ML18145A289

COL Docs - FW: Draft Revised Response to RAI LAR-17-037-2 for Structural Engineering Branch - Critical Sections

ML18145A289
Person / Time
Site:	Vogtle
Issue date:	05/25/2018
From:	NRC
To:	NRC/NRO/DNRL/LB4
References
Download: ML18145A289 (13)

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Vogtle PEmails From: Habib, Donald Sent: Friday, May 25, 2018 3:06 PM To: Vogtle PEmails

Subject:

FW: Draft revised response to RAI LAR-17-037-2 for Structural Engineering Branch -

Critical Sections Attachments: RAI LAR-17-037-2_eRAI 9530_SEB (Draft to NRC-052518).pdf From: Haggerty, Neil [1]

Sent: Friday, May 25, 2018 2:31 PM To: Habib, Donald <Donald.Habib@nrc.gov>; Hoellman, Jordan <Jordan.Hoellman2@nrc.gov>

Cc: Patel, Chandu <Chandu.Patel@nrc.gov>; Aughtman, Amy G. <AGAUGHTM@SOUTHERNCO.COM>; Sparkman, Wesley A. <WASPARKM@southernco.com>; Redd, Jason P. <JPREDD@southernco.com>; Hicks, Thomas E.

<X2TEHICK@southernco.com>; Amundson, Theodore Edwin <X2TAMUNS@southernco.com>; Haggerty, Neil

<X2NHAGGE@SOUTHERNCO.COM>

Subject:

[External_Sender] Draft revised response to RAI LAR-17-037-2 for Structural Engineering Branch - Critical Sections

Don, The attached draft response is provided for Staff review. This is the revised response to RAI LAR 037-2 from the Structural Engineering Branch (SEB) regarding their review of LAR-17-037, Changes to Tier 2* Departure Evaluation Process. Specifically, this RAI addresses the evaluation of changes to Tier 2* information re: Critical Sections. Yellow highlighted text represents changes that have been made subsequent to the previous version that was discussed with the NRC staff in a Public meeting on May 3rd.

Please provide this response to the appropriate staff to allow their review in advance of next Thursdays (5/31) Public meeting/call.

Please contact Jason Redd, Wes Sparkman, or myself if you have any questions or comments regarding this draft response.

Thank you, Neil Haggerty Neil Haggerty l Southern Nuclear Operating Company Nuclear Development Regulatory Affairs - VEGP 3&4 Licensing SNC-Inverness: 205.992.7047 l office: 301.874.8537 l mobile: 240.566.2442 x2nhagge@southernco.com neil.haggerty@excelservices.com This e-mail and any attachments thereto are intended only for the use by the addressee(s) named herein and may contain proprietary and confidential information. If you have received this e-mail in error, please immediately notify me by telephone and permanently delete the original and any copy of any e-mail and any printout thereof.

1

2 Hearing Identifier: Vogtle_COL_Docs_Public Email Number: 282 Mail Envelope Properties (BY1PR09MB0935B3235368559824D33F8797690)

Subject:

FW: Draft revised response to RAI LAR-17-037-2 for Structural Engineering Branch - Critical Sections Sent Date: 5/25/2018 3:06:10 PM Received Date: 5/25/2018 3:06:16 PM From: Habib, Donald Created By: Donald.Habib@nrc.gov Recipients:

"Vogtle PEmails" <Vogtle.PEmails@nrc.gov>

Tracking Status: None Post Office: BY1PR09MB0935.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2186 5/25/2018 3:06:16 PM RAI LAR-17-037-2_eRAI 9530_SEB (Draft to NRC-052518).pdf 924382 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Southern Nuclear Operating Company ND-18-0xxx Enclosure X DraVogtle Electric Generating Plantt (VEGP (VEGP) U nits 3 an Units and 4 (0 ft R 5- e 25 sp Response to NRC Request Additional uest for Ad Information (RAI) 17-037-2 itional Info Informa

-2 on Regarding Regardi tthe LAR-17-037 7-037 Review e LAR-17 LAR 01 s (LAR-17-037S3)

(LAR-17 (LAR 7-037 0

8) e Supplement 3 changes to the original LAR text are shown as blue-underlined text; deletions of original LAR text are shown as red strikethrough text.

