function of the support disks.

The applicant revised its AMR result for the 17-4 PH martensitic stainless-steel fuel basket support discs in section 3.2.1.2.8 and table 3.2-1 of the renewal application to include thermal aging as a credible aging mechanism. The applicant also supplemented the fuel basket TLAA described in section 3.3.3.1 and appendix B (NAC Calculation No. 30013-2001, Fatigue Evaluation of NAC-MPC and NAC-UMS Storage System Components for Extended Storage) of the renewal application to include its evaluation of thermal aging of the support discs considering the time-dependent effect of thermal aging on the support disc structural evaluation in accordance with the 1995 Edition of the ASME BPV Code,Section III, Subsection NG. In addition, the applicant updated its proposed final safety analysis report (FSAR) supplement in FSAR section 14.2 to include a new TLAA subsection (14.2.4) that documents the applicants evaluation demonstrating that thermal aging will not adversely impact the structural safety function of the fuel basket support discs during the period of extended operation.

The staff reviewed the applicants thermal aging evaluation for the fuel basket support discs against the information in the NAC-UMS System FSAR and verified that, for normal service

3-19 conditions, the maximum stress intensity resulting from the small static inertial load is only a small fraction of the allowable stress intensity based on the requirements of the 1995 Edition of the ASME BPV Code,Section III, Subsection NG. Therefore, the staff substantiated the applicants conclusion that any embrittlement effect due to thermal aging would have negligible impact on the structural safety function of the support disks for normal service conditions during the period of extended operation.

With respect to the VCC tip-over accident, which the RAI response did not address, the staff noted that the higher loads on the support discs for the tip-over event could potentially lead to fracture if the discs undergo significant thermal aging embrittlement during the extended storage term. However, the staff noted that fracture of the discs would require the presence of a planar flaw of sufficient size and optimal orientation in the thermally embrittled portion of the discs, and this flaw would need to experience sufficient crack-driving force during the tip-over event for a crack to initiate at the flaw tip and propagate through the disc, including those portions of the disc that are not embrittled since they are not subjected to temperatures above 243°C (470°F) during the 60-year extended storage term. The staff determined that it is unlikely that a flaw of such size and geometry exists in the localized region of the discs that may experience thermal embrittlement since, for the construction of internal support components, the support disc material was required to receive a nondestructive examination for acceptance, in accordance with the ASME BPV Code,Section III, Subsection NG. Further, since the support discs are internal fuel basket components in an inert helium environment with no cyclic loading, there are no credible aging mechanisms (e.g., SCC and fatigue) that would lead to the formation of new cracks in the discs as a result of in-service aging. Even in the unlikely event that a large preexisting flaw of optimal geometry is present in the thermally embrittled portion of the disc (having gone undetected during the required material acceptance nondestructive examination),

any initial crack propagation in the thermally embrittled portion during the tip-over event would likely lead to crack arrest in the portion of the disc that is not embrittled since the material fracture resistance would likely be sufficient to prevent the crack from propagating all the way through the disc, thereby preventing its complete fracture. Considering these factors, the staff determined that the thermal aging embrittlement of 17-4 PH martensitic stainless steel is unlikely to have an adverse impact on the structural safety function of the fuel basket support disks for tip-over accident conditions during the period of extended operation.

The staff also confirmed that the applicant appropriately updated table 3.2-1, section 3.2.1.2.8, section 3.3.3.1, appendix B (NAC Calculation No. 30013-2001), and FSAR section 14.2 in the renewal application to include its evaluation of the potential effect of thermal aging and associated loss of fracture toughness on the structural performance of the 17-4 PH martensitic stainless-steel fuel basket support discs. While the applicant chose to include its thermal aging evaluation as part of the fuel basket TLAA, the staff determined that this evaluation only needed to be included as part of the AMR results and not as a specific TLAA since it does not meet the strict regulatory definition of a TLAA in Title 10 of the Code of Federal Regulations (10 CFR) 72.3, Definitions, because the analysis of thermal aging embrittlement is not contained or incorporated by reference in the NAC-UMS System design bases. However, this determination does not affect the staffs findings on the technical merits of the applicants evaluation for demonstrating that thermal aging is not expected to have an adverse effect on the structural safety function of the fuel basket support discs during the period of extended operation. Therefore, based on the foregoing review of the applicants technical evaluation of thermal aging for the fuel basket support discs and associated updates to the renewal application, the staff finds that the applicants RAI response and associated updates to the renewal application to address thermal aging of these components are acceptable.

3-20 3.3.1.2 Galvanic Corrosion of Vertical Concrete Cask Internal Steel Surfaces In table 3.2-2 and section 3.2.1.1.3 of the renewal application, the applicant determined that the internal steel components exposed to the sheltered air environment inside the VCC are not prone to significant galvanic corrosion. The application included an evaluation of the dissimilar metal contact between the top of the steel VCC baffle weldment base plate (the bottom supporting structure for the TSC) and the stainless-steel cover plate. This stainless-steel cover plate prevents the TSC bottom from directly contacting the steel VCC baffle weldment base plate. The applicant stated that the steel VCC baffle weldment base plate has an epoxy or inorganic zinc coating and that significant galvanic corrosion of the steel VCC baffle weldment base plate is not credible because of the base plates large thickness of 2 inches.

The staff reviewed the system design and operating experience, including the preapplication inspection results for the NAC-UMS System at Maine Yankee documented in appendix E to the renewal application. For the inspections of the 16-year-old Maine Yankee system, the steel VCC baffle weldment base plate region was visually inspected with a robotic crawler and remote camera through the VCC inlet vents. No recordable indications were identified in the steel VCC base plate and baffle weldments. In its review of the design drawings, the staff noted that the geometry of the dissimilar metal contact between the steel base plate and the stainless-steel cover plate is not susceptible to moisture accumulation that would cause galvanic corrosion.

Further, since these components are in contact with the TSC bottom, they remain significantly warmer and less prone to moisture condensation than other internal VCC metallic surfaces that will be directly inspected under the Internal VCC Metallic Components Monitoring AMP.

Therefore, based on (1) the favorable Maine Yankee inspection results, (2) component geometry and temperature that do not favor moisture accumulation, and (3) the AMP inspection activities for other VCC internal surfaces that are expected to be leading indicators of corrosion, the staff finds the applicants determination that galvanic corrosion of the steel VCC baffle weldment base plate is not a credible aging mechanism to be acceptable.

3.3.1.3 Galvanic Corrosion of Vertical Concrete Cask Steel Lid Exposed to Outdoor Air In table 3.2-2 of the original renewal application, the applicant noted that the VCC steel lid, which is in contact with the stainless-steel lid bolts and exposed to an outdoor air environment, is not susceptible to galvanic corrosion. In section 3.2.1.1.3 of the original renewal application, the applicant evaluated the galvanic corrosion of the VCC internal steel components exposed to a sheltered air environment. However, this evaluation did not include the VCC steel lid in contact with the stainless-steel lid bolts in the outdoor air environment. NUREG-2214 indicates that galvanic corrosion is a credible aging mechanism for steel VCC items exposed to an outdoor air environment if there is a dissimilar metal contact with a more electrochemically noble or passive metallic component.

The staff reviewed the system design and operating experience, including the preapplication inspection results for the NAC-UMS System at Maine Yankee documented in appendix E to the renewal application. The inspections of the 16-year-old system at Maine Yankee found that the inner surfaces of the threaded bolt holes in the carbon steel VCC lid experienced galvanic corrosion due to their contact with the stainless-steel lid bolts in the outdoor air environment.

Considering this operating experience, the staff issued RAI 3-1 on December 21, 2021 (NRC, 2021b), asking that the applicant justify the conclusion that galvanic corrosion of the VCC steel lid is not an aging effect requiring management.

3-21 In its response to the RAI (NAC International, 2022a), the applicant stated that it reviewed the drawings for the NAC-UMS VCC and TFRs and transfer adapters to identify metallic components with dissimilar material contacts in the outdoor air environment that are potentially susceptible to galvanic corrosion. The applicant revised section 3.2.1.1.3 in the updated renewal application to include the results of its evaluation of galvanic corrosion for components with dissimilar metal contacts in the outdoor air environment. The applicant determined that galvanic corrosion is a credible aging mechanism for threaded bolt holes in carbon steel components that that are in contact with stainless-steel bolting if exposed to outdoor air. These components include the stainless-steel VCC lid bolting hardware in contact with the carbon steel VCC lid in the outdoor air environment and the stainless-steel TFR retaining ring bolts in contact with the carbon steel TFR retaining ring in the outdoor air environment. Therefore, the applicant added loss of material due to galvanic corrosion as an aging effect requiring management for these components in AMR tables 3.2-2 and 3.2-3 in the updated renewal application. The revisions to the AMR results in tables 3.2-2 and 3.2-3 in the updated renewal application specify that loss of material due to galvanic corrosion for these components is to be managed using the External VCC Metallic Components Monitoring AMP described in table A-3 of the renewal application and the TFRs and Transfer Adapters AMP described in table A-5 of the renewal application.

The applicant stated that these components are inspected under these AMPs for loss of material due to corrosion and visual evidence of loose, displaced, or missing bolts.

The staff reviewed the applicants updates to the renewal application to address galvanic corrosion of VCC and TFR components with dissimilar metal contacts in the outdoor air environment. The staff verified that the applicants revision to section 3.2.1.1.3 in the updated renewal application includes a valid evaluation of galvanic corrosion for carbon steel VCC and TFR components in contact with stainless-steel bolting items exposed to the outdoor air environment. The staff also verified that the AMR results for these items in tables 3.2-2 and 3.2-3 in the updated renewal application were appropriately revised to specify that loss of material due to galvanic corrosion is to be managed using the External VCC Metallic Components Monitoring AMP described in table A-3 and the TFRs and Transfer Adapters AMP described in table A-5 of the renewal application. The staff also determined that these AMPs include the inspection and evaluation activities that are needed to adequately detect and manage loss of material due to galvanic corrosion for these components. SER tables 3.5-3 and 3.5-5 document the staffs detailed review of these AMPs. Therefore, based on the foregoing review of the applicants updates to the renewal application to address evaluation of galvanic corrosion for components with dissimilar metal contacts in the outdoor air environment, the staff finds that the applicants RAI response and associated updates to the renewal application to address galvanic corrosion of these components are acceptable.

3.3.2 Evaluation Findings The staff reviewed the AMR results provided in the renewal application for the NAC-UMS System to verify that they adequately identify the materials, environments, aging effects, and proposed aging management activities for the in-scope SSCs. The staff performed its review by following the guidance in NUREG-1927, Revision 1, and NUREG-2214. Based on its review, the staff finds the following:

F3.1 The applicants AMR process is comprehensive in identifying the materials of construction and associated operating environmental conditions for those SSCs within the scope of renewal, and the applicant has provided an adequate summary of this information in the renewal application and the FSAR supplement.

3-22 F3.2 The applicants AMR process is comprehensive in identifying all pertinent aging mechanisms and effects applicable to the SSCs within the scope of renewal, and the applicant has provided an adequate summary of the information in the renewal application and the FSAR supplement.

3.4 Time-Limited Aging Analyses As discussed in section 3.3.3 of the renewal application, the applicant identified three TLAAs for SSCs within the scope of the renewal review.

(1)

Fatigue of Transportable Storage Canisters and Fuel Baskets (2)

Corrosion Analysis of Vertical Concrete Cask Internal Steel Subcomponents (3)

Aging of Neutron Absorber and Neutron Shield Components Based on its review of the design-basis documents, the staff confirmed that the applicant identified all calculations and analyses that meet the six criteria in 10 CFR 72.3 that define a TLAA. The following sections document the staffs evaluation of the applicants TLAAs.

3.4.1 Fatigue of Transportable Storage Canisters and Fuel Baskets In section 3.3.3.1 and appendix B (NAC Calculation No. 30013-2001) of the renewal application, the applicant analyzed the time-dependent effects of normal operating stress fluctuations on the potential for structural fatigue of the NAC-UMS TSCs, including the TSC confinement boundary and internal fuel baskets, for the period of extended operation. For the 60-year extended storage term, the applicant noted that the confinement boundary of the NAC-UMS canisters satisfies all conditions specified in paragraph NB-3222.4(d)(1) through (6) of the 1995 Edition of the ASME BPV Code,Section III, Subsection NB, Class 1 Components (ASME, 1995). The applicant also noted that the fuel baskets inside the NAC-UMS canisters satisfy all conditions specified in paragraph NG-3222.4(d)(1) through (4) of the 1995 Edition of the ASME BPV Code,Section III, Subsection NG, for 60 years. Accordingly, the applicant determined that the NAC-UMS canisters do not require further fatigue analysis, in accordance with the more detailed fatigue analysis procedures in paragraphs NB-3222.4(e) and NG-3222.4(e), to evaluate for potential cumulative fatigue damage for the 60-year extended storage term. The SER subsections below address the NRC staffs review of the applicants ASME BPV Code,Section III, paragraph NB-3222.4(d) and NG-3222.4(d), fatigue screening calculations for the TSC confinement boundary and fuel baskets.

3.4.1.1 Fatigue of the Canister Confinement Boundary In appendix B to the renewal application, the applicant evaluated the potential for fatigue of the TSC confinement boundary due to cyclic operation by analyzing the projected number of accumulated operating cycles associated with a bounding set of fluctuating service load conditions for the period of extended operation. The staff noted that the applicant applied the methodology of the 1995 Edition of the ASME BPV Code,Section III, paragraph NB-3222.4(d)(1) through (6), as a basis for determining that a more detailed analysis of cumulative fatigue usage for cyclic operation is not needed. Paragraph NB-3222.4(d) indicates that a more detailed analysis of potential cumulative fatigue damage, in accordance with paragraph NB-3222.4(e), is not required, and it may be assumed that the limits on peak stress for determining susceptibility to fatigue have been satisfied for a component, provided the specified cyclic service loading of the component meets all of the conditions specified in

3-23 subparagraphs (1) though (6) of paragraph NB-3222.4(d), and the component is in compliance with all other applicable construction code requirements.

