NESCC 12-097 - NRC Perspectives on AISC N 690 and Appendix

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
• The 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 Containments
– Section 3.8.4 – 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
– N690-1984 in Section Regulatory Guidance
• 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 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 N6901994, including Supplement 2 (2004), for steel structures.
• No supplemental criteria added
• SRP 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)
Review of ANSI/AISC
• 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
– 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 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)
Modular Composite
Construction (SC)
• Steel plate and concrete composite modular (SC) have
been adopted for safety-related structures of new reactor
– 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
NRC Research Activities
• Sponsored research at Brookhaven National Laboratory (1990s) to
review technical bases for regulatory guidance (NUREG/CR-6486,
• 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
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)
Harmonization with international standards
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.,
• Background work is being done to review AISC’s white
paper or other publicly available publication on the SC
standard under development (Appendix N9)
American Institute of Steel Construction
American National Standards Institute
Allowable Stress Design
Japan Electric Association Code
Korea Electric Power Industry Code
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
• SRP –
Standard Review Plan