(This Enclosure consists of nine pages, including this cover page.)

ND-18-0xxx Enclosure X Response to NRC RAI LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)

The following is a question provided by the NRC Staff [Request for Additional Information (RAI)

LAR 17-037-2] regarding the review of Southern Nuclear Operating Company (SNC) License Amendment Request (LAR)17-037, which was submitted by SNC letter ND-17-1726 on December 21, 2017 [ADAMS Accession No. ML17355A416].

Question The final safety analysis report of the Vogtle Electric Generating Plant (VEGP) Units 3 and 4 references the Westinghouse AP1000 certified design. Appendix D to 10 CFR Part 52, Design Certification Rule for the AP1000 Design, provides the regulatory requirements for the AP1000 design. 10 CFR Part 52, Appendix D, Section VIII.B.6.c provides a list of Tier 2* matters, including a design summary of critical sections, that a licensee who references this appendix may not depart from without NRC approval.

Furthermore, SECY-17-0075, Planned Improvements in Desig esig Certification Tiered Design Information Designations, described the staffs approach ach usin the Tier 2*

h to using D

designation for safety significant information. The SECY ra ers in Tier 1 rather than in Tier 2. The staff considers Y noted that rently in Tier eliminated, certain safety-significant information currently s that a crit c cal th if Tier 2* were to be Tie 2* should be included al section critical s has attributes (0 ft R e integrity of that make it safety significant in maintaining the o the plant structure. The designed capacity of the critical sections support pport th the reasonable reasonable asonable ass as assurance of safety 5- e determination for the AP1000 DCD, Rev.19 9 design in the staff safety ev.19 safet evaluation.

sa 25 sp The staff reviewed the LAR and noted oted that the t criteria criteria pertaining to critical sections is not well defined.

def ned.

teria for screening sc s re Tier 2* information

-2 on In Enclosure 3, Proposedd Changes to o Licensing icensing Basis Documents, of the LAR, the 01 s licensee proposed to revise evise condition to address the combined se its com e Tier 2* change d license (COL) ned (C to include a new license process. The licensee included a new license ange proces

8) e ed License Condition condition, proposed C ndition ition 13, 13 Departures De from Plant-Specific DCD Tier 2*

Information. The proposed license e propos propose cense condition states that the licensee ense cond conditio

. . . is exempt from the requirements require requirem of 10 CFR Part 52, Appendix D, B.6 Paragraphs II.F and VIII.B.6 6 tthat invoke the Tier 2* change process that requires prior NRC approval via a license amendment for departures from Tier 2* information; and Paragraph VIII.B.5.a for Tier 2 information that involves a change to, or departure from, Tier 2* information; except for departures from Tier 2* information that:

1. Involve design methodology or construction materials that deviate from a code or standard credited in the plant-specific DCD for establishing the criteria for the design or construction of a structure, system, or component (SSC) important to safety.

The proposed license condition is not clear as to how the critical sections associated with the steel-concrete (SC) modular construction would be screened using the above criteria because information from analysis and tests were used in conjunction with

[DRAFT 5/11/18] Page 2 of 9

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3) codes and standards for the design of SC modules. As approved in the certified design, linear analysis, nonlinear analysis, and testing of the SC module design were performed and the results were compared to provisions of two different codes in order to validate the use of the codes.

The staff considers that the critical sections have safety significance in assuring the integrity of the building which house safety related systems and components. The proposed Criterion 1 relies on code compliance in the design and detailing of the critical sections to screen out details that are code controlled. The application of this criteria may lead the applicant to conclude that the parameters of the critical sections can be modified in the field using available NRC change processes without resorting to the license amendment process. The staff finds instances where here tthe application of this criterion will not yield the desired results. The staff has identified ntifie the following cases as x

D exceptions to the Criterion 1:

ra ndwich wich construction, Critical sections using steel concrete sandwich constru con ctio and ction x

(0 ft R the capacity aspects such as area of steel provid nforced prov rced concrete ratio of critical sections using reinforced concr con te ed d or the demand provided dem to capacity 5- e 25 sp mined that neit In both cases, the staff has determined her er the des neither design nor the cited attributes of ned, making the critical sections are code defined, mak terion 1 in-applicable Criterion iin in these instances. The staff requestss the th applicant app applican th Criterion to revise the C 1 such that the