The staff confirmed that the applicants use of the paragraph NB-3222.4(d) methodology is applicable for evaluating the potential for fatigue of the TSC confinement boundary through the period of extended operation since the methodology is consistent with the system design bases and the six cyclic loading conditions specified in this code paragraph encompass all applicable types of pressure, thermal, and mechanical stress cycles for the confinement boundary. The staff also confirmed that the applicants analysis in appendix B to the renewal application conservatively bounds the projected number of accumulated cycles for each of the six conditions specified in this code paragraph over the 60-year extended storage period (20-year initial license plus 40-year period of extended operation). The staff verified that the applicants evaluation of the potential for fatigue of the confinement boundary satisfies all six cyclic loading conditions specified in paragraph NB-3222.4(d). Therefore, the staff determined that the applicants evaluation of the impact of cyclic operations on the potential for fatigue of the TSC confinement boundary demonstrates that it will not be susceptible to fatigue failure through the period of extended operation.

3.4.1.2 Fatigue of the Canister Fuel Baskets In appendix B to the renewal application, the applicant evaluated the potential for fatigue of the TSC fuel baskets due to cyclic operation by analyzing the projected number of accumulated operating cycles associated with a bounding set of fluctuating service load conditions for the period of extended operation. The staff noted that the applicant applied the methodology of the 1995 Edition of the ASME BPV Code,Section III, paragraph NG-3222.4(d)(1) through (4), as a basis for determining that a more detailed analysis of cumulative fatigue usage for cyclic operation is not needed. Paragraph NG-3222.4(d) indicates that a more detailed analysis of potential cumulative fatigue damage, in accordance with paragraph NG-3222.4(e), is not required, and it may be assumed that the limits on peak stress for determining susceptibility to fatigue have been satisfied for a component, provided the specified cyclic service loading of the component meets all of the conditions specified in subparagraphs (1) though (4) of paragraph NG-3222.4(d), and the component is in compliance with all other applicable construction code requirements.

The staff confirmed that the applicants use of the paragraph NG-3222.4(d) methodology is applicable for evaluating the potential for fatigue of the TSC fuel baskets through the period of extended operation since the methodology is consistent with the system design bases and the four cyclic loading conditions specified in this code paragraph encompass all applicable types of thermal and mechanical stress cycles for the fuel baskets. The staff also confirmed that the applicants analysis in appendix B to the renewal application conservatively bounds the projected number of accumulated cycles for each of the four conditions specified in this code paragraph over the 60-year extended storage period (20-year initial license plus 40-year period of extended operation). The staff verified that the applicants evaluation of the potential for fatigue of the TSC fuel baskets satisfies all four cyclic loading conditions specified in paragraph NG-3222.4(d). Therefore, the staff determined that the applicants evaluation of the impact of cyclic operations on the potential for fatigue of the TSC fuel baskets demonstrates that they will not be susceptible to fatigue failure through the period of extended operation.

3-24 3.4.2 Corrosion Analysis of Vertical Concrete Cask Internal Steel Subcomponents General Corrosion of Vertical Concrete Cask Internal Steel Subcomponents In section 3.3.3.2 and appendix B (NAC Calculation No. 30013-2002, Corrosion Analysis of NAC-UMS VCC Steel Components for Extended Storage) of the renewal application, the applicant analyzed the time-dependent effects of general corrosion of the VCC internal carbon steel subcomponents exposed to the sheltered air environment. The applicant performed its corrosion analysis to determine whether potential loss of material due to general corrosion may have an adverse impact on the VCCs intended structural, thermal, and radiation shielding safety functions over the 60-year extended storage period (20-year initial license term plus 40-year period of extended operation).

The applicant evaluated general corrosion of the VCCs internal carbon steel subcomponents by selecting a constant general corrosion rate that was applied over the entire 60-year extended storage term to calculate a total projected 60-year general corrosion allowance. The applicants calculated 60-year general corrosion allowance is a projected depth of material loss due to general corrosion, over 60 years, of a carbon steel surface directly exposed to the sheltered air environment inside the VCC. The applicants selection of the corrosion rate and calculation of the total 60-year corrosion allowance assumes that the internal carbon steel surfaces are directly exposed to the sheltered air environment inside the VCC throughout the entire 60-year storage term. The applicant stated that its corrosion calculation does not take any credit for corrosion protection provided by the protective coating on the exposed steel surfaces inside the VCC and does not credit any heat generated from radioactive decay of spent fuel that may elevate steel surface temperatures inside the VCC.

The staff reviewed the applicants selected corrosion rate by comparing it with the general corrosion rates specified in NUREG-2214 for exposed carbon steel and with those provided in metallurgical references (ASM International, 2005) for carbon steel exposed to several types of ambient air environments. The staff determined that the applicants selected corrosion rate provides a reasonable estimate of the rate of general corrosion for exposed carbon steel surfaces in a sheltered air environment, considering the potential for deliquescence of moisture with dissolved compounds directly onto the VCCs internal carbon steel surfaces during the 60-year storage term. The staff also noted that the applicants selected general corrosion rate has adequate conservatism for the intended application of projecting a total 60-year general corrosion allowance for the VCC internal carbon steel surfaces since the corrosion rate and total corrosion allowance do not credit the presence of the protective coating on the exposed steel surfaces inside the VCC, nor does the applicant credit the potential for elevated steel surface temperatures due to decay heat inside the VCC that could impede deliquescence of moisture with dissolved compounds. Therefore, the staff determined that the applicants calculation of the total 60-year corrosion allowance for the VCC internal carbon steel surfaces is acceptable.

The applicant provided analyses to demonstrate that the total 60-year corrosion allowance for the VCC internal carbon steel components would not have an adverse effect on the ability of the VCC to perform its intended structural, thermal, and radiation shielding safety functions. The NRC staff reviewed the applicants detailed evaluations of the impact of the projected 60-year cumulative corrosion of the VCC internal carbon steel components on the structural, thermal, and shielding safety functions of the VCC. The staff confirmed the applicants conclusions, as follows:

3-25 The staff confirmed that the applicants structural evaluation of the VCC for the bottom lift by hydraulic jacks demonstrates that the maximum bearing stress in the concrete will remain within the allowable stress limits, considering the total projected corrosion of the steel plates that line the concrete at the end of a 60-year service life.

The staff confirmed that the applicants structural evaluation demonstrates that the total projected corrosion of the exposed side of the plates to which the Nelson studs are welded will not adversely impact the design function of the Nelson studs during the 60-year service life.

The staff confirmed that the applicants finite element analysis of the VCC pedestals, considering the total projected 60-year corrosion, demonstrates that the maximum stress intensities in the pedestal base and ring remain below the allowable stress limits. The staff also confirmed the applicants conclusion that the margins of safety in the pedestal base and ring for the bottom lift with hydraulic jacks are adequate, considering the total projected 60-year corrosion of these components.

The staff noted that the applicants structural evaluation of the VCC for dead load, live load, flood, tornado wind, and seismic loading did not take any structural credit for the VCC steel liner. Therefore, the staff confirmed the applicants conclusion that any reduction in the VCC liner thickness resulting from corrosion does not change the results of the VCC structural evaluation for these load conditions.

The staff noted that the applicants structural evaluation considering thermal stresses induced by thermal gradient demonstrates that a reduction of the VCC steel liner thickness due to the total 60-year corrosion allowance would result in a negligible change in the thermal stresses in the concrete and rebar. For the steel liner, the staff confirmed the applicants conclusion that the thermal stress would be slightly reduced due to corrosion since the reduction of the liner thickness will result in a smaller through-wall thermal gradient.

The staff noted that the applicants analysis of local damage to the VCC concrete shell due to tornado missile impacts did not take any structural credit for the VCC steel liner.

Therefore, the staff confirmed the applicants conclusion that any reduction in the VCC liner thickness resulting from corrosion does not change the results of the VCC concrete damage analysis for tornado missile impact.

The staff confirmed that the applicants structural evaluation demonstrated that the VCC lid assemblys strength remained adequate to prevent perforation by a missile due to a design-basis tornado even if its thickness were to be reduced by the total 60-year corrosion allowance.

For the 6-inch design-basis drop, the staff noted that the applicants structural evaluation of the performance of the VCC concrete did not take any structural credit for the VCC steel liner. Therefore, the staff confirmed the applicants conclusion that any reduction in the VCC liner thickness resulting from corrosion does not change the results of the VCC concrete structural evaluation for the 6-inch design-basis drop condition.

For the 6-inch design-basis drop, the applicants structural evaluation of the performance of the VCC pedestal determined that the maximum deformation of the pedestal due to

3-26 the drop will result in a certain reduction of the air inlet cross sectional area. The applicant analyzed the impact of the reduction in pedestal thickness due to the total 60-year corrosion allowance to determine the increase in the reduction of the air inlet cross sectional area. Considering the effects of the total 60-year corrosion allowance, the staff confirmed that the applicant adequately demonstrated that the increased reduction in the air inlet cross sectional area would remain bounded by the design-basis thermal performance analysis where the air inlets are half blocked.

The applicants structural evaluation of the VCC assembly during a tip-over accident adequately demonstrated that general corrosion of the VCC steel inner shell will slightly reduce the overall beam-bending and ring-bending stiffness of the VCC, which will slightly reduce the acceleration loads that are imparted to the TSC and basket components. Accordingly, the staff confirmed that the applicant adequately demonstrated that the projected corrosion of the VCC steel liner will not have an adverse impact on the structural performance of the VCC and TSC for the tip-over accident.

The applicants thermal analysis concluded that corrosion of the steel plates that line the VCC air passage will improve the surface properties with respect to thermal performance. However, the applicant determined that the growth of any rust layer into the air passage could potentially reduce the air flow cross section by up to 10 percent.

The staff confirmed that the applicant adequately demonstrated that the net effect of corrosion of the steel surfaces that line the air passage on the thermal performance of the VCC is insignificant.

The staff confirmed that the applicants shielding analysis of the VCC assembly adequately demonstrated that the small reduction in gamma shielding resulting from loss of steel due to the total 60-year corrosion allowance is offset by the decay of the radiation source over the same timeframe.

Based on the foregoing evaluation, the NRC staff determined the applicants TLAA of the impact of general corrosion on the VCCs internal carbon steel components demonstrates that the VCC will be capable of performing the applicable structural, thermal, and radiation shielding safety functions through the period of extended operation. Therefore, the staff finds the applicants TLAA of general corrosion of the VCC internal steel components to be acceptable.

Pitting and Crevice Corrosion of Vertical Concrete Cask Internal Steel Subcomponents The applicant did not provide a detailed analytical evaluation of the effects of localized pitting and crevice corrosion on the safety functions of the VCC internal carbon steel components.

Rather, the applicant stated, as part of this TLAA, that its detailed analysis of general corrosion is applicable to localized pitting and crevice corrosion, provided that the projected depth of the localized corrosion does not exceed the projected total 60-year general corrosion allowance described above. The applicant did not estimate the actual rate of localized pitting or crevice corrosion or attempt to determine a projected 60-year cumulative estimate of their extent.

Therefore, the staff could not verify the accuracy of the applicants statements.

Given the lack of specific information in the application on localized corrosion estimates for steel components inside the VCC, the staffs review of the adequacy of the proposed aging management activities for localized corrosion of the VCC internal steel components was based on the applicants proposed AMP inspections, rather than its statements in the TLAA. The applicants AMR results cite the use of both the TLAA and the internal and external VCC

3-27 metallic components monitoring AMPs to manage loss of material due to pitting and crevice corrosion for steel VCC components in both the sheltered air and outdoor air environments. The staff noted that NUREG-2214 recommends only a metallic components monitoring AMP to manage these localized aging effects. As documented in SER tables 3.5-2 and 3.5-3, the staff verified that the applicants internal and external VCC metallic components monitoring AMPs are consistent with the corresponding AMP guidance in NUREG-2214 for managing loss of material due to pitting and crevice corrosion of VCC steel components exposed to both the sheltered air and outdoor air environments of the VCC. Therefore, the staff determined that the applicants proposed aging management approach, which includes AMPs for internal and external VCC metallic components described in SER tables 3.5-2 and 3.5-3, is acceptable, and a specific TLAA of the effects of loss of material due to pitting and crevice corrosion on the functionality of carbon steel components inside the VCC is not needed.

3.4.3 Aging of Neutron Absorber and Neutron Shield Components In section 3.3.3.3 and appendix B (NAC Calculation No. 30013-5001) of the renewal application, the applicant analyzed the time-dependent effects of aging on the safety functions of the Boral neutron absorbers and the NS-4-FR (borated polymeric) and NS-3 (cementitious) neutron shielding materials in the NAC-UMS System. The aging mechanisms evaluated include the following:

depletion of boron-10 in the Boral neutron absorbers used in the TSC fuel baskets depletion of boron-10 in the NS-4-FR neutron shielding material used in the TFRs and VCC shield plugs radiation damage of the NS-4-FR shielding material used in the TFRs and VCC shield plugs and the cementitious NS-3 shielding material used in the VCC shield plugs thermal aging of the NS-4-FR shielding material used in the TFRs and VCC shield plugs and the NS-3 shielding material used in the VCC shield plugs For the NAC-UMS system neutron shielding, only the NS-4-FR is used for the neutron shielding material in the TFRs. For the neutron shielding material in the VCC shield plugs, either NS-3 or the NS-4-FR may be used as optional materials. If the NS-3 shielding material is used in the VCC shield plug, there is an option for it to include boron, but there is no requirement for it to contain boron. Therefore, for conservatism, it was not originally analyzed with boron for the NAC-UMS VCC shielding design. Accordingly, the applicants analysis of boron-10 depletion only addresses the NS-4-FR neutron shielding material. The staffs review of the applicants TLAA for these materials is addressed in the subsections below.

