ML21334A471

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Enclosure 5 CoC 1021 Renewal - Safety Evaluation Report- December 2021
ML21334A471
Person / Time
Site: 07201021
Issue date: 12/08/2021
From:
Division of Fuel Management
To:
JACOBS C NMSS/DFM 301-415-6825
Shared Package
ML21334A465 List:
References
CAC 001028, EPID L-2020-RNW-0009
Download: ML21334A471 (75)
v • d • e


Text

SAFETY EVALUATION REPORT

FOR THE TN-32 DRY STORAGE CASK CERTIFICATE OF COMPLIANCE RENEWAL

DOCKET NO. 72-1021

Office of Nuclear Material Safety and Safeguards United States Nuclear Regulatory Commission

December 2021

CONTENTS

EXECUTIVE

SUMMARY

.............................................................................................................. iv

1 GENERAL INFORMATION................................................................................................ 1-1 1.1 CoC and CoC Holder Information............................................................................. 1-1 1.2 Safety Review........................................................................................................... 1-1 1.3 Application Content................................................................................................... 1-2 1.4 NRC Guidance Documents....................................................................................... 1-2 1.5 Evaluation Findings.................................................................................................. 1-3

2 SCOPING EVALUATION................................................................................................... 2-1 2.1 Scoping and Screening Methodology....................................................................... 2-1 2.1.1 Scoping Process........................................................................................... 2-2 2.1.2 Scoping Results............................................................................................ 2-2 2.1.3 Structures, Systems, and Components Within the Scope of the ren ewal Review.......................................................................................................... 2-3 2.1.4 Structures, Systems, and Components Not Within the Scope of the Renewal Review........................................................................................... 2-5 2.2 Evaluation Findings.................................................................................................. 2-7

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......................................................................... 3-2 3.3.1 Materials and Service Environments............................................................. 3 -2 3.3.2 Operating Experience................................................................................... 3-6 3.3.3 Aging Mechanisms and Aging Effects........................................................... 3-6 3.3.4 Supplemental Evaluation............................................................................ 3-32 3.4 Evaluation Findings................................................................................................ 3-33 3.5 Time-Limited Aging Analyses Evaluation................................................................ 3-34 3.5.1 Boron Depletion in the in the borated aluminum plates.............................. 3-34 3.5.2 Establishment of fuel cladding temperature limits....................................... 3-35 3.5.3 Ensure cavity pressure remains above one atmosphere on the cold est day at the end of the storage period........................................................... 3-36 3.5.4 Evaluation Findings..................................................................................... 3-37 3.6 Aging Management Programs................................................................................ 3-38 3.6.1 TN-32 AMP................................................................................................. 3-39 3.6.2 Storage pad AMP........................................................................................ 3-44 3.6.3 Earthen berm AMP...................................................................................... 3-50 3.6.4 Changes to the Updated Final Safety Analysis Report............................... 3-54 3.6.5 Evaluation Findings..................................................................................... 3-54

4 CONDITIONS TO ADDRESS RENEWAL.......................................................................... 4-1 4.1 Changes to Certificate of Compliance...................................................................... 4-1 4.2 Changes to Technical Specifications........................................................................ 4-2

5 CONCLUSIONS................................................................................................................. 5-1

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

ii TABLES

Table Page

2.1-1 SSCs/contents within and not within the scope of the rene wal review....................... 2-3

3.3-1 Aging management reviewmaterials....................................................................... 3-4

3.3-2 Aging management reviewenvironments................................................................ 3-5

3.3-3 Summary of the aging mechanisms and aging effects for ste el............................... 3-17

3.3-4 Summary of the aging mechanisms and aging effects for sta inless steel................ 3-18

3.3-5 Summary of the aging mechanisms and aging effects for alu minum........................ 3-19

3.3-6 Summary of the aging mechanisms and aging effects for nic kel alloys................... 3-20

3.3-7 Summary of the aging mechanisms and aging effects for pol ymer materials.......... 3-21

3.3-8 Summary of the aging mechanisms and aging effects for bor ated aluminum.......... 3-21

3.3-9 Summary of the aging mechanisms and aging effects for con crete......................... 3-22

3.3-10 Summary of the aging mechanisms and aging effects for sp ent fuel assembly cladding materials.................................................................................................... 3-23

3.3-11 Summary of the aging mechanisms and aging effects for sp ent fuel assembly hardware materials................................................................................................... 3-24

3.3-12 Summary of the aging mechanisms and aging effects for so il materials................. 3-25

3.3-13 Aging mechanisms and effects that require aging manageme ntTN-32 Dry Storage Cask............................................................................................................ 3-2 7

3.3-14 Aging mechanisms and effects that require aging manageme ntISFSI Storage pad............................................................................................................................ 3-29

3.3-15 Aging mechanisms and effects that require aging manageme ntEarthen Berm..... 3-31

iii EXECUTIVE

SUMMARY

In accordance with 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, the U.S. Nuclear Regulatory Commission (NRC) issued TN Americas LLC a Certificate of Compliance for 20 years, with an expiration date of April 19, 2020. The NRC approved the TN-32 Dry Storage Cask design under 10 CFR Part 72, Subpart K for storage of spent nuclear fuel (SN F) in an independent spent fuel storage installation (ISFSI) at power reactor sites to persons authorized to possess or operate nuclear power reactors under 10 CFR Part 50 or 10 CFR Part 52.

By letter dated March 5, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML20065J427), as supplemented by lette rs dated November 11, 2020 (ADAMS Accession Number ML20316A030), February 5, 2021 (AD AMS Accession Number ML21036A237), and March 17, 2021 (ADAMS Accession Number ML21076A040), TN Americas LLC (applicant) submitted an application to the NRC fo r renewal of Certificate of Compliance (CoC or certificate) No. 1021, for a period of 40 ye ars beyond the initial certificate period. The applicant submitted the renewal application in acc ordance with the regulatory requirements of 10 CFR 72.240, Conditions for spent fuel stora ge cask renewal. Under 10 CFR 72.240(b), because the applicant submitted the renewal appl ication more than 30 days before the Certificates expiration date, this application cons titutes a timely renewal. In the application, the applicant documented the technical bases for r enewal of the certificate and commitments to actions for managing the potential aging effects of the systems, structures, and components (SSCs) of the dry storage system to ensure that thes e SSCs will maintain their intended functions during the period of operation that extends beyond the length of the term certified by the current certificate (referred to hereafter as the period of extended operation (PEO) or extended storage).

The TN-32 Dry Storage Cask is a bolted lid, metal cask dry stor age system (DSS). The TN-32 Dry Storage Cask has integrated trunnions that allow the cask t o be lowered into the spent fuel pool for loading, and transferred to the storage pad after dryi ng, and inerting. The TN-32 Dry Storage Cask has integrated gamma and neutron shielding to mini mize the radiation dose rate from the ISFSI. The TN-32 Dry Storage Cask is designed to with stand all normal, off-normal, and credible accident conditions.

In the renewal application, the applicant presented general inf ormation about the DSS design with a scoping analysis to determine the SSCs that are within t he scope of the renewal and subject to an aging management review (AMR). The applicant fur ther screened the in-scope SSCs to identify and describe the subcomponents that support th e in-scope SSC intended function(s). The applicant documented the technical bases for renewal of the CoC and proposed actions for managing potential aging effects on the SS Cs that are within the scope of renewal to ensure that these SSCs will maintain their intended functions during the PEO. For each in-scope SSC subcomponent, the applicant provided one of t he following to assure that the SSC will maintain its intended function(s) during the PEO: (1) an analysis which supports finding that no aging management is necessary because no aging effects are relevant for the SSC; (2) updated, time-limited aging analyses (TLAA); (3) a sup plemental aging analysis; or (4) an aging management program (AMP).

The NRC staff (staff) reviewed the technical bases for safe ope ration of the DSS for an additional 40 years beyond the current CoC term of 20 years. T his safety evaluation report (SER) summarizes the results of the staffs review for complian ce with 10 CFR 72.240. In its

iv review of the application and development of the SER, the staff followed 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 Fue l, dated June 2016 (NRC, 2016a) (ADAMS Accession No. ML16179A148), and (2) NUREG-2214, Managing Aging Processes In Storage (MAPS) Report, issued July 2019 (NRC, 201 9) (ADAMS Accession No. ML19214A111). NUREG-2214 establishes a generic technical basis for the safety review of ISFSI license and DSS CoC renewal applications, in terms of the evaluation of (1) aging mechanisms and effects that could affect the ability of ISFSI a nd DSS SSCs to fulfill their safety functions in the PEO (i.e., credible aging mechanisms and effec ts) and (2) aging management approaches to address credible aging effects, including example s of aging management programs that are considered generically acceptable to address the credible aging effects to ensure that the design bases will be maintained in the PEO. Th e staff evaluated the applicants technical basis for its aging management review and proposed ag ing management programs and compared it to the generic technical basis in NUREG-2214. For comparison to the generic technical basis in NUREG-2214, the staff ensured that the desig n features, environmental conditions, and operating experience for the TN-32 Dry Storage Cask are bounded by those evaluated in NUREG-2214.

This SER is organized into six sections. Section 1 provides th e staffs review of the general information of the DSS. Section 2 presents the staffs review of the scoping evaluation performed for determining which SSCs are within the scope of th e renewal. Section 3 provides the staffs evaluation of the aging management review for asses sment of aging effects and aging management activities for SSCs within the scope of the re newal. Section 4 documents the additions and changes to the license that resulted from the review of the license renewal application. Section 5 presents the staffs conclusions from i ts review. Section 6 lists the references supporting the staffs review and technical determin ations.

v 1 GENERAL INFORMATION

1.1 CoC and CoC Holder Information

On March 5, 2020, (ADAMS Accession Number ML20065J427), as supp lemented on November 11, 2020 (ADAMS Accession Number ML20316A030), February 5, 2021 (ADAMS Accession Number ML21036A237), and March 17, 2021 (ADAMS Accession Number ML21076A040), TN Americas LLC (applicant or TN) submitted an application to rene w Certificate of Compliance (CoC or certificate) No. 1021 for the TN-32 Dry Storage Cask un der the provisions of 10 CFR Part 72, subparts K and L.

The applicant requested renewal of the initial CoC and Amendmen t No. 1. The NRC issued the initial CoC (Amendment 0) on April 19, 2000, and Amendment No. 1 on February 20, 2001. In its renewal application, TN provided a description of the certi fication basis for the TN-32 Dry Storage Cask initial issuance; general descriptions of the chan ges and reasons for Amendment No. 1; the date of CoC and CoC amendment issuance; and the corr esponding updated final safety analysis report (UFSAR) revisions which incorporated the changes from Amendment No.

1. The applicant also provided a list of the amendments (i.e., Amendment No. 0 and Amendment No. 1) in Chapter 1 of the renewal application, with details and references.

1.2 Safety Review

The objective of this safety review is to determine whether the TN-32 Dry Storage Cask continues to meet the requirements of 10 CFR Part 72 during the period of operation that extends beyond the length of the term certified by the current certificate (referred to hereafter as the period of extended operation (PEO) or extended storage). T he NRC staff safety review is a detailed and in-depth assessment of the technical aspects of th e TN-32 Dry Storage Cask conducted for the CoC No. 1021 renewal application. Pursuant t o 10 CFR 72.240(c)(1),

72.240(c)(2), and 72.240(c)(3), an application for renewal of a spent fuel storage cask CoC must be accompanied by a safety analysis report (SAR). The SAR must include the following:

(i) design-bases information as documented in the most recently updated final safety analysis report as required by 10 CFR 72.248, (ii) time-limited aging an alyses (TLAAs) that demonstrate that structures, systems, and components (SSCs) important to sa fety will continue to perform their intended function for the requested PEO, and (iii) a desc ription of the aging management program(s) (AMP(s)) for management of issues associated with ag ing that could adversely affect structures, systems, and components important to safety.

The applicant stated that the renewal application Section 1.1 i s consistent with guidance provided in NUREG-1927, Revision 1, Standard Review Plan for R enewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel issued June 2016 (ADAMS Accession No. ML16179A148) (NRC 2016a). In addition, th e applicant stated that credible aging mechanisms for the SSC material/environment comb inations included in the scope of the renewal was consistent with the evaluation in NURE G-2214, Managing Aging Processes in Storage (MAPS) Report, issued July 2019 (ADAMS Ac cession No.

ML19214A111) (NRC 2019). The applicant provided a scoping eval uation; an aging management review (AMR); and TLAAs and AMPs to assure that the SSCs within the scope of the renewal will continue to perform their intended function du ring the PEO.

1-1 The applicant stated that the renewal application is based on t he continuation of the approved design basis throughout the PEO in accordance with NUREG-1927. In addition, the applicant stated that the identification and management of potential agin g degradation mechanisms for different material/environment com binations was consistent with the generic evaluation in NUREG-2214 in support of the renewal application. This review documents the staffs evaluation of the applicants scoping and screening evaluation, AMR, and supporting TLAAs, and AMPs per the guidance in NUREG-1927, as informed by NUREG-2 214.

1.3 Application Content

The applicants renewal application provided the following:

  • general information
  • scoping evaluation
  • operating experience (OE) review
  • TLAAs and other supplemental evaluations
  • changes to the TN-32 Dry Storage Cask UFSAR
  • changes to the TN-32 Technical Specifications (TS)

The applicant had previously provided UFSAR revisions for all C oC amendments. The UFSAR revisions incorporated all changes to the TN-32 Dry Storage Cas k previously made without prior NRC approval in accordance with 10 CFR 72.48(c) and (d). The a pplicant included the UFSAR changes for the updated TLAAs and AMPs in Attachment A of the r enewal application. The applicant included proposed changes to the TS and CoC condition s in Attachment B of the renewal application.

1.4 NRC Guidance Documents

The staff relied on the guidance in NUREG-1927 to conduct the r eview of the renewal application. Specifically, the staff used the guidance in NURE G-1927, Chapter 2, Scoping Evaluation, to review the process used by the applicant for the scoping evaluation and the scoping evaluation results. The guidance in NUREG-1927, Chapte r 3, Aging Management Review, was used to evaluate the applicants AMR process, and r esults. The guidance in NUREG-1927, Section 3.4, Materials, Service Environments, Aging Mechanisms and Effects, and Aging Management Activities, was used to review the applica nts evaluation of aging mechanisms and effects of the materials and service environment s for the SSCs and their subcomponents that were in the scope of renewal. The guidance in NUREG-1927, Section 3.5, Time-Limited Aging Analyses, was used to review the applicants updated TLAAs, and supplemental analyses and the guidance in Section 3.6, Aging Ma nagement Programs, was used to review the applicants AMPs.

The staff used the information in NUREG-2214 to inform its use of the guidance in NUREG-1927. NUREG-2214 is a technical basis document that provides a dditional guidance to NRC staff to improve the effectiveness and efficiency of the renewa l process for the dry storage of SNF. NUREG-2214 provides a generic evaluation of the aging mec hanisms that have the potential to challenge the ability of the dry storage system (D SS) SSCs to fulfill their important-to-safety functions. NUREG-2214 also describes acceptable gene ric AMPs that an applicant may use to maintain the approved design bases of its storage sy stem during the 20- to 60-year

1-2 PEO. The staff used the information in NUREG-2214 to inform th e review of the information in the renewal application related to the identification of materi als, environments, aging mechanisms, and aging effects for the SSCs and their subcompone nts within the scope of renewal. The staff used the ex ample aging management programs in NUREG-2214, Chapter 6, Example Aging Management Programs, to supplement the guidance o n AMPs in NUREG-1927, Section 3.6.

The staff developed Interim Staff Guidance (ISG) to clarify or to address issues not addressed in a Standard Review Plans (SRP), which includes NUREG-1536, S tandard Review Plan for Spent Fuel Dry Storage Systems at a General License Facility, Revision 1 (NRC 2010)

(ADAMS Accession No. ML101040620), and NUREG-1927. ISGs are to be used by the staff, industry, and other interested stakeholders until incorporated into staff guidance documents such as an NRC Regulatory Guide (RG) and SRPs. The applicant s pecifically referenced ISG-2, Revision 0 (ADAMS Accession No. ML092800367) (NRC 1998), and ISG-11, Revision 3 (ADAMS Accession No.ML033230335) (NRC 2003). Therefore, the st aff used the guidance contained in these ISGs to review the applicants evaluation of retrievability and fuel cladding temperatures in the renewal application.

In addition to NUREG-2214, ISG-2, and ISG-11 described above, t he staff also used information included in additional NRC documents and other references to in form the guidance in NUREG-1927. These additional references are cited in this SER with d escriptions of the information in these references and how the staff used the information to info rm the guidance in NUREG-1927.

The staff evaluated the information included in the renewal app lication by comparing the description of the AMR process and results to the guidance in N UREG-1927 as informed by NUREG-2214, ISG-2, and ISG-11, as well as additional NRC docume nts and other references as necessary. The staff determined that the information and de scriptions in the renewal application that followed the guidance in NUREG-1927 were accep table. For the evaluation and descriptions of materials, environments, aging mechanisms, agin g effects, and AMPs for the SSCs and their subcomponents within the scope of renewal, the s taff determined that the information and description provided in the renewal application was acceptable if it was consistent with, or bounded by, the generic evaluation in NUREG -2214.

1.5 Evaluation Findings

The staff reviewed the general information provided in Chapter 1 of the renewal application.

The staff performed its review following the guidance provided in NUREG-1927, and relevant ISGs. Based on its review, the staff finds:

F1.1 The information presented in the renewal application sati sfies the requirements of 10 CFR 72.48, Changes, tests, and experiments, and 10 CFR 72.240, Conditions for spent fuel storage cask renewal.

F1.2 The applicant has provided a tabulation of all supporting information and docketed material incorporated by reference, in compliance with 10 CFR 7 2.240, Conditions for spent fuel storage cask renewal.

1-3 2 SCOPING EVALUATION

As described in NUREG-1927, Chapter 2, a scoping evaluation is necessary to identify the SSCs subject to an AMR, where the effects of aging are assessed. More specifically, NUREG-1927, Section 2.4.2, states that the scoping evaluation i s used to identify SSCs (and associated subcomponents) meeting any of the following criteria (scoping criteria 1 and 2):

(1) SSCs (and associated subcomponents) that are classified as important to safety (ITS),

as they are relied on for one of the following functions:

i. maintain the conditions required by the regulations or the s pecific license, or CoC to store spent fuel safely;

ii. prevent damage to the spent fuel during handling and storag e; or

iii. provide reasonable assurance that spent fuel can be receiv ed, handled, packaged, stored, and retrieved without undue risk to the healt h and safety of the public.

(2) SSCs (and associated subcomponents) that are classified as not important to safety (NITS) but, according to the design bases, their failure could prevent fulfillment of a function that is ITS.

The applicant stated that the ITS functions include (1) sub-cri ticality control, (2) radiation shielding, (3) confinement, (4) heat-removal capability, (5) st ructural integrity, and (6) retrievability. If SSCs and associated subcomponents satisfy o ne of these criteria, they are within the scope of the renewal review.

After the determination of in-scope SSCs, the SSCs are screened to identify and describe the subcomponents that support the SSC intended functions. This sc reening identifies the SSC subcomponents that the applicant evaluates for potential aging effects and mechanisms that may require an aging management activity in the PEO.

2.1 Scoping and Screening Methodology

In Section 2 of the renewal application, the applicant performe d a scoping evaluation and provided the following information:

  • a description of the scoping and screening methodology for the inclusion of SSCs and SSC subcomponents in the scope of the renewal review
  • a list of sources of information used for the scoping evaluati on
  • descriptions of the SSCs; and
  • a list of the SSCs identified to be within and outside the sco pe of the renewal review and the basis for the scope determination.

