1. NRC Perspectives on AISC N690 and Appendix on Modular Composite Construction (SC)
Dr. Jose Pires
Structural, Geotechnical and Seismic Engineering Branch
NRC Office of Nuclear Regulatory Research
NESCC Meeting
November 29, 2012

2. ANSI / AISC N690
The Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (NUREG-0800), 2010 (SRP), refers to:
N including Supplement 2 (2004)
In:
Section – Concrete and Steel Internal Structures of Steel or Concrete Containments
Section – Other Seismic Category I Structures
The Standard Review Plan for the Review of an Application for a Mixed Oxide (MOX) Fuel Fabrication Facility (NUREG-1718), 2000, refers to
N in Section Regulatory Guidance

3. ANSI/AISC N690
SRP (3.8.3 and 3.8.4) refer to N690 in relation to the following for steel structures
Applicable codes, standards and specifications
Loads and load combinations
Design and analysis procedures
Structural acceptance criteria
Materials, quality control, special construction techniques and quality assurance
Example - SRP 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 for concrete structures, and AISC N , including Supplement 2 (2004), for steel structures.
No supplemental criteria added

4. ANSI/AISC N690 SRP references (additional examples)
SRP II.3 Loads and Load Combinations
All loads and load combinations are to be in accordance with AISC N 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 II.3 Structural Acceptance Criteria
ANSI/AISC N 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)

5. Review of ANSI/AISC N
Current guidance (staff review guidance) addresses the older standard
Still considered adequate for safety
Supplements to 1994 edition
Still 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 regard
What are new technical and regulatory issues addressed and what are their safety significance? (previous presentations address some of this)
Examples of technical/regulatory issues
Technologies and understanding of relevant phenomena (e.g., materials, construction, analysis and characterization of loads) evolved
N uses ANSI/AISC , Specification for Structural Steel Buildings, as the baseline document (instead of standalone document)
Discontinuation of Supplements to 1994 edition
Use 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)

6. Modular Composite Construction (SC)
Steel plate and concrete composite modular (SC) have been adopted for safety-related structures of new reactor designs
E.g., containment internal structures
SC construction is still outside the scope of existing US standards for safety-related structures
Case-by-case review is still done for current applications, license amendments and potential new applications
Standard under development by Ad-hoc subcommittee to AISC’s Task Committee 12 (TC 12)
Planned as Appendix N9 to ANSI/AISC N690 6

7. NRC Research Activities
Sponsored 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 designs
Staff participates in the activities of TC 12’s ad-hoc subcommittee
Outside 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 tools
Reviewing international codes and guidance
JEAC-4618 (2009) – Japan – ASD approach
KEPIC (2010) – Korea – LRFD approach

8. Review of SC Standard Resulting designs must satisfy regulations
Resulting designs would (as examples):
Provide adequate strength and stiffness
Prevent non-ductile failure modes
Provide durability through the use of adequate materials, control of concrete cracking, prevention of steel and rebar corrosion
Provide clear load paths avoiding load path discontinuities
Other items of interest
Materials and material properties (steel plates, studs, tie bars, etc)
Type of concrete (e.g., conventional vs. self-consolidating)
Constructability
Inspection
Harmonization with international standards

9. Review of SC Standard Challenges (examples)
Design criteria for connections and connections to other construction types, e.g., reinforced concrete
Experimental database for combined load effects
Designs should be based on sound engineering principles and validated methods
Staff 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 provisions
Effort includes review of existing international standards (E.g., JEAC and KEPIC)
Background work is being done to review AISC’s white paper or other publicly available publication on the SC standard under development (Appendix N9)

10. Acronyms AISC – American Institute of Steel Construction
ANSI – American National Standards Institute
ASD – Allowable Stress Design
JEAC – Japan Electric Association Code
KEPIC – Korea Electric Power Industry Code
LRFD – Load and Resistance Factor Design
SC – 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 Plan