3.4.3.1 Boron-10 Depletion in the Neutron Absorbers and the Neutron Shielding In section 3.3.3.3 of the renewal application, the applicant summarized its evaluation of the impact of the depletion of boron-10 in the Boral neutron absorbers in the TSC fuel baskets and the depletion of boron-10 in the NS-4-FR neutron shielding material in the TFRs and VCC shield plugs.

3-28 Boron-10 Depletion in the Boral Neutron Absorbers The staff reviewed the applicants analysis of boron-10 depletion in the Boral neutron absorbers in the TSC fuel baskets to determine whether adequate criticality safety will be maintained through the period of extended operation. The applicant evaluated the neutron flux produced by the design-basis spent fuel contents with the maximum allowable burnup of 60 gigawatt days per metric ton of uranium (GWd/MTU). The staff determined that this is acceptable since the neutron source term increases with burnup, and this maximizes the neutron fluence and boron-10 depletion over the 60-year storage period. The staff noted that the boron-10 in the Boral neutron absorber sheets is a thermal neutron absorber, whereas dry spent fuel primarily emits fast neutrons. The staff also noted that the applicant assumed that all neutrons emitted by the design-basis spent fuel are absorbed in the neutron absorber sheets. The staff found this to be conservative since fast neutrons emitted by the dry spent fuel will escape the TSC fuel baskets and get absorbed in the NS-4-FR or NS-3 neutron shielding materials, escape to the environment, or contribute to external dose. The staff confirmed that the applicants assumptions are acceptable because they overpredict the boron-10 depletion rate in the neutron absorbers. The applicant calculated a boron-10 depletion fraction in the neutron absorbers of less than 1 percent after 60 years of continuous storage. Considering the margin provided by assuming that the entire 60-year neutron fluence is absorbed by the boron-10 in the neutron absorber sheets, the staff determined that the applicant adequately demonstrated that the Boral neutron absorbers will continue to ensure the required level of criticality safety for the NAC-UMS System during the period of extended operation.

Boron-10 Depletion in the NS-4-FR Neutron Shielding Material The staff reviewed the applicants analysis of boron-10 depletion in the NS-4-FR neutron shielding material used in the TFRs and the VCC shield plugs to determine whether adequate neutron radiation safety will be maintained through the period of extended operation. The applicant evaluated the neutron flux produced by the design-basis spent fuel contents with the maximum allowable burnup of 60 GWd/MTU. The staff determined that this is acceptable since the neutron source term increases with burnup, and this maximizes the neutron fluence and boron-10 depletion over the 60-year storage period. The applicant used the XSDRN code in the SCALE 4.3 code suite to determine the neutron fluence in the shield regions. The staff noted that this methodology has not changed from the previously approved CoC applications, which the staff found acceptable in its previous SERs for the NAC-UMS System. The applicants initial design-basis neutron source was fuel with an initial enrichment of 3.7 weight percent (wt.%)

burned to 40 GWd/MTU and water cooled for 5 years. The applicant scaled up the neutron fluence by a specified factor to represent the increase in source strength for fuel with 3.7 wt.%

enrichment burned to 60 GWd/MTU (maximum allowable burnup) and water cooled for 12 years. The applicants source calculation as a function of burnup is unchanged from the design-basis evaluation. The staff finds the applicants use of a 12-year cooling time acceptable since the actual required cooling time for the design-basis fuel at the maximum allowable burnup is longer due to thermal constraints, and this assumption will overpredict the neutron source.

The applicants analysis determined that the NS-4-FR shielding location with the highest neutron fluence is the TFR bottom door shield. The applicants calculation determined the factor by which the neutron fluence for the TFR bottom door shield exceeds the neutron fluence for the TFR radial shield. The staff noted that the neutron fluence values for both the TFR bottom door shield and the TFR radial shield exceed that of the VCC shield plugs. Rather than evaluating the boron-10 depletion in the TFR bottom door shield, the applicant analyzed the TFR radial shield

3-29 since the TFR designs for the NAC-UMS System and the separate NAC-Multi-Purpose Canister (MPC) System both have radial neutron shields, but only the NAC-UMS TFR has a bottom door neutron shield; the applicant chose to use one boron-10 depletion calculation that bounds all NS-4-FR shielding locations for both the NAC-UMS and the NAC-MPC Systems. Therefore, as a conservative assumption, the applicant calculated the boron-10 depletion in the TFR radial shield and multiplied it by a safety factor that bounds the neutron fluence for the TFR bottom door shield. The applicant showed that the use of this safety factor bounds the results for the TFR bottom door shield, the TFR radial shield, and the VCC shield plugs for both the NAC-UMS and NAC-MPC Systems. The staff determined that this approach is acceptable because it overpredicts the boron-10 depletion in the TFR radial and bottom door shields and in the VCC shield plugs.

Using the above assumptions, the applicant calculated the boron-10 depletion fraction in the NS-4-FR neutron shielding material to be less than 1 percent over the entire 60-year extended storage period. Based on its review of this calculation, and the conservative assumptions regarding the neutron source and bounding fluence for the locations where the NS-4-FR neutron shielding material is used, the staff determined that the applicant adequately demonstrated that the boron-10 depletion in the NS-4-FR neutron shielding material will be inconsequential to the neutron radiation safety of the NAC-UMS System during the period of extended operation.

3.4.3.2 Radiation Damage and Thermal Aging of Neutron Shielding The applicant evaluated the potential for radiation damage and thermal aging to affect the shielding performance of the NS-4-FR and NS-3 shielding materials used in the TFRs and VCC shield plugs. The applicants TLAA applied the results of historical radiation and thermal exposure testing of these shielding materials to conservatively estimate the potential effects of radiation damage and thermal aging on shielding performance during the entire 60-year operating period. The radiation testing was performed in a research reactor that exposed the shielding materials to high levels of neutron and gamma radiation that exceed the expected radiation exposure in the NAC-UMS System over 60 years. The historical radiation and thermal exposure tests measured weight loss and chemical off-gassing due to exposure and examined the exposed materials for physical deterioration. The applicant evaluated the test data to define acceptable levels of radiation and thermal exposure that do not result in significant material degradation and hydrogen loss, which could adversely impact shielding effectiveness.

Radiation Effects NS-4-FR Shielding Material For the NS-4-FR shielding material used in the TFR bottom door shield, TFR radial shield, and VCC shield plug, the applicants calculation determined that the accumulated neutron fluence over 60 years of continuous exposure to the neutron source is less than 10 percent of the levels that were previously shown in research reactor testing to result in a hydrogen loss of less than 1 percent and no significant physical deterioration of the material, such as shrinkage, deformation, or cracking. For gamma radiation exposure, the applicants calculation determined that the deposited gamma energy in the TFR radial shield and the VCC shield plug over 60 years of continuous exposure is less than 1 percent of the gamma radiation exposure defined by the previous research reactor tests, which resulted in a hydrogen loss of less than 1 percent and no significant physical deterioration of the material. For the TFR bottom door shield, the applicant calculated a much higher level of gamma energy deposition than those

3-30 calculated for the TFR radial shield and the VCC shield plug. Based on the higher gamma dose rates, the applicant determined that the TFR bottom door shield could be exposed continuously for 37 years before reaching the gamma radiation limits used in the NS-4-FR exposure tests.

Given that the TFRs will receive only intermittent use for transferring a TSC loaded with spent nuclear fuel, the applicant noted that the gamma radiation exposure of the NS-4-FR shielding material in the TFR bottom door shield will occur for significantly less than 37 years during the 60-year extended operating term. Therefore, the applicant concluded that gamma radiation exposure would not have an adverse effect on the neutron shielding performance of the TFR bottom door shield.

The staff reviewed the applicants evaluation of the effects of radiation on the NS-4-FR shielding material and verified that the applicants calculated radiation exposure levels for this material over 60 years of operation, considering intermittent exposure in the TFR shields for spent fuel transfer operations and continuous exposure in the VCC shield plugs for spent fuel storage, are lower than the radiation exposure levels in the research reactor tests of NS-4-FR. The staff also verified that the applicant documented no significant radiation-induced damage to NS-4-FR from research reactor testing since the applicant reported a hydrogen loss of less than 1 percent and no significant physical deterioration. Therefore, based on its review of the reported data, the staff verified the applicants determination that shielding performance would be adequately maintained for radiation exposure levels that bound the projected 60-year exposure levels for the NS-4-FR shielding locations in the NAC-UMS System. Based on these considerations, the staff finds that the applicants TLAA adequately evaluated the impact of radiation-induced aging on the shielding performance of NS-4-FR; therefore, it is acceptable.

NS-3 Shielding Material For the NS-3 material used in the VCC shield plug, the applicants calculation determined that the accumulated neutron fluence and deposited gamma radiation over 60 years of spent fuel storage is less than 1 percent of the maximum exposure limits used in the prior research reactor testing. The applicant determined that research reactor testing at the highest radiation exposure levels resulted in significant weight loss and a corresponding loss of a specified amount of hydrogen gas from the NS-3 material. Given the significant hydrogen losses reported for NS-3 from both the radiation and thermal exposure testing (addressed below), the applicant determined that it needed to consider the combined hydrogen loss due to radiation and thermal exposure testing to credibly validate the expected shielding performance of NS-3 in the VCC shield plugs for a 60-year storage period. Therefore, the applicant calculated a combined hydrogen loss based on the radiation and thermal exposure tests and used this value in its bounding evaluation of the potential effects of radiation damage and thermal aging of NS-3 for the entire 60-year storage period.

The applicant noted that, in its design-basis VCC shielding analysis model, it had applied a reduced hydrogen density (i.e., reduced mass density times hydrogen weight fraction) relative to the supplier-specified values in the NS-3 material data sheet as conservative assumptions.

Therefore, the applicant compared the reduced hydrogen density based on the radiation and thermal exposure tests to the reduced hydrogen density used in the VCC shielding analysis model. The applicant determined that the lower bound hydrogen density, considering combined hydrogen losses from the exposure tests, is about 1.5 percent lower than the reduced hydrogen density used in its VCC shielding analysis model. To address this slight nonconservative discrepancy, the applicant calculated a higher and more realistic (yet still bounding) estimate of the hydrogen density after 60 years of storage by reducing the radiation-induced hydrogen loss from the value that was measured for the highest radiation exposure test to a value that was

3-31 measured for a lower tested radiation exposure level that still bounds the calculated radiation exposure for the entire 60-year extended storage period. The staff noted that this reduction in the radiation-induced hydrogen loss from the highest measured radiation-induced loss to the lower measured radiation-induced loss is appropriate since the applicants 60-year neutron fluence and gamma energy deposition calculations showed that the accumulated neutron fluence and gamma radiation levels for the VCC shield plug over 60 years of spent fuel storage are substantially lower than even the lower tested radiation exposure level from the prior research reactor testing. Based on these calculations, the applicant determined that any potential change in the shielding performance of the NS-3 material due to hydrogen loss from both radiation and thermal exposure over 60 years of storage would be bounded by the design-basis VCC shielding analysis model and would therefore be insignificant.

The staff reviewed the applicants evaluation of the effects of radiation on the NS-3 shielding material and verified that the applicants calculated 60-year radiation exposure levels for NS-3 in the VCC shield plugs over 60 years of continuous storage are substantially lower than the exposure levels in the research reactor tests of NS-3. The staff also verified that the applicants documented hydrogen losses at the radiation exposure levels from research reactor tests are sufficiently limited, such that there is assurance that the shielding performance would be adequately maintained in accordance with the design-basis VCC shielding analysis model considering the combined effects of thermal and radiation-induced hydrogen losses at exposure levels that bound the projected 60-year exposure levels for NS-3 in the NAC-UMS System.

Based on these considerations, the staff finds that the applicants TLAA adequately evaluated the impact of radiation-induced aging on the shielding performance of NS-3; therefore, it is acceptable.

Thermal Effects NS-4-FR Shielding Material For its evaluation of thermal aging of the NS-4-FR shielding material, the applicant cited the results of laboratory testing at 170°C (338°F) to determine that no significant reduction in NS-4-FR shielding effectiveness is expected due to thermal aging during the entire 60-year operating period. A small reduction in the weight of the material was measured as a result of the 170°C (338°F) thermal exposure test. The applicant considered the small weight reduction to be acceptable since it was observed to be primarily water vapor, and the applicant reported a hydrogen loss of less than 1 percent over extended exposure at this elevated temperature.

The staff reviewed the applicants evaluation of the thermal exposure test data for NS-4-FR and compared it to the operating temperature data for the TFR and VCC shielding items in section 4.4 of the NAC-UMS System FSAR. The staff noted that the maximum normal operating temperature of the NS-4-FR shielding material in the TFR radial and bottom door shields is 130°C (267°F), which bounds the normal operating temperature of the VCC shield plug. The staff verified that the thermal exposure test data for NS-4-FR, as cited by the applicant, supports the applicants determination that shielding performance will be adequately maintained for the 130°C (267°F) maximum normal operating temperature of the NS-4-FR shielding material during the entire 60-year operating period of the NAC-UMS System. Based on these considerations, the staff finds that the applicants TLAA adequately evaluated the impact of thermal aging on the shielding performance of NS-4-FR; therefore, it is acceptable.