-2 on conditions identified above e are screened scre ned in and a license licen amendment process followed 01 s for any changes to these se cases, or that at the applic applican provide additional explanation as applicant eria wo to why the proposed criteria wou not would ot need to be revised in order to maintain a

8) e reasonable assuranceance of safety.

safe SNC Response to RAI Q Question on n

Tier 2* information is intended to have ve substantial safety significance, commensurate with information designated as Tier 1. However, as noted in SECY-17-0075, Planned Improvements in Design Certification Tiered Information Designations, [ADAMS Accession Number ML16196A321], the Tier 2* scope identified in previous design certifications, such as AP1000, may be broader than necessary, and includes information more appropriately designated as Tier 2. SNC proposes to invoke a process whereby VEGP 3 and 4 Tier 2* departures would be submitted to the NRC for prior approval when the safety level of the change rises to that which is commensurate with the safety level of Tier 1 information.

While Updated Final Safety Analysis Report (UFSAR) Appendix 3H, Auxiliary and Shield Building Critical Sections, contains significant critical section detailed design, including detailed figures of critical sections, the majority of the AP1000 structural design requirements are derived from applicable codes. SNC acknowledges that for the shield building design, nonlinear analysis and testing were performed to validate the use of applicable codes. The performance of these activities, however, does not invalidate SNCs position that the design of the shield

[DRAFT 5/22/18] Page 3 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3) building and other critical sections is based in large part on meeting applicable industry codes.

Hence, the proposed evaluation Criterion 1, which requires prior NRC approval for any Tier 2*

text, table or figure change that deviates from these codes, combined with the 10 CFR Part 52, Appendix D, Section VIII.B.5 evaluation criteria, does provide a reasonable assurance of safety.

Nevertheless, SNC has identified enhancements to Criterion 1 that expand the scope of this criterion to include requirements described in the UFSAR that supplement code requirements for critical sections (discussed below).

In addressing the staffs question, this response is divided into three areas: reinforced concreted (RC) design; concrete-filled steel plate construction (SC) module design; and shield building design.

RC Design D

Design requirements for RC structures are governed by accepted in the following UFSAR subsections:

x ra UFSAR Subsection 3H.3.1, Governing Codes epted indus ind industry codes as described odes and Standards, Stand St ards, describes ards des the primary (0 ft R codes and standards used in the design Concrete Institute (ACI) standard ACI n of the auxiliary CI 349 aux auxilia y and 49--01, Code 349-01, nd shield bbuildings: American Code Requirements for Nuclear Safety 5- e Related Concrete Structures (and d Subsection ernative and Subsection 3.8.4.4.1 for alternative bsection 3 .4.5.1

.4.5 ative requirements);

req requir 1 for supplementary 3.8.4.5.1 supp ments); American A

Americ requirements National Standards 25 sp N690-1994, Specification for nstitute of S Institute (ANSI) / American Institute or the Des Design Stee Coonstruction (AISC)

Steel Construction Design, Fabrication (A standard ANSI/AISC rication and Erection of Safety-Related

-2 on clear Facilities Steel Structures for Nuclear acili acilities and Subsection (and S ubsec 3.8.4.5.2 for supplemental rican requirements); American an Welding Weld Society (AWS),

Society (AW S Structural Welding Code - Steel, AWS 01 s D1.1-2000 (provides es an acceptable accep e alternative forfo AISC N690 weld requirements as bsections ections 3.8.3.2 described in Subsections 3

3. 2 and 3.8.4.2).

3.8.4.

8) e x section 3H.5.1, UFSAR Subsection 3H.5 Shear hear Walls, Walls stastates that the wall sections are designed in wi tthe accordance with he requirements re rements ements of ACI 349-01.

x ection 3H.5.2, UFSAR Subsection 5. , Composite 5.2 Compo Structures (Floors and Roof), states that the conforma confo designs of the floors are in conformance with AISC N690 and ACI 349. This section also ment si requires that the reinforcement size and spacing are based on loads and spans for this type of floor and are determinedne at each location based on the requirements in ACI 349 and ACI 318-11. The slab concrete and the reinforcement is designed to meet the requirements of ACI 349-01.

