Development And Implementation Of Seismic Design And Evaluation Criteria For Nif

The National Ignition Facility (NIF) is being built at the Lawrence Livermore National Laboratory (LLNL) as an international research center for inertial confinement fusion (ICF). This paper will provide an overview of NIF, review NIF seismic criteria, and briefly discuss seismic analyses of NIF optical support structures that have been performed by LLNL and the Ralph M. Parsons Company, the Architect and Engineer (A & E) for NIF. The NIF seismic design and evaluation criteria is based on provisions in DOE Standard 1020 (DOE-STD-1020), the Uniform Building Code (UBC), and the LLNL Mechanical Engineering Design Safety Standards (MEDSS). Different levels of seismic requirements apply to NIF structures, systems, and components (SSCs) based on their function. The highest level of requirements are defined for optical support structures and SSCs which could influence the performance of optical support structures, while the minimum level of requirements are Performance Category 2 (PC2) requirements in DOE-STD-1020. To demonstrate that the NIF seismic criteria is satisfied, structural analyses have been performed by LLNL and Parsons to evaluate the responses of optical support structures and other SSCs to seismic-induced forces.

One of the primary goals of the Department of Homeland Security's Federal Emergency Management Agency (FEMA) is prevention or mitigation of this country's losses from hazards that affect the built environment. To achieve this goal, we as a nation must determine what level of performance is expected from our buildings during a severe event, such as an earthquake. To do this, several years ago FEMA contracted with the Applied Technology Council (ATC) to develop next-generation performance-based seismic design guidelines, which would allow stakeholders and their representatives to assess the probable seismic performance of new and existing buildings, and to be able to design or improve their structures to meet their performance goals. These guidelines could be voluntarily used by engineers and designers to: (1) assess and improve the performance of buildings that are currently designed to a building code “life safety” level, which would, in all likelihood, still suffer significant structural and nonstructural damage in a severe event; and (2) more effectively meet the performance targets of current building codes by providing verifiable alternatives to current prescriptive code requirements. This program is based on a long-term plan published as FEMA 445, which was developed with the input of the nation's leading seismic professionals. One of the key requirements in performance based seismic design is the ability to test and evaluate the intended performance of the various structural and nonstructural components that make up a building. The Applied Technology Council (ATC), with funding from the Federal Emergency Management Agency (FEMA), Department of Homeland Security, commenced work on a multi-year project to development performance-based seismic design guidelines for eventual incorporation in existing standards for the seismic design of new buildings and the upgrade of existing buildings (ATC-58 project). The plan for development of the guidelines is defined in the companion FEMA 445 report, Next-Generation Performance-Based Seismic Design Guidelines, Program Plan for New and Existing Buildings, which was prepared under the ATC-58 project and published by FEMA in 2006. As part of the initial work on the ATC-58 project, interim recommended protocols (documented herein) were developed for testing of structural and nonstructural components and systems found in buildings, for the purpose of establishing their seismic performance characteristics. The protocols were developed through a cooperative effort of ATC and the three National Science Foundation-funded Earthquake Engineering Research Centers (EERCs): the Mid-America Earthquake (MAE) Center at the University of Illinois, Urbana; the Multidisciplinary Center for Earthquake Engineering Research (MCEER), University at Buffalo, The State University of New York; and the Pacific Earthquake Engineering Research (PEER) Center at the University of California, Berkeley. Two interim protocol types are provided in this document: Interim Protocol I – Quasi-Static Cyclic Testing, which should be used for the determination of performance characteristics of components whose behavior is primarily controlled by the application of seismic forces or seismic-induced displacements (e.g., cladding panels, glazing panels, drywall partitions, piping and ducting system connections, ducts, and various types of anchors and braces); and Interim Protocol II – Shake Table Testing, which should be used to assess performance characteristics of components whose behavior is affected by the dynamic response of the component itself, or whose behavior is velocity sensitive, or sensitive to strain-rate effects (e.g., mechanical and electrical equipment).

Seismic design and evaluation criteria are based on probabilistic performance goals for Department of Energy (DOE) facilities across the United States. These criteria, utilize probabilistic seismic hazard curves for specification of earthquake loading combined with deterministic response evaluation methods and permissible behavior limits. Through the use of such a design/evaluation approach, it may be demonstrated that there is high likelihood that probabilistic performance goals can be achieved. These criteria have been described in previous technical papers. The purpose of this paper is to present proposed modifications to DOE seismic design and evaluation criteria. These modifications account for various slopes of seismic hazard curves, make corrections to earlier versions, and take advantage of an improved quantitative basis for the acceptance criteria.