3-32 NS-3 Shielding Material For the NS-3 material used in the VCC shield plug, the applicant evaluated the potential effect of thermal aging at the 93°C (200°F) normal operating temperature for 60 years of storage by considering the results of thermal exposure testing. Long-term thermal exposure testing at 121°C (250°F) resulted in a specified loss of hydrogen gas from the NS-3 material. The applicant calculated an estimated hydrogen loss for steady-state thermal conditions at the normal operating temperature by extrapolating the measured hydrogen loss at the test temperature to the lower operating temperature value. As addressed above, the applicant combined the hydrogen loss due to thermal exposure with that observed during radiation exposure testing of NS-3 to obtain a lower bound estimate of the hydrogen density. As addressed above, the lower bound hydrogen density based on radiation and thermal exposure testing was estimated to be 1.5 percent lower than the reduced hydrogen density used in the applicants design-basis VCC shielding analysis model. As addressed above, the applicant determined that 60-year radiation levels in the VCC shield plug are less than 1 percent of the radiation exposure limits used in the prior research reactor testing. Therefore, to address the 1.5 percent nonconservative discrepancy relative to the reduced hydrogen density used in the design-basis VCC shielding analysis model, the applicant calculated a higher and more realistic (yet still bounding) estimate of the hydrogen density after 60 years of storage by reducing the radiation-induced hydrogen loss from the value that was measured for the highest radiation exposure test to a value that was measured for a lower tested radiation exposure level that still bounds the calculated radiation exposure for the 60-year extended storage period. The staff noted that this reduction in the radiation-induced hydrogen loss from the highest measured radiation-induced loss to the lower measured radiation-induced loss is appropriate since the applicants 60-year neutron fluence and gamma energy deposition calculations determined that the accumulated neutron fluence and gamma radiation levels for the VCC shield plug over 60 years of spent fuel storage are substantially lower than even the lower tested radiation exposure level from the prior research reactor testing. Based on these calculations, the applicant determined that any potential change in the shielding performance of the NS-3 material due to hydrogen loss from both radiation and thermal exposure over 60 years of storage would be bounded by the VCC shielding analysis model and would therefore be insignificant.

The staff reviewed the applicants evaluation of the thermal exposure test data for NS-3 material and verified that the applicant appropriately used the data to conservatively estimate the potential effects of thermal aging on the shielding performance of NS-3 in the VCC shield plug.

The staff determined that the thermal exposure test data for NS-3, as cited by the applicant, supports the applicants determination that shielding performance will be adequately maintained for the normal operating temperature during the 60-year storage period for the NS-3 material, considering the combined thermal and radiation-induced hydrogen losses. Based on these considerations, the staff finds that the applicants TLAA adequately evaluated the impact of thermal aging on the shielding performance of NS-3; therefore, it is acceptable.

3.4.4 Evaluation Findings The staff reviewed the TLAAs provided in the renewal application for the NAC-UMS System to verify that the TLAA assumptions, input values, and calculation methods are adequate and bound the environments, aging mechanisms, and aging effects for the pertinent SSCs. The staff performed its review by following the guidance in NUREG-1927, Revision 1, and NUREG-2214.

Based on its review, the staff finds the following:

3-33 F3.3 The applicant identified all applicable aging mechanisms and effects for SSCs within the scope of renewal that involve TLAAs. The assumptions, values of input parameters, and calculation methods for the applicants TLAAs are adequate. Therefore, the applicants TLAAs provide reasonable assurance that the SSCs will maintain their intended functions for the period of extended operation, require no further aging management activities, and meet the requirements in 10 CFR 72.240(c)(2).

3.5 Aging Management Programs In accordance with 10 CFR 72.240(c)(3), the applicant must describe AMPs for management of issues associated with aging that could adversely affect the design functions of SSCs important to safety. Section 3.4 and appendix A of the renewal application include descriptions of the six AMPs listed below. Appendix C to the renewal application includes a proposed FSAR supplement (new FSAR chapter 14) to incorporate the AMPs. Each of the six AMPs listed follows the standard 10-element format described in NUREG-1927, Revision 1:

(1)

Localized Corrosion and SCC of Welded Stainless-Steel TSCs (2)

Internal VCC Metallic Components Monitoring (3)

External VCC Metallic Components Monitoring (4)

Reinforced VCC Structures Concrete Monitoring (5)

TFRs and Transfer Adapters (6)

NAC-UMS High-Burnup (HBU) Fuel Monitoring and Assessment The staff reviewed the proposed AMPs in the renewal application for the NAC-UMS System by following the guidance in NUREG-1927, Revision 1. The staff evaluated the proposed AMPs by comparing the 10 elements of each of the AMPs with the corresponding elements of the generically acceptable example AMPs in NUREG-2214, as follows:

The NAC-UMS Localized Corrosion and SCC of Welded Stainless-Steel TSCs AMP was compared to the NUREG-2214 example AMP for localized corrosion and SCC of welded stainless-steel dry storage canisters (see SER table 3.5-1).

The NAC-UMS Internal and External VCC Metallic Components Monitoring AMPs were compared to the NUREG-2214 example AMP for monitoring of metallic surfaces (see SER tables 3.5-2 and 3.5-3).

The NAC-UMS Reinforced VCC Structures Concrete Monitoring AMP was compared to the NUREG-2214 example AMP for reinforced concrete structures (see SER table 3.5-4).

The NAC-UMS TFRs and Transfer Adapters AMP was compared to the NUREG-2214 example AMP for TFRs (see SER table 3.5-5).

The NAC-UMS HBU Fuel Monitoring and Assessment AMP was compared to the NUREG-2214 example AMP for HBU fuel monitoring and assessment (see SER table 3.5-6).

SER tables 3.5-1 through 3.5-6 provide the staffs findings that the proposed AMPs in the renewal application are consistent with the applicable example AMPs in NUREG-2214. The staff

3-34 documents its review on an element-by-element basis, consistent with the standard 10-element AMP format for the example AMPs provided in NUREG-2214.

Table 3.5-1 AMP Review ResultsNAC-UMS Localized Corrosion and SCC of Welded Stainless-Steel TSCs AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application includes examination of accessible external surfaces of the welded stainless-steel TSCs for localized corrosion and SCC. This element states that accessible surfaces of the TSC are those surfaces that can be examined using a given examination method without moving the TSC.

The applicant revised AMP element 4 in the updated renewal application (NAC International, 2022a) to include more detailed requirements for visual examination of welded TSCs. AMP element 6 was also revised to include requirements for analysis of indications of localized corrosion and SCC if a supplemental examination of a major indication is not possible or is unable to provide sufficient data.

The staff provides a detailed review of these criteria below for AMP elements 4 and 6. The staffs review determined that, with the incorporation of the revisions to AMP elements 4 and 6, the Scope of Program element is consistent with element 1 of the example AMP in NUREG-2214.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. The staff confirmed that NUREG-2214 does not specify any preventive actions for addressing localized corrosion and SCC of welded stainless-steel TSCs during the period of extended operation since this AMP is for condition monitoring.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application includes a summary of the parameters that are monitored and inspected under this AMP. These parameters include visual evidence of localized corrosion and SCC,

3-35 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters size and location of visual indications on TSC welds and heat-affected zones (HAZs), and appearance and location of discontinuities on the examined TSC surfaces.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

4. Detection of Aging Effects Consistent. The Detection of Aging Effects AMP element in the updated renewal application specifies a minimum of one TSC inspected at each ISFSI site, and preference for selection of TSC(s) should be given to TSC(s) with the greatest susceptibility to localized corrosion and SCC. This element also indicates that the inspection frequency should include a baseline inspection at the beginning of the period of extended operation; subsequent inspections every 10 years, if there are no indications of localized corrosion or SCC; or subsequent inspections every 5 years, if there are indications of localized corrosion or SCC. The staff confirmed that the inspection sample size, TSC selection criteria, and inspection frequency specified for this AMP element are consistent with the guidance in NUREG-2214.

The staff encountered the issues described below during its review of this AMP element that prompted RAIs and resulted in revisions to this AMP element in the updated renewal application.

In its response (NAC International, 2022a) to RAI A-1 (NRC, 2021b) on this AMP element, the applicant revised this element to delete the option that would allow a general licensee using the NAC-UMS System at an ISFSI site to not conduct inspections for localized corrosion and SCC of welded stainless-steel TSCs that are in service. The staff determined that the revision to delete this option is acceptable since it ensures that all general licensees using the NAC-UMS System for spent fuel storage at their ISFSI sites will adequately inspect their welded stainless-steel TSCs using this AMP.

Element 4 of the NUREG-2214 example AMP and ASME BPV Code Case N-860, Inspection Requirements and Evaluation Standards for Spent Nuclear Fuel Storage and Transportation Containment Systems,Section XI, Division 1 (ASME Code Case, 2020), provide guidance on specific methods for supplemental examinations to identify and characterize the extent and severity of indications of localized corrosion and SCC of welded stainless-steel canisters.

However, the staff noted that this AMP element did not originally propose a clear methodology for supplemental examinations of such indications that are capable of identifying and sizing a flaw that may be caused by localized corrosion or SCC, or both. Therefore, the staff issued RAI A-2 (NRC, 2021b), requesting that the applicant justify how the proposed inspection methodology for supplemental

3-36 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters examinations of indications will be capable of identifying and sizing a flaw.

In its response to RAI A-2 (NAC International, 2022a), the applicant revised AMP elements 4 and 6 in the renewal application to specify requirements for VT-1 visual assessment examinations of suspect indications found during VT-3 visual screening examinations. The revisions to these AMP elements include additional requirements to perform supplemental examinations in accordance with section 2400 of ASME Code Case N-860 (ASME Code Case, 2020), using surface or volumetric examination techniques for indications that are confirmed, based on VT-1 visual assessment examinations, to be localized corrosion or SCC. The revisions specify that supplemental examinations for sizing flaws using surface or volumetric examination techniques are to be performed in accordance with the ASME BPV Code,Section XI, Subarticles IWA-2220 or IWA-2230, respectively.

The applicant also revised AMP element 6 to include requirements for analysis in accordance with section 2440 of ASME Code Case N-860 for indications of localized corrosion or SCC if a supplemental examination of the indications is not possible or is unable to provide sufficient data for characterizing and sizing a flaw in accordance with these requirements.

The staff reviewed the revisions to this AMP element in the updated renewal application (NAC International, 2022a) and determined that the applicants proposed methods for assessment examinations of suspect visual indications and supplemental examinations of confirmed visual indications of localized corrosion or SCC in the welded regions of the TSC are consistent with the guidance in NUREG-2214 and ASME Code Case N-860. The staff also reviewed the applicants proposed methods for analysis of indications of localized corrosion or SCC if a supplemental examination is not possible or is unable to provide sufficient data for characterizing and sizing a flaw. The staff determined that the applicants methods for analysis of such indications are acceptable since they are based on section 2440 of ASME Code Case N-860, which is consistent with the guidance in NUREG-2214.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will establish a baseline at the beginning of the period of extended operation for the selected TSC and track and trend subsequent inspections of the selected TSC. This element states that tracking and trending of subsequent inspections includes the appearance of the selected TSC, particularly at welds and crevice

3-37 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters locations, documented with images or video, or both, that will allow comparison; changes to the locations and sizes of any areas of localized corrosion or SCC; and changes to the size and number of any rust-colored stains resulting from iron contamination of the surface.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application describes the applicants proposed acceptance criteria for general visual examinations of TSC nonweld and non-HAZ accessible external surfaces, VT-3 screening examinations of TSC welds and HAZs, VT-1 assessment examinations of suspect visual indications in the TSC welds and HAZs, and supplemental examinations of confirmed visual indications of localized corrosion or SCC in the TSC welds and HAZs.

The applicant revised AMP elements 4 and 6 in its response to RAI A-2 (NAC International, 2022a), to specify requirements and acceptance criteria for VT-1 visual assessment examinations of suspect indications found during VT-3 visual screening examinations.

The revisions to these AMP elements include additional requirements and acceptance criteria for supplemental examinations in accordance with section 2400 of ASME Code Case N-860, using surface or volumetric examination techniques for indications that are confirmed based on VT-1 visual assessment examinations to be localized corrosion or SCC. The revisions specify that supplemental examinations for sizing flaws using surface or volumetric examination techniques are to be performed in accordance with the ASME BPV Code,Section XI, Subarticles IWA-2220 or IWA-2230, respectively.

The applicant also revised AMP element 6 to state that, if a supplemental examination is not possible or is unable to provide sufficient data for flaw evaluation in accordance with section 2400 of ASME Code Case N-860, an analysis of indications of localized corrosion or SCC shall be used when justified in accordance with section 2440 of ASME Code Case N-860. The update to this element also states that, depending on the results of the examinations, the additional actions of section 2432 of ASME Code Case N-860 shall be followed, or section 2441 of ASME Code Case N-860 shall be followed if an analysis is employed in lieu of a supplemental examination.

The staff reviewed this AMP element, as updated based on the applicants response to RAI A-2, and confirmed that the examination acceptance criteria and actions proposed are consistent with the guidance in NUREG-2214 and ASME Code Case N-860. The staff also confirmed that the applicants proposed criteria for analysis of

3-38 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters indications of localized corrosion or SCC, or both, in lieu of a supplemental examination, if a supplemental examination is not possible or is unable to provide sufficient data for flaw evaluation, is consistent with the guidance in NUREG-2214 and ASME Code Case N-860.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that inspection results that do not meet the acceptance criteria are addressed under the general licensees approved quality assurance (QA) program. This element also states that the QA program will ensure that corrective actions are completed within the general licensees corrective action program.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that confirmation and evaluation processes will be commensurate with the general licensees approved QA program. The QA program will ensure that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

3-39 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Localized Corrosion and SCC of Welded Stainless-Steel Dry Storage Canisters This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The renewal application included prior inspection results and relevant operating experience for this AMP. The applicant discussed the results from two prior inspections of NAC-UMS System TSCs:

In 2016, a TSC containing greater-than-Class-C waste was inspected at Maine Yankee. The inspection did not identify any indications of corrosion or SCC of the TSC. The inspection identified a small grouping of embedded iron particles of no appreciable depth or height. The areas were determined to be the result of iron contamination during original manufacturing or handling of the canister. The applicant determined that these indications have no adverse impact on the continued safety function performance of the TSC.