x UFSAR Subsection 3H.5.3, Reinforced Concrete Slabs, states that the design of these floors is in conformance with AISC N690 and ACI 349. The reinforcement size and spacing are determined for each location, based on specific loads and spans, and satisfy the requirements in ACI 349 and ACI 318-11. The precast panels are connected to the concrete placed above them by shear reinforcement which satisfies the requirements of ACI 349.

x UFSAR Subsection 3H.5.4, Concrete Finned Floors, states that the finned floors are designed as reinforced concrete slabs in accordance with ACI 349. Composite section properties, based on an all steel-transformed section, as detailed in Section Q1.11 of ANSI/AISC N690-94 are used to design the weld strength between stiffener and the steel plate and the spacing of the shear studs for the composite action. The plate is designed against the criteria for bending and shear, specified in ANSI/AISC N690-94.

[DRAFT 5/22/18] Page 4 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)

These codes provide requirements for, in part, capacity aspects such as the demand-to-capacity ratio of walls and floors using reinforced concrete. Nevertheless, to address the NRC staffs concern regarding the ability to change the demand-to-capacity ratios for reinforcement in critical sections, SNC proposes to add restrictions to Criterion 1 regarding these ratios as described below.

Potential changes in reinforcement that need to be accommodated due to construction are generally localized (e.g., a missing reinforcing bar due to an interference) and are readily accommodated within design basis code commitments. Changes that affect the overall capacity of a structural member (e.g., changing the overall size and spacing of the reinforcement in a reinforced concrete wall) are not anticipated, and NRC staff review of such a change aligns with the spirit of the Tier 2* designation. Therefore, it is proposed to add language to exclude from Criterion 1 localized conditions that continue to meet the design basis code and supplemental code requirements except for adherence to a reported capacity measure meas in one of the critical section UFSAR Section 3.8 or Appendix 3H tables (e.g. area of reinforcing reinfo steel in a wall face).

Dra An example is where a reinforcing bar is moved or cannot 349 code requirements for strength, development, and ot be placed plac due to interference. If ACI d detailing are met, met and it is clear that (0 ft R redistribution of demand is accommodated by adjacent cent reinf reinforcement, men the then the local deviation has insignificant effect on the overall capacity of the section.

sectio Another example exam is a localized reduction in a structural module faceplate thickness kness due du to a surface im imperfection such as from 5- e grinding. While there is a localized reduction, structural response.

on, it does not no affect the section s capacity or the 25 sp Therefore, proposed Criterion 1 is revised evised as follows w to o address addre changes in the demand-to-

-2 on capacity ratios for reinforcement nt in critical ca sections:

ons:

01 s

1. Involve design methodology ethodology odology o or structural uctural tural construction constru cons materials that.; involve deviations from the e deman demand-to-capacity capacity ratios rati specified in UFSAR Section 3.8 and

8) e Appendix 3H Tier 2* table tables that at do not meet m all of the following criteria:

a. The impact of thet variance ariance is localized over a height or length that is no wider than the he thic thicknesss of the section sec for reinforced concrete and structural module walls andd floors, or the depth de of a structural steel section.

b. The local provided reinforcement reinfo is greater than the local required reinforcement.

c. The localized variance does not adversely impact the ability of the structural member to perform its intended service function or the service function of other structures, systems, or components.

Local variations that meet a, b, and c above are acceptable because the effects can be distributed using the standard engineering approaches consistent with licensed methodology as described in ACI 349, AISC N690, and the UFSAR, and do not affect the overall capacity of the section. In addition, localized variations that meet a, b, and c above do not affect the global building analyses because there is insignificant effect on overall section stiffness, mass, and response.

SNC also acknowledges that the UFSAR describes requirements for the design of critical sections that supplement the code requirements in some areas, as follows:

[DRAFT 5/22/18] Page 5 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3) x UFSAR Subsection 3.8.4.5.1, provides supplemental requirements for concrete structures beyond ACI 349.

Therefore, proposed evaluation Criterion 1 will be revised to add a requirement that prior NRC staff review is needed to deviate from these supplemental requirements in addition to the existing Criterion 1 topic of code provisions.

