ML18145A289
| ML18145A289 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/25/2018 |
| From: | NRC |
| To: | NRC/NRO/DNRL/LB4 |
| References | |
| Download: ML18145A289 (13) | |
Text
1 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.
2
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Southern Nuclear Operating Company ND-18-0xxx Enclosure X Vogtle Electric Generating Plant (VEGP) Units 3 and 4 Response to NRC Request for Additional Information (RAI) 17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)
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.)
Draft Regardi Regardi
Response
Plant (VEGP) U t (VEGP uest for Ad uest for t
(05-25-2018) nits 3 an nits 3 an itional Informa itional Info e LAR e LAR-177-037 (LAR (LAR-177-037 0
ND-18-0xxx Enclosure X Response to NRC RAI LAR-17-037-2 Regarding the LAR-17-037 Review (LAR-17-037S3)
[DRAFT 5/11/18] Page 2 of 9 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 Design Certification Tiered Information Designations, described the staffs approach to using the Tier 2*
designation for safety significant information. The SECY noted that if Tier 2* were to be eliminated, certain safety-significant information currently in Tier 2* should be included in Tier 1 rather than in Tier 2. The staff considers that a critical section has attributes that make it safety significant in maintaining the integrity of the plant structure. The designed capacity of the critical sections support the reasonable assurance of safety determination for the AP1000 DCD, Rev.19 design in the staff safety evaluation.
The staff reviewed the LAR and noted that the criteria for screening Tier 2* information pertaining to critical sections is not well defined.
In Enclosure 3, Proposed Changes to Licensing Basis Documents, of the LAR, the licensee proposed to revise its combined license (COL) to include a new license condition to address the Tier 2* change process. The licensee included a new license condition, proposed License Condition 13, Departures from Plant-Specific DCD Tier 2*
Information. The proposed license condition states that the licensee
... is exempt from the requirements of 10 CFR Part 52, Appendix D, Paragraphs II.F and VIII.B.6 that 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 d Changes Changes evise its com se its com the Tier 2*
e Tier 2*
ed License C ed License e propose e propos
Response
Desig esig ach to using h to usin SECY noted th Y noted currently in Tie rently in ers that a crit s that a c the integrity o e integrity support the r pport th ev.19 design in 9 design oted that the c oted that t not well def not well o
(05-25-2018) cal s al s the plant the plant easonable ass asonable as the staff safet the staff sa riteria for sc teria for s re ned.
icensing Basis icensing ned license (C d license ange process.
ange proces ndition 13, De ition 13 cense conditio ense cond requirem require B.6 t 6 t
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)
[DRAFT 5/22/18]
Page 3 of 10 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 the application of this criterion will not yield the desired results. The staff has identified the following cases as exceptions to the Criterion 1:
x Critical sections using steel concrete sandwich construction, and x
the capacity aspects such as area of steel provided or the demand to capacity ratio of critical sections using reinforced concrete In both cases, the staff has determined that neither the design nor the cited attributes of the critical sections are code defined, making Criterion 1 in-applicable in these instances. The staff requests the applicant to revise the Criterion 1 such that the conditions identified above are screened in and a license amendment process followed for any changes to these cases, or that the applicant provide additional explanation as to why the proposed criteria would not need to be revised in order to maintain a reasonable assurance of safety.
SNC Response to RAI Question Tier 2* information is intended to have 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 s the s th e are scre are scre se cases, or cases, or criteria wou eria wo ance of safe ance of safe Q
Response
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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)
[DRAFT 5/22/18]
Page 4 of 10 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 Design requirements for RC structures are governed by accepted industry codes as described in the following UFSAR subsections:
x UFSAR Subsection 3H.3.1, Governing Codes and Standards, describes the primary codes and standards used in the design of the auxiliary and shield buildings: American Concrete Institute (ACI) standard ACI 349-01, Code Requirements for Nuclear Safety Related Concrete Structures (and Subsection 3.8.4.5.1 for supplementary requirements and Subsection 3.8.4.4.1 for alternative requirements); American National Standards Institute (ANSI) / American Institute of Steel Construction (AISC) standard ANSI/AISC N690-1994, Specification for the Design, Fabrication and Erection of Safety-Related Steel Structures for Nuclear Facilities (and Subsection 3.8.4.5.2 for supplemental requirements); American Welding Society (AWS), Structural Welding Code - Steel, AWS D1.1-2000 (provides an acceptable alternative for AISC N690 weld requirements as described in Subsections 3.8.3.2 and 3.8.4.2).
x UFSAR Subsection 3H.5.1, Shear Walls, states that the wall sections are designed in accordance with the requirements of ACI 349-01.
x UFSAR Subsection 3H.5.2, Composite Structures (Floors and Roof), states that the designs of the floors are in conformance with AISC N690 and ACI 349. This section also requires that the reinforcement size and spacing are based on loads and spans for this type of floor and are determined 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.
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Response
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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)
[DRAFT 5/22/18]
Page 5 of 10 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 in one of the critical section UFSAR Section 3.8 or Appendix 3H tables (e.g. area of reinforcing steel in a wall face).
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.