In 2018, a TSC containing spent nuclear fuel was selected for inspection at Maine Yankee. The specific TSC was determined to have high susceptibility to localized corrosion or SCC, or both.

The TSC was inspected in accordance with the requirements of this AMP. It was considered bounding for all NAC-UMS TSCs in service. The inspection of the selected TSC did not reveal any reportable indications of corrosion or SCC.

The applicant stated that, during the period of extended operation, each general licensee will perform tollgate assessments of aggregated operating experience and other information related to the aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3-40 Table 3.5-2 AMP Review ResultsNAC-UMS Internal VCC Metallic Components Monitoring AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application includes inspection of the accessible internal surfaces of steel components that are sheltered within the VCC (coincident with the TSC inspections) and managing the effects of aging of these components. This element states that accessible surfaces of the internal VCC metallic components are those surfaces that can be examined using a given examination method without moving the TSC.

The applicant revised AMP element 4 in the updated renewal application (NAC International, 2022a) to include more detailed requirements for performing visual examinations of internal VCC metallic components. It also revised AMP element 6 to include additional acceptance criteria for visual examinations of internal VCC metallic components. The staff gives a detailed review of these criteria below for AMP elements 4 and 6. The staff determined that, with the incorporation of the revisions to AMP elements 4 and 6, the Scope of Program element is consistent with element 1 of the example AMP in NUREG-2214.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. The staff confirmed that NUREG-2214 does not specify any preventive actions for addressing corrosion of VCC metallic components during the period of extended operation since this AMP is for condition monitoring.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application states that the parameters to be monitored or inspected include visual indications of significant loss of base metal due to corrosion and the condition of the VCC lid seal gasket and the lid bolts and lid flange bolt holes if the VCC lid is removed.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of

3-41 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

4. Detection of Aging Effects Consistent. The Detection of Aging Effects AMP element in the updated renewal application includes general visual examination of accessible internal VCC metallic components to detect corrosion resulting in significant loss of metal, component displacement or degradation, or blockage of air passage through the VCC. This AMP element also includes requirements for sample size, inspection frequency, inspection timing, and data collection.

Considering the recommendations for this AMP element in NUREG-2214, the staff noted that the AMP in the original renewal application did not cite standard criteria or other suitable methods that describe how procedures are controlled to ensure that visual inspections of internal VCC metallic components will use sufficient resolution and lighting to adequately detect applicable aging effects, including loss of base metal due to corrosion, component displacement or degradation, and air passage blockage.

Therefore, the staff issued RAI A-6 (NRC, 2021b), requesting that the applicant state how visual inspection parameters will be controlled to ensure that the AMP will be capable of identifying degradation; the staff also requested that the applicant revise the AMP as needed to clarify the expectations of general licensees for controlling visual inspection parameters.

In its response to RAI A-6 (NAC International, 2022a), the applicant revised elements 4 and 6 of the Internal VCC Metallic Components Monitoring AMP in the renewal application to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, Subsection IWE, Requirements for Class MC and Metallic Liners of Class CC Components of Light-Water Cooled Plants (ASME, 2007), for general visual examinations of internal VCC metallic components.

Element 4 includes new provisions requiring the following:

Visual examinations shall comply with the requirements of the ASME BPV Code,Section XI, paragraph IWE-2311, or their equivalent.

Personnel performing visual examinations for this AMP shall meet the qualification requirements of the ASME BPV Code,Section XI, paragraph IWE-2330(b), or their equivalent.

The staff reviewed the new requirements for general visual examinations of internal VCC metallic components and confirmed that they provide the procedural attributes needed for effective visual examinations by qualified personnel, including equipment resolution,

3-42 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces lighting standards, distance, surface coverage, and surface assessment to adequately detect applicable aging effects. Therefore, the staff determined that these methods are acceptable for detection of aging effects.

The revisions to element 6 include new acceptance criteria for visual inspections that incorporate paragraph IWE-3511 of the ASME BPV Code,Section XI. The staff provides a detailed review of these acceptance criteria below for AMP element 6.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will establish a baseline at the beginning of the period of extended operation and track and trend subsequent inspections of the selected VCC. This element states that tracking and trending of subsequent inspections will include documentation of the appearance of the internal metallic components of the VCC to allow comparison and changes to any metallic components with reportable aging effects.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application describes the applicants proposed acceptance criteria for visual inspections of the internal VCC metallic components. Acceptance criteria include no loss of base metal, no indications of displaced or degraded components, and no indications of damaged bolts or bolt holes.

The applicant revised AMP elements 4 and 6 in its response to RAI A-6 (NAC International, 2022a) to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Subsection IWE, for general visual examinations of internal VCC metallic components. Revisions to element 4 are addressed above for that AMP element. The revisions to element 6 include new acceptance criteria for visual inspections, specifying that the inspected condition of the examined area must meet the ASME BPV Code,Section XI, IWE-3511, acceptance standard or its equivalent.

3-43 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces IWE-3511 specifies that the condition of the examined area is acceptable if the examination determines that there is no evidence of damage or degradation sufficient to warrant further evaluation or performance of a repair or replacement activity; suspect conditions shall be evaluated to the extent necessary to ensure that the component function is not impaired. The staff noted that this additional acceptance criterion for general visual examinations of internal VCC metallic components is to be used in concert with the other acceptance criteria included for this AMP element. The staff verified that, collectively, these acceptance criteria provide suitable standards for general licensees to use in their AMP procedures for determining whether significant loss of base metal, displaced or degraded components, and damaged bolts or bolt holes are present for the internal VCC metallic components; corrective actions will be taken by general licensees if such aging effects are present.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that inspection results that do not meet the acceptance criteria are addressed under the general licensees approved QA program. This element also states that the QA program will ensure that corrective actions are completed within the general licensees corrective action program.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that the confirmation process is commensurate with the general licensees approved QA program.

The QA program ensures that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the

3-44 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The renewal application included prior inspection results and relevant operating experience for this AMP. The applicant discussed the results from two prior inspections of NAC-UMS System internal VCC metallic component surfaces:

In 2016, the internal metallic components of a VCC containing a greater-than-Class-C-waste canister were inspected at Maine Yankee. The inspection identified localized areas of coating damage (peeling and blistering) on the internal VCC metallic surfaces. The exposed base metal was observed to have minimal surface corrosion. The applicant determined that these conditions have no adverse impact on the continued safety function performance of the internal VCC metallic components.

In addition, one VCC lid bolt was replaced following lid removal due to corrosion.

In 2018, the internal metallic components of a VCC containing a spent nuclear fuel canister were inspected at Maine Yankee.

The accessible VCC internal surfaces were inspected for localized corrosion and pitting. An estimated 95 percent of accessible VCC internal surfaces were inspected. Coating deterioration and localized corrosion were identified on the interior VCC liner surface exposed to the sheltered environment.

The applicant reviewed the indications and evaluated potential subsequent corrosion. The applicant determined that any subsequent corrosion would not compromise the intended safety functions of the VCC over the 60-year extended storage term.

The applicant stated that, during the period of extended operation, each general licensee will perform tollgate assessments of aggregated operating experience and other information related to the

3-45 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

Table 3.5-3 AMP Review ResultsNAC-UMS External VCC Metallic Components Monitoring AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application includes inspection of the accessible external surfaces of VCC steel components and managing the effects of aging of these components. The scope of the AMP includes all normally accessible and visible exterior metallic surfaces of all VCCs.

The applicant revised AMP element 4 in the updated renewal application (NAC International, 2022a) to include more detailed requirements for performing visual examinations of external VCC metallic components. It also revised AMP element 6 to include additional acceptance criteria for visual examinations of external VCC metallic components. The staff gives a detailed review of these criteria below for AMP elements 4 and 6. The staff determined that, with the incorporation of the revisions to AMP elements 4 and 6, the Scope of Program element is consistent with element 1 of the example AMP in NUREG-2214.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. The staff confirmed that NUREG-2214 does not specify any preventive actions for addressing corrosion of VCC metallic components during the period of extended operation since this AMP is for condition monitoring.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the

3-46 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application states that the parameters to be monitored or inspected include visual evidence of significant coating loss or galvanic corrosion, which, left uncorrected, could result in obvious loss of base metal. Parameters monitored or inspected also include visual evidence of loose or missing bolts, galvanic corrosion of bolted connections, physical displacement, and other conditions indicative of loss of bolt preload for VCC bolting.

In its response to RAI A-6 (NAC International, 2022a), the applicant revised element 3 of the External VCC Metallic Components Monitoring AMP in the renewal application to add galvanic corrosion to the list of corrosion mechanisms and associated aging effects requiring management. The staff confirmed that this addition is appropriate to support condition monitoring of items with dissimilar metal contacts in the outdoor air environment.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

4. Detection of Aging Effects Consistent. The Detection of Aging Effects AMP element in the updated renewal application includes general visual examination using direct visual methods of the external VCC metallic components for significant corrosion or significant coating loss resulting in loss of base metal. The extent of inspection shall cover all normally accessible VCC lid surfaces, VCC lid flange, exposed steel surfaces of the inlet and outlet vents, VCC lifting lugs, and associated bolting.

This element specifies that inspection sample size shall encompass all normally accessible and visible exterior metallic surfaces of all VCCs. This AMP element also includes requirements for inspection frequency, inspection timing, and data collection.

Considering the recommendations for this AMP element in NUREG-2214, the staff noted that the AMP in the original renewal application did not cite standard criteria or other suitable methods that describe how procedures are controlled to ensure that visual inspections of external VCC metallic components will use sufficient resolution and lighting to adequately detect applicable aging effects.

Therefore, the staff issued RAI A-6 (NRC, 2021b), requesting that the applicant state how visual inspection parameters will be controlled to ensure that the AMP will be capable of identifying aging degradation; the staff also requested that the applicant revise the AMP as needed to clarify the expectations of general licensees for controlling visual inspection parameters.

3-47 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces In its response to RAI A-6 (NAC International, 2022a), the applicant revised elements 4 and 6 of the External VCC Metallic Components Monitoring AMP in the renewal application to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Subsection IWE, for general visual examinations of external VCC metallic components.

Element 4 includes new provisions requiring the following:

Visual examinations shall comply with the requirements in the ASME BPV Code,Section XI, paragraph IWE-2311, or their equivalent.

Personnel performing visual examinations for this AMP shall meet the qualification requirements of the ASME BPV Code,Section XI, paragraph IWE-2330(b), or their equivalent.

The staff reviewed the new requirements for general visual examinations of external VCC metallic components and confirmed that they provide the procedural attributes needed for effective visual examinations by qualified personnel, including equipment resolution, lighting standards, distance, surface coverage, and surface assessment to adequately detect applicable aging effects. Therefore, the staff determined that these methods are acceptable for detection of aging effects.

The revisions to element 6 include new acceptance criteria for visual inspections that incorporate paragraph IWE-3511 of the ASME BPV Code,Section XI. The staff gives a detailed review of these acceptance criteria below for AMP element 6.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will establish a baseline at the beginning of the period of extended operation and track and trend subsequent inspections of the VCC. This element states that tracking and trending of subsequent inspections will include changes to any metallic components with aging effects, the location and size of areas of coating loss that could result in corrosion and loss of base metal, and loose bolts or other anomalies on the VCC lid or lift lug hardware.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is

3-48 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application describes the applicants proposed acceptance criteria for visual inspections of the external VCC metallic components. Acceptance criteria include no active corrosion resulting in loss of base metal and no indications of loose or displaced bolts or hardware, and areas of base metal coating failures must remain bounded by the assumptions of the corrosion TLAA.

The applicant revised AMP elements 4 and 6 in its response to RAI A-6 (NAC International, 2022a) to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Subsection IWE, for general visual examinations of external VCC metallic components. Revisions to element 4 are addressed above for that AMP element. The revisions to element 6 include new acceptance criteria for visual inspections specifying that the inspected condition of the examined area must meet the ASME BPV Code,Section XI, IWE-3511, acceptance standard or its equivalent.

IWE-3511 specifies that the condition of the examined area is acceptable if the examination determines that there is no evidence of damage or degradation sufficient to warrant further evaluation or performance of a repair or replacement activity; suspect conditions shall be evaluated to the extent necessary to ensure that the component function is not impaired. The staff noted that this additional acceptance criterion for general visual examinations of external VCC metallic components is to be used in concert with the other acceptance criteria included for this AMP element. The staff verified that, collectively, these acceptance criteria provide suitable standards for general licensees to use in their AMP procedures for determining whether coating loss and corrosion have resulted in unacceptable loss of base metal for external VCC metallic components; corrective actions will be taken by general licensees if such aging effects are present.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that inspection results that do not meet the acceptance criteria are addressed under the general licensees approved QA program. This element also states that the QA program

3-49 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces will ensure that corrective actions are completed within the general licensees corrective action program.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that the confirmation process is commensurate with the general licensees approved QA program.

The QA program ensures that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The renewal application included prior inspection results and relevant operating experience for this AMP. The applicant stated that thousands of external VCC metallic component inspections have occurred to date on both NAC-UMS and NAC-MPC Systems as part of the annual inspection requirements of the applicable FSAR

3-50 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Monitoring of Metallic Surfaces licensing bases. The applicant summarized these inspection results in the renewal application by stating the following:

No obvious metal loss has occurred to date for any VCC system.

Coating damage has been observed in many instances and is usually repaired in the field as part of a coating touch-up campaign. The general licensee schedules this activity at convenient intervals and during optimum weather conditions. At no time has coating damage led to obvious metal loss.

In 2018, the external metallic components of an NAC-UMS System VCC were inspected at Maine Yankee in accordance with the requirements of this AMP as part of the preapplication inspection. The inspection of the external metallic items for the selected VCC did not identify any significant corrosion or loss of base metal.