The staff reviewed the scoping process and results provided in the renewal application. The following section discusses the staffs review and findings on the applicants scoping evaluation.

2-1 2.1.1 Scoping Process

In Section 2.2 of the renewal application, the applicant discus sed the scoping evaluation process and methodology used to determine the SSCs and associat ed subcomponents and subcomponent parts that are within the scope of the renewal. T he applicants scoping evaluation process and methodology identified SSCs as either be ing scoped into the review under scoping criteria 1 and 2, or not scoped into the review f or NITS items that did not meet scoping criterion 2.

The staff reviewed the applicants scoping process and determin ed that the applicants process followed the guidance described in NUREG-1927, Section 2.4, and was acceptable.

2.1.2 Scoping Results

The applicant provided a summary of the results of the scoping evaluation in the renewal application, Table 2-1, and Section 2.3. The applicant provide d detailed scoping analysis results for the all the TN-32 Dry Storage Cask variants includi ng the TN-32, TN-32A, and TN-32B in renewal application, Table 2-2. The applicant provided the detailed scoping analysis results for the spent fuel assemblies in renewal application, T able 2-3.

The applicant stated that, as part of the scoping evaluation, i t reviewed the following sources of information which describe the approved design basis and the in tended safety functions of the SSCs (and associated subcomponents):

  • TN-32 Dry Storage Cask UFSAR, Revision 6, April 2014. (ADAMS A ccession No.

ML14108A025).

  • CoC No. 1021 Certificate and TN-32 TS for each amendment as fo llows.

o Amendment 0 CoC and TS: (ADAMS Accession No. ML003696874).

o Amendment 1: CoC (ADAMS Accession No. ML010460308) and TS (ADA MS Accession No. ML010460423).

The applicant stated that, in defining if SSCs and their subcom ponents were ITS or NITS, it used the drawings in Section 1.5 and Table 2.3-1 of the UFSAR a s the source of both the TN-32 Dry Storage Cask SSCs and subcomponents, the material specifica tions, and safety classification. SSCs that were ITS were determined to be withi n the scope of the renewal per criterion 1. The applicant provided additional information con cluding that the storage pad for the ISFSI should be scoped in under criterion 2 in the renewal appl ication Section 2.3.3. The applicant stated that while the TN-32 Dry Storage Cask does not require the use of an earthen berm to meet regulatory dose limits, Section 10.2 of the TN-32 UFSAR does contain analyses modeling a berm. In the renewal application, the applicant pre sumes that if a general licensee chose to rely on an earthen berm to meet regulatory dose limits, the berm would be classified as an ITS structure and would satisfy criterion 1.

The staff reviewed the scoping results to determine whether the applicant reviewed all SSCs in the approved design bases and whether the conclusions regarding the out-of-scope SSCs accurately reflected the design bases in the TN-32 UFSAR. SER Table 2.1-1 lists the SSCs included and excluded from the scope of the renewal review per the renewal application. SER

2-2 Section 2.1.3 provides the staffs conclusions regarding SSCs ( and SSC subcomponents) within the scope of the renewal review. SER Section 2.1.4 provides th e staffs conclusions regarding SSCs (and SSC subcomponents) outside the scope of the renewal r eview.

Table 2.1-1. SSCs/Contents Within and Not Within the Scope of t he renewal Review

SSC / Contents Criterion 1 Criterion 2 In-Scope (Yes / No)

TN-32 Dry Storage Cask1 Yes N/A Yes Spent Fuel Assemblies Yes N/A Yes ISFSI Concrete Storage Pad No Yes Yes Auxiliary Equipment2 No No No Miscellaneous Equipment3 No No No Earthen Berm4 Yes N/A Yes

1 Includes the TN-32, TN-32A, and TN-32B Dry Storage Casks.

2 Auxiliary equipment used to facilitate cask loading, draining, drying, inerting, and sealing operations include, but are not limited to, special lifting devices, vertical cask transporter, and vacuum drying/helium leak test equipment.

3 Miscellaneous Equipment includes ISFSI security fence and gates, lighting, lightning protection, communications, and monitoring equipment.

4 This is in-scope if an earthen berm is credited by the general licensee in meeting regulatory dose limits. If the general licensee does not credit it, it is not in-scope.

2.1.3 Structures, Systems, and Components Within the Scope of the renewal Review

Per the scoping evaluation process and methodology, as discusse d in Section 2.2 of the renewal application, the applicant identified the SSCs and subc omponents considered to be within the scope of the renewal review. As previously discusse d in SER Section 2.1.1, this approach is consistent with the criteria defined in NUREG-1927. The applicant provided the scoping evaluation of TN-32 Dry Storage Cask system SSCs in ren ewal application, Table 2-1.

The scoping evaluation of the TN-32 Dry Storage Cask subcompone nts and the spent fuel assembly subcomponents are tabulated in renewal application, Ta bles 2-2 and 2-3, respectively.

The following discussions address the applicants basis for inc lusion of an SSC and its subcomponents within the scope of the renewal review and clarif y the staffs review of that basis.

TN-32 Dry Storage Cask

The applicant included the TN-32 Dry Storage Casks within the s cope of the renewal review because these are classified as ITS in accordance with renewal application, Table 2-1. The applicant clarified that the TN-32 Dry Storage Casks are within the scope of renewal under criterion 1. The applicant stated that the ITS functions provi ded by the TN-32 Dry Storage Casks and its subcomponents include confinement, radiation shie lding, sub-criticality control, structural integrity, heat-removal capability, and retrievabili ty. The applicant provided a scoping evaluation for the TN-32 Dry Storage Casks subcomponents in ren ewal application, Table 2-2.

2-3 The scoping evaluation included the subcomponent classification, the subcomponent safety function (if any), the subcomponent material, and if the failur e of the subcomponent would affect the function of another ITS subcomponent (i.e., criterion 2 in NUREG 1927, Section 2.4.1). For the NITS TN-32 Dry Storage Cask subcomponents that were not scr eened in under criterion 2, the applicant provided a description of these subcomponents alo ng with an analysis of the consequences of a failure of these subcomponents to support the determination for the subcomponents were categorized as NITS and not screened in unde r criterion 2.

The staff confirmed that the TN-32 Dry Storage Casks subcompone nts are scoped within the renewal review because these are classified as ITS in accordanc e with drawings in Section 1.5 and Table 2.3-1 of the TN-32 Dry Storage Cask UFSAR. The staff compared the ITS functions to determine the accuracy and completeness of the scoping evalu ation. The staff also used the information in NUREG/CR-6407, Classification of Transportation Packaging and Dry Spent Fuel Storage System Components According to Importance to Safet y, issued February 1996 (ADAMS Accession No. ML15127A114) (NRC, 1996a), as a reference for classifying components as ITS. The staff reviewed that the applicants des cription and analysis for the NITS subcomponents not screened in under criterion 2. The staf f determined that the applicants assessment of these subcomponents followed the guid ance in NUREG-1927, Section 2.4.2, which includes equipment associated with cask lo ading and unloading; instrumentation and other active components/systems; and miscel laneous hardware that does not support or perform any function that is ITS. The staff con firmed that the applicant provided scoping evaluation results for the subcomponents of the TN-32 D ry Storage Casks in Table 2-2 of the renewal application. Therefore, the staff determined th at the applicants screening assessment for the TN-32 Dry Storage Cask subcomponents followe d the guidance in NUREG-1927, Chapter 2, and the results of the applicants scoping eva luation were acceptable.

Spent Fuel Assemblies

The applicant included the spent fuel assemblies within the sco pe of the renewal review because the ITS functions for the fuel assemblies include confi nement, sub-criticality control, structural integrity, and heat-removal capability as shown in r enewal application, Table 2-1.

Therefore, the applicant stated that the spent fuel assemblies satisfy criterion 1 and are within the scope of the renewal review. The applicant provided a scop ing evaluation of the subcomponents of the spent fuel assemblies in Table 2-3 of the renewal application.

The staff noted that, in accordance with drawings in Section 1. 5 and Table 2.3-1 of the TN-32 UFSAR, the subcomponents of the spent fuel assemblies are not c lassified as ITS.

Nevertheless, the applicants classification of the spent fuel assemblies as ITS is consistent with NUREG-1927, Section 2.4.2, which states that the renewal applic ation should demonstrate that the analyzed fuel configuration relied on in the safety analyse s will be maintained. In addition, NUREG-1927, Section 2.4.2.1, states that the spent fuel claddin g and assembly hardware provide structural support to ensure that the spent fuel is mai ntained in a known geometric configuration and that the criticality and shielding safety ana lyses for a DSS may rely on the fuel assembly having a specific configuration. The staff confirmed that the applicant provided a scoping evaluation of the subcomponents of the spent fuel assem blies in Table 2-3 of the renewal application.

ISFSI Concrete Storage Pad

The applicant stated that the ISFSI concrete storage pad is cla ssified as NITS; however, the applicant clarified that a portion of the pad is included in th e thermal models. The applicant

2-4 stated that failure of the pad could affect the heat removal ca pability of the system. Therefore, the reinforced concrete storage pad meets criterion 2 and is wi thin the scope of the renewal review as indicated in the CoC renewal application, Table 2-1.

The staff noted that, in accordance with drawings in Section 1. 5 and Table 2.3-1 of the TN-32 UFSAR, the ISFSI concrete storage pad is not classified as ITS. The staff reviewed the applicants assessment for including the ISFSI concrete storage pad under scoping criterion 2 and determined that this assessment is appropriate because a po rtion of the ISFSI concrete storage pad is credited in the analysis for heat removal capabi lity.

Earthen Berm

The applicant stated that while the TN-32 Dry Storage Cask does not require the use of an earthen berm to meet regulatory dose limits, Section 10.2 of th e UFSAR does contain analyses modeling a berm and indicates that a berm may be used as necess ary to keep the site boundary dose rate within the 25 mrem/year limit. The applican t stated that the renewal application presumes that if a general licensee chose to rely o n an earthen berm to meet regulatory dose limits, the berm will be classified as an ITS s tructure. Therefore, the applicant determined that if an earthen berm is credited, it satisfies cr iterion 1 and is within the scope of the renewal review.

The staff noted that the optional earthen berm is not included in the drawings in Section 1.5 nor is the berm identified in Table 2.3-1 of the TN-32 UFSAR. Ther efore, the staffs review of the applicants assessment of the optional berm was limited to the information provided in the renewal application. The staff reviewed the applicants assess ment for the optional earthen berm under scoping criterion 1 and determined that this assessm ent is appropriate because a general licensee may choose to rely on an earthen berm to meet regulatory dose limits.

Scoping Findings

The staff reviewed the applicants screening of the SSCs and su bcomponents within the scope of the renewal review. The staffs safety review followed the guidance in NUREG-1927. The staff reviewed the intended function of the SSC and subcomponen t; its safety classification per the UFSAR, and the basis for inclusion in the scope of the rene wal review; and design-bases information in the UFSAR. The staff notes that NUREG-2214 incl udes aging management tables developed using the UFSAR drawings for the TN-32 Dry Sto rage Cask which provide a generic basis for scoping of the SSCs. The staff compared the applicants scoping evaluation results to the TN-32 Dry Storage Cask aging management tables i n NUREG-2214. Based on this review, the staff finds that the applicant screened the in -scope SSCs and subcomponents in a manner consistent with NUREG-1927. Therefore, the staff find s the screening results for in-scope SSCs and subcomponents to be acceptable.

2.1.4 Structures, Systems, and Components Not Within the Scope of the Renewal Review

Per the scoping evaluation process and methodology, as discusse d in Section 2.2 of the renewal application, the applicant identified the SSCs and subc omponents considered to be not within the scope of the renewal review. As previously discusse d in SER Section 2.1.1, this approach is consistent with the criteria defined in NUREG-1927. Consistent with that scoping evaluation, the applicant identified these SSCs and subcomponen ts as not needing an AMR.

These SSCs are identified in Table 2-1 of the CoC renewal appli cation. The following

2-5 discussions address the applicants basis for exclusion of an S SC from the scope of the renewal review. The discussions also provide clarifications on the sta ffs review of that basis for exclusion.

Auxiliary Equipment

The applicant stated that auxiliary equipment used to facilitat e cask loading, draining, drying, inerting, and sealing operations include, but are not limited t o, special lifting devices, vertical cask transporter, and vacuum drying/helium leak test equipment. The applicant cited CoC No.

1021 condition 1(b) which states, The auxiliary equipment nece ssary for ISFSI operation is not included as part of the TN-32 Dry Storage Cask reviewed for a C ertificate of Compliance under 10 CFR Part 72, Subpart L. Such equipment may include, but is not limited to, special lifting devices, transfer trailers or equipment, and vacuum drying/heli um leak test equipment. Based on condition 1(b) in CoC No. 1021 and the results of the applic ant scoping evaluation, the applicant concluded that the auxiliary equipment is not within the scope of the CoC No. 1021 renewal.

The staff reviewed the applicants description in the renewal a pplication and CoC condition 1(b).

The staff noted that the TN-32 UFSAR Table 2.3-1 does not provi de a safety classification for the auxiliary equipment. Nevertheless, the staff finds that th e applicants determination that the auxiliary equipment is NITS and will not prevent fulfillment of an ITS function to be acceptable because the equipment does not meet any of the scoping criteria that would bring it within the scope of the renewal review. Thus, the staff determined that t he identification of the auxiliary equipment as NITS is consisten t with the guidance in NUREG-1927, Section 2.4.3 which states that such equipment may be excluded from the scope of renewal r eview. This equipment is necessary for cask loading, drying, and transfer operations but are not relied on for ITS functions in cask storage operations. Therefore, the staff fin ds the applicants exclusion of the auxiliary equipment from the scope of the renewal review to be acceptable.

Miscellaneous Equipment

The applicant stated that miscellaneous ISFSI equipment includi ng ISFSI security fences and gates, lighting, lightning protection, communications, and moni toring equipment are not part of the TN-32 Dry Storage Cask approved in accordance with 10 CFR P art 72, Subpart L. The applicant further stated that this miscellaneous equipment is n ot classified as ITS, nor would its failure prevent the fulfillment of a function that is ITS. Bas ed on the safety classification and the results of the scoping evaluation, the applicant stated that th e miscellaneous equipment is not within the scope of the CoC No. 1021 renewal review.

The staff reviewed the applicants assessment of the miscellane ous ISFSI equipment and noted that the guidance in NUREG-1927, Section 2.4.3, states that thi s type of equipment is specifically excluded from the scope of the renewal review prov ided that the equipment does not meet the scoping criteria in Section 2.4.2 of that report. The staff finds that the applicants determination is consistent with staffs review guidance. The staff determined that the miscellaneous ISFSI equipment identified by the applicantinclu ding ISFSI security fences and gates, lighting, lightning protection, communications, and moni toring equipmentare not part of the TN-32 Dry Storage Cask, the miscellaneous equipment is NITS, and failure of the miscellaneous equipment would not affect an ITS function. Ther efore, the staff finds the applicants exclusion of the miscellaneous equipment from the s cope of the renewal review to be acceptable.

2-6 Scoping Findings

The staff reviewed the applicants screening of the out-of-scop e SSCs. The staffs review considered the SSC and subcomponent; its safety classification per the UFSAR, or basis for inclusion in the scope of the renewal review; and design-bases information in the UFSAR.

Based on this review, the staff finds that the applicant screen ed the out-of-scope SSCs and subcomponents in a manner consistent with NUREG-1927. Therefor e, the staff finds the screening results for out-of-scope SSCs and subcomponents to be acceptable.

2.2 Evaluation Findings

The staff reviewed the scoping evaluation provided in the renew al application. The staff performed its review following the guidance provided in NUREG-1 927. To determine the accuracy and completeness of the scoping evaluation, the staff also used the information in NUREG/CR-6407, as a reference for classifying components as ITS.

Based on its review, the staff finds the following:

F2.1 The applicant has identified all SSCs important to safety and all SSCs whose failure could prevent an SSC from fulfilling its safety function, per t he requirements of 10 CFR 72.3, Definitions; 10 CFR 72.124, Criteria for nuclea r criticality safety; 10 CFR 72.236, Specific requirements for spent fuel storage cask approval and fabrication and 10 CFR 72.240, Conditions for spent fuel storage cask rene wal.

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

2-7 3 AGING MANAGEMENT REVIEW

3.1 Review Objective

The objective of the staffs evaluation of the applicants AMR is to determine if the applicant has reviewed applicable materials, environments, and aging mechanis ms and effects, as well as to determine whether the applicant has proposed acceptable aging m anagement activities for in-scope SSCs. The AMR addresses aging mechanisms and effects tha t could adversely affect the ability of the SSCs and associated subcomponents to perform their intended functions during the PEO.

3.2 Aging Management Review Process

In the renewal application Section 3.2, the applicant described its AMR methodology as consisting of three steps:

(1) identification of materials and environments (2) identification of aging mechanisms and effects requiring ma nagement (3) determination of the activities required to manage the effe cts and mechanisms of aging

The applicant stated that the AMR follows the methodology provi ded in NUREG-1927, which provides an acceptable methodology for applicants to use, and w hich results in an assessment of the aging effects that could adversely affect the ability of the SSCs to perform their intended safety functions during the PEO. The applicant provided a desc ription of the SSCs and their subcomponents within the scope of renewal. For each SSC subcom ponent, the applicant identified the materials of construction and the operating envi ronments. The applicant also reviewed OE as part of the AMR process. For the TN-32 Dry Stor age Casks, the fuel assemblies, the ISFSI concrete pad, and the earthen berm, the a pplicant identified aging mechanisms and aging effects for these material and environment combinations along with the necessary activities to manage the effects of aging.

The staff reviewed the applicants AMR process, including a des cription of the review process, and the design-bases references. The staff determined that the applicant evaluated the SSCs and their subcomponents using the SSC design, intended function of the subcomponent, and the subcomponent materials and operational environments. The s taff then evaluated potential aging mechanisms and effects identified for these SSCs and thei r subcomponents to determine whether aging management was required to ensure that the intend ed functions of these SSCs and subcomponents were maintained throughout the PEO. Based on its review, the staff finds that the applicants AMR process was consistent with the method ology in NUREG-1927, and was acceptable for identifying credible aging effects for the S SCs within the scope of the renewal. The staff determined that the applicants AMR process was consistent with the generic evaluations for the TN-32 Dry Storage Cask components, spent fu el assemblies and hardware, and ISFSI concrete pad included in NUREG-2214. In addition, the staff determined that the applicants AMR process for the earthen berm was consistent wit h appropriate OE, NRC guidance, and industry guidance on earthen structures. Therefo re, the staff finds the applicants AMR process to be acceptable.

3-1 3.3 Aging Management Review Results

The applicant identified the materials of construction for the SSCs and the subcomponents that were determined to be within the scope of the review. Specific ally, the applicant identified the materials for the subcomponents of the TN-32 Dry Storage Casks, the ISFSI concrete pad, the optional earthen berm, and the spent fuel assemblies to be with in the scope. The applicant stated that the materials of construction and the operating env ironments for the SSCs and their subcomponents were identified through a review of the drawings provided in the UFSAR, along with other pertinent design information.