SC (Sandwich) Design Design requirements for SC module design are primarily governed by accepted industry codes as described in the following UFSAR subsections:

x UFSAR Subsection 3.8.3.5.3, Structural Wall Modules, states at that structural modules ntainme without concrete fill, such as the west wall of the in-containment inme refueling water storage tank, are designed as steel structures, according to the e requirements requirem require of AISC N690.

D Concrete-filled structural wall modules are designed ra accordance with the requirements of ACI 349 and this UFSAR subsection. The reinforcing steel ed as reinforced reinforce reinfo d other code concrete structures in co requirements as detailed in el used to anchor anch an orr the modules to the (0 ft R concrete has a development that satisfies s the requirements req re uireme uire ts of ACI AC 349.

x UFSAR Subsection 3H.3.1, Governing Codes odes and St ndards, describes Standards, desc descri the primary codes and standards used in the design gn of the auxiliary sign a iaryy and shield aux shie buildings: ACI 349-5- e 01, Code Requirements for Nuclear Subsection 3.8.4.5 for supplementary earr Safety Rela Re ted mentary requirements ed Concrete Related Concre Structures requirements and Subsection requ Subs S (and 3.8.4.4.1 for 25 sp Fabrication and Erection of NSI/AISC N690-1994, alternative requirements); ANSI/AISC o Safety-Related Safety-Relat Safety Re N690 1994, N 994, Specification Specific Spec d Steel Stru Structu for the Design, Structures for Nuclear Facilities (and

-2 on Subsection 3.8.4.5 for supple Structural Welding Code supp e - Steel, ental requirements);

en supplemental Stee AWSAW r quirements);

uirements) American WS D1.1-2000 A

D1.1 20 (provides

(

Welding Society (AWS),

an acceptable alternative for x UFSAR Subsection 01 s AISC N690 weld requirements ction uiremen as described on 3H.5.5, 3H.5.5 Structural escribed in S uctural Mod Module Subsections 3.8.3.2 and 3.8.4.2).

Modules, states that the design methodology of

8) e these modulesles in the au aux auxiliaryry building is similar si to the design of the structural modules inment iint in the containment internall structures described de in Subsection 3.8.3.5.3. These modules ent fuel include the spent fu pool,ool, ol, fuel tr transfe transfer canal, and cask loading and cask washdown pits.

o UFSAR Subsection 3H.5.5.1,3H.5 West Wall of Spent Fuel Pool, states that the concrete filled structural wall modules are designed as reinforced concrete structures in accordance with the requirements of ACI 349. The face plates are treated as reinforcing steel.

These codes provide a comprehensive set of requirements for SC structures. However, SNC acknowledges that the UFSAR describes requirements for the design of SC modules that supplement the code requirements in some areas, as follows:

x UFSAR Subsection 3.8.4.5.2, provides supplemental requirements for steel structures beyond AISC N690.

x UFSAR Subsection 3H.3.4, provides supplemental requirements to AISC N690 for load combinations and stress limit coefficients.

[DRAFT 5/22/18] Page 6 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)

Therefore, proposed evaluation Criterion 1 will be revised to add a requirement that prior NRC staff approval is needed to deviate from these supplemental requirements in addition to the existing Criterion 1 topic of code provisions.

Shield Building Design The shield building uses SC as well as RC construction. As described in the UFSAR, Subsection 3.8.4.1.1, Shield Building, and Appendix 3H the design of much of the shield building is based on compliance to codes. This point is stated in NUREG-1793, Final Safety Evaluation Related to Certification of the AP1000 Standard Design, Supplement 2, Subsection 3.8.4.1.1.3.1, Design Methodology and Process for Shield Building Design, [ADAMS Accession No. ML112061231] which states:

P1000 000 sh the concrete design of the following areas of the AP1000 sshield building falls directly within the scope of ACI 349:

x x

D shield building roof ra CWST wall knuckle region of the roof near the PCCWST wa (0 ft R x compression ring x PCCWST 5- e The applicant designed these areaseas in n accordance accordance accorda lastic analysis design codes by using linear elastic analys methods.

e with the provisions prov methods. Specifically, S

Specifi in the established the design for the 25 sp ased on compliance sections in these areas is based compliance com ce with the ACI Re ulatoryy Guide supplemented with guidance in NRC Regulatory AC 349 Code, as Guid (RG)

( 1.142 for concrete

-2 on th sections structures. The design of the ecti ections thods listed codes and analysis methods lis d in n these areas, in area which uses established design n Section 3.8.4 3 of NUREG-0800, satisfies the 01 s sted d above and regulatory basis listed a is, therefore therefore, ac acceptable to the staff.