The applicant stated that, during the period of extended operation, each general licensee will perform tollgate assessments of aggregated operating experience and other information related to the aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

Table 3.5-4 AMP Review ResultsNAC-UMS Reinforced VCC Structures Concrete Monitoring AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application includes general visual inspection by direct observation of the above-grade VCC concrete structures that are directly exposed to outdoor air and managing the effects of aging.

The applicant revised AMP elements 3 and 6 in the updated renewal application (NAC International, 2022a) to include criteria for performing gamma radiation dose rate measurements if certain visual indications are revealed during the visual inspections of VCC concrete that are performed in accordance with the standard methods of American Concrete Institute (ACI) 349.3R, Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete

3-51 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures Structures, issued January 2018 (American Concrete Institute, 2018). The staff gives a detailed review of these criteria below for AMP elements 3 and 6. The staff determined that, with the incorporation of the revisions to AMP elements 3 and 6, the Scope of Program element is consistent with element 1 of the example AMP in NUREG-2214.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. The staff confirmed that NUREG-2214 does not specify any preventive actions for addressing aging degradation of reinforced concrete structures during the period of extended operation since this AMP is for condition monitoring.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application specifies inspections and monitoring for significant VCC concrete structure aging effects exceeding the acceptance criteria of ACI 349.3R, including Tier 3 cracking under ACI 349.3R, loss of material due to spalling or scaling, and significant porosity or permeability of concrete surfaces.

Section 3.4.3.4 of the original renewal application cited the May 2019 NRC study of ACI 349.3R Tier 2 criteria impacts on dose rates for several spent nuclear fuel storage systems (NRC, 2019a) as a basis for determining that periodic radiation surveys are not needed to verify VCC concrete shielding performance. The NUREG-2214 example AMP for reinforced concrete structures recommends the performance of periodic radiation surveys. However, the NUREG-2214 guidance states that renewal applicants may have the option to rely on ACI 349.3R visual inspections in lieu of periodic radiation surveys if (1) the applicant provides a technical evaluation demonstrating that the generic shielding evaluations documented in the May 2019 NRC study apply to (or are bounding for) the renewal applicants storage system design, including consideration of the assumptions and system parameters for both design and contents used in the NRC evaluations, and (2) the applicants evaluation demonstrates that generic shielding evaluations in the May 2019 NRC study show that the implementation of ACI 349.3R visual

3-52 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures inspections for the renewal applicants design would be sufficiently conservative to protect against a loss of shielding performance.

The applicant originally determined that visual inspection results that meet ACI 349.3R Tier 2 concrete evaluation criteria are sufficient to ensure that the VCC concrete has not deteriorated and that radiation shielding tests and evaluations are not required. Accordingly, the NAC-UMS Reinforced VCC Structures Concrete Monitoring AMP in the original renewal application did not include any provision for performing radiation surveys and relied only on the performance of visual inspections under ACI 349.3R for monitoring the conditions of the VCC concrete, as well as detection and evaluation of aging effects.

The staff noted that the original application only cited the May 2019 NRC study of ACI 349.3R Tier 2 criteria impacts on dose rates. The application did not provide a technical justification for demonstrating, consistent with the guidance in NUREG-2214, that the shielding evaluations for the May 2019 NRC study are applicable to or bounding for the NAC-UMS System design, or that implementation of ACI 349.3R visual inspections for the NAC-UMS System would be sufficiently conservative to protect against a loss of shielding performance, consistent with the guidance in NUREG-2214.

Therefore, the staff issued RAI A-4 (NRC, 2021b), requesting that the applicant justify the basis for the conclusion that the ACI 349.3R visual inspections without radiation surveys will be capable of verifying the shielding performance of VCC concrete.

In its response to RAI A-4 (NAC International, 2022a), the applicant revised AMP elements 3 and 6 in the renewal application to require performance of radiation surveys for specified conditions.

Element 3 includes a new provision to measure for increases in gamma radiation dose rates to determine if they exceed the levels specified in Limiting Condition for Operation (LCO) A 3.2.2 in the NAC-UMS System technical specifications (TS). The revisions to element 6 include new acceptance criteria for visual inspections under ACI 349.3R that would prompt the need for gamma radiation dose rate measurements for certain types of visual indications. The staff gives a detailed review of these acceptance criteria below for AMP element 6. Based on its evaluation of the new element 6 acceptance criteria for performing gamma dose rate measurements, the staff determined that the new element 3 provision is sufficient to address performance monitoring for VCC shielding.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3-53 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures

4. Detection of Aging Effects Not Consistent. The Detection of Aging Effects AMP element in the updated renewal application includes general visual inspections of the external VCC concrete surfaces using the methods of ACI 349.3R for cracking, loss of material, rebar corrosion, and compromised concrete integrity. This element states that the extent of inspection coverage will include all normally accessible and visible concrete surfaces of all VCCs in operation at the ISFSI. The element states that visual inspections of the VCC concrete structures will be conducted at least once every 5 years in accordance with ACI 349.3R.

Element 4 of the NUREG-2214 example AMP for reinforced concrete structures recommends a two-part approach to visual assessment and inspection of VCC concrete: (1) all concrete casks should be visually assessed annually during general area walkdowns, and (2) at least two casks per ISFSI site should be selected for more rigorous visual inspections every 5 years using the standard methods in ACI 349.3R. Instead of specifying requirements for annual general area walkdowns, the application AMP proposed a single approach, whereby general licensees will visually inspect all concrete casks at their ISFSI sites every 5 years using the ACI 349.3R criteria.

For detection and evaluation of aging effects, the staff compared the adequacy of performing annual general area walkdowns covering all concrete casks, with just two casks selected for comprehensive visual inspections under ACI 349.3R every 5 years (as recommended in NUREG-2214), with the adequacy of performing comprehensive visual inspections under ACI 349.3R on all casks every 5 years without any general area walkdowns of the concrete casks.

The staff noted that the annual general area walkdowns recommended in NUREG-2214 are not comprehensive or rigorous visual inspections that are controlled using an established concrete inspection standard, such as ACI 349.3R. Rather, the general area walkdowns, as recommended in NUREG-2214, are intended to verify the absence of deleterious aging effects as determined by engineering judgment. Detailed examination and evaluation methods, and associated acceptance standards and corrective actions, are not specified for general area walkdowns, whereas the visual inspections under ACI 349.3R provide sufficient detail and rigor to ensure that emergent aging effects are identified, evaluated, and addressed in a timely manner. The staff determined that the 5-year interval for performing the ACI 349.3R visual inspection of all concrete casks at the ISFSI site is sufficient without the annual general area walkdowns since the 5-year interval visual inspection of all concrete casks under ACI 349.3R provides superior capabilities and methods for timely detection and evaluation of aging effects before a loss of concrete safety function. Accordingly, the staff found the applicants proposal to be adequate for ensuring that visual aging effects for all concrete casks in service would be detected and

3-54 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures evaluated in a timely manner before the occurrence of more severe aging degradation that results in a loss of concrete safety function.

In addition, the staff determined that the applicants revisions to AMP elements 3 and 6 for addressing RAI A-4 will provide for adequate performance monitoring of the concrete radiation shielding function if the ACI 349.3R visual inspection results show degradation that exceeds the ACI 349.3R Tier 2 criteria or show a loss of material that could degrade shielding performance.

Based on the foregoing review of the applicants proposal to perform visual inspections under ACI 349.3R of all concrete casks every 5 years in lieu of annual general area walkdowns, and the applicants revisions to this AMP to require performance of radiation surveys for the types of visual indications specified in element 6, the staff determined that the applicants description of this AMP element, while not completely consistent, is sufficient to meet the intent of element 4 of the example AMP in NUREG-2214, and it follows the guidance in NUREG-1927. Therefore, the staff finds that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will establish a baseline at the beginning of the period of extended operation using the three-tier criteria of ACI 349.3R and track and trend location and size of any areas of cracking, loss of concrete material, rebar corrosion, or compromised concrete that could result in the impaired functionality and safety of the VCC.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application describes the applicants proposed acceptance criteria for visual inspections of the VCC concrete. This element summarizes the applicants implementation of the three-tier criteria for visual inspection results in ACI 349.3R.

As addressed above for AMP element 3, the staff issued RAI A-4 (NRC, 2021b) requesting that the applicant justify the basis for the conclusion (in the original renewal application) that the ACI 349.3R visual inspections without radiation surveys will be capable of verifying the shielding performance of VCC concrete.

In its response to RAI A-4 (NAC International, 2022a), the applicant revised AMP elements 3 and 6 in the renewal application to require

3-55 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures performance of radiation surveys for specified conditions. Changes to element 3 are addressed above for that AMP element.

Element 6 includes new acceptance criteria requiring that new Tier 3

[visual] indications or any other indication which could potentially increase dose rates shall be inspected with gamma dose rate measurements and verified to be less than [the NAC-UMS technical specification (TS)] LCO A 3.2.2 acceptance criteria. The revisions to this element also add increases in gamma dose rates exceeding

[the NAC-UMS TS] LCO A 3.2.2 acceptance criteria to the list of findings that are to be addressed by the ACI 349.3R Tier 3 criteria for further evaluation.

The staff evaluated the new criteria for performing gamma dose rate measurements in the revised AMP (NAC International, 2022a) by considering whether the visual indications that would prompt the dose rate measurements adequately bound the material loss and streaming path considerations, as addressed in the May 2019 NRC study of ACI 349.3R Tier 2 criteria impacts on dose rates. The staff verified that the applicants proposed visual inspection criteria are sufficient to ensure that the dose rate measurements will be performed if visual inspections of the VCC concrete under ACI 349.3R reveal indications of loss of material or Tier 3 cracks that could result in higher dose rates, consistent with determinations in the May 2019 NRC study. The staff confirmed that the AMP includes an acceptable listing of the visual indications that would prompt the need for dose rate measurements if the indications exceed the Tier 2 criteria in ACI 349.3R. Further, the applicants condition requiring gamma dose rate measurements for any other [visual] indication which could potentially increase dose rates ensures that visual conditions associated with loss of material and streaming paths, as considered in the May 2019 NRC study, will be evaluated for their potential impact on shielding performance. Therefore, the staff determined that the applicants revisions to AMP elements 3 and 6 for addressing RAI A-4 will provide for adequate performance monitoring of the concrete radiation shielding function if the ACI 349.3R visual inspection results show degradation that exceeds the ACI 349.3R Tier 2 criteria or show a loss of material that could degrade shielding performance.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that inspection results that do not meet the acceptance criteria are addressed under the general licensees approved QA program. This element also states that the QA program

3-56 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures will ensure that corrective actions are completed within the general licensees corrective action program.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that the confirmation process is commensurate with the general licensees approved QA program.

The QA program ensures that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The renewal application included prior inspection results and relevant operating experience for this AMP. The applicant stated that thousands of VCC concrete inspections have occurred to date on both NAC-UMS and NAC-MPC Systems as part of the annual inspection requirements of the applicable FSAR licensing bases. The

3-57 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for Reinforced Concrete Structures applicant summarized these inspection results in the renewal application by stating the following:

Passive cracking has been observed, which has been attributed to shrinkage cracking during construction. The cracks that have been trended have not changed in size, shape, or extent.

Spalling has been observed at cold weather sites, which has been attributed to the forces associated with thermal expansion differences between the concrete and the base plate or the prying action of freeze and thaw damage. The applicant stated that this type of spalling is an active degradation mechanism for the VCC concrete.

Efflorescence (visual indications of salt deposits on exterior concrete surfaces) has been observed to varying degrees at different sites. It is generally considered benign and has not been associated with concrete degradation.

No staining or spalling due to rebar corrosion has been identified for any VCC in service.

The applicant stated that, during the period of extended operation, each general licensee will perform tollgate assessments of aggregated operating experience and other information related to the aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

Table 3.5-5 AMP Review ResultsNAC-UMS TFRs and Transfer Adapters AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application includes inspections for aging effects on the accessible internal and external surfaces of steel NAC-UMS TFRs and transfer adapter subcomponents that are exposed to indoor and outdoor air environments.

Element 1 of the TFRs and Transfer Adapters AMP in the original renewal application stated that this AMP is not applicable to facilities not maintaining a TFR or transfer adapter on site. The staff noted that this statement did not include any description of controls that will be in place to ensure that aging of the TFR and transfer adapter

3-58 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs components will be adequately managed during the period of extended operation for facilities that do not normally maintain these components on site. Therefore, the staff issued RAI A-5 (NRC, 2021b), requesting that the applicant clarify whether controls will be in place for facilities that do not normally maintain a TFR and transfer adapter on site to ensure that aging management activities will be performed before placing TFRs and transfer adapters into service at the site.

In its response to RAI A-5 (NAC International, 2022a), the applicant explained that it always intended that any TFR and transfer adapter provided to NAC-UMS general licensees must meet the requirements of this AMP or the applicable requirements of the TFR procurement specification if new TFR equipment is used. The applicant revised FSAR chapter 1, section 1.2.1, to add the following:

For decommissioned sites that have disposed of their auxiliary equipment, new or refurbished equipment shall be used to allow the successful transfer of the NAC-UMS transportable storage canisters (TSCs) from the VCC to the appropriate NAC-UMS system transport cask certified for the transport of the NAC-UMS TSCs. New transfer equipment including the transfer cask and transfer adapter shall be procured, inspected, and tested in accordance with approved NAC procurement specification and applicable license drawings. If currently existing equipment is to be utilized, the refurbished equipment will be required to comply with all requirements of the applicable transfer cask and transfer adapter aging management program, as will equipment that is in storage at some of the decommissioned sites prior to delivery to the NAC-UMS licensees.

The applicant also revised element 1 of the TFRs and Transfer Adapters AMP to add a statement specifying that, before use of a refurbished TFR and transfer adapter for future campaigns, the equipment shall be inspected in accordance with this AMP.