The staff reviewed the materials of construction, the operating environments, and the AMR provided by the applicant. To conduct this review the staff co mpared the information provided by the applicant to the guidance in NUREG-1927, Chapter 3, Agin g Management Review, and the information included in NUREG-2214, Chapter 2, Definitions, and Chapter 3, Evaluation of Aging Mechanisms, along with appropriate industry guidance. If the staff determined that the applicants conclusions were consistent with expected aging man agement activities per NUREG-2214, the staff considered the results acceptable, and this determination is documented in this SER. The discussions in the following secti ons address the applicants AMR results including materials and environments in SER Section 3.3.1, OE in SER Section 3.3.2, and aging mechanisms and effects in SER Section 3.3.3.

3.3.1 Materials and Service Environments

In the renewal application Section 3.2.1, the applicant stated that the first step in the AMR process was to identify the materials of construction for each subcomponent of the in-scope SSCs and the environments to which those materials are exposed during normal storage conditions. The applicant then used these combinations of mate rials and environments to identify the potential aging effects that require management du ring the PEO.

In the renewal application Section 3.3.1, the applicant provide d a description of the TN-32 Dry Storage Cask and its subcomponents. The applicants descriptio n included the materials of construction and applicable codes for design, fabrication, and inspection. The applicant cited the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV)

Code sections used for the TN-32 Dry Storage Cask design and fa brication. The applicant provided a listing of the TN-32 Dry Storage Cask subcomponents in renewal application Table 3-5, which included the material group and the operating enviro nment(s) for each subcomponent.

The applicant described the ISFSI reinforced concrete storage p ad in renewal application Section 3.3.2. The applicant stated that the storage pad is a 3-foot thick (minimum) reinforced concrete structure designed and constructed in accordance with codes and standards set by the general licensee, and is subject to site-specific foundation an alyses and design considerations, including licensee-specific TN-32 cask loading configurations. The applicant stated that the reinforced concrete pad was composed of concrete and steel rein forcement and identified the operating environments for these materials in renewal applicati on Table 3-7.

The applicant described the spent fuel assemblies and their sub components in renewal application Section 3.3.3. The applicant stated that the TN-32 Dry Storage Cask is designed to store 32 pressurized water reactor (PWR) spent fuel assemblies with or without burnable poison rod assemblies or thimble plug assemblies. The applicant provi ded the fuel types, cladding material, and burnup limits approved for storage in the TN-32 D ry Storage Casks in renewal

3-2 application Table 3-1. The applicant provided a listing of the spent fuel assembly subcomponents, the subcomponent material group, and the operati ng environment in renewal application Table 3-8.

The applicant described the optional earthen berm in renewal ap plication Section 3.3.4. The applicant described material and operating environments for the optional earthen berm in renewal application Table 3-9.

The staff used the guidance in NUREG-1927, Section 3.4.1.1, Ide ntification of Materials and Environments, to review the SSC subcomponents materials and ope rational environments provided in the renewal application. The staff also used the i nformation in NUREG-2214, Chapter 2, to inform the review of the applicants descriptions of materials and environments.

The staff compared the materials identified in the CoC renewal application Section 3.2.1 to the list of materials included in NUREG-2214, Table 2-1. SER Table 3.3-1 identifies the materials of construction for the SSC within the scope of the renewal that w ere included in renewal application Table 3-2. SER Table 3.3-1 also provides a compari son of the materials in the renewal application and the materials evaluated in NUREG-2214. The staff determined that the materials of construction identified by the applicant were cons idered in NUREG-2214 for the assessment of aging mechanisms and aging effects of the storage system components. The staff noted that soil used for the construction of the optional earthen berm was not a material evaluated in NUREG-2214. The staff reviewed the applicants de scription of soil used in the construction of the optional earthen berm and determined that t he description provided by the applicant was accurate. Therefore, the staff finds the applica nts AMR process for the identification of materials relevant to the TN-32 Dry Storage C ask, spent fuel assemblies, the optional earthen berm, and the concrete storage pad to be accep table.

The staff compared the environments identified in the CoC renew al application Section 3.2.1 to the environments evaluated in NUREG-2214, Table 2-2, to determi ne equivalency. SER Table 3.3-2 identifies the environments considered for SSC subc omponents, as defined in the renewal application Section 3.2.1. SER Table 3.3-2 also identi fies the comparison results for the SSC operating environment in the renewal application and th e SSC operating environments evaluated in NUREG-2214. The staff determined that the operati ng environments for the SSCs identified by the applicant in the renewal application are cons istent with the environments considered in NUREG-2214 for the assessment of aging mechanisms and aging effects of the storage system components. Therefore, the staff finds the appl icants AMR process for the identification of environments relevant to the TN-32 Dry Storag e Cask, spent fuel assemblies, the optional earthen berm, and the concrete storage pad to be a cceptable.

3-3 Table 3.3-1. Aging Management ReviewMaterials

Material group in Material Description in the CoC 1021 Equivalent Material(s) the CoC 1021 Renewal Application Section 3.2.1 and in NUREG-2214, Renewal Application Table 3-2 Table 2-1 Steel Carbon steels, alloy steels, high-strength Steel low-alloy (HSLA) steels, galvanized steel, aluminum-coated steel, and electroless nickel-plated steel Stainless steel Austenitic, martensitic, and chrome-Stainless steel plated stainless steel Aluminum Commercially pure aluminum (1100) and Aluminum precipitation-hardened alloys 6061 and 6063 Concrete A mixture of hydraulic cement, Concrete aggregates, and water, with or without admixtures, fibers, or other cementitious materials.

Spent fuel assembly Zircaloy Zirconium-based alloys cladding Spent fuel assembly Stainless steel, zirconium-based alloys, Stainless steel, hardware nickel alloys zirconium-based alloys, nickel alloys Borated aluminum An aluminum alloy typically containing up Borated aluminum to 4.5 weight percent boron used as a neutron poison material. The boron is incorporated in the aluminum matrix as discrete particles of AlB 2 or TiB2 (for alloys also containing titanium).

Aluminum alloys 1100, 6063, and 6351 have been used as base materials for boron additions.

Nickel Alloys This group is limited to the nickel alloy Nickel alloys option for the liner of the metallic seals.

Polymers This group includes the polypropylene Borated polymers used in the top neutron shield and the borated polyester used in the radial neutron shield.

Soil Soil is a mixture of inorganic materials Not Applicable1 produced by the weathering of rock and clay minerals, and organic material produced by the decomposition of vegetation.

1 Soil is not included in NUREG-2214

3-4 Table 3.3-2. Aging Management ReviewEnvironments

Environment in Description of the environment in the CoC 1021 Equivalent CoC 1021 Renewal Application Section 3.2.1 Environment in Renewal NUREG-2214, Application Table 2-2 Air-Outdoor The components are directly exposed to all outdoor Air-Outdoor (OD) weather conditions including insolation, wind, rain, snow, and site-specific ambient air conditions including moist, possibly salt-laden atmospheric air, ambient temperatures, and humidity.

Embedded-in-One or more surfaces of a component are in Embedded in Concrete contact with concrete. This may prevent ingress of concrete (E-C) water and contaminants to the embedded surface, depending on the permeability of the embedding environment.

Embedded-in-Embedded in metal Metal1 One or more surfaces of a component are in contact with another component or material. While (E-M) this may prevent ingress of water and contaminants to the embedded surface, the materials in this environment are treated as though they are exposed to the surrounding environment.

Fully Encased The component is fully enclosed inside another Fully encased or component, or the surface between two lined (FE) components is sealed or fully lined by another material which prevents ingress of water and contaminants.

Helium The component surface is exposed to the helium Helium (HE) fill gas inside the cask and trace quantities of other gases, such as nitrogen, oxygen, argon, and fission product gases.

Groundwater/Soil The component surface is exposed to a soil Groundwater/soil environment with groundwater. Soil is a mixture of (GW) organic and inorganic materials produced by the weathering of rock and clay minerals or the decomposition of vegetation.

1 For the Embedded-in-Metal environment, the applicant assumed that the materials in this environment are treated as though they are exposed to the environment surrounding the embedding material.

3-5 3.3.2 Operating Experience

In the renewal application Section 3.9 and Appendix 3C, the app licant also discussed the review of OE it conducted for the AMR in the renewal application. The sources of OE reviewed by the applicant included:

  • Internal and industrywide condition reports
  • Relevant international and non-nuclear OE
  • Previous independent spent fuel storage installation inspectio n results at the Prairie Island and North Anna ISFSIs
  • Licensee event reports
  • Vendor-issued safety bulletins
  • NRC generic communications
  • Updated consensus codes, standards, or guides
  • Applicable industry-initiatives The applicant stated that the OE review did not identify any ag ing mechanisms and/or effects that were not already identified in either NUREG-2214 for the T N-32 Dry Storage Cask components, or Electrical Power Research institute (EPRI) 10150 78, Plant Support Engineering: Aging Effects for Structures and Structural Compon ents (Structural Tools) (EPRI 2007), for the berm. The applicant also stated that no inciden ts were identified where aging effects led to the loss of intended safety functions of the TN-32 Dry Storage Cask SSCs. Based on this review, the applicant concluded that the aging effects identified in the AMR will be managed so that the SSC intended safety functions will be maint ained during the PEO.

The staff reviewed the applicants OE review. As noted by the applicant, the OE review in the renewal application takes credit for the OE review conducted as part of the Prairie Island ISFSI Renewal Application (ADAMS Accession No. ML11304A068) and North Anna ISFSI Renewal Application (ADAMS Accession No. ML16153A140). The Prairie Isl and ISFSI uses the TN-40 Dry Storage Casks which has designs and subcomponent materials that are similar to the TN-32 Dry Storage Cask. Because the designs and materials are sim ilar, the OE and aging effects observed in the TN-40 Dry Storage Cask is expected to be a good analog to the TN-32 Dry Storage Cask. The North Anna ISFSI uses TN-32 Dry Storage Cask s. The review also included the various sources for new age-related degradation OE. The staff compared the list of sources for OE cited by the applicant to NUREG-1927, Section 3.6.1.10. The staff determined that the OE review by the applicant followed the gui dance in NUREG-1927.

Therefore, the staff determined that the OE review conducted by the applicant was acceptable.

3.3.3 Aging Mechanisms and Aging Effects

To determine the potential aging mechanisms and effects, the ap plicant used the environments to which the SSCs and associated subcomponents are usually expo sed. The applicant determined the environmental conditions to which the SSCs and s ubcomponents are typically exposed using the information presented in the TN-32 Dry Storag e Cask UFSAR, Chapter 2, Principal Design Criteria, and Chapter 4, Thermal Evaluation, w hich includes allowable temperature ranges for components under normal conditions and a ccident conditions. The applicant provided the relevant materials and environments in C oC renewal application Section 3.2.1. More specifically, the applicant provided the maximum c omponent and fuel cladding temperatures during normal storage in renewal application Table 3-3.

3-6 The applicant described the TN-32 Dry Storage Cask design, subc omponents and the fabrication considerations; the reinforced concrete storage pad subcomponents; spent fuel assembly subcomponents; and the earthen berm in CoC No.1021 ren ewal application Section 3.3. The applicant provided an evaluation of materials of cons truction, environments, and the potential aging effects, and the associated aging mechanisms fo r each SSC and associated subcomponents within the scope of the renewal review in renewal application Section 3.4. In Section 3.4.3 of the renewal application, the applicant provide d an assessment of the possible aging mechanisms for the materials used in the TN-32 Dry Storag e Cask subcomponents, reinforced concrete storage pad, spent fuel assembly subcompone nts, and the earthen berm.

Aging mechanisms deemed credible were evaluated by the applican t to determine if the aging mechanisms could result in aging effects requiring management i n the PEO. The applicant provided a summary of the aging mechanisms for materials used i n the TN-32 Dry Storage Cask, concrete storage pad, spent fuel assemblies and the earth en berm in renewal application Table 3-4.

The staff relied on the guidance in NUREG-1927, Section 3.4.1.2, Identification of Aging Mechanisms and Effects, to review the applicants assessment of the aging mechanisms and effects for the SSC subcomponents. The staff also used the inf ormation in NUREG-2214, Section 2.3, Aging Mechanisms, Section 2.4, Aging Effects, and the information in Chapter 3, Evaluation of Aging Mechanisms, to review of the applicants AM R for the material and environment combinations that relevant to the TN-32 Dry Storage Cask, the reinforced concrete storage pad, and the spent fuel assemblies. In this evaluation, the staff ensured that the materials, design features, environments, and OE for the TN-32 Dry Storage Cask described in the renewal application are bounded by those evaluated in NUREG -2214. The staff conducted this evaluation by comparing the information provided by the applicant for the TN-32 Dry Storage Cask in the renewal application to the information cont ained in NUREG-2214, Chapter 2, for the description of materials, environments, aging mechan isms and aging effects; Chapter 3 for the evaluation of aging mechanisms for the material/envir onment combinations. NUREG-2214, Chapter 4, Analysis of Dry Storage Systems and Spent Fuel Assemblies, provides AMR tables for those SSCs and their subcomponents for selected DSS designs, concrete storage pads, and fuel assemblies. The AMR tables included in Chapter 4 identify the aging mechanisms and effects that could challenge the capability of e ach of the SSCs and their subcomponents to fulfill its impor tant-to-safety function(s) in the 20- to 60-year PEO. For those credible aging effects, the AMR tables recommend aging manageme nt approaches including AMPs, TLAAs, or supplemental analyses. The staff used the info rmation in NUREG-2214, Section 4.4, TN-32 and TN-68 Systems, that was specifically dev eloped to inform the review of the applicants AMR results for those dry storage casks. In ad dition, the staff used the information in Sections 4.7 and 4.8 to inform the review of the applicants AMR results for the concrete pad and fuel assembles, respectively.

In addition, the staff reviewed the applicants AMR of the opti onal earthen berm using the information included in EPRI-1015078 cited by the applicant. T he staff has reviewed EPRI-1015078, Chapter 8, Earthen Structures, and finds that it descr ibes the possible aging mechanisms and effects for earthen structures, such as the eart hen berm. The applicants reliance on it is, therefore, acceptable. The staff also revie wed the information in (1) NUREG-0800, Standard Review Plan for the Review of Safety Analysis R eports for Nuclear Power Plants: LWR Edition, Section 2.5.4 Stability of Subsurface Ma terials and Foundations (ADAMS Accession No. ML13311B744) (NRC 2014), (2) NRC RG 1.127, Revision 2, Criteria and Design Features for Inspection of Water Control Structures Associated with Nuclear Power Plants (ADAMS Accession No. ML15107A412), Section C.5.b. Onsi te Inspection Program, (3) the aging management of the berm at the Prairie Island Nuclear Generating Plant ISFSI

3-7 (ADAMS Accession No. ML15285A007), and (4) the staff evaluation of the TN-40 Dry Storage Cask AMP in the Prairie Island Nuclear Generating Plant ISFSI S ER (ADAMS Accession No. ML15336A230). Staff used the information in EPRI-1015078 and N UREG-0800, Section 2.5.4, for additional insight into aging mechanisms and effects for ea rthen structures. The staff used the information in NRC RG 1.127, Section C.5.b, for information on the inspection of earthen embankment structures for the detection of aging effects. As p reviously noted, the applicant referenced the OE at the Prairie Island Nuclear Generating Plan t ISFSI. As noted above, because of the similarities in the design, materials, and opera tion of the TN-40 Dry Storage Cask and TN-32 Dry Storage Cask, staff compared the TN-32 Dry S torage Cask AMP to the previously approved AMP for the TN-40 Dry Storage Casks AMP in the Prairie Island ISFSI renewal.

SER Tables 3.3-3 through 3.3-12 provide a summary of the aging mechanisms and aging effects for the material and environment combinations for the c omponents and subcomponents from the AMR. In addition, SER Tables 3.3-3 through 3.3-12 identify whether the approach taken by the applicant is consistent with aging mechanism and a ging effects analysis included in NUREG-2214 for the comparable material and environment combinat ion. For all cases where the applicants approach differs from that in NUREG-2214, addit ional information is provided in the discussion of each material and identified in the footnotes for each table.

Steel Materials

The summary of the aging mechanisms and aging effects for carbo n steel included in renewal application Section 3.4.3.1 is shown in SER Table 3.3-3. The a pplicants evaluation of corrosion mechanisms, creep, thermal aging, and radiation embrittlement f or the steel materials was consistent with the evaluation in NUREG-2214, Section 3.2.1, an d is therefore acceptable.

Additional details of the applicants evaluation of fatigue, st ress relaxation, and wear of steel subcomponents are provided in the following paragraphs.

NUREG-2214, Section 3.2.1.7 states that reviewer should review all fatigue analyses contained in the applicants design bases documents to determine whether the renewal application adequately addresses the implications of extending the operatin g period to 60 years. In renewal application Section 3.4.3.1.7 the applicant stated that the des ign basis review for the TN-32 Dry Storage Cask review did not identify any fatigue analyses/evalu ations for the TN-32 Dry Storage Cask system components. Further the applicant stated that the only source of potential thermal fatigue of the TN-32 cask is ambient seasonal and daily tempera ture fluctuation but due to the large thermal inertia of the TN-32 cask, it does not experience the full amplitude of ambient temperature cycles, and a gradual, long-term temperature decrea se occurs during the course of storage. The staff reviewed the applicants evaluation and con firmed that the TN-32 Dry Storage Cask did not include a fatigue assessment. The staff d etermined that thermal fluctuations are insufficient to result in fatigue of the TN-32 confinement boundary. Therefore, the staff determined that no fatigue evaluation is required for the PEO.

The applicant stated in the renewal application Section 3.4.3.1.10 that the TN-32 Dry Storage Cask bolts in contact with the lid and top neutron shield may b e at temperatures where stress relaxation could occur. Therefore, the applicant stated that s tress relaxation is considered credible for an air-outdoor environment. The applicant stated that there are no bolts used in concrete, helium, or fully encased environments, and therefore, stress relaxation of steel in these environments is not a credible aging mechanism. The staf f noted that the evaluation of stress relaxation in NUREG-2214, Section 3.2.1.10, is limited t o bolts and assumes that the bolts are torqued and are placed in service under an applied te nsile load but are at

3-8 temperatures below those necessary for stress relaxation to occ ur. Although different from the assessment in NUREG-2214, Section 3.2.1.10, the staff noted tha t in renewal application Section 3.4.3.1.10, the applicant provided a justification for the evaluation that stress relaxation of bolts is a credible aging mechanism in an air-outdoor enviro nment. Therefore, the staff determined that the applicants assessment was acceptable, and that stress relaxation is an aging effect that requires aging management in the PEO.

The assessment of wear in NUREG-2214, Section 3.2.1.11, indicat es that wear is a credible aging mechanism for carbon steels used in moving components suc h as doors used on transfer casks. The applicant indicated in renewal application Section 3.4.3.1.11 that rolling contact wear results from the repeated mechanical stressing of the surf ace of a body rolling on another body. The applicant stated that wear is not a credible aging m echanism because there are no moving components while the TN-32 Dry Storage Casks are in stor age. The staff finds this justification for excluding wear acceptable because the staff c onfirmed that there are no moving components while the TN-32 Dry Storage Casks are in storage. T he staff determined that the applicants assessment of aging effects and aging mechanisms fo r carbon steel materials was acceptable because the applicants assessment is consistent wit h the evaluation in NUREG-2214 and the applicant provided acceptable justification for th e exclusion of wear consistent with the design and operation of the TN-32 Dry Storage Casks. There fore, the staff determined that no aging management for wear of the steel subcomponents is requ ired for the PEO.