8) e ants integrated The applicants integra esign process design proce also makes use of the design process for teel eel components structural steel compo ts s in certain are areas of the shield building. Specifically, it uses ANSI/AISC N690 690 in designing signing gning structura struct structural steel components of seismic Category I structures. The applicantnt used ANSI/AISC AN ANS N690 in designing the following areas of the shield building:

x the steel roof that supports the concrete roof slab x tension ring x SC/RC connection The design process uses provisions from two different design codes: ACI 349 Code for RC components, which uses an ultimate strength design approach and ANSI/AISC N690 Standard for steel and composite components, which uses an allowable stress design approach.

The proposed evaluation Criterion 1, which addresses deviations from codes, does provide sufficient restrictions (i.e., obtain prior NRC staff approval) on shield building design changes involving these above areas when the change deviates from these codes.

[DRAFT 5/22/18] Page 7 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)

However, SNC acknowledges that ACI 349 and ANSI/AISC N690 are not exclusively applicable to the shield building SC wall modules, including connections to RC. For example, there is significant design requirement information beyond code requirements in UFSAR Subsection 3.8.7, Reference 57, APP-GW-GLR-602, Revision 5 (Proprietary) and APP-GW-GLR-603, Revision 5 (Non-Proprietary), "AP1000 Shield Building Design Details for Select Wall and RC/SC Connections" [ADAMS Accession No. ML110910541]. Furthermore, there are additional UFSAR sections that provide supplemental design requirements beyond code requirements that SNC acknowledges are important to the design of the shield building. For example, UFSAR Subsection 3.8.4.5.5, Shield Building Structural Wall Modules, states that design requirements for shield building concrete-filled structural wall modules are addressed in UFSAR referenced codes and supplemental requirements not addressed in codes:

[Concrete-filled structural wall modules are designed ass reinforced rei concrete structures suppleme pplem in accordance with the requirements of ACI 349, and supplemented with additional requirements discussed in subsection 3.8.3.5.3 and d below]*

below]*

D ra

[Note that UFSAR Subsection 3.8.3.5.3 is Tier 2 text.)) Within UFSAR hield eld building supplemental Tier 2* design requirements for the shield UFS buildin a Subsection 3.8.4.5.5, e add are ad addressed in Subsection (0 ft R 3.8.4.5.5.5, Design of Shear Studs and Tie Bars.

g requirements By including these additional shield building requ equirements reme hin the scope of proposed within 5- e evaluation Criterion 1, combined with thee 10 0 CFR Part 52, 52,, Appendix D,Section VIII.B.5.b pr vide a reasonable evaluation criteria, the new evaluation process will provide reasona rea assurance of safety.

25 sp n respon Changes to Original LAR-17-037 in response to o RAI LAR-17 LAR LAR-17-037-2

-2 on Changes to Enclosure 1:

On Page 10 of 19, revise 01 s se the Criteri Criterion 1 detailed guidance guida gu as follows:

Criterion 1 (Codes guidance

8) e Codes and Standards ndards an and Su Supplemental Design Requirements) detailed x Any change to the design requirements described in UFSAR Subsections 3.8.4.5.1, 3.8.4.5.2, 3.8.4.5.5.5, or 3H.3.4 is a deviation.

x Any change to UFSAR Subsection 3.8.7, Reference 57 is a deviation.

x Involve a change in the demand-to-capacity ratios specified in UFSAR Section 3.8 and Appendix 3H Tier 2* tables that does not meet all of the following criteria:

o The impact of the variance is localized over a height or length that is no wider than the thickness of the section for reinforced concrete and structural module walls and floors, or the depth of a structural steel section.

o The local provided reinforcement is greater than the local required reinforcement.

[DRAFT 5/22/18] Page 8 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3) o The localized variance does not adversely impact the ability of the structural member to perform its intended service function or the service function of other structures, systems, or components.