The staff reviewed the proposed revisions to FSAR chapter 1, section 1.2.1, and element 1 of the TFRs and Transfer Adapters AMP and confirmed that they provide adequate controls to ensure that, for facilities that do not normally maintain a TFR and transfer adapter on site, the TFR and transfer adapter components for refurbished equipment and equipment that is in storage will receive the requisite inspections and associated activities required by this AMP.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3-59 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. The staff confirmed that NUREG-2214 does not specify any preventive actions for addressing aging or degradation of reinforced concrete structures during the period of extended operation since this AMP is for condition monitoring.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application states that parameters monitored or inspected for accessible TFR and transfer adapter surfaces include visual evidence of corrosion resulting in obvious loss of base metal; visual evidence of coating loss, which, left uncorrected, could result in loss of base metal; visual evidence of wear resulting in loss of base metal; and cracking or excessive wear or galling of trunnion surfaces.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

4. Detection of Aging Effects Consistent. The Detection of Aging Effects AMP element in the updated renewal application specifies general visual inspections of steel surfaces of all TFRs and transfer adapters using direct examination methods to identify applicable aging effects, including coating damage, cracking, and loss of base material due to corrosion and wear. The extent of visual inspection coverage will include all normally accessible TFR and transfer adapter interior cavities and exterior surfaces, retaining rings and associated bolting, shield doors, and shield door rails. This element also includes dye penetrant examinations of accessible TFR trunnion surfaces for the presence of fatigue cracks in accordance with ASME BPV Code,Section III, Subsection NF, NF-5350.

The staff noted that the AMP In the original renewal application did not cite consensus standard criteria or other suitable methods that describe how procedures are controlled to ensure that visual inspections of the TFRs and transfer adapters will use sufficient resolution and lighting to adequately detect the applicable aging effects, including coating degradation, loss of base metal due to

3-60 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs wear, loss of base metal due to corrosion, and indications of cracking.

Therefore, the staff issued RAI A-6 (NRC, 2021b), requesting that the applicant state how visual inspection parameters will be controlled to ensure that the TFRs and Transfer Adapters AMP will be capable of identifying degradation; the staff also requested that the applicant revise the AMP as needed to clarify the expectations of general licensees for controlling visual inspection parameters.

In its response to RAI A-6 (NAC International, 2022a), the applicant revised elements 4 and 6 of the TFRs and Transfer Adapters AMP in the renewal application to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Subsection IWE, for general visual examinations of the TFRs and transfer adapters.

Element 4 includes new provisions requiring the following:

Visual examinations shall comply with the requirements in the ASME BPV Code,Section XI, paragraph IWE-2311, or their equivalent.

Personnel performing visual examinations for this AMP shall meet the qualification requirements of ASME BPV Code,Section XI, paragraph IWE-2330(b), or their equivalent.

The staff reviewed the new requirements for general visual examinations of TFRs and transfer adapters and confirmed that they provide the procedural attributes needed for effective visual examinations by qualified personnel, including equipment resolution, lighting standards, distance, surface coverage, and surface assessment to adequately detect applicable aging effects. Therefore, the staff determined that these methods are acceptable for detection of aging effects.

The revisions to element 6 include new acceptance criteria for visual inspections that incorporate paragraph IWE-3511 of the ASME BPV Code,Section XI. The staff gives a detailed review of these acceptance criteria below for AMP element 6.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will establish a baseline during the first inspection in the period of extended operation. This element also states that tracking

3-61 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs and trending of inspections will include locations, size, and depth of any areas of corrosion or coating loss that could result in measurable loss of base metal, locations of wear that results in measurable loss of base metal, and indications on the TFR trunnions.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application states that, for accessible surfaces, acceptance criteria are no loss of base material due to corrosion or wear; no large areas of coating failures that could expose base material to active corrosion; and, for accessible trunnion surfaces, acceptable dye penetrant examination results in accordance with the acceptance criteria of the ASME BPV Code,Section III, Subsection NF, NF-5350.

In its response to RAI A-6 (NAC International, 2022a), the applicant revised elements 4 and 6 of the TFRs and Transfer Adapters AMP in the renewal application to require the use of in-service inspection criteria from the 2007 Edition of the ASME BPV Code,Section XI, Subsection IWE, for general visual examinations of the TFRs and transfer adapters. Changes to element 4 are addressed above for that AMP element.

Element 6 of the TFRs and Transfer Adapters AMP includes an additional acceptance criterion specifying that the inspected condition of the examined area must meet the ASME BPV Code,Section XI, IWE-3511, acceptance standard or its equivalent.

IWE-3511 specifies that the condition of the examined area is acceptable if the examination determines that there is no evidence of damage or degradation sufficient to warrant further evaluation or performance of a repair or replacement activity; suspect conditions shall be evaluated to the extent necessary to ensure that the component function is not impaired. The staff noted that this additional acceptance criterion for general visual examinations of the TFRs and transfer adapters is to be used in concert with the other acceptance criteria included for this AMP element. The staff verified that, collectively, these acceptance criteria provide suitable standards for general licensees to use in their AMP procedures for determining whether or not coating degradation, loss of base metal due to wear, loss of base metal due to corrosion, or indications of cracking are present for the TFRs and transfer adapters; general licensees will take corrective actions if such aging effects are present.

3-62 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that inspection results that do not meet the acceptance criteria are addressed under the general licensees approved QA program. This element also states that the QA program will ensure that corrective actions are completed within the general licensees corrective action program.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that the confirmation process is commensurate with the general licensees approved QA program.

The QA program will ensure that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is

3-63 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for TFRs consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The renewal application included prior inspection results and relevant operating experience for this AMP. The applicant summarized these inspection results in the renewal application as described below.

During the periods of use of the TFRs and transfer adapters at general licensee facilities, these components were maintained and inspected in accordance with the standard requirements of American National Standards Institute N14.6-1993, American National Standard for Radioactive MaterialsSpecial Lifting Devices for Shipping Containers Weighing 10 000 Pounds (4500 Kg) or More (American National Standards Institute, 1993). During operation of the TFRs and transfer adapters, areas of coating degradation were repaired by reapplication of coatings. No issues with general, pitting, crevice, or galvanic corrosion have been identified. No excessive wear or loss of material has been identified on shield door rail or transfer adapter surfaces. No cracking of TFR lifting trunnions has been identified.

The applicant stated that, during the period of extended operation, each general licensee maintaining a TFR and transfer adapter will perform tollgate assessments of aggregated operating experience and other information related to the aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge.

Based on its review of the revisions to this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

Table 3.5-6 AMP Review ResultsNAC-UMS HBU Fuel Monitoring and Assessment AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment

1. Scope of Program Consistent. The Scope of Program AMP element in the updated renewal application states that the HBU Fuel Monitoring and Assessment AMP is a generic program applicable to all licensees storing uncanned HBU fuel assemblies in the NAC-UMS System.

This AMP is based on the use of the testing performed under the Electric Power Research Institute (EPRI) HBU Dry Storage Cask Research and Development Project (HDRP) (Electric Power Research Institute, 2014) as a surrogate demonstration program to provide data on HBU fuel performance. The element states that HBU fuel assemblies stored in the NAC-UMS System are limited by TS to

3-64 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment an assembly average burnup no greater than 60 GWd/MTU. The maximum HBU fuel assembly burnup loaded into an NAC-UMS System had a nominal burnup of less than 55 megawatt days (MWd)/MTU and was loaded on July 18, 2014. The HBU fuel assemblies have zirconium alloy fuel cladding (e.g., Zirc-4, ZIRLO, low-tin Zirc-4, and M5). All HBU fuel assemblies will be stored in a high-purity helium atmosphere and are bounded by the temperature limits of the NRC interim staff guidance (ISG) in ISG-11, Revision 3, Cladding Considerations for the Transportation and Storage of Spent Fuel, dated November 17, 2003 (NRC, 2003). The program will manage issues that may affect the ability to comply with 10 CFR 72.122(h)(1), including fuel cladding temperature, fuel cladding breach, assembly distortion, residual moisture after drying, changes in hydride structure of the cladding, and cladding creep.

The staff noted that the applicants description of this AMP element did not justify the applicability of the EPRI HDRP to the HBU fuel stored in the NAC-UMS System, considering that the HBU fuel assemblies stored in the NAC-UMS System are limited by TS to an average burnup of 60 GWd/MTU, which is 5 GWd/MTU greater than the maximum specified nominal burnup of the HBU fuel stored in the HDRP cask. However, the staff noted that there are casks that are currently licensed for storage of HBU fuel with burnups that exceed the 60 GWd/MTU TS limit for the NAC-UMS System, and to date, the maximum burnup for HBU fuel loaded into a NAC-UMS System had a nominal burnup of less than 55 MWd/MTU. Therefore, considering that the AMP provides for incorporation of industry operating experience with higher burnups, including those potentially exceeding 60 GWd/MTU, the staff determined there is no concern with the NAC-UMS System TS limit of 60 GWd/MTU for HBU fuel stored in the NAC-UMS System.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

2. Preventive Actions Consistent. The Preventive Actions AMP element in the updated renewal application states that this AMP is for condition monitoring and does not include preventive actions. However, the applicant included information on the NAC-UMS System TS requirements for initial loading operations of the NAC-UMS TSCs to show that the HBU fuel is stored in a dry and inert environment to prevent cladding degradation due to oxidation mechanisms and that loading of the TSCs is within the temperature limits of ISG-11, Revision 3 (NRC, 2003).

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the

3-65 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3. Parameters Monitored or Inspected Consistent. The Parameters Monitored or Inspected AMP element in the updated renewal application states that the AMP uses the EPRI HDRP to monitor fuel cladding temperature and cavity gas temperature, pressure, and composition. This element also states that monitoring of these parameters and physical examinations of fuel performed under the HDRP should be able to provide information on the degradation models, condition of the fuel, and degradation mechanisms.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

4. Detection of Aging Effects Consistent. The Detection of Aging Effects AMP element in the updated renewal application states that this AMP relies on the EPRI HDRP to verify there are no unexpected aging effects or to identify aging effects if they occur. The staff noted that the applicants description of parameters monitored and physical examinations of fuel performed under the HDRP, addressed in AMP element 3, are adequate to cover this AMP element.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

5. Monitoring and Trending Consistent. The Monitoring and Trending AMP element in the updated renewal application states that monitoring and trending methods will be used to assess information and data from the HDRP or from other sources (such as testing or research results and scientific analyses) when it becomes available. Licensees will monitor, evaluate, and trend the information through their operating experience program to determine what actions should be taken to manage fuel and cladding performance, if any. Formal evaluations (AMP tollgate assessments) of the aggregate information from the HDRP and other available domestic or international operating experience (including data from monitoring and inspection programs, NRC-generated communications, and other information) will be performed at specific points in time during the period of extended operation, as delineated in table 14.5-2 of the NAC-UMS System FSAR. If any of the acceptance criteria of element 6 are not met, additional assessments and appropriate corrective actions must be implemented in accordance with element 7.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element

3-66 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

6. Acceptance Criteria Consistent. The Acceptance Criteria AMP element in the updated renewal application lists and describes eight fuel performance criteria that, if not met in the HDRP, would necessitate corrective action. The fuel performance criteria described in the application include cladding temperature, cavity gas temperature, cavity gas pressure, cladding creep, hydrogen content, moisture content, fuel rod condition and performance (as ascertained through nondestructive and destructive tests), and fuel rod cladding breach.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

7. Corrective Actions Consistent. The Corrective Actions AMP element in the updated renewal application states that corrective actions should be implemented if data from the HDRP or other sources of information indicate that any of the HDRP acceptance criteria are not met. This element describes actions that licensees will take if any acceptance criteria are not met, including assessment of fuel performance and assessment of the design bases and safety analyses, considering degraded fuel performance. This element also states that licensees will determine what corrective actions should be taken to manage fuel performance and manage impact related to degraded fuel performance to ensure that all intended functions of the NAC-UMS System are met. NRC approval will be obtained for any needed modification of the design bases to address any condition outside of the approved design bases.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

8. Confirmation Process Consistent. The Confirmation Process AMP element in the updated renewal application states that the confirmation process will be commensurate with the general licensees approved QA program.

The QA program ensures that the confirmation process includes provisions to preclude repetition of significant conditions adverse to quality. This element specifies that the confirmation process will describe or reference procedures to determine follow-up actions to verify effective implementation of corrective actions and monitor for adverse trends due to recurring or repetitive findings or observations.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element

3-67 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

9. Administrative Controls Consistent. The Administrative Controls AMP element in the updated renewal application states that administrative controls will be in accordance with the general licensees approved QA program. The QA program ensures that administrative controls include provisions that define instrument calibration and maintenance, inspector requirements, record retention requirements, and document control.

This element also specifies that the administrative controls describe or reference methods for reporting results to the NRC and address the frequency for updating an AMP based on site-specific, design-specific, and industrywide operating experience.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

10. Operating Experience Consistent. The applicant stated that NAC-UMS general licensees have no specific operating experience with the performance of HBU fuel in dry storage to date. The applicant stated that during the period of extended operation, each general licensee will perform tollgate assessments of aggregated operating experience and other information related to the aging effects and mechanisms addressed by this AMP to determine whether changes to the AMP are required to address the current state of knowledge. HBU fuel tollgate assessments will reference and evaluate applicable operating experience, including the following:

internal and industrywide condition reports internal and industrywide corrective action reports vendor-issued safety bulletins NRC information notices and NUREGs International Atomic Energy Agency publications on operating experience for HBU fuel performance applicable U.S. Department of Energy or industry initiatives, including the EPRI HDRP applicable research (e.g., Oak Ridge National Laboratory studies on bending responses of the fuel, Argonne National Laboratory and Central Research Institute of Electric Power Industry studies on hydride reorientation effects)

3-68 AMP Element Staff Evaluation of Consistency with NUREG-2214 Example AMP for HBU Fuel Monitoring and Assessment The applicant stated that the review of operating experience will clearly identify any HBU fuel degradation as either age related or event driven, with proper justification for that assessment. Review of operating experience will inform and support the adequacy of the HDRP.