Stainless Steel Materials

The aging mechanisms and aging effects for stainless steel incl uded in renewal application Section 3.4.3.2 are shown in SER Table 3.3-4. The staff review ed the operational environments and potential aging mechanisms provided by the applicant using the information in NUREG-2214, Section 3.2.2. The applicants evaluations for general co rrosion, pitting and crevice corrosion, galvanic corrosion, creep, fatigue, radiation embrit tlement, and stress relaxation for the stainless steel materials were consistent with the evaluati on in NUREG-2214, Section 3.2.2, and is therefore acceptable. Additional details of the applica nts evaluation of stress corrosion cracking (SCC), thermal aging, and wear of stainless steel subc omponents are provided in the following paragraphs.

The applicant stated that all austenitic stainless steels are s usceptible to chloride-induced SCC in the normal wrought condition and the susceptibility increase s when the material is sensitized.

The applicant stated that in the welded condition, the heat aff ected zone (HAZ), which is a thin band located adjacent to the weld, can be sensitized by the pre cipitation of carbides that extract chromium out of the metal matrix. The applicant stated that th ere is a lack of halides and very little residual water in internal environments of a TN-32 Dry S torage Cask following drying and refilling with inert helium gas. Thus, the applicant concluded that SCC is not considered credible. Similarly, there is a lack of halides and very littl e moisture in a fully encased environment and, thus, SCC is not considered credible. The app licant stated that the construction of the TN-32 Dry Storage Cask system does not invo lve welding of stainless steel material together in an air-outdoor environment. The applicant determined that SCC of the stainless steel material is not credible in air-outdoor, helium, or fully encased environments.

The staff reviewed the TN-32 Dry Storage Cask design and determ ined that there is no welded stainless steel in an air outdoor environment. The staff note that NUREG-2214 identified multiple sources of applied and residual stresses that could be sufficient for the initiation of stress corrosion crackling. In addition to welding residual st resses, these include from fabrication processes, contacts between components, and bolted structures. However, the staff

3-9 note that OE with SCC of stainless steels is usually associated with welds or associated with fabrication processes. The staff determined that because the T N-32 Dry Storage Cask design does not used welded stainless steels exposed to an air-outdoor environment, SCC is not a credible aging mechanism.

The applicant stated that thermal aging of stainless steel was not a credible aging mechanism for the TN-32 Dry Storage Casks. The evaluation of thermal agi ng of stainless steels in NUREG-2214, Section 3.2.2.8, inc ludes assessments for welded and nonwelded austenitic and precipitation-hardened martensitic stainless steels. The appli cant indicated that the TN-32 Dry Storage Casks do not include precipitation-hardened martensitic stainless steels. For the austenitic stainless steels, the applicant indicated that based on the maximum temperatures the austenitic stainless steel will experience, as laid out in Tabl e 3-3 of the renewal application, that the austenitic stainless steels will not reach temperatures whe re thermal aging could occur. The staff reviewed the material specifications for the subcomponent s of the TN-32 Dry Storage Cask and confirmed that precipitation-hardened martensitic stainless steels are not specified and therefore, no evaluation of these materials were required. The staff noted that the applicants assessment for the austenitic stainless steels is consistent wi th the evaluation in NUREG-2214, Section 3.2.2.8. The staff determined that the maximum tempera ture of the austenitic stainless steel components in the TN-32 Dry Storage Casks are below the t emperatures necessary for thermal aging and the temperatures of these subcomponents will decrease over time as a result of the gradual decrease in decay heat. Therefore, the staff de termined that the applicants assessment was acceptable, and that thermal aging of the austen itic stainless steel materials is not a credible aging effect and no aging management is required for the PEO.

The evaluation of wear in NUREG-2214, Section 3.2.2.11, and Tab le 4-11 indicate that wear is a credible aging mechanism for stainless steel materials in com ponents that are subjected to repeated motion such as transfer operations. The applicant ind icated in the renewal application Section 3.4.3.2.11 that rolling contact wear results from the r epeated mechanical stressing of the surface of a body rolling on another body. The applicant s tated that wear is not a credible aging mechanism because there are no moving components while th e TN-32 Dry Storage Casks are in storage. The staff finds this justification for e xcluding wear acceptable because the TN-32 Dry Storage Cask has no moving components in normal s torage operations.

Therefore, the staff determined that the applicants assessment was acceptable, and that wear of the steel subcomponents is not a credible aging effect and n o aging management is required for the PEO.

The staff determined that the applicants assessment of aging e ffects and aging mechanisms for stainless steel materials was acceptable because the applicant s assessment was consistent with the evaluation in NUREG-2214. The staff determined that t he applicant provided an acceptable justification for the exclusion of thermal aging and wear of the stainless steel subcomponents consistent with the design and operation of the T N-32 Dry Storage Casks.

Aluminum Materials

The aging mechanisms and aging effects for aluminum alloys incl uded in renewal application Section 3.4.3.3 are shown in SER Table 3.3-5. The staff review ed the operational environments and potential aging mechanisms provided by the applicant using the information in NUREG-2214, Section 3.2.3. The applicants evaluations for creep, fa tigue, thermal aging, and radiation embrittlement were consistent w ith the evaluation in NUREG-2214, Section 3.2.3. The staffs review of the applicants evaluation of general corrosion, pitt ing and crevice corrosion, galvanic corrosion, and microbiologically influenced corrosion of the al uminum alloys are provided in the

3-10 following paragraphs. In addition, information with respect to the applicants evaluation of creep and thermal aging are also described in the following paragraph s.

The applicant stated that general corrosion, pitting corrosion, crevice corrosion, galvanic corrosion of aluminum are credible in an air-outdoor environmen t, but are not credible in either a fully encased or a helium environment as a result of the lack o f available water. The applicant stated that an air-outdoor environment does not have the contin uous electrolyte necessary to sustain microbial activity nece ssary for microbiologically infl uenced corrosion. The staff determined that the applicants assessment of corrosion mechani sms in fully encased and helium environments is consisten t with the assessment in NUREG-2214, Section 3.2.3. The staff noted that these corrosion mechanisms were not evaluated for an air-outdoor environment in NUREG-2214 because most dry storage systems do not use this material-environment combination. Nevertheless, the applicants evaluation is consi stent with the available information regarding the corrosion mechanisms of aluminum allo ys (ASM International 2000; Revie 2000), which indicates that general corrosion, pitting co rrosion, crevice corrosion, galvanic corrosion are credible in an air-outdoor environment. In addition, the available information on aluminum alloys indicates that microbiologically influenced corrosion is not credible in an air-outdoor environment because of the lack of a suitable environment for the sustained microbial activity necessary for microbiologically in fluenced corrosion to occur.

Therefore, the staff found that the applicants assessment of c orrosion related aging mechanisms and aging effects for aluminum alloys was acceptable.

The applicant provided an analysis showing that creep of the al uminum alloys was not expected based on the maximum temperature alloy type and the applied loa ds on the aluminum alloy components. The staff reviewed the applicants analysis and de termined that the applicant accurately considered the operating conditions for the aluminum components where the onset of creep of the aluminum alloys could occur. The staff determi ned that the applicants assessment of creep for the aluminum alloys was consistent with the evaluation in NUREG-2214, Section 3.2.3.5. Therefore, the staff found that the app licants assessment of creep aging mechanisms and aging effects for aluminum alloys was acceptable.

The applicant provided an analysis for thermal aging of the alu minum alloy basket materials that include precipitation-hardened 6061-T6 or 6061-T651 aluminum. The applicant cited the evaluation in NUREG-2214, Section 3.2.3.7, which stated that wh en alloy 6061-T6 is held at 392 °F its yield strength drops from approximately 18 ksi at 10,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> (1.14 years) to approximately 11.5 ksi at 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> (11.4 years). The appl icant stated that because of this sensitivity to exposure time, ASME B&PV Code,Section II, requires that time-dependent properties be used for exposures above 350 degrees F (177 degre es C) for this alloy. Table 3-3 of the renewal application shows that the maximum temperature f or the basket is 339 degrees F (171 degrees C), which is lower than the 350 degrees F (177 deg rees C) threshold in ASME B&PV Code,Section II. Therefore, the applicant determined tha t thermal aging of the aluminum basket is not an aging effect that must be managed. Neverthele ss, the applicant provided a supplemental evaluation in Appendix 3B of the renewal applicati on for the TN-32 cask basket during a tip-over event. The staff found that the applicants supplemental evaluation in Appendix 3B is consistent with the ASME B&PV Code Section II, P art D, temperature limits for aluminum alloys and the evaluation in NUREG-2214, Section 3.2.3.7. Therefore, the staff found that the applicants assessment of thermal aging for aluminum a lloy basket materials was acceptable. The staffs review of the applicants supplemental evaluation of the basket for a tip-over event is included in SER Section 3.3.4.

3-11 Nickel Alloys

The aging mechanisms and aging effects for nickel alloys includ ed in renewal application Section 3.4.3.4 are shown in SER Table 3.3-6. The staff review ed the operational environments and potential aging mechanisms provided by the applicant using the information in NUREG-2214, Section 3.2.4. The applicants evaluations for nickel al loy corrosion mechanisms, fatigue, radiation embrittlement, stress relaxation, and wear for the ni ckel alloy materials were not consistent with the evaluation in NUREG-2214, Section 3.2.4, be cause NUREG-2214 only evaluated the aging mechanisms for nickel alloys in and air-out door environment. The applicant stated that the nickel alloy metallic seal components are only exposed to a helium environment.

The evaluation of fatigue in NUREG-2214, Section 3.2.4.5, indic ates that fatigue is a credible aging mechanism for nickel alloy materials in components that a re subjected to repeated cyclic loads including cyclic loads as a result of thermal effects. T he applicant stated that the nickel alloy metallic seals are crushed during installation and the th ermal cycling of the liner will not result in fatigue or affect the ability of the aluminum jacket to fulfill the confinement function.

The staff finds this justification for excluding fatigue accept able because the TN-32 Dry Storage Cask seal is not subjected to cyclic loading in normal storage operations.

The evaluation of wear in NUREG-2214, Section 3.2.4, states tha t the only credible aging mechanism for nickel alloys in an air-outdoor environment is we ar. NUREG-2214, Section 3.2.4.8, indicates that wear is a credible aging mechanism for nickel alloy materials in components that are subjected to repeated motion such as transf er operations. The applicant indicated in renewal application Section 3.4.3.4.7 that rolling contact wear results from the repeated mechanical stressing of the surface of a body rolling on another body. The applicant stated that wear is not a credible aging mechanism because ther e are no moving components while the TN-32 Dry Storage Casks are in storage. The staff fi nds this justification for excluding wear acceptable because the TN-32 Dry Storage Cask has no movin g components in normal storage operations.

The staff determined that the applicants assessment of aging e ffects and aging mechanisms for nickel alloy materials was acceptable because the applicant fol lowed the guidance in NUREG-1927. The staff noted that NUREG-2214, Section 3.2.4 indicates that nickel alloys are not susceptible to stress relaxation or radiation embrittlement. W hile NUREG-2214 only assesses stress relaxation and radiation embrittlement for an air-outdoo r environment, the evaluation in NUREG-2214 can be applied to helium environments because these aging mechanisms are dependent on temperature and radiation exposure and are not dep endent on the chemical composition of the environment. Therefore, the staff determine d that the applicants evaluation was acceptable. The staff noted that the while helium environm ents were not evaluated in NUREG-2214, nickel alloys have sufficient corrosion resistance such that corrosion mechanisms are not credible in air-outdoor environments. Becau se helium environments inside the dry storage cask do not contain moisture or contaminants th at would promote corrosion, the staff determined that the applicants evaluation was acceptable, meaning corrosion is not a credible aging mechanism.

Polymer Materials

The aging mechanisms and aging effects for polymer materials in cluded in renewal application Section 3.4.3.5 are shown in SER Table 3.3-7. The staff review ed the operational environments and potential aging mechanisms provided by the applicant using the information in NUREG-2214, Section 3.3.1. The applicants evaluations for thermal a ging and radiation embrittlement

3-12 were acceptable because these assessments were consistent with the evaluations in NUREG-2214, Sections 3.3.1.2 and 3.3.1.3, respectively. The followin g paragraph provides additional information on the boron depletion of the polymer neutron shiel ding materials.

The applicant provided a calculation for the boron-10 depletion of the neutron shield that considered the boron-10 density. Using the generic analysis fo r the depletion of boron-10 from the stainless steel neutron poison material in NUREG-2214, Sect ion 3.4.1.1, the applicant stated that boron depletion was negligible for the PEO. The ap plicant stated that thermal aging and radiation embrittlement of the polymer material in a fully encased environment are credible aging effects for the PEO. The staff noted that the analysis f or the borated stainless steel in NUREG-2214, Section 3.4.1.1, may not be applicable to the borat ed polymer as the polypropylene and polyester from the polymer shield would slow down neutrons more than stainless steel and have a larger absorption/depletion of boron. However, the staff found that conclusions about the borated polymer can be drawn from the app licants analysis that provide confidence that boron depletion within the polymer material is minimal for the following reasons.

The applicant performed an analysis for the borated aluminum wi thin the basket with very conservative assumptions, which are discussed in Section 3.5.1 of this SER. This analysis demonstrates that the boron loss is minimal and independent of the material the boron is within (i.e. only based on the number of boron atoms and does not acco unt for the aluminum).

Additionally, the analysis for borated aluminum and steel repre sent neutron flux inside the basket. The borated polymer resin would get a lower neutron fl ux because it is outside of the basket. Performing this demonstration is consistent with the e valuation in NUREG-2214, Section 3.3.1.1, and conservative with respect to the analysis provided in NUREG-2214, Section 3.4.1.1, because of the concentration of boron in the T N-32 shielding material is on the higher end of the range used. Based on the above consideration s, the staff determined that the applicants analysis for boron depletion is acceptable for demo nstrating that the boron depletion is negligible for the PEO.

Borated Aluminum Materials

The aging mechanisms and aging effects for borated aluminum mat erials included in renewal application Section 3.4.3.6 are shown in SER Table 3.3-8. The staff reviewed the operational environments and potential aging mechanisms provided by the app licant using the information in NUREG-2214, Section 3.4.2. The applicant stated that genera l corrosion and galvanic corrosion of the borated aluminum alloys are not credible in an inert environment. The staff determined that the applicants analyses for these corrosion me chanisms in inert environments was acceptable because the assessment was consistent with the e valuation including in NUREG-2214, Sections 3.4.2.1 and 3.4.2.2. The applicant provid ed an assessment for creep, thermal aging, and radiation embrittlement to support the concl usion that these aging mechanisms are not credible for the borated aluminum alloys. T he staff determined that the applicants assessment was acceptable because the assessments w ere consistent with the evaluations included in NUREG-2214, Sections 3.4.2.5, 3.4.2.6, and 3.4.2.7, respectively.

For the depletion of boron, the applicant referenced the analys is included in TN-32 UFSAR Section 6.3.2 that showed boron-10 depletion of the borated alu minum alloys is negligible over a period of 1,000 years and is therefore, negligible during the PEO. The applicant determined that the analysis in UFSAR Section 6.3.2 met the criteria for a TLAA and therefore, the applicant included this analysis as a TLAA in CoC No 1021 renewal applica tion Appendix 3A. The staffs review of the TLAA for boron-10 depletion is included in SER Se ction 3.5.1.

3-13 Concrete

The aging mechanisms and aging effects for concrete included in renewal application Section 3.4.3.7 are shown in SER Table 3.3-9. The staff reviewed the o perational environments and potential aging mechanisms provided by the applicant using the information in NUREG-2214, Section 3.5.1. The applicant stated that creep, shrinkage, rad iation damage, fatigue, and dehydration at high temperatures are not credible air-outdoor o r groundwater/soil environments.

The applicant stated that freeze-thaw, reaction with aggregates, aggressive chemical attack, corrosion of reinforcing steel, leaching of calcium hydroxide a nd salt scaling are credible aging mechanisms for air-outdoor or groundwater/soil environments. T he staff determined that the assessments by the applicant were acceptable because they are c onsistent with the evaluation in NUREG-2214, Section 3.5.1. The applicant stated that differential settlement and microbiological degradation are credible in groundwater/soil en vironments but not credible in air-outdoor environments. The staff determined that the assessment s by the applicant were acceptable because they are consistent with the evaluation in N UREG-2214, Section 3.5.1, which states that differential settlement and microbiological d egradation are potential aging mechanisms and have aging effects on concrete in groundwater/so il environments but not in air-outdoor environments.

The staff noted that the analysis of concrete aging effects inc luded in NUREG-2214 was based on concrete having only a structural function. Concrete aging effects such as cracks and loss of material can affect the concrete ITS structural function. Heat transfer is dependent on materials properties and material interfaces and discontinuities. Concre te aging effects that result in a loss of material or cracks are discontinuities that could affec t heat transfer. The staff determined that the aging effects for concrete that result in a loss of material or the formation of cracks could affect the heat transfer by creating discontinuiti es in the concrete structure.

Therefore, the staff determined that the evaluation provided in NUREG-2214, Section 3.5.1, developed for a structural function may be applied to concrete having a thermal function.

The applicant indicated that delayed ettringite formation (DEF) is considered credible in air-outdoor or groundwater/soil environments. The staff noted that while the assessment of delayed ettringite formation by the applicant is different from NUREG-2214, Section 3.5.1.13, which states that the conditions necessary for the occurrence o f DEF are excessive temperatures during concrete placement and curing, the presence of internal sulfates, and a moist environment. As noted in NUREG-2214, Section 3.5.1.13, t he American Concrete Institute (ACI) guidelines during concrete placement and curing can effectively limit the concrete temperature to below 70 degrees C (158 degrees F), therefore pr eventing the development of DEF. As such, NUREG-2214 states that DEF is not a credible agi ng mechanism in any environment. While the applicants assessment differs from NUR EG-2214, the staff determined that the applicants assessment is conservative, and therefore acceptable.

The applicant provided an assessment for concrete hardening and determined that hardening was not a credible aging mechanism, as no appreciable hardening is expected during the PEO.

The staff noted that some degree of concrete hardening with tim e is expected. As such, NUREG-2214 does not consider concrete hardening as an aging mec hanism. The staff reviewed the applicant assessment which was based on the data i n Table 2.13 of NUREG/CR-6424 (NRC, 1996b). Based on a review of the available data, th e applicant stated that concrete hardening is not expected in the PEO. The staff determined tha t the applicants assessment of hardening was acceptable based on the data provided to support the analysis that concrete hardening beyond 20 years is not a credible aging mechanism.

3-14 Spent Fuel Assembly Cladding Materials

The aging mechanisms and aging effects for spent fuel assemblie s included in renewal application Section 3.4.3.8 are shown in SER Table 3.3-10. The staff reviewed the operational environments and potential aging mechanisms provided by the app licant using the information in NUREG-2214, Section 3.6.1. The applicant stated that there are no credible aging mechanisms for the spent fuel stored in an inert helium environ ment. Based on this evaluation, the applicant concluded that no aging management activities are required for the spent fuel assembly cladding material stored in the TN-32 Dry Storage Cask. The staff reviewed the AMR of the spent fuel assemblies provided by the applicant in the r enewal application, Table 3-8.

The staff noted that per NUREG-2214, Section 3.6.1, hydride reo rientation and thermal creep are only considered credible for high burnup fuel with an avera ge burnup > 45 gigawatt-day per metric ton uranium (Gwd/MTU). Because the TN-32 Dry Storage Ca sk TS limit the TN-32 Dry Storage Cask to a maximum average burnup of 45 Gwd/MTU, these aging mechanisms are not credible for fuel loaded into TN-32 Dry Storage Casks. Bas ed on this, the staff determined that the applicants assessment that no aging management activi ties are required for the spent fuel assemblies stored in the TN-32 Dry Storage Cask system was consistent with the evaluation in NUREG-2214, Section 3.6.1. Therefore, the staff found that the applicants assessment of aging effects and aging mechanisms for spent fuel assembly cladding materials was acceptable and no aging management is required in the PEO.