On Page 10 of 19, revise Criterion 1 Bases discussion by adding the following paragraph after the existing paragraph:

It is also noted that the UFSAR describes additional requirements for the design of critical sections that supplement the code requirements in some areas such as reinforced concreted (RC) design; concrete-filled steel plate construction (SC) module design; and shield building design. References to these requirements are included in this Criterion and prior NRC approval is required if deviations ations are proposed to these requirements.

D Furthermore, Criterion 1 contains restrictions regarding ra garding The Criterion requires prior NRC approvall for any cha rding the ability to-capacity ratios for reinforcement in critical sections abi to increase demand-tions without witho t prior chang p NRC staff approval.

change that involves inv a deviation from (0 ft R the demand-to-capacity ratios specified in n UFSAR Section tables that does not meet all of the following owing criteria:

cri n 3.8 and Appendix 3H Tier 2*

x 5- e The impact of the variance nce is localized localiz over a height he or length that is no wider 25 sp than the thickness off the section for reinforced walls and floors, or the e depth de inforced concrete co of a structural steel st and structural module section.

x x -2 on The local provided ded reinforcement re ent is greater gre than the local required reinforcement.

01 s The localized variance does not adversely advers impact the ability of the structural member to o perform its intended ntended serv service function or the service function of other

8) e structures, tures, syste systems, orr components.

compo Potential changes nges iin reinforcement forcement that need to be accommodated due to construction are generally localized (e.g.,

.g., a missing m reinforcing bar due to an interference) and are readily accommodated within n design de basis code commitments. Changes that affect the overall capacity of a structural member (e.g., changing the overall size and spacing of the reinforcement in a reinforced concrete wall) are not anticipated, and NRC staff review of such a change aligns with the spirit of the Tier 2* designation.

An example is where a reinforcing bar is moved or cannot be placed due to interference.

If ACI 349 code requirements for strength, development, and detailing are met, and it is clear that redistribution of demand is accommodated by adjacent reinforcement, then the local deviation has insignificant effect on the overall capacity of the section. Another example is a localized reduction in a structural module faceplate thickness due to a surface imperfection such as from grinding. While there is a localized reduction, it does not affect the section capacity or the structural response.

[DRAFT 5/22/18] Page 9 of 10

ND-18-0xxx Enclosure X Response to NRC Request for Additional Information (RAI) LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)

Local variations that meet the above criteria are acceptable because the effects can be distributed using the standard engineering approaches consistent with licensed methodology as described in ACI 349, AISC N690, and the UFSAR, and do not affect the overall capacity of the section. In addition, localized variations that meet the above criteria do not affect the global building analyses because there is insignificant effect on overall section stiffness, mass, and response.

Changes to Enclosure 3:

To address the concerns addressed by the NRC staff in the question, SNC agrees to broaden the scope of proposed evaluation Criterion 1 to address additional requirements. Proposed Criterion 1 is revised to address RC design, SC module design, and shield building design as follows:

1. Involve design methodology or structural construction nstruction ction ma m

materials that deviate from D

a code or standard credited in the plant-specific ra for the design or construction of a structure, important to safety, deviate from the design pecific re, system, cture, fic DCD for establishing the criteria system or esign methodology method met o component (SSC) ology described in UFSAR (0 ft R Subsection 3.8.7, Reference 57, deviate te from the supplemental suppleme design requirements described in UFSAR ARR Subsect Subsections Subsection 3.8.4.5.1, 3.8.4.5.1 8.4.5.1, 3.8.4.5.2, 3

3.8 3.8.4.5.5.5, or 3H.3.4, or involve deviations from the demand-to-capacity nd-t -capacit ratios specified in 5- e UFSAR Section 3.8 and Appendix following criteria:

pendix 3H T Tier 2* tables that t do not meet all of the 25 sp

a. The impact off the variance varianc is localized wider than the thickne ocalized over ov a height or length that is no thickness off the section for reinforced concrete and

-2 on structural section..

al module mod walls w and nd floors, floor or the depth of a structural steel 01 s

b. The local provided pro d reinforcement reinforcem is greater than the local required

8) e reinforcement.

reinforcem cc. Thee loc localized ed variance does not adversely impact the ability of the structural member to perform its intended service function or the service struc function of other structures, s systems, or components.

Similar conforming changes are also applicable to Enclosures 1, 4, and 5 of the original LAR 17-037.

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