Based on its review of this AMP in the updated renewal application, the staff finds that the applicants description of this AMP element follows the guidance in NUREG-1927 and is consistent with the example AMP in NUREG-2214. Therefore, the staff determined that the applicants description of this AMP element is acceptable.

3.5.1 Aging Management Tollgates In section 3.5 of the renewal application for the NAC-UMS System, the applicant described periodic aging management tollgate assessments that general licensees are to perform during the period of extended operation. Periodic tollgate assessments are part of the applicants aging management requirements for the NAC-UMS System certificate of compliance (CoC) renewal.

The applicants requirements and schedule for the periodic tollgate assessments will be incorporated into chapter 14 of the NAC-UMS System FSAR. The purpose of the tollgate concept is to provide a structured way for licensees to formally assess aggregated aging management feedback at specific points in time during the period of extended storage and perform a safety assessment that confirms the safe storage of spent nuclear fuel. The staff noted that the applicants approach to periodic tollgate assessments is based on the recommendations in Nuclear Energy Institute (NEI) report, NEI 14-03, Revision 2, Format, Content and Implementation Guidance for Dry Cask Storage Operations-Based Aging Management, issued December 2016 (NEI, 2016), which has been endorsed (with clarifications) by the NRC in Regulatory Guide 3.76, Implementation of Aging Management Requirements for Spent Fuel Storage Renewals, issued July 2021 (NRC, 2021a).

The applicant stated that general licensees are required to perform and document periodic tollgate assessments based on a review of aging-related operating experience, research findings, monitoring data, and inspection results to ascertain the ability of in-scope NAC-UMS System SSCs to continue to perform their intended safety functions throughout the period of extended operation. The applicant stated that the requirements for the periodic tollgate assessments must be addressed in the procedures that are established, maintained, and implemented by each general licensee for the NAC-UMS System AMPs.

The applicant stated that each general licensee shall complete the initial tollgate assessment within 5 years following the 20th in-service year of the first UMS system loaded at each site or 6 years after the effective date of the CoC renewal, whichever is later. Subsequent tollgate assessments will be performed at a 10-year (+/- 1 year) frequency thereafter. The initial tollgate assessment is timed to allow the initial round of AMP inspections to be completed at the general licensed site before the initial tollgate assessment, such that the operating experience gained from the initial round of AMP inspections can be evaluated and assessed. The applicant further stated that the 10-year frequency for subsequent tollgate assessments reflects the risk significance of the aging effects managed by AMPs. The applicant stated that, if the results of previous tollgate assessments indicate unanticipated or accelerated aging effects, the period for follow-up assessments will be reduced, based on the rate of progression of the aging

3-69 mechanisms identified and their risk significance. The tollgate assessment report shall include the basis for any adjustments in the tollgate assessment frequency.

The applicant stated that the periodic tollgate assessments to be performed by each general licensee shall consider the operating experience related to the aging effects managed by the AMPs from the general licensees completed inspections and those of other general licensees that use the NAC-UMS System. The assessments will also consider new information on relevant aging effects from related industry operating experience, research findings, monitoring data and inspection results, NRC generic communications, U.S. Department of Energy research updates, and relevant information and reports from industry organizations such as the NEI, EPRI, and the Institute of Nuclear Power Operations, as applicable. The aggregated operating experience will be evaluated to identify any new aging effects or aging mechanisms that may be applicable to the in-scope SSCs of the NAC-UMS System or existing aging effects that are not adequately managed by the current AMPs or TLAAs. The assessment will also evaluate whether continued safe storage is expected until the next tollgate assessment, or whether additional aging management activities are necessary to address newly identified aging effects requiring management.

The applicant further stated that each general licensee shall document the periodic tollgate assessment in a report, which will include the following information, at a minimum:

the sources of operating experience, aggregated research findings, monitoring data, and inspection results considered in the assessment a summary of the operating experience, research findings, monitoring data, and inspection results the potential impact, if any, of the operating experience, research findings, monitoring data, and inspection results on the AMPs or TLAAs for the in-scope SSCs recommended corrective actions to be implemented to address newly identified aging effects that are not adequately managed by the existing AMPs or TLAAs summary and conclusions The applicant stated that general licensees will maintain tollgate assessment reports as permanent records in accordance with the requirements of the QA program, and the reports will be available for NRC inspection. A copy of each tollgate assessment report will also be provided to the CoC holder. The tollgate assessment reports will be disseminated through an industry organization.

The staff reviewed the applicants description of proposed actions to ensure that the AMPs for the NAC-UMS System remain adequate during the period of extended operation based on a review of new aging management operating experience, inspection results, and component aging-related research. Based on the review of the proposed FSAR supplement, to be included in FSAR chapter 14, covering aging management activities for the NACUMS System, the staff confirmed that the applicants periodic tollgate assessments incorporate the use of the ISFSI Aging Management Institute of Nuclear Power Operations Database (ISFSI AMID). The staff considers that the applicants implementation of periodic tollgate assessments and the use of the ISFSI AMID, in addition to other periodic operating experience reviews consistent with the

3-70 site QA program, provide reasonable assurance that the applicants AMPs will remain adequate for managing the effects of aging during the period of extended operation.

3.5.2 Evaluation Findings The staff reviewed the AMPs provided in the renewal application for the NAC-UMS System and in the proposed FSAR supplement. The staff performed its review by following the guidance in NUREG-1927, Revision 1, and NUREG-2214. The staff evaluated the 10 elements of the proposed AMPs to determine their adequacy for managing the applicable aging mechanisms and aging effects for the in-scope SSCs and their subcomponents. For each program element, the staff either confirmed its consistency with the corresponding element of the example AMP in NUREG-2214 or confirmed that the applicants alternative approach is adequate to manage all credible aging effects. Based on its review, the staff finds the following:

F3.4 The applicant has identified programs that provide reasonable assurance that aging mechanisms and effects will be managed effectively during the period of extended operation, in accordance with 10 CFR 72.240(c)(3).

4-1 4 CHANGES TO CERTIFICATE OF COMPLIANCE AND TECHNICAL SPECIFICATIONS This section provides a consolidated list of the changes to the certificate of compliance (CoC) conditions and technical specifications resulting from the review of the renewal application. The basis of the changes is provided here for those changes that the U.S. Nuclear Regulatory Commission (NRC) staff does not describe elsewhere in this safety evaluation report.

Changes to the Certificate of Compliance

1.

Added the following condition to the initial CoC (Amendment 0) and Amendments 1-9:

FSAR UPDATE FOR RENEWED CoC The CoC holder shall submit an updated final safety analysis report (FSAR) to the Commission, in accordance with 10 CFR 72.4, within 90 days of the effective date of the CoC renewal. The UFSAR shall reflect the changes resulting from the review and approval of the CoC renewal.

The CoC holder shall continue to update the UFSAR pursuant to the requirements of 10 CFR 72.248.

The CoC holder has indicated that changes will be made to the updated FSAR to address aging management activities resulting from the renewal of the CoC. This condition ensures that the updated FSAR changes are made in a timely fashion to enable general licensees using the storage system during the period of extended operation to develop and implement necessary procedures.

The CoC holder proposed changes in FSAR section 8.0 that outlined administrative controls intended to clarify the approach to various short-term operations (NAC International, 2022c).

After additional consideration, in a subsequent supplement (NAC International, 2022e), the CoC holder requested that the renewal application no longer include those administrative controls.

The staff confirms that these administrative controls are not included in this CoC condition.

2.

Added the following condition to the initial CoC (Amendment 0) and Amendments 1-9:

10 CFR 72.212 EVALUATIONS FOR RENEWED CoC USE Any general licensee that initiates spent fuel dry storage operations with the NAC-MPC System after the effective date of the CoC renewal and any general licensee operating a NAC-MPC System as of the effective date of the CoC renewal, including those that put additional storage systems into service after that date, shall:

a. As part of the evaluations required by 10 CFR 72.212(b)(5), include evaluations related to the terms, conditions, and specifications of this CoC amendment as modified (i.e., changed or added) as a result of the renewal of the CoC.

4-2

b. As part of the document review required by 10 CFR 72.212(b)(6),

include a review of the FSAR changes resulting from the renewal of the CoC and the NRC Safety Evaluation Report related to the renewal of the CoC.

c. Ensure that the evaluations required by 10 CFR 72.212(b)(7) and (8) capture the evaluations and review described in (a.) and (b.) of this CoC condition.

The general licensee shall complete this Condition prior to entering the period of extended operation or no later than one year after the effective date of the CoC renewal, whichever is later.

The staff considers it important to ensure that appropriate considerations for the period of extended operation are evaluated in the general licensees report required by Title 10 of the Code of Federal Regulations (10 CFR) 72.212, Conditions of general license issued under

§ 72.210. These considerations arise from the analyses and assumptions in the renewal application regarding operations during the period of extended operation. This includes potential use by general licensees that may use a new NAC Universal Multi-Purpose Storage (NAC-UMS) System after the CoC has been renewed either at a new or an existing general-licensed independent spent fuel storage installation. The renewal of the CoC is based on assumptions and analyses of the dry storage system and the sites where it is used.

Licensees considering the use of the NAC-UMS System must evaluate it for use at their respective sites. This condition also makes it clear that general licensees that currently use an NAC-UMS System will need to update their 10 CFR 72.212 reports, even if they do not put additional dry storage systems into service after the renewals effective date, in accordance with 10 CFR 72.212(b)(11).

3.

Added the following condition to the initial CoC (Amendment No. 0) and Amendments 1-9:

AMENDMENTS AND REVISIONS FOR RENEWED CoC All future amendments and revisions to this CoC shall include evaluations of the impacts to aging management activities (i.e., time-limited aging analyses and aging management programs) to ensure they remain adequate for any changes to SSCs within the scope of the CoC renewal.

The applicant proposed the above CoC condition in appendix D to the renewal application. The staff recognizes that the CoC may continue to be amended after it has been renewed. This condition ensures that future amendments to the CoC address the renewed design bases for the CoC, including aging management considerations that may arise from the changes to the system in proposed future amendments.

4.

Revised initial CoC (Amendment 0) and Amendments Nos. 1-9 to address change to language in 10 CFR 72.210 and other updates to the regulations:

This change is made for consistency with the language currently in 10 CFR 72.210, General license issued, and other cited regulations and is not pertinent to the safety review conducted for the renewal application. Changes to the text are in bold, which only involves adding new text.

4-3 AUTHORIZATION The NAC-UMS System, which is authorized by this certificate, is hereby approved for general use by holders of 10 CFR Part 50 and 10 CFR Part 52 licenses for nuclear reactors at reactor sites under the general license issued pursuant to 10 CFR 72.210, subject to the conditions specified by 10 CFR 72.212, and the attached appendix A and appendix B.

Any CoC and technical specification language that discusses licensees under 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, was modified to also include licensees under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants. In addition, updates to the regulation citations referenced in the applicable CoC and technical specifications have been changed to reflect citations currently in the regulations.

CHANGES TO TECHNICAL SPECIFICATIONS

1.

Added section A.5.X to appendix A to the technical specifications associated with the initial CoC (Amendment No. 0) and Amendments Nos. 1-9:

The new technical specification [A.5.X] was added:

Aging Management Program Each general licensee shall have a program to establish, implement, and maintain written procedures for each aging management program (AMP) described in the updated final safety analysis report (UFSAR). The program shall include provisions for changing AMP elements, as necessary, and within the limitations of the approved licensing bases, to address new information on aging effects based on inspection findings and/or industry operating experience provided to the general licensee during the renewal period. The program document shall contain a reference to the specific aspect of the AMP element implemented by that procedure, and that reference shall be maintained even if the procedure is modified.

The general licensee shall establish and implement this program document prior to entering the period of extended operation or no later than one year after the effective date of the CoC renewal, whichever is later. The general licensee shall maintain the program document for as long as the general licensee continues to operate NAC-MPC Systems in service for longer than 20 years.

The CoC holder proposed a condition to revise or create programs or procedures for implementing the AMPs in the supplement to the FSAR. This specification ensures that programs or procedures address AMP activities required for extended storage operations.

5-1 5 CONCLUSION Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 72.240(d), the U.S. Nuclear Regulatory Commission (NRC) will renew the certificate of compliance (CoC) of a design of a spent fuel storage cask if (1) the quality assurance requirements in 10 CFR Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater than Class C Waste, Subpart G, Quality Assurance, are met, (2) the requirements of 10 CFR 72.236(a) through (i) are met, and (3) the application includes a demonstration that the storage of spent fuel has not, in a significant manner, adversely affected the structures, systems, and components important to safety. Additionally, 10 CFR 72.240(c) requires that the safety analysis report accompanying the application contain time-limited aging analyses and aging management programs that demonstrate that the dry storage systems structures, systems, and components will continue to perform their intended functions for the requested period of extended operation.

The NRC staff reviewed the renewal application for the NAC-Universal Multi-Purpose Storage (NAC-UMS) System, in accordance with NRC regulations in 10 CFR Part 72. The staff followed the guidance in NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, issued June 2016 (NRC, 2016). Based on its review of the renewal application and the CoC conditions, the staff determines that the dry storage system has met the requirements of 10 CFR 72.240, Conditions for spent fuel storage cask renewal.

6-1 6 REFERENCES American Concrete Institute (ACI), ACI 349.3R-18, Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete Structures, Farmington Hills, Michigan, January 2018.

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_____. NUREG-1927, Revision 1, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, Final Report, Washington, DC, June 2016. ML16179A148.

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