The applicant referenced the analysis in TN-32 UFSAR Section 3. 5.1, which indicates that the maximum fuel cladding temperature of the hottest fuel rod in th e cask shall not exceed the temperature limit calculated in accordance with PNL-6189 (Levy et al., 1987) in order to prevent cladding creep. The applicant determined that the analysis in UFSAR Section 3.5.1 met the criteria for a TLAA and therefore, the applicant included this analysis as a TLAA in CoC No 1021 renewal application Appendix 3A. The staffs review of th e TLAA for the maximum fuel cladding temperature is included in SER Section 3.5.2.

Spent Fuel Assembly Hardware Materials

The aging mechanisms and aging effects for spent fuel assembly hardware materials included in renewal application Section 3.4.3.9 are shown in SER Table 3.3-11. The staff reviewed the operational environments and potential aging mechanisms provide d by the applicant using the information in NUREG-2214, Section 3.6.2. The applicant stated that there are no credible aging mechanisms for the spent fuel assembly hardware which are stored with the fuel assemblies in an inert helium environment. The staff determine d that the applicant assessment is consistent with NUREG-2214, Section 3.6.2, which states that there are no credible aging mechanisms for spent fuel assembly hardware in a helium environ ment. Therefore, the staff found that the applicants assessment of aging effects and agin g mechanisms for spent fuel assembly hardware materials was acceptable and no aging managem ent is required in the PEO.

Soil

The aging mechanisms and aging effects for soil material includ ed in renewal application Section 3.4.3.10 are shown in SER Table 3.3-12. The applicant used information included in EPRI-1015078, to assess the potential aging mechanism for the s oil berm. The applicant stated that credible aging mechanisms include wind erosion, surface fl ow of soil materials, settlement, frost action, and desiccation. The applicant stated that rain impact, subsurface flow of soil material, wave action, and sedimentation are not credible aging mechanisms. The staff

3-15 reviewed the applicants assessment, the information included i n EPRI-1015078; NUREG-0800, Section 2.5.4; and NRC RG 1.127, Revision 2, Criteria and Desi gn Features for Inspection of Water Control Structures Associated with Nuclear Power Plants (ADAMS Accession No ML15107A412) (NRC 2016b), Section C5.b, Onsite Inspection Prog ram. The staff also reviewed the aging management of the berm at the Prairie Island Nuclear Generating Plant ISFSI and the staffs evaluation of the AMP in the Prairie Isla nd Nuclear Generating Plant ISFSI SER (ADAMS Accession No. ML15285A007). The staff determined th at the applicants assessments of soil aging mechanisms are consistent with indust ry guidance in EPRI-1015078, RG 1.127, Revision 2, Section C.5.b, and the previous evaluatio n used to support the Prairie Island ISFSI renewal. Therefore, the staff found that the appl icants assessment of aging effects and aging mechanisms for soil material was acceptable a nd aging management is necessary for the wind erosion, surface flow of soil materials, settlement, frost action, and desiccation aging mechanisms.

3-16

SER Tables 3.3-13 through 3.3-15 show only the aging mechanisms and aging effects for the TN-32 Dry Storage Cask, storage pad, and the optional earthen b erm, respectively, with the material group-environment combinations that the applicant dete rmined to be credible and which require an AMP to address the aging effect(s). SER Table s 3.3-13 and 3.3-14 identify whether the applicants evaluation of aging management activiti es for each credible aging effect is consistent with the generic technical bases and conclusions discussed in NUREG-2214. SER Table 3.3-15 identifies whether the applicants evaluation of a ging management activities for each credible aging effect for the earthen berm is consistent w ith the generic technical bases and conclusions discussed in EPRI-1015078.

The aging mechanisms and effects that require aging management applicable to the TN-32 Dry Storage Cask subcomponents are shown in SER Table 3.3-13. The staff reviewed the AMR provided by the applicant for the TN-32 Dry Storage Cask subcom ponents in the renewal application, Tables 3-5 and 3-6. The staff determined that the applicants evaluation of necessary aging management activities was consistent with the r esults of the AMR and the identification of the credible aging mechanisms and effects for the TN-32 Dry Storage Cask subcomponents. The staff determined that the applicants asses sment was consistent with the evaluation in NUREG-2214. Therefore, the staff found that the applicants necessary aging management activities were acceptable.

The aging mechanisms and effects that require aging management applicable to the storage pad for the TN-32 Dry Storage Casks are shown in SER Table 3.3-14. The staff reviewed the AMR provided by the applicant for the TN-32 Dry Storage Cask st orage pad in the renewal application, Table 3-7. The staff determined that the applican ts evaluation of necessary aging management activities was consistent with the results of the AM R and the identification of the credible of aging mechanisms and effects for the storage pad. The staff determined that the applicants assessment either (1) consistent with the evaluatio n in NUREG-2214 or (2) was conservative with respect to the evaluation in NUREG-2214. The refore, the staff found that the applicants necessary aging management activities were acceptab le.

The aging mechanisms and effects that require aging management applicable to the optional earthen berm are shown in SER Table 3.3-15. The staff reviewed the AMR provided by the applicant in the renewal application, Table 3-9. In response t o a request for additional information (RAI) (ADAMS Accession No. ML21036A237) the applica nt stated that the effects of vegetation and roots would be beneficial for reducing wind driv en surface water runoff erosion and desiccation. The applicant also stated that the effects of burrowing animals would be treated as an operational event that would be detected in norma l maintenance activities. The staff determined that the applicants evaluation of necessary a ging management activities was consistent with the results of the AMR and the identification o f the credible of aging mechanisms and effects for the optional earthen berm. The staff determine d that the applicants assessment is consistent with the technica l bases and conclusions discusse d in EPRI-1015078. Therefore, the staff found that the applicants necessary aging management activities were acceptable.

3-26

3.3.4 Supplemental Evaluation

The applicant assessed the thermal aging of the aluminum basket plates in the TN-32 Dry Storage Cask in Appendix 3B of the renewal application to asses s the effect on structural integrity of the plates. This analysis was included as a suppl emental evaluation because the TN-32 UFSAR did not include this analysis in the original desig n basis for the TN-32 Dry Storage Cask.

The applicant stated that for the TN-32 Dry Storage Cask, the s tructural effectiveness of the aluminum basket plates is only credited for the tip-over accident conditions. The applicant referenced a supplemental evaluation of a TN-32 Dry Storage Cas k which addressed the effects of thermal aging of the aluminum basket plates during a tip-ove r accident (Virginia Electric and Power Company, 2017). This evaluation was originally performed in response to an RAI for the renewal of Special Nuclear Material license number SNM-2507 and previously approved by the staff. The applicant reviewed the referenced evaluation and co ncluded that it was applicable and comprehensive in addressing the thermal aging of aluminum b asket plates for the CoC No.

1021 renewal.

The referenced evaluation included a tip-over analysis of a TN-32 Dry Storage Cask which considered the structural analysis of the aluminum basket plate s. The analysis considered previous work on the thermal aging of Al 6061-T6 showing that a fter exposure to elevated temperatures for extended periods the aluminums yield and tens ile strength decrease until they reach the properties of the fully annealed alloy, 6061-O (Farre ll, 1995). To account for the effects of annealing and temperature, the applicants structura l analysis for the basket materials was conducted using temperature dependent material properties o f aluminum 6061-O (Kaufman, 1999) with lower bound values for the yield and tensile strength at t he maximum temperature for the aluminum alloy basket plates in the PEO (i. e., the maximum temperature of the basket plates after 20 years of storage). The evaluation s howed that maximum stress intensities in the thermally aged aluminum plates remain below applicable limits defined in the TN-32 UFSAR for the tip-over analysis. The applicant concluded that this referenced evaluation sufficiently demonstrated that the TN-32 Dry Storage Cask maint ains structural integrity while considering the effects of thermal aging of the aluminum basket plates.

The staff reviewed the applicants assessment of thermal aging of the aluminum basket plates in Appendix 3B of the renewal application and the supplemental eva luation (Virginia Electric and Power Company, 2017) incorporated by reference. Since the refe renced evaluation was performed on a TN-32 Dry Storage Cask system using the same mat erials, the NRC staff finds the referenced evaluation is applicable to all TN-32 Dry Storag e Cask variants. The staff reviewed the structural analysis of the TN-32 basket in the TN-32 UFSAR and determined that the tip-over accident conditions are the bounding accident cond itions for the aluminum basket.

Based on the staffs review of the material properties and stre ss analysis of the aluminum basket in the referenced evaluation, the staff finds the applic ant sufficiently addressed the potential for thermal aging of the aluminum components and demo nstrated the structural functions of the aluminum components are not adversely affected. The staff finds the applicants assessment of thermal aging of the aluminum basket plates in the TN-32 system to be consistent with evaluation in NUREG-2214, Section 3.2.3.7, a nd is therefore acceptable.

3-32

3.4 Evaluation Findings

The staff reviewed the AMR provided in the renewal application and supplemental documentation to verify it identified the materials, environmen ts, and aging effects of the in-scope SSCs. The staff performed its review following the guida nce provided in NUREG-1927, and consistent with the evaluation in NUREG-2214. Based on its review of the renewal application, the staff finds the following:

F3.1 The applicants AMR process is comprehensive in identifyi ng the materials of construction and associated oper ating environmental conditions for those SSCs within the scope of the renewal, and the applicant provided appropriat e descriptions of the materials and operating environments for those SSCs within the scope of the renewal in the renewal application.

F3.2 The applicants AMR process is comprehensive in identifyi ng all pertinent aging mechanisms and effects applicable to the SSCs within the scope of the renewal, and the applicant provided an acceptable summary of the AMR results in the renewal application.

3-33 3.5 Time-Limited Aging Analyses Evaluation

The applicant reviewed the initial application for TLAAs (i.e., calculations or analyses) used to demonstrate that in-scope SSCs will maintain their intended saf ety function throughout an explicitly stated period of operation. Under 10 CFR 72.3, Def inition, TLAAs are the calculations/analyses that meet all six of the following criter ia:

1. involve structures, systems, and components ITS within the s cope of the license renewal, as delineated in Subpart F of Part 72, or within the s cope of the spent fuel storage certificate renewal, as delineated in Subpart L of Part 72, respectively;
2. consider the effects of aging;
3. involve time-limited assumptions defined by the current oper ating term, for example, 40 years;
4. were determined to be relevant by the licensee or certificat e holder in making a safety determination;
5. involve conclusions or provide the basis for conclusions rel ated to the capability of structures, systems, and components to perform their intended s afety functions; and
6. are contained or incorporated by reference in the design bas es.

Based on its review, the applicant identified the following ana lyses as meeting all six TLAA criteria:

  • Ensure cavity pressure remains above one atmosphere on the col dest day at the end of the storage period

The staff used the guidance in NUREG-1927, Section 3.5, to revi ew the applicants updated TLAAs and supplemental analyses. The staff also used the AMR ta bles in NUREG-2214, Chapter 4, that identify aging management approaches including AMPs, TLAAs, or supplemental analyses for credible aging effects that could cha llenge the capability of each of the SSCs and their subcomponents to fulfill its important-to-sa fety function(s) in the 20- to 60-year PEO.

The staff reviewed the TLAAs provided by the applicant in suppo rt of conclusions regarding potential aging effects for SSCs and SSC subcomponents within t he scope of the renewal.

Based on its review of the design-bases documents, the staff co nfirmed that the applicant identified all calculations and analyses that meet all six crit eria in 10 CFR 72.3 and therefore concludes that the applicant identified all TLAAs. The staffs review of the applicants TLAAs is provided in the following subsections.

3.5.1 Boron Depletion in the in the borated aluminum plates

The applicant stated that the TN-32 UFSAR, Section 6.3.2, evalu ated the potential for boron-10 depletion in the poison plates of the basket. The evaluation u sed a calculated neutron scalar flux of 8.41x105 n/cm2-s at the center of the basket and was based on a period of 1,0 00 years.

This analysis uses cross section data for thermal neutrons as b oron-10 has the highest absorption for thermal neutrons, making this a conservative ass umption. The applicants

3-34 analysis also makes the conservative assumption that the neutro n fluence is constant, rather than decreasing over time. The evaluation determined that the fraction of the original boron-10 that would be depleted is negligible. The applicant stated tha t because the existing analysis assumes 1,000 years of service, the evaluation remains valid an d demonstrates that the boron poison plates will continue to perform their intended function through the end of the PEO.

The staff reviewed the applicants analysis for boron depletion of the poison plates by comparing the applicants analysis to the generic evaluation in cluded in Section 3.4.2.4 of NUREG-2214. This comparison suppor ts the conclusion that boron depletion is not a significant aging mechanism and no aging management activity for boron depl etion is required for the poison plates in the TN-32 Dry Storage Cask. The staff noted t hat the applicants evaluation used calculated neutron scalar flux that is toward the upper en d of the range typical for dry cask storage (NRC 2011). This is a conservative assumption and show s that even if TN-32 has a neutron flux on the higher end of what is typical, the analysis shows negligible boron depletion of the poison plates for a period of 1,000 years. The staff de termined that the applicants assessment was acceptable because the applicants evaluation is consistent with the evaluation provided in NUREG-2214, Section 3.4.2.4. Therefore, the applic ants calculation for negligible boron depletion covers the PEO.

3.5.2 Establishment of fuel cladding temperature limits

The applicant stated that per TN-32 UFSAR Section 3.5.1, the ma ximum fuel cladding temperature of the hottest fuel rod in the cask shall not excee d the temperature limit calculated in accordance with PNL-6189 (Levy et al., 1987). The applicant stated that the temperature limit was established to prevent cladding creep. The applicant state d that the methodology in PNL-6189 is based on a storage period of 40 years. The applicant c alculated this limit to be 631 degrees F (333 degrees C) for 7-year cooled fuel and 622 degree s F (328 degrees C) for 10-year cooled fuel. The applicant noted that the thermal analyse s in TN-32 UFSAR Section 4 selected the more conservative value of 622 degrees F (328 degr ees C) for the fuel cladding temperature limit.

The applicant stated that the PNL-6189 methodology predates the current accepted limit for low burnup fuel in ISG-11, Revision 3. The applicant noted that be cause the TN-32 TS limit the Zircaloy clad fuel to an average burnup of 45 Gwd/MTU, the fuel stored in the TN-32 Dry Storage Cask is not considered to be high burnup fuel. The app licant concluded that since (1) the fuel cladding temperature limits applied to the fuel stored in the TN-32 Dry Storage Cask are lower than the current accepted limit identified in ISG-11, and (2) the temperature of the fuel assemblies will continue to decrease with time, the maximum fue l cladding temperature calculations remain valid for the PEO and demonstrate that the cladding will continue to perform its intended safety function through the end of the PEO.

The staff reviewed the methodology, assumptions, and conclusion s for temperature limits for the spent fuel cladding in the TN-32 Dry Storage Cask. As noted in NUREG-2214, Section 3.6.1 and 3.6.2, there are no aging effects that are considered credi ble for spent fuel cladding or spent fuel assembly hardware for assemblies with average burnup s that do not exceed 45 Gwd/MTU. The staff noted that the applicants analysis is in a greement with the analysis provided in NUREG-2214. Further, the methodology used by the a pplicant for the maximum fuel assembly temperature based on PNL-6189 is conservative wit h respect to ISG-11, Rev 3.

The staff determined that the applicants analysis for temperat ure limits for the spent fuel cladding materials are bounded by the technical basis in NUREG-2214, and are therefore acceptable.

3-35 3.5.3 Ensure cavity pressure remains above one atmosphere on the coldest day at the end of the storage period

The applicant stated that TN-32 USFAR Section 2.2.5.3.3 contain s a design criterion that one atmosphere of pressure must exist in the cavity (i.e., the cask interior) on the coldest day at the end of the PEO. As noted by the applicant, the purpose of pres surizing the cavity above atmospheric pressure is to prevent in-leakage of air. The appl icant stated that preventing leakage of air into the TN-32 Dry Storage Cask is necessary to avoid corrosion of the pressure boundary components that could lead to a loss of material. The applicant stated that while the design of the overpressure monitoring system ensures there will be no out-leakage past the seals during normal operations, the cavity pressure decreases o ver time as the decay heat decreases. The applicant clarified that the end of life cavity pressure analysis assumes a cavity gas temperature corresponding to the end of the 20-year storage period and therefore, the end of life cavity pressure analysis must be revised or updated to demonstrate that the cavity pressure will be above one atmosphere at the end of the PEO, i. e., a total of 60 years.

The applicant provided an updated cavity pressure calculation t hat demonstrates that the cavity pressure of a TN-32 Dry Storage Cask remains above atmospheric pressure on the coldest day regardless of how long it has been in storage. The applicants analysis was based on the ideal gas law which governs the change in cavity pressure as the temp erature inside the cavity decreases. The applicant cited Section 7.2.2.1 of the TN-32 UF SAR for the initial gas temperature of 411 degrees F (211 degrees C) and TN-32 TS 3.1.2 for the cavity minimum allowed pressure of 2.10 atm (2,130 mbar). The applicant state d the minimum average daily ambient design temperature for the TN-32 Dry Storage Cask is 2 0 degrees F (29 degrees C).

Assuming that the helium gas temperature is the same as the amb ient air temperature, the applicant determined that the minimum pressure in the cask woul d be 1.06 atm (1,074 mbar).

In response to an RAI regarding the effect of cask leak rate on the cavity gas pressure the applicant indicated (ADAMS Accession No. ML21036A238) that UFSA R Section 2.3.2.1, Confinement Barriers and Systems, considered permeation through the confinement vessel negligible and leakage past the higher pressure of the monitori ng system physically impossible.

Therefore, the applicant concluded the decrease in cavity press ure during the storage period occurs only as a result of a reduction in the cavity gas temper ature with time.

The NRC reviewed the applicants original assessment in TN-32 U SFAR Section 2.2.5.3.3 and the basis for the revised calculation. The TLAA provided by th e applicant considers the decay heat of the fuel, time in service at the end of the PEO, and th e minimum ambient operating temperature for the TN-32 Dry Storage Cask. The staff verified that Section 7.2.2.1 of the TN-32 UFSAR indicates that the average cavity gas temperature is 4 11 degrees F (211 degrees C) with 100 degrees F (38 degrees C) ambient air and maximum solar load. In addition, the staff verified that TN-32 TS 3.1.2 stipulates the cavity minimum allo wed pressure of 2.10 atm (2,130 mbar). The staff confirmed that the minimum average daily ambi ent design temperature for the TN-32 Dry Storage Cask is 20 degrees F (29 degrees C) as show n in Table 2.5-1 of the TN-32 USFAR. The staff noted that the assumption of the helium fi ll gas temperature as being the same as the minimum daily ambient temperature is conservative b ecause the residual decay heat from the stored spent fuel will result in internal tempera tures above that of the ambient external environment. The staff verified that the applicants calculation was based on initial and assumed final helium gas temperatures, which resulted in a fina l pressure greater than one atm.

The staff determined that the applicants revised assessment wa s acceptable because the calculation shows that the TN-32 Dry Storage Cask design criter ia is met for the PEO.

3-36 3.5.4 Evaluation Findings

The staff reviewed the renewal application and design-bases doc umentation to confirm that the applicant did not omit any TLAAs that were part of the approved design bases. The staff performed its review following the guidance provided in NUREG-1 927 and NUREG-2214.

Based on its review of the renewal application, the staff finds the following:

F3.3 The applicant appropriately evaluated all aging mechanisms and effects pertinent to SSCs within the scope of the renewal that had the potential to involve TLAAs.