Therefore, proposed Criterion 1 is revised as follows to address changes in the demand-to-capacity ratios for reinforcement in critical sections:
- 1. Involve design methodology or structural construction materials that.; involve deviations from the demand-to-capacity ratios specified in UFSAR Section 3.8 and Appendix 3H Tier 2* tables that do not meet all of the following criteria:
- a. 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.
- b. The local provided reinforcement 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:
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Response
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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)
[DRAFT 5/22/18]
Page 6 of 10 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 that structural modules without concrete fill, such as the west wall of the in-containment refueling water storage tank, are designed as steel structures, according to the requirements of AISC N690.
Concrete-filled structural wall modules are designed as reinforced concrete structures in accordance with the requirements of ACI 349 and other code requirements as detailed in this UFSAR subsection. The reinforcing steel used to anchor the modules to the concrete has a development that satisfies the requirements of ACI 349.
x UFSAR Subsection 3H.3.1, Governing Codes and Standards, describes the primary codes and standards used in the design of the auxiliary and shield buildings: ACI 349-01, Code Requirements for Nuclear Safety Related Concrete Structures (and Subsection 3.8.4.5 for supplementary requirements and Subsection 3.8.4.4.1 for alternative requirements); ANSI/AISC N690-1994, Specification for the Design, Fabrication and Erection of Safety-Related Steel Structures for Nuclear Facilities (and Subsection 3.8.4.5 for supplemental requirements); American Welding Society (AWS),
Structural Welding Code - Steel, AWS D1.1-2000 (provides an acceptable alternative for AISC N690 weld requirements as described in Subsections 3.8.3.2 and 3.8.4.2).
x UFSAR Subsection 3H.5.5, Structural Modules, states that the design methodology of these modules in the auxiliary building is similar to the design of the structural modules in the containment internal structures described in Subsection 3.8.3.5.3. These modules include the spent fuel pool, fuel transfer canal, and cask loading and cask washdown pits.
o UFSAR Subsection 3H.5.5.1, 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.
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Response
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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)
[DRAFT 5/22/18]
Page 7 of 10 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:
the concrete design of the following areas of the AP1000 shield building falls directly within the scope of ACI 349:
x shield building roof x
knuckle region of the roof near the PCCWST wall x
compression ring x
PCCWST The applicant designed these areas in accordance with the provisions in the established design codes by using linear elastic analysis methods. Specifically, the design for the sections in these areas is based on compliance with the ACI 349 Code, as supplemented with guidance in NRC Regulatory Guide (RG) 1.142 for concrete structures. The design of the sections in these areas, which uses established design codes and analysis methods listed in Section 3.8.4 of NUREG-0800, satisfies the regulatory basis listed above and is, therefore, acceptable to the staff.
The applicants integrated design process also makes use of the design process for structural steel components in certain areas of the shield building. Specifically, it uses ANSI/AISC N690 in designing structural steel components of seismic Category I structures. The applicant used ANSI/AISC 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.
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Response
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(05-25-2018) ce with the prov e with the methods. Specifi ethods. S nce with the AC ce with the ulatory Guide (
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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)
[DRAFT 5/22/18]
Page 8 of 10 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 as reinforced concrete structures in accordance with the requirements of ACI 349, and supplemented with additional requirements discussed in subsection 3.8.3.5.3 and below]*
[Note that UFSAR Subsection 3.8.3.5.3 is Tier 2 text.] Within UFSAR Subsection 3.8.4.5.5, supplemental Tier 2* design requirements for the shield building are addressed in Subsection 3.8.4.5.5.5, Design of Shear Studs and Tie Bars.
By including these additional shield building requirements within the scope of proposed evaluation Criterion 1, combined with the 10 CFR Part 52, Appendix D, Section VIII.B.5.b evaluation criteria, the new evaluation process will provide a reasonable assurance of safety.
Changes to Original LAR-17-037 in response to RAI LAR-17-037-2 Changes to Enclosure 1:
On Page 10 of 19, revise the Criterion 1 detailed guidance as follows:
Criterion 1 (Codes and Standards and Supplemental Design Requirements) detailed guidance 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 se the Criteri the Criteri (Codes and Codes and D
Response
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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)
[DRAFT 5/22/18]
Page 9 of 10 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 are proposed to these requirements.
Furthermore, Criterion 1 contains restrictions regarding the ability to increase demand-to-capacity ratios for reinforcement in critical sections without prior NRC staff approval.
The Criterion requires prior NRC approval for any change that involves a deviation from 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:
x 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.
x The local provided reinforcement is greater than the local required reinforcement.
x 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.
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.
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.
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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)
[DRAFT 5/22/18]
Page 10 of 10 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 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, deviate from the design methodology described in UFSAR Subsection 3.8.7, Reference 57, deviate from the supplemental 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, or involve deviations from the demand-to-capacity ratios specified in UFSAR Section 3.8 and Appendix 3H Tier 2* tables that do not meet all of the following criteria:
- a. 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.
- b. The local provided reinforcement 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.
Similar conforming changes are also applicable to Enclosures 1, 4, and 5 of the original LAR 17-037.
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