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1NRC Perspectives on AISC N690 and Appendix on Modular Composite Construction (SC)Dr. Jose PiresStructural, Geotechnical and Seismic Engineering BranchNRC Office of Nuclear Regulatory ResearchJose.Pires@nrc.gov

NESCC MeetingNovember 29, 20121ANSI / AISC N690The Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (NUREG-0800), 2010 (SRP), refers to:N690-1994 including Supplement 2 (2004)In:Section 3.8.3 Concrete and Steel Internal Structures of Steel or Concrete ContainmentsSection 3.8.4 Other Seismic Category I StructuresThe Standard Review Plan for the Review of an Application for a Mixed Oxide (MOX) Fuel Fabrication Facility (NUREG-1718), 2000, refers toN690-1984 in Section 11.4.6.1 Regulatory Guidance2ANSI/AISC N690SRP (3.8.3 and 3.8.4) refer to N690 in relation to the following for steel structuresApplicable codes, standards and specificationsLoads and load combinationsDesign and analysis proceduresStructural acceptance criteriaMaterials, quality control, special construction techniques and quality assuranceExample - SRP 3.8.4 - II.5 Structural Acceptance Criteria For each of the loading combinations delineated in Subsection II.3 of this SRP section, the structural acceptance criteria appear in ACI 349 and RG 1.142 for concrete structures, and AISC N690-1994, including Supplement 2 (2004), for steel structures.No supplemental criteria added

3ANSI/AISC N690SRP references (additional examples)SRP 3.8.4 - II.3 Loads and Load Combinations All loads and load combinations are to be in accordance with AISC N690-1994 including Supplement 2 (2004). This specification uses the allowable stress design (ASD) method. The supplemental criteria on the use of loads and load combinations presented above for concrete structures also apply to steel structures.SRP 3.8.3 - II.3 Structural Acceptance Criteria ANSI/AISC N690-1994 including Supplement 2 (2004) defines the structural acceptance criteria for steel structures. This specification uses the ASD method. Use of the LRFD version of the specification (N690L) is reviewed on a case-by-case basis.Reference is to ASD methods (as opposed to the use of LRFD for concrete structures)4Review of ANSI/AISC N690-2012Current guidance (staff review guidance) addresses the older standardStill considered adequate for safetySupplements to 1994 editionStill used by end users (licensees and applicants)Should the NRC review and endorse the new standard?NRC has been contacted by the AISC in that regardWhat are new technical and regulatory issues addressed and what are their safety significance? (previous presentations address some of this)Examples of technical/regulatory issuesTechnologies and understanding of relevant phenomena (e.g., materials, construction, analysis and characterization of loads) evolved N690-2012 uses ANSI/AISC 360-10, Specification for Structural Steel Buildings, as the baseline document (instead of standalone document)Discontinuation of Supplements to 1994 editionUse of LRFD approach (with ASD as an alternative) which is consistent with the code for concrete structures (ACI-349)Standard for Modular Composite Construction (SC) (planned Appendix N9)5Modular Composite Construction (SC)6Steel plate and concrete composite modular (SC) have been adopted for safety-related structures of new reactor designsE.g., containment internal structuresSC construction is still outside the scope of existing US standards for safety-related structuresCase-by-case review is still done for current applications, license amendments and potential new applications Standard under development by Ad-hoc subcommittee to AISCs Task Committee 12 (TC 12)Planned as Appendix N9 to ANSI/AISC N690

6NRC Research ActivitiesSponsored research at Brookhaven National Laboratory (1990s) to review technical bases for regulatory guidance (NUREG/CR-6486, 1997)Engaged outside experts (academia and industry) to inform confirmatory reviews of certain proposed designsStaff participates in the activities of TC 12s ad-hoc subcommitteeOutside experts informed staff review of technical bases (2011)Held public meeting (August 2011) Sponsoring numerical modeling research for interpretation of testing, benchmarking and confirmatory analysis toolsReviewing international codes and guidanceJEAC-4618 (2009) Japan ASD approachKEPIC (2010) Korea LRFD approach

7Resulting designs must satisfy regulationsResulting designs would (as examples):Provide adequate strength and stiffnessPrevent non-ductile failure modesProvide durability through the use of adequate materials, control of concrete cracking, prevention of steel and rebar corrosionProvide clear load paths avoiding load path discontinuitiesOther items of interestMaterials and material properties (steel plates, studs, tie bars, etc)Type of concrete (e.g., conventional vs. self-consolidating)ConstructabilityInspection Harmonization with international standardsReview of SC Standard8Review of SC StandardChallenges (examples)Design criteria for connections and connections to other construction types, e.g., reinforced concreteExperimental database for combined load effectsDesigns should be based on sound engineering principles and validated methodsStaff continues the review of the technical bases for the provisions in the US standard under development as well as review of the scope of the provisionsEffort includes review of existing international standards (E.g., JEAC and KEPIC)Background work is being done to review AISCs white paper or other publicly available publication on the SC standard under development (Appendix N9)

9AcronymsAISC American Institute of Steel ConstructionANSI American National Standards InstituteASD Allowable Stress DesignJEAC Japan Electric Association CodeKEPIC Korea Electric Power Industry CodeLRFD Load and Resistance Factor DesignSC Modular Composite Construction (Wall modules constructed from large prefabricated sections of steel plates spaced apart and joined with intermittent steel members or tie bars, joined with other modules at the site, and then filled with concrete)SRP Standard Review Plan10