Therefore, the applicants evaluation provides reasonable assur ance that the SSCs will maintain their intended functions for the PEO, require no furth er aging management activities, and meet the requirements in 10 CFR 72.240(c)(2).

3-37 3.6 Aging Management Programs

Under 10 CFR 72.240 requirements, the applicant must provide a description of AMPs for management of issues associated with aging that could adversely affect ITS SSCs. The applicant provided the following AMPs in the renewal applicatio n:

(1) TN-32 AMP (2) Storage pad AMP (3) Earthen berm AMP

The staff used the guidance in NUREG-1927, Section 3.6, to revi ew the applicants AMPs. In particular, the staff used the guidance in NUREG-1927, Section 3.6.1, which provides detailed review instructions for the ten elements of an AMP to meet the regulatory requirements of 10 CFR 72.240(c)(3). The staff also used the information in NUREG -2214, Chapter 6, Example Aging Management Programs, that contains example AMPs that an a pplicant may use to address the credible aging effects identified in the AMR tables. The staff used the information in NUREG-2214, Sections 6.6, Reinforced Concrete Structures, and t he example AMP for concrete structures in NUREG-2214, Table 6-3, to inform the rev iew of the applicants AMP for the reinforced concrete storage pad. The staff used the inform ation in NUREG-2214, Section 6.7, Monitoring of Metallic Surfaces, and Section 6.8, Bolted C ask Seal Leakage Monitoring, along with the example AMP for monitoring of metallic surfaces in NUREG-2214, Table 6-4, and the example AMP for bolted cask seal leakage monitoring in NURE G-2214, Table 6-5, to inform the review of the applicants AMP for the TN-32 Dry Storage Cas k.

In addition, the staff reviewed the applicants AMR for the opt ional earthen berm using the information included in EPRI-1015078 cited by the applicant. T he staff also reviewed the information in (1) NUREG-0800, Standard Review Plan for the Re view of Safety Analysis Reports for Nuclear Power Plants: LWR Edition, Section 2.5.4 Stability of Subsurface Materials and Foundations (ADAMS Accession No. ML13311B744) (N RC 2014), (2) NRC RG 1.127, Revision 2, Criteria and Design Features for Inspection of Water Control Structures Associated with Nuclear Power Plants (ADAMS Accession No. ML15 107A412), Section C.5.b.,

Onsite Inspection Program, (3) the aging management of the be rm at the Prairie Island Nuclear Generating Plant ISFSI (ADAMS Accession No. ML15285A007 ), and (4) the staff evaluation of the TN-40 Dry Storage Cask AMP in the Prairie Isl and Nuclear Generating Plant ISFSI SER (ADAMS Accession No. ML15336A230). The staff used th e information in EPRI-1015078 and NUREG-0800, Section 2.5.4, for addition insight int o aging mechanisms and effects for earthen structures. The staff used the information in NRC RG 1.127, Section C.5.b, for information on the inspection of earthen embankment structu res for the detection of aging effects.

The staff compared the content of the AMPs provided by the appl icant to the results of the AMR.

The staff determined that the AMPs provided by the applicant ar e consistent with the results of the AMR for SSCs within the scope of the renewal and address cr edible aging effects that were not dispositioned with TLAAs or supplemental analyses. The sta ff conducted the safety review of the proposed AMPs in the renewal application per the guidanc e in NUREG-1927, and, when applicable, to the generically acceptable example AMPs in NUREG -2214. The staffs review of the AMPs provided by the applicant in the renewal application a long with the changes to the AMPs in response to RAIs (ADAMS Accession No. ML20316A030, ML21 036A237 and ML21076A040) is provided in the following subsections.

3-38 3.6.1 TN-32 AMP

The staff conducted the safety review of the proposed AMPs in t he renewal application per the guidance in NUREG-1927, Section 3.6.1, specific to each AMP ele ment. In addition, the staff used the generically acceptable example AMPs in NUREG-2214, Tab le 6-4, for the visual inspection of the TN-32 Dry Storage Cask external surfaces and Table 6-5 for the review of the pressure monitoring system.

Scope of program: The applicant stated that the program calls f or general licensees to visually inspect and monitor the condition of the TN-32 subcomponents li sted in the renewal application, Table 4-1. The applicant stated that the renewal application S ection 4.3 identifies the materials aging effects to be managed as follows:

  • Steel o Loss of material due to general, pitting, crevice, and galvani c corrosion o Loss of preload due to stress relaxation of bolts
  • Stainless Steel o Loss of material due to pitting, crevice, and galvanic corrosi on
  • Polymers o Shrinkage/cracking due to thermal aging and radiation embrittl ement
  • Aluminum o Loss of material due to general, pitting, crevice, and galvani c corrosion

The staff reviewed the applicants description of the scope of program for the TN-32 AMP and determined that the description follows the guidance in NUREG-1 927, Section 3.6.1.1. The staff verified that the scope of program identifies the specific SSCs and subcomponents covered by the AMP, the intended function to be maintained, and identifies the specific materials, environments, and aging mechanisms and effects to be managed. The staff determined that the scope of program for the TN-32 AMP covers the all of the po tential aging mechanisms and effects identified in the AMR for the subcomponents of the TN-3 2 Dry Storage Cask that are within the scope of renewal review. Therefore, the staff deter mined that the applicants description for the scope of program AMP element was acceptable.

Preventive actions: The applicant stated that the TN-32 AMP is a condition-monitoring program that does not include preventive actions.

The staff determined that the applicants description of the pr eventive actions AMP element follows the guidance in NUREG-1927, Section 3.6.1.2, which stat es that some condition or performance monitoring programs do not rely on preventive actio ns and thus this information need not be provided. Therefore, the staff determined that the applicants description for the preventive actions AMP element was acceptable.

Parameters monitored or inspected: The applicant stated that th e TN-32 AMP consists of interseal pressure monitoring, radiation monitoring, and visual inspections of the subcomponents within the scope of the TN-32 AMP for the aging m echanisms and effects identified in the renewal application, Table 4-1. The applican t stated that monitoring of the interseal pressure of the TN-32 Dry Storage Cask is used to ver ify the integrity of the TN-32 Dry Storage Cask seals. The applicant stated that gamma and neutro n radiation monitoring will be conducted to ensure that there is no loss of the shielding inte nded safety function. The

3-39 applicant stated that visual inspections will be performed on t he TN-32 Dry Storage Cask looking for loss of material for steel and stainless steel subc omponents.

The staff reviewed the applicants description of the parameter s monitored and inspected for the TN-32 AMP and determined that the description was acceptable be cause program element identifies the specific parameters that will be monitored or in spected to identify degradation before a loss of intended function, meaning the program element follows the guidance in NUREG-1927, Section 3.6.1.3. Therefore, the staff determined t hat the applicants description of the parameters monitored on in spected AMP element was accept able.

Detection of aging effects: The applicant stated that the inter seal pressure is monitored by measuring the pressure in the overpressure system. Monitoring of the overpressure system, which controls the interseal pressure, is used to determine if the TN-32 Dy Storage Cask seals continue to function as designed. A decrease in pressure is an indication that one of the seals in TN-32 Dry Storage Cask is allowing helium gas to leak past t he seal. The TN-32 AMP uses the same equipment, methods, and frequency used to comply with TN-32 TS 3.1.5, Cask Interseal Pressure. In addition, the applicant stated that th e TS Surveillance Requirement (SR) 3.1.5.1 requires verification that the cask interseal helium pr essure is above 3.2 atm absolute every seven days.

The applicant stated that the detection of gamma and neutron ra diation is accomplished by placing thermoluminescent dosimeters (TLDs) at the ISFSI perime ter fence and conducting surveys of neutron radiation around the perimeter of the storag e pad. The applicant stated that TLDs for monitoring neutron radiation shall be capable of detec ting low, intermediate, and high energy neutrons. This can be accomplished with a Columbia Resi n (CR) 39 chip or equivalent dosimetry equipment. The placement of the TLDs depends on the characteristics of each site and justification of the placement of the TLDs must be document ed in a sites program documentation. The applicant stated that the TLD readings are obtained quarterly and the neutron surveys will be performed annually. Increases in dose rates are attributable to deterioration of the gamma and neutron shielding because radiat ion from spent fuel decreases over time. Thus, the results from these monitoring activities provide a means to detect deterioration of the TN-32 Dry Storage Cask gamma and neutron s hielding due to loss of material, shrinkage, or cracking before the limits in 10 CFR 20.1301 and 10 CFR 72.104 are exceeded. This is because radiation from spent fuel decreases over time and an increase is detected, it would likely be from degradation to the shielding.

The applicant stated that visual inspection, referenced under t he Parameters monitored or inspected, AMP element (either direct or remote) will be perfo rmed on the surfaces of in-scope subcomponents in the normally accessible and non-accessible are as. The applicant stated that accessible surfaces of all TN-32 Dry Storage Casks will be visu ally inspected on an annual basis. In addition, the applicant stated that a scheduled visu al inspection of normally non-accessible areas of a lead TN-32 Dry Storage Cask will be perfo rmed within two years prior to 20 years of the first loaded TN-32 Dry Storage Cask being place d in storage, or no later than eighteen months after the effective date of the CoC renewal, wh ichever is later. The applicant stated that the initial inspection will serve as a baseline and subsequent inspections would occur on a frequency of every 20 +/- 1 years thereafter.

The applicant stated that visual inspections are looking for lo ss of material indicated by corrosion or rust stains on steel or stainless steel surfaces a nd rust stains on the concrete pad.

The applicant clarified that removal of bolts for the annual in spection of the accessible surfaces is not required. The applicant stated that ASME non-destructiv e examination (NDE)

3-40 qualifications are not required to perform the visual inspectio ns of accessible areas; however, the inspectors of accessible areas shall be trained/qualified p er the licensees specific procedures. For the visual examinations of the normally non-ac cessible areas, the applicant stated that the personnel performing the inspection shall be qu alified and certified in accordance with ASME Section XI, IWA-2300.

The staff reviewed the applicants detection of aging effects f or the TN-32 AMP and determined that the description was acceptable because the program element identifies the inspection method, samples size, timing of inspections, and inspection fre quency necessary to identify degradation before a loss of intended function.

The staff found that the detection of aging effects using inter seal pressure monitoring was acceptable because the TN-32 AMP utilizes the same equipment, m ethods, and frequency used to comply with TN-32 TS 3.1.5. The staff noted that the TN-32 Dry Storage Cask design uses an inner and outer seal with the interseal region at a higher p ressure than either the cask interior or the external environment. By monitoring the pressu re in the interseal region using the overpressure system, any leak of either the inner or the outer seal would be readily detected.

The staff noted that the pressure monitoring systems on bolted lid spent fuel storage systems have detected seal leakage as a result of seal corrosion prior to a loss of intended function.

The staff found that the radiation monitoring was capable of de tecting any degradation to the gamma and neutron shield based on TLDs constantly monitoring th e area, annual inspections, and annual radiation surveys. The TLDs are in place to confirm compliance with limits in 10 CFR 20.1301 and 10 CFR 72.104 and increases in radiation beyond these limits would be detected. TLDs may not be able to detect localized failure of a single cask as they detect an average dose rate at a distance. Localized degradation that wo uld result in a hot spot near an individual cask would affect workers near the area of degradati on and would be detected when surveys are performed to obtain a radiation work permit before workers entered the area as stated in the March 17, 2021 supplement (ADAMS Accession No. ML 21076A040). Any areas that have unexpectedly high radiation would be entered into the corrective action program as a matter of standard radiation protection practices. The annual visual inspections additionally ensure that degradation to the gamma shielding would be detecte d because corrosion of the steel cask would be readily identified by the visual inspection and annual neutron surveys ensure that degradation to the neutron shielding would be detec ted. These additional factors provide assurance that any shielding degradation resulting in s treaming paths not seen by the TLDs would be detected.

The staff found that the stated visual inspections looking for loss of material indicated by corrosion or rust stains on steel or stainless steel surfaces a nd rust stains on the concrete pad are acceptable because corrosion of the carbon steel and stainl ess steel components will produce corrosion products that are readily apparent. In addit ion, the staff determined that the personnel requirements, which stipulate that the annual inspect ion be performed by staff trained by the general licensee, and the inspection of the normally non -accessible areas, which the applicants requirements mandate be performed by ASME qualified personnel, are sufficient for the detection of aging effects to prevent a loss of intended fu nction. The staff determined that the 20 year inspection interval for the normally non-accessible components of the TN-32 Dry Storage Cask was acceptable because the cask design provides pr otection of these subcomponents and the OE review did not identify aging-related issues that would require more frequent inspection intervals.

3-41 The staff determined that the applicants description for the d etection of aging effects AMP element follows the guidance in NUREG-1927, Section 3.6.1.4, an d identifies how the potential aging effects for the TN-32 Dry Storage Cask will be detected b y the inspection and monitoring methods specified in the AMP. Therefore, the staff determined that the applicants description of the detection of aging effects AMP element was acceptable.

Monitoring and trending: The applicant stated that general lice nsees perform the inspections and monitoring activities in the TN-32 AMP periodically to iden tify areas of degradation and that conditions that do not meet the acceptance criteria are entered into the general licensees corrective action program. The applicant stated that visual in spections consider the cumulative OE from previous inspections and assessments in order to monito r the progression of aging effects over time. The applicant stated that general licensees will compare the data taken from inspections and monitoring activities to past site data taken a s well as to industry OE, including data gathered by the Institute of Nuclear Power Operations (INP O) Aging Management INPO Database (AMID), as discussed in Nuclear Energy Institute (NEI) 14-03 (NEI 2016).

The staff reviewed the applicants description of the monitorin g and trending element of the TN-32 AMP and determined that the applicants description follows the guidance in NUREG-1927, Section 3.6.1.5. Specifically, the applicants description for the AMP element includes a baseline inspection established at the beginning of the PEO and the applicant described how the data will be collected and evaluated against the results of past inspection data. The staff found the frequency of the radiation monitoring and trending re asonable and acceptable based on the requirement that there be multiple modes of detection wi th acceptance criteria to identify aging effects. These include, as described above in this and t he preceding sections, annual visual inspections, annual neutron monitoring, continuous monit oring by the TLDs, and the necessary radiation surveys as needed to support radiation work permits. Therefore, the staff determined that the applicants description of the detection of aging effects AMP element was acceptable.

Acceptance criteria: The applicant stated that the acceptance c riterion for interseal pressure monitoring is the limit specified in TN-32 Dry Storage Cask TS 3.1.5i.e., it must be at least 3.2 atm absolute. The applicant stated that the acceptance criteri a for radiation monitoring is the absence of an annual increasing trend in neutron or gamma quart erly TLD readings at the ISFSI perimeter fence and absence of an annual increasing trend in th e neutron surveys at the storage pad perimeter. The applicant stated that the acceptanc e criteria for the visual inspections are no observed corrosion, no rust stains on steel or stainless steel surfaces, and no rust stains on the concrete pad. In addition, the applicant stated that if any of the above acceptance criteria are not met, further evaluation is required through the general licensees corrective action program.

The staff reviewed the description and determined that the appl icants description of the acceptance criteria AMP elemen t follows the guidance in NUREG-1927, Section 3.6.1.6. The staff determined that the acceptance criterion for interseal pr essure monitoring is acceptable because it is based on the limit specified in TN-32 Dry Storage Cask TS 3.1.5, which assures that the original design basis is maintained throughout the PEO. The staff determined that the applicants acceptance criteria for gamma and neutron radiation monitoring were acceptable because the TN-32 AMP specifies measurement and monitoring of g amma and neutron radiation trends. An increasing trend might indicate degradati on of the shielding, as the radiation source should decay over time. Therefore, the staff found that the acceptance criteria for gamma and neutron radiation monitoring were appropriate. T he staff determined that the applicants acceptance criteria for visual inspection of corros ionwhich specifies no observed

3-42 corrosion, no rust stains on steel or stainless steel surfaces, and no rust stains on the concrete padwere acceptable because corrosion products are readily obse rved in visual inspection and the observed presence of corrosion products indicates corrosion that could result in a loss of material. The staff verified the applicant stated that any ins pection or monitoring result that does not meet the acceptance criteria would be entered into the general licensees corrective action program for further evaluation. Therefore, the NRC staf f found the applicants description of the acceptance criteria AMP element to be acceptable.

Corrective actions: The applicant stated that under the AMP, ge neral licensees implement quality assurance (QA) procedures; review and approval processe s; and administrative controls according to the requirements of 10 CFR Part 50, Appendix B. T his ensures that general licensees promptly identify and correct conditions adverse to q uality. These procedures include root cause determination and prevention of recurrence. The app licant stated that general licensees either correct deficiencies (i.e., inspection results that do not meet acceptance criteria) or evaluate the cask to be acceptable for continued service thr ough engineering analysis. This engineering analysis provides reasonable assurance that the int ended safety function is maintained consistent with current licensing basis conditions. In addition, the applicant stated that the extent of condition investigation per the general lice nsees corrective action program may cause additional inspections through use of a different met hod, increased inspection frequency, and/or expanded inspection sample size.

The staff reviewed the applicants description of the correctiv e action element for the TN-32 AMP and verified that the corrective actions for the TN-32 Dry Storage Cask AMP state the measures to be taken when the acceptance criteria are not met i nclude root cause determination and prevention of recurrence for significant cond itions adverse to quality. Based on this, the staff determined that the corrective actions follo wed the guidance in NUREG-1927, Section 3.6.1.7, which states that an applicant may reference t he use of the corrective action program approved under 10 CFR Part 50, Appendix B. Therefore, the staff finds the applicants description of the corrective actions AMP element to be accepta ble.

Confirmation process: The applicant stated that the confirmatio n process will be commensurate with the general licensees QA programs approved under 10 CFR P art 50, Appendix B, this means the confirmation process includes provisions to verify that appropriate corrective actions have been completed and are effective. The applicant stated th at the general licensees QA programs approved under 10 CFR Part 50, Appendix B, also contai n provisions to preclude repetition of significant conditions adverse to quality.

The staff reviewed the applicants description of the confirmat ion process element for the TN-32 AMP and determined that the description follows the guidance in NUREG-1927, Section 3.6.1.8, which states that the confirmation process AMP element is inten ded to verify that preventive actions are adequate and that appropriate corrective actions ha ve been completed and are effective. The staff verified that the confirmation process fo r the TN-32 AMP includes provisions to verify that appropriate corrective actions have been complet ed and are effective and relies on the general licensees QA programs approved under 10 CFR Part 5 0, Appendix B, which contains provisions to preclude repetition of significant condi tions adverse to quality. Therefore, the staff determined that the applicants description of the co nfirmation process AMP element was acceptable.

Administrative controls: The applicant stated that the administ rative controls under the CoC holders or general licensees QA procedures and corrective act ion program provide a formal review and approval process. The applicant stated that the adm inistrative controls are

3-43 implemented in accordance with the requirements of 10 CFR Part 50, Appendix B, and will continue for the PEO. The applicant stated that general licens ees and CoC holders use the 10 CFR Part 72 regulatory requirements to determine if a particula r aging-related degradation condition or event identified via OE, research, monitoring, or inspection is reportable to the NRC.

The staff reviewed the applicants description of the administr ative controls element for the TN-32 AMP using the guidance in NUREG-1927, Section 3.6.1.9. The staff confirmed that the applicants description of the administrative controls under th e CoC holders or general licensees QA procedures and corrective action program provide a formal review and approval process for the TN-32 AMP. The staff determined that the appli cants description states that the administrative controls are in accordance with the general lice nsee QA program approved under 10 CFR Part 50, Appendix B, and will continue for the PEO. The refore, the staff determined that the applicants description of the administrative controls AMP element was acceptable.

Operating experience: The applicant stated that renewal applica tion Appendix 3C documents the review of various sources of OE relevant to the TN-32 Dry S torage Cask and includes the results of inspections of the TN-32 and TN-40 Dry Storage Casks in service. The applicant stated that the TN-32 AMP will be updated, as necessary, to inc orporate new information on degradation due to aging effects identified from plant-specific inspection findings, related industry OE, and related industry research. The applicant note d that future plant-specific and industry aging management and aging-related OE are captured thr ough the general licensees review processes. The ongoing review of both plant-specific an d industry OE will continue through the PEO to ensure that this AMP continues to be effecti ve in managing the identified aging effects.

The staff reviewed the applicants description of the operating experience AMP element for the TN-32 AMP and determined that the description follows the guida nce in NUREG-1927, Section 3.6.1.10. Specifically, the staff determined that the applican ts description identified the relevant sources of OE listed in NUREG-1927, Section 3.6.1.10. The staf f determined that the applicant assessed current OE and included provisions to capture future p lant-specific and industry aging management and aging-related OE through the OE review process. Therefore, the staff determined that the applicants description of the operating ex perience AMP element was acceptable.

The staff review verified that each element of the TN-32 AMP co ntained the provisions necessary so that the AMP will be effective for identifying deg radation of the TN-32 Dry Storage Casks and implementing corrective actions before a loss of inte nded function. The staff determined that the AMP for the TN-32 Dry Storage Casks is cons istent with the guidance provided in NUREG-1927, Section 3.6.1. Thus, the staff determined that the AMP for the TN-32 Dry Storage Casks in the renewal application was acceptable for managing the aging effects as a result of credible aging mechanisms.

3.6.2 Storage pad AMP

This subsection documents the staff review of the storage pad A MP. The staff used the review guidance in NUREG-1927, Section 3.6.1, specific to each AMP ele ment. In addition, the staff

3-44 used the generically acceptable example AMPs in NUREG-2214, Tab le 6-3, for the review of the reinforced concrete structures.

Scope of program: The applicant stated that the program calls f or general licensees to visually inspect the surfaces of the storage pad subcomponents listed in the renewal application, Table 4-2. The applicant stated that renewal application Section 4.4 identifies the materials aging effects to be managed, as follows:

  • Steel o Loss of material due to general corrosion, pitting corrosion, and crevice corrosion
  • Concrete o Loss of material due to freeze-thaw, aggressive chemical attac k, corrosion of reinforcing steel, delayed ettringite formation, salt scaling, and microbiological degradation o Cracking due to freeze-thaw, reaction with aggregates, differe ntial settlement, aggressive chemical attack, corrosion of reinforcing steel, and delayed ettringite formation o Loss of strength due to reaction with aggregates, aggressive c hemical attack, corrosion of reinforcing steel, leaching of calcium hydroxide, delayed ettringite formation, and microbiological degradation o Reduction of concrete pH due to aggressive chemical attack, le aching of calcium hydroxide, and microbiological degradation o Loss of concrete/steel bond due to corrosion of reinforcing st eel o Increase in porosity and permeability due to leaching of calci um hydroxide and microbiological degradation

The staff reviewed the applicants description of the scope of program for the storage pad AMP and determined that the description was acceptable because the program element follows the guidance in NUREG-1927, Section 3.6.1.1, and is consistent with the example AMP in NUREG-2214, Table 6-3. The staff verified that the scope of program identifies the specific SSCs and subcomponents covered by the AMP, the intended function to be m aintained, and identifies the specific materials, environments, and aging mechanisms and effe cts to be managed. The staff determined that the scope of the program for the Storage pad AM P covers the all of the potential aging mechanisms and effects identified in the AMR fo r the subcomponents of the storage pad for the TN-32 Dry Storage Cask that are within the scope of renewal. Therefore, the staff determined that the applicants description for the s cope of program AMP element was acceptable.

Preventive actions: The applicant stated that the storage pad A MP is a condition-monitoring program that does not include preventive actions.

The staff determined that the applicants explanation is accept able because, as noted in NUREG-1927, Section 3.6.1.2, some condition or performance monitoring programs do not rely on preventive actions and thus this information need not be pro vided. Therefore, the staff determined that the applicants description for the preventive actions AMP element was acceptable.

Parameters monitored or inspected: The applicant stated that th e storage pad AMP consists of visual inspections to monitor for material degradation as ident ified in renewal application, Table

3-45 4-2. The applicant stated that accessible areas of the storage pad will undergo direct visual inspection, including the aboveground exposed surface of the st orage pad. The applicant stated that the normally non-accessible areas of the storage pa d include external surfaces of the storage pad under the TN-32 Dry Storage Casks and that the inaccessible areas of the storage pad include below-grade surfaces of the storage pad, an d the components embedded in concrete. The applicant did not include inspection of the n ormally non-accessible concrete surface area under the TN-32 Dry Storage Casks or the inaccessi ble areas of the storage pad that is below-grade.

The staff reviewed the applicants description of the parameter s monitored and inspected for the storage pad AMP and determined that the applicants description of the AMP element follows the guidance in NUREG-1927, Secti on 3.6.1.3. The staff determined that the applicants description identifies the specific parameters that will be mon itored or inspected to identify degradation before a loss of intended function. The staff dete rmined that the applicants AMP element description is also consistent with the example AMP in NUREG-2214, Table 6-3.

Therefore, the staff determined that the applicants descriptio n of the parameters monitored or inspected AMP element was acceptable.

Detection of aging effects: The applicant stated that under the AMP, general licensees are to conduct direct visual inspections utilizing ACI-349.3R, Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete Structures, (ACI 2018 ) Section 3.6.1, Visual inspection, for the above-grade portions of the concrete storage pad, allow ing for detection of aging effects listed in renewal application, Table 4-2. In res ponse to an RAI (ADAMS Accession No. ML20316A030), the applicant stated that the visual inspecti on of the storage pad shall be conducted by staff that meet the qualification requirements of ACI-349.3R, Chapter 7. The applicant stated that for storage pad concrete, under the AMP g eneral licensees develop crack maps and document dimensions in photographic records by inclusi on of a tape measure/crack gauge, a comparator, or both.

The applicant stated that general licensees assess potential de gradation of the below-grade portion of the concrete pad by inspecting the aboveground, expo sed surfaces of the storage pads for indications of aging and by reviewing the results of g roundwater sampling at a minimum of three locations in the area of the ISFSI to ensure t he below-grade portions are not exposed to an aggressive environment. The applicant stated tha t the approach is consistent with the Type 1 below-grade inaccessible areas in Section 6 of ACI 349.3R-2018 except the AMP does not explicitly call for inspections of opportunity if the below-grade concrete is exposed due to excavation for any reason. In response to an RA I (ADAMS Accession No. ML20316A030), the applicant stated that the inspection of oppor tunity was not included in the AMP because the likelihood of excavating adjacent to an existin g ISFSI pad is so small that the potential aging management benefit does not warrant the additio nal procedural complexity required to ensure that the inspections of opportunity would be performed.

The applicant stated that the baseline AMP visual inspection an d groundwater sampling is to be conducted at most two years prior to 20 years of the first load ed TN-32 Dry Storage Cask being placed in storage, or no later than eighteen months after the e ffective date of the CoC renewal, whichever is later. The applicant stated that subsequent inspe ctions and groundwater sampling are to be conducted every 5 years +/- 1 year following the baseli ne inspection.

The staff reviewed the applicants description for the detectio n of aging effects for the storage pad AMP element and determined that the AMP element description follows the guidance in NUREG-1927, Section 3.6.1.4. The applicants description ident ifies the inspection method,

3-46 sample size, timing of inspections, and inspection frequency. The staff determined that the applicant described how the potential aging effects for the sto rage pad will be detected by the inspection and monitoring methods identified in this AMP. The staff also determined that the description for the detection of aging effects for the storage pad AMP element is consistent with the example AMP in NUREG-2214, Table 6-3, with the exception of the opportunistic inspection associated with excavations. The staff noted that the example AMP for reinforced concrete structures in NUREG-2214, Table 6-3, relies on the methodology included in ACI 349.3R including the inspection techniques, frequency of inspection, a nd personal qualification requirements. The staff determined that the inspection of the aboveground, accessible portions of the concrete pad combined with groundwater chemistry monitor ing is sufficient to monitor for aging of the storage pad and identify degradation before a loss of intended function and, based on that, inspection of opportunity is not necessary to find the applicants description of this AMP element acceptable. Therefore, the staff determined that the a pplicants description of the detection of the aging effects AMP element was acceptable.

Monitoring and trending: The applicant stated that general lice nsees perform the inspections and monitoring activities in the storage pad AMP periodically t o identify areas of degradation and to ensure that conditions that do not meet the acceptance c riteria are entered into the general licensees corrective action programs. The applicant s tated that the monitoring and trending AMP element considers the cumulative OE from previous storage pad inspections and assessments in order to monitor and trend the progression of ag ing effects over time. The applicant stated that general licensees will monitor data from the inspections and ground water sampling. The applicant stated that the data obtained will be c ompared to past site data as well as to industry OE, including data gathered by the AMID as discu ssed in NEI 14-03.

The staff reviewed the applicants description of the monitorin g and trending element for the storage pad AMP and determined that the description follows the guidance in NUREG-1927, Section 3.6.1.5. The staff determined that the AMP element inc ludes a baseline inspection established at the beginning of the PEO, describes how the insp ection and monitoring data will be collected, and describes the evaluation of the results again st the AMP acceptance criteria to ensure that the timing of the next scheduled inspection will oc cur before a loss of intended function. Therefore, the staff determined that the applicants description of the parameters monitored or inspected AMP element was acceptable.

Acceptance criteria: The applicant listed the visual inspection acceptance criteria which are consistent with those in ACI 349.3R in renewal application Sect ion 4.4.6. In response to an RAI (ADAMS Accession No. ML20316A030), the applicant stated that th e justification for using the ACI 349.3R acceptance criteria was because ACI 349.3R is the re cognized industry standard for managing aging effects of concrete. The applicant stated t hat the majority of the second-tier criteria in ACI 349.3R address conditions where the degradation results in the concrete material being replaced by discrete air pockets such as cracking or spal ling. The applicant stated that since air has lower heat conductivity than the concrete materia l, the acceptance criteria in ACI 349.3R can be extended to be applicable for monitoring the conc rete thermal function. The applicant noted that the magnitude of the acceptance criteria s uch as the size of cracks or spalling is very small compared to the surface area of the pad under the cask. Therefore, the applicant concluded that while the focus of ACI 349.3R may be t he structural performance of the concrete, it can also be used to ensure that the thermal functi on is maintained. The applicant also included acceptance criteria for the groundwater chemistry -sampling program with specific criteria for pH, and the concentrations of chlorides and sulfat es. In addition, the applicant stated that if any of the above acceptance criteria are not met, furth er evaluation is required through the general licensees corre ctive action program.

3-47 The staff reviewed the applicants description and determined t hat the acceptance criteria follow the guidance in NUREG 1927, Section 3.6.1.6, and are based on t he ACI 349.3R code second-tier acceptance criteria for the inspection of concrete structu res and included specific numerical values to ensure that the design bases are maintained. The sta ff determined that the applicants description of the groundwater monitoring program i s also consistent with the criteria in ACI 349.3R and ASME Code Section XI, Subsection IWL. In add ition, the staff determined that the applicants acceptance criteria for visual inspection and groundwater monitoring in the storage pad acceptance criteria AMP description are consistent with the example AMP in NUREG-2214, Table 6-3. Therefore, the NRC staff found the appl icants description of the acceptance criteria AMP element to be acceptable.

Corrective actions: The applicant stated that under the AMP, ge neral licensees implement QA procedures; review and approval processes; and administrative c ontrols according to the requirements of 10 CFR Part 50, Appendix B. This ensures that general licensees promptly identify and correct conditions adverse to quality. These proc edures include root cause determination and prevention of recurrence. The applicant stat ed that general licensees either correct deficiencies or are evaluate the storage pad to be acce ptable for continued service through engineering analysis. This engineering analysis provid es reasonable assurance that the intended safety function is maintained consistent with curr ent licensing basis conditions. In addition, the applicant stated that the extent of condition inv estigation per the general licensees corrective action program may cause additional inspections thro ugh means of a different method, increased inspection frequency, and/or expanded inspect ion sample size.

The staff reviewed the applicants description of the correctiv e action AMP element and determined that the description follows the guidance in NUREG-1 927, Section 3.6.1.7. The staff verified that the corrective action descriptions for the Storag e pad AMP state the measures to be taken when the acceptance criteria are not met and include r oot cause determination and prevention of recurrence of significant conditions adverse to q uality. Based on this, the staff determined that the corrective action descriptions followed the guidance in NUREG-1927, which states that an applicant may reference the use of the correctiv e action program approved under 10 CFR Part 50, Appendix B. Therefore, the staff finds the app licants description of the corrective actions AMP element to be acceptable.

Confirmation process: The applicant stated that under the AMP, the confirmation process will be commensurate with the general licensees QA programs approved u nder 10 CFR Part 50, Appendix B, which ensures that the confirmation process include s provisions to verify that appropriate corrective actions have been completed and are effe ctive. The applicant stated that the general licensees QA programs approved under 10 CFR Part 5 0, Appendix B, also contain provisions to preclude repetition of significant conditions adv erse to quality.

The staff reviewed the applicants description of the confirmat ion process element for the storage pad AMP and determined that the description follows the guidance in NUREG-1927, Section 3.6.1.8, which states that the confirmation process AMP element is intended to verify that preventive actions are adequate and that appropriate corre ctive actions have been completed and are effective. The staff verified that the confi rmation process for the storage pad AMP includes provisions to verify that appropriate corrective a ctions have been completed and are effective and that the AMP relies on the general licensees QA programs approved under 10 CFR Part 50, Appendix B, which contains provisions to preclude repetition of significant conditions adverse to quality. Therefore, the staff determined that the applicants description of the confirmation process AMP element was acceptable.

3-48 Administrative controls: The applicant stated that the administ rative controls under the CoC holders or general licensees QA procedures and corrective act ion programs provide a formal review and approval process. The applicant stated that the CoC holder and general licensees implement the administrative controls in accordance with the re quirements of 10 CFR Part 50, Appendix B, and will continue to do so for the PEO. The applic ant stated that general licensees and the CoC holder use the 10 CFR Part 72 regulatory requiremen ts to determine if a particular aging-related degradation condition or event identified via OE, research, monitoring, or inspection is reportable to the NRC.

The staff reviewed the applicants description of the administr ative controls element for the storage pad AMP and determined that the description follows the guidance in NUREG-1927, Section 3.6.1.9. The staff confirmed that the applicants desc ription of the administrative controls under the CoC holders or general licensees QA proced ures and corrective action program provides a formal review and approval process for the s torage pad AMP. The staff determined that the applicants description states that the adm inistrative controls are in accordance with the general licensees QA program approved unde r 10 CFR Part 50, Appendix B, and will continue for the PEO. Therefore, the staff determi ned that the applicants description of the administrative controls AMP element was acceptable.

Operating experience: The applicant described the results of in spections of TN-32 and TN-40 Dry Storage Casks and the storage pad at a specifically license d ISFSI that have been in service for several years in renewal application, Appendix 3C. The storage pad inspections at the specifically licensed ISFSI did not identify storage pad ag ing effects. The applicant stated that the storage pad AMP will be updated, as necessary, to inco rporate new information on degradation due to aging effects identified from plant-specific inspection findings, related industry OE, and related industry research. The applicant note d that future plant-specific and industry aging management and aging-related OE are captured thr ough the general licensees OE review process. The ongoing review of both plant-specific a nd industry OE will continue through the PEO to ensure that this AMP continues to be effecti ve in managing the identified aging effects.

The staff reviewed the applicants description of the operating experience AMP element for the storage pad AMP and determined that the description follows the guidance in NUREG-1927, Section 3.6.1.10. Specifically, the staff determined that the applicants description identified the relevant sources of OE listed in NUREG-1927, Section 3.6.1.10. The staff determined that the applicant assessed current OE and included provisions to captur e future plant-specific and industry aging management and aging-related OE through the OE r eview process. Therefore, the staff determined that the applicants description of the op erating experience AMP element was acceptable.

The staff review verified that each element of the storage pad AMP contained the provisions necessary so that the AMP will be effective for identifying deg radation of the storage pads for the TN-32 Dry Storage Casks and implementing corrective actions before a loss of intended function. The staff determined that the AMP for the storage pad is consistent with the guidance provided in NUREG-1927, Section 3.6.1. Therefore, the staff de termined that the AMP for the storage pad in the renewal application was acceptable for manag ing the aging effects as a result of credible aging mechanisms.

3-49 3.6.3 Earthen berm AMP

This subsection documents the staff review of the earthen berm AMP. The staff used the review guidance in NUREG-1927, Section 3.6.1, specific to each AMP element. This guidance describes an acceptable way for applicants to meet the relevant regulatory requirements.

Scope of program: The applicant stated that under the program, general licensees visually inspect the exterior surfaces of an earthen berm if the general licensee credits an earthen berm in meeting regulatory dose limits. The aging effects/mechanism s managed include:

  • Loss of material due to wind erosion and surface flow
  • Loss of form due to surface flow, settlement, and frost action
  • Change in material properties due to desiccation

The staff reviewed the applicants description of the scope of program for the earthen berm AMP and determined that the AMP element follows the guidance in NUREG-1927, Section 3.6.1.1. The staff verified that the scope of program identifi es the specific SSCs and subcomponents covered by the AMP, the intended function to be m aintained, and identifies the specific materials, environments, and aging mechanisms and effe cts to be managed. The staff determined that the scope of the program for the earthen berm A MP covers the all of the potential aging mechanisms and effects identified in the AMR fo r the subcomponents of the earthen berm that are within the scope of renewal review. Ther efore, the staff determined that the applicants description for the scope of program AMP elemen t was acceptable.

Preventive actions: The applicant stated that the earthen berm AMP is a condition-monitoring program that does not include preventive actions.

The staff determined that the applicants description follows t he guidance in NUREG-1927, Section 3.6.1.2, which states that some condition or performanc e monitoring programs do not rely on preventive actions and thus this information need not b e provided. Therefore, the staff determined that the applicants description for the preventive actions AMP element was acceptable.

Parameters monitored or inspected: The applicant stated that th e earthen berm AMP consists of periodic visual inspections of the berms surface looking for s igns of erosion, formation of gullies, settlement, or frost heaving. The applicant stated th at the frequency of these inspections will ensure that the loss of material or change in the size/shape of the berm is detected prior to the loss of an intended safety function. In response to an RAI (ADAMS Accession No. ML20316A030), the applicant stated that data coll ected from visual inspections typically consists of inspector notes, potentially photos, and is typically attached to the work package or procedure controlling/documenting the inspection.

The staff reviewed the applicants description of the parameter s monitored and inspected for the earthen berm AMP and determined that the description of the AMP element follows the guidance in NUREG-1927, Section 3.6.1.3. The description ident ifies the specific parameters that will be monitored or inspected to identify degradation bef ore a loss of intended function. In addition, the staff determined that the parameters monitored or inspected AMP element is consistent with the guidance in EPRI-1015078, Chapter 8, which identifies loss of material from wind and water runoff, loss of form as a result of settlement o r frost action, and change in material properties as a result of desiccation as aging mechani sms to be managed for passive

3-50 and long-lived earthen structures. Therefore, the staff determ ined that the applicants description of the parameters moni tored on inspected AMP elemen t were acceptable.

Detection of aging effects: The applicant stated that under the AMP, general licensees conduct direct visual inspections on all accessible surfaces of the ear then berm. The applicant also stated that a baseline AMP visual inspection is to be conducted no more than two years prior to 20 years of the first loaded TN-32 Dry Storage Cask being place d in storage, or no later than eighteen months after the effective date of the CoC renewal, wh ichever is later. In response to an RAI (ADAMS Accession No. ML20316A030), the applicant stated that the inspector will be looking for signs of erosion such as scours and gullies, settle ment, and frost heaving, i.e., the acceptance criteria listed in Section 4.5.6 of the renewal appl ication. Renewal application Section 3.4.3.10 describes the AMR of the soil material, indica ting how the AMP acceptance criteria are tied to the various aging effects. Specifically, the renewal application describes the data to be collected, and how the data will be used to assess t he aging effects described in renewal application Section 4.5.1 Earthen Berm AMP - Scope of Program. Renewal application Sections 3.4.3.10.1 and 3.4.3.10.3 describe how win d can erode loose surface soil from an earthen structure, surfa ce flow can cause soil surfaces to erode resulting in surface scour or gullies. Sections 3.4.3.10.6 and 3.4.3.10.7 describe the loss of form aging effect due to settlement and frost heaving, and Section 3.4.3.10.9 describes how desiccation coupled with surface flow or wind action may accelerate these effects of ero sion. The applicant stated that subsequent inspections are to be conducted every 5 +/- 1 years fo llowing the baseline inspection.

The staff reviewed the applicants detection of aging effects f or the earthen berm AMP and determined that the description was acceptable because the prog ram element identifies the inspection method, samples size, timing of inspections, and ins pection frequency. The staff determined that the specific inspection intervals in the AMP ar e appropriate based on information in NRC RG 1.127, which describes periodic inspections to be performed at least once every 5 years. The staff reviewed the applicants detecti on of aging effects for the earthen berm and determined that the description was consistent with NU REG-1927, Section 3.6.1.4, and is acceptable because the program element identifies the in spection method, samples size, timing of inspections, and inspection frequency necessary to id entify degradation before a loss of intended function.

Monitoring and trending: The applicant stated that general lice nsees perform the inspections and monitoring activities in the earthen berm AMP periodically in order to identify areas of degradation and that conditions that do not meet the acceptance criteria are entered into the general licensees corrective action program. The applicant st ated that the monitoring and trending AMP element considers the cumulative OE from previous earthen berm inspections and assessments in order to monitor and trend the progression o f aging effects over time. In response to an RAI (ADAMS Accession No. ML20316A030), the appli cant stated that per renewal application Sections 4.5.5 and 4.5.6 general licensees enter observations that do not meet the acceptance criteria into their corrective action progr am for further evaluation. The applicant stated that it is the general licensees corrective a ction programs that perform the trending of any conditions that do not meet the acceptance crit eria. In addition, the applicant stated that the acceptance criteria listed in Section 4.5.6 are very conservative in that any signs of erosion, scours, gullies, settlement, or frost heaving are t o be entered into the general licensees corrective action programs for further evaluation.

The staff determined that the applicants description of the mo nitoring and trending AMP element follows the guidance in NUREG-1927, Section 3.6.1.5. T he applicants description for the AMP element includes a baseline inspection established at t he beginning of the PEO and

3-51 the applicant described how the data will be collected and eval uated against the AMP acceptance criteria to ensure that the timing of the next sched uled inspection will occur before a loss of intended function and compared to the results of past i nspection data for trending. The staff found the frequency of inspection was acceptable based on the guidance provided in NRC RG 1.127. Therefore, the staff determined that the applicants description of the monitoring and trending AMP element was acceptable.

Acceptance criteria: The applicant stated that the acceptance c riteria for the earthen berm AMP are the absence of (1) erosion; (2) scours or gullies from surf ace runoff; (3) settlement; and (4) frost heaving. In addition, the applicant stated that if any o f the above acceptance criteria are not met, further evaluation is required through the general lic ensees corrective action program.

The staff determined that the applicants description of the ac ceptance criteria AMP element follows the guidance in NUREG 1927, Section 3.6.1.6. The appli cant described the acceptance criteria for visual inspection of the berm. The acceptance cri teria specify no observed erosion, scours, or gullies from surface runoff, settlement, or frost he aving. The staff determined that these aging effects are readily observed in visual inspection b ased on the inspection guidance provided in NRC RG 1.127, Section C.5.b. Therefore, the NRC sta ff found the applicants description of the acceptance criteria AMP element to be accept able.

Corrective actions: The applicant stated that under the AMP, ge neral licensees implement QA procedures; review and approval processes; and administrative c ontrols according to the requirements of 10 CFR Part 50, Appendix B. This ensures that general licensees promptly identify and correct conditions adverse to quality. These proc edures include root cause determination and prevention of recurrence. The applicant stat ed that general licensees either correct deficiencies or evaluate the earthen berm to be accepta ble for continued service through engineering analysis. This engineering analysis provides reaso nable assurance that the intended safety function is maintained consistent with current licensing basis conditions. In addition, the applicant stated that the extent of condition inv estigation per the general licensees corrective action program may cause additional inspections thro ugh use of a different method, increased inspection frequency, and/or expanded inspection samp le size.

The staff reviewed the applicants description of the correctiv e action element for the earthen berm AMP and determined that it follows the guidance in NUREG-1 927, Section 3.6.1.7, which states that an applicant may reference the use of the correctiv e action program approved under 10 CFR Part 50, Appendix B. The staff verified that the correc tive actions for the earthen berm AMP state the measures to be taken when the acceptance criteria are not met including root cause determination and prevention of recurrence for significan t conditions adverse to quality.

Therefore, the staff finds the applicants description of the c orrective actions AMP element to be acceptable.

Confirmation process: The applicant stated that the confirmatio n process will be commensurate with the general licensees QA programs approved under 10 CFR P art 50, Appendix B, which ensures that the confirmation process includes provisions to ve rify that appropriate corrective actions have been completed and are effective. The applicant s tated that the general licensees QA programs approved under 10 CFR Part 50, Appendix B, also con tains provisions to preclude repetition of significant conditions adverse to quality.

The staff reviewed the applicants description of the confirmat ion process element for the earthen berm AMP and determined that the description follows th e guidance in NUREG-1927, Section 3.6.1.8, which states that the confirmation process AMP element is intended to verify

3-52 that preventive actions are adequate and that appropriate corre ctive actions have been completed and are effective. The staff verified that the conf irmation process for the earthen berm AMP includes provisions to verify that appropriate correct ive actions have been completed and are effective and relies on the general licensees QA progr am approved under 10 CFR Part 50, Appendix B, which contains provisions to preclude repetitio n of significant conditions adverse to quality. Therefore, the staff determined that the a pplicants description of the confirmation process AMP element was acceptable.

Administrative controls: The applicant stated that the administ rative controls under the CoC holders or general licensees QA procedures and corrective act ion programs provide a formal review and approval process. The applicant stated that the adm inistrative controls are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B, and will continue for the PEO. The applicant stated that general licens ees and CoC holder use the 10 CFR Part 72 regulatory requirements to determine if a particula r aging-related degradation condition or event identified via OE, research, monitoring, or inspection is reportable to the NRC.

The staff reviewed the applicants description of the administr ative controls element for the earthen berm AMP and determined that the description follows th e guidance in NUREG-1927, Section 3.6.1.9. The staff confirmed that the applicants desc ription of the administrative controls under the CoC holders or general licensees QA proced ures and corrective action program describes a formal review and approval process for the earthen berm AMP. The staff determined that the applicants description states that the adm inistrative controls are in accordance with the general licensee QA program approved under 10 CFR Part 50, Appendix B, and will continue for the PEO. Therefore, the staff determi ned that the applicants description of the administrative controls AMP element was acceptable.

Operating experience: The applicant stated that Section 8.3.4 o f EPRI-1015078 indicates that an operational history review was performed to review the gener ic communications related to earthen structures and the related aging effects. This operati onal history review found no correspondence that was directly related to aging of earthen st ructures. The applicant stated that the lack of reports reflects the high reliability of earth en structures and the lack of significant aging-related degradation. The applicant stated that the earth en berm AMP will be updated, as necessary, to incorporate new information on degradation due to aging effects identified from plant-specific inspection findings, related industry OE, and re lated industry research. The applicant noted that future plant-specific and industry aging m anagement and aging-related OE are captured through the general licensees OE review process. The ongoing review of both plant-specific and industry OE will continue through the PEO to ensure that this AMP continues to be effective in managing the identified aging effects.

The staff reviewed the applicants description of the operating experience AMP element for the earthen berm AMP and determined that the description follows th e guidance in NUREG-1927, Section 3.6.1.10. The staff determined that the applicants de scription identified the relevant sources of OE listed in NUREG-1927, Section 3.6.1.10. The staf f determined that the applicant assessed current OE and included provisions to capture future p lant-specific and industry aging management and aging-related OE through the OE review process. Therefore, the staff determined that the applicants description of the operating ex perience AMP element was acceptable.

The staff review verified that each element of the earthen berm AMP contained the provisions necessary so that the AMP will be effective for identifying deg radation of the earthen berm and

3-53 implementing corrective actions before a loss of intended funct ion. The staff determined that the AMP for the optional earthen berm is consistent with the gu idance provided in NUREG-1927, Section 3.6.1. Therefore, the staff determined that the AMP for the optional earthen berm for the TN-32 Dry Storage Cask in the renewal application was a cceptable for managing the aging effects as a result of credible aging mechanisms.

3.6.4 Changes to the Updated Final Safety Analysis Report

The applicant provided an appendix to the renewal application t hat included changes to the UFSAR. Appendix Table A-1 documents the changes to the UFSAR a ssociated with the renewal and describes the basis for the changes. These changes included updated TLAAs and supporting analyses for the PEO. The applicant stated that a n ew Section 15, Aging Management, will be added to the UFSAR that incorporates the a pproved AMPs including the TN-32 AMP, the storage pad AMP, and the optional earthen berm A MP.

The staff reviewed the changes to the UFSAR and determined that the changes are acceptable because the applicant has included updated TLAAs and supporting analyses for the PEO and the AMPs that will be incorporated into the UFSAR.

3.6.5 Evaluation Findings

The staff reviewed the AMPs in the CoC No. 1027 renewal applica tion. The staff performed its review following the guidance provided in NUREG-1927, and the g eneric evaluations in NUREG-2214. Based on its review, the staff finds the following :

F3.4 The applicant has identified programs that provide reason able assurance that aging effects will be adequately managed during the PEO, in accordanc e with 10 CFR 72.240(c)(3).

3-54 4 CONDITIONS TO ADDRESS RENEWAL

This section provides a consolidated list of the changes to the conditions resulting from the review of the renewal application, some which have been describ ed throughout the previous sections of this SER. The basis of the changes is provided her e for those changes that are not described elsewhere in this SER.

4.1 Changes to Certificate of Compliance

1. Added the following condition to the initial CoC (Amendment 0) and Amendment 1:

UFSAR UPDATE FOR RENEWED COC

The CoC holder shall submit an updated final safety analysis re port (UFSAR) to the Commission, in accordance with 10 CFR 72.4, with in 90 days of the effective date of the renewal. The UFSAR shall reflect the changes and CoC holder commitments resulting from the review an d approval of the renewal of the CoC. The CoC holder shall conti nue 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 U FSAR to address aging management activities resulting from the renewal of the CoC. T his condition ensures that the UFSAR changes are made in a timely fashion to enable g eneral licensees using the storage system during the period of extended operation to d evelop and implement necessary procedures.

2. Added the following condition to the initial CoC (Amendment 0) and Amendment 1:

72.212 EVALUATIONS FOR RENEWED COC USE

Any general licensee that initiates spent fuel dry storage oper ations with the TN-32 dry storage cask system after the effective date of t he CoC renewal and any general licensee operating a TN-32 dry storage cask system as of the effective date of the CoC renewal, including t hose that put additional storage systems into service after that date, sh all:

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;

b. as part of the document review required by 10 CFR 72.212(b)(6), include a review of the UFSAR changes resulting from the renewal of the CoC and the NRC Safety Evaluation Report related to the renewal of the CoC; and

4-1

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

The general licensee shall complete [this] Condition [13] prior to entering the period of extended operation or no later than one year afte r the effective date of the CoC renewal, whichever is later.

The staff considers it important to ensure that appropriate con siderations for the period of extended operation are evaluated in the general licensees r eport required by 10 CFR 72.212, Conditions of general license issued under § 72.210. These considerations arise from the analyses and assumptions in the r enewal application regarding operations during the PEO. This includes potential u se of the TN-32 dry storage cask system by general licensees after the CoC has been renewed either at a new or an existing general license ISFSI. The renewal of the C oC is based on assumptions and analyses of the DSS and the sites where it is u sed. Licensees considering the use of the TN-32 dry storage cask system must e valuate it for use at their respective sites. This condition also makes it clear tha t general licensees that currently use a TN-32 dry storage cask system will need to upda te their 10 CFR 72.212 reports even if they do not put additional DSSs into service af ter the renewals effective date, in accordance with 10 CFR 72.212(b)(11).

3. Added the following condition to the initial CoC (Amendment 0) and Amendment 1:

AMENDMENTS AND REVISIONS FOR RENEWED COC

All future amendments and revisions to this CoC shall include e valuations of the impacts to aging managemen t activities (i.e., time-limited aging analyses and aging management programs) to ensure that they rem ain adequate for any changes to SSCs within the scope of renewal.

The CoC may continue to be amended after it has been renewed. This condition ensures that amendments to the CoC also address aging managemen t impacts that may arise from the changes to the system in proposed amendments.

4.2 Changes to Technical Specifications

1. Added the following section, Aging Management Program, to the initial CoC (Amendment 0) and Amendment 1 as Section 5.2.4 :

Aging Management Program

Each general licensee shall have a program to establish, implem ent, 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 fi ndings

4-2 and/or industry operating experience provided to the general li censee during the renewal period. The program document shall contain a reference to the specific aspect of the AMP element implemented by that program document, and that reference shall be maintained even i f the program document 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, whic hever is later. The general licensee shall maintain the program documen t for as long as the general licensee continues to operate a TN-32 dry s torage cask system in service for longer than 20 years.

The CoC holder proposed a condition to revise or create program s or procedures for implementing the AMPs in the FSAR supplement. This specificati on ensures that programs or procedures address AMP activities required for exte nded storage operations.

4-3 5 CONCLUSIONS

Pursuant to 10 CFR 72.240(d), the design of a spent fuel storag e cask will be renewed if (1) the QA requirements in 10 CFR Part 72, Subpart G, Quality Assuranc e, are met, (2) the requirements of 10 CFR 72.236(a) through (i) are met, and (3) t he application includes a demonstration that the storage of spent fuel has not had signif icant adverse effects on ITS SSCs. Additionally, 10 CFR 72.240(c), among other things, requ ires that the safety analysis report accompanying the application contain TLAAs demonstrating that the DSS SSCs will continue to perform their intended functions for the requested PEO and a description of the AMP for management of issues associated with aging that could a dversely affect ITS SSCs.

The NRC staff reviewed the renewal application for the TN-32 Dr y Storage Cask, in accordance with 10 CFR Part 72. The staff followed the guidance in NUREG-1927. Based on its review of the renewal application and the CoC conditions, the staff deter mined that renewal of CoC No.

1021 for the TN-32 Dry Storage Cask meets the requirements of 1 0 CFR 72.240.

5-1 6 REFERENCES

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ASM International, ASM Handbook - Volume 13 Corrosion, Materi als Park, OH: ASM International, 2000.

Electric Power Research Institute (EPRI) 1015078, Plant Suppor t Engineering: Aging Effects for Structures and Structural Components (Structural Tools), D ecember 2007.

Farrell, K., "Assessment of Aluminum Structural Materials for S ervice within the ANS Reflector Vessel," ORNL/TM-13049, Oak Ridge National Laboratory, August 1 995, https://inis.iaea.org/search/search.aspx?orig_q=RN:27048252.

Kaufman, J.G., ed., "Properties of Aluminum Alloys: Tensile, Cr eep, and Fatigue Data and High and Low Temperatures," The Alumi num Association, Washington, D. C. and ASM International, Metals Park, Ohio, 1999.

Levy, I.S.,.. Beyer, B.A. Chin, E.R. Gilbert, E.P. Simonen and A.B. Johnson, Jr, Recommended Temperature Limits for Dry Storage of Spent Light Water Reactor Zircaloy-Clad Fuel Rods in Inert Gas, PNL-6189, Pacific Northwest Laboratory, May 1987, https://inis.iaea.org/search/search.aspx?orig_q=RN:19005447.

Nuclear Energy Institute, NEI 14-03, Format, Content and Imple mentation Guidance for Dry Cask Storage Operations-Based Ag ing Management, Revision 2, December 21, 2016, ADAMS Accession No. ML16356A204.

Revie, R.W. Uhligs Corrosion Handbook, Second Edition, Hoboken, New Jersey:

John Wiley and Sons, 2000.

U.S. Nuclear Regulatory Commission (NRC), Classification of Tr ansportation Packaging and Dry Spent Fuel Storage System Components According to Importanc e to Safety, NUREG/CR-6407, Washington, DC, February 1996a, ADAMS Accession No. ML15127A114.

U.S. NRC, Report on Aging of Nuclear Power Plant Reinforced Co ncrete Structures, NUREG/CR-6424, March 1996b, ADAMS Accession No. ML072830854.

U.S. NRC, Fuel Retrievability, Spent Fuel Project Office Inte rim Staff Guidance (ISG) - 2, Washington, DC, 1998, ADAMS Accession No. ML092800367.

U.S. NRC, Cladding Considerations for the Transportation and S torage of Spent Fuel, Spent Fuel Project Office Interim Staff Guidance (ISG) - 11, Revision 3 Washington, DC, 2003, ADAMS Accession No. ML033230335.

U.S. NRC, Standard Review Plan for Spent Fuel Dry Storage Syst ems at a General License Facility, NUREG-1536, Revision 1, Washington, DC, July 2010, A DAMS Accession No. ML101040620.

6-1 U.S. NRC, Materials Aging Issues and Aging Management for Exte nded Storage and Transportation of Spent Nuclear Fuel, NUREG/CR-7116, Washingto n, DC, November 2011, ADAMS Accession No. ML11321A182.

U.S. NRC, Standard Review Plan for the Review of Safety Analys is Reports for Nuclear Power Plants: LWR Edition, - Stability of Subsurface Materials and Fo undations, NUREG-0800 Section 2.5.4, Revision 5 Washington, DC, July 2014, ADAMS Acc ession No. ML13311B744.

U.S. NRC, Standard Review Plan for Renewal of Specific License s and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, NUREG-1927, Revision 1, Washington, DC., June 2016a, ADAMS Accession No. ML16179A148.

U.S. NRC, Regulatory Guide 1.127, Revision 2, Criteria and Des ign Features for Inspection of Water Control Structures Associated with Nuclear Power Plants, February 2016b, ADAMS ML15107A412.

U.S. NRC, Managing Aging Processes In Storage (MAPS) Report, NUREG-2214, Washington, DC., July 2019, ADAMS Accession No. ML19214A111.

Virginia Electric and Power Company, Letter from Mark Sartain t o Document Control Desk (NRC), Second Request for Additional Information Response to R AI 3-15 (CAC No.L25121),

License No. SNM-2507, August 16, 2017, ADAMS Accession Number M L17233A170.

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