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THE DEVELOPMENT AND IMPLEMENTATION OF SEISMIC DESIGN
AND EVALUATION CRITERIA FOR NIF
Stanley C. Sommer
NIF System Integration - Engineering Analysis, Lawrence Livermore National Laboratory
P.O. Box 808, L-495, Livermore, California, U.S.A. 94551
Paul B. MacCalden, Ph.D., P.E.
Manager, Technology Group, The Ralph M. Parsons Company
100 West Walnut Street, Pasadena, California, U.S.A. 91124
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.
NIF SEISMIC CRITERIA
Description of NIF
After NIF becomes fully operational at LLNL in 2003, it will
be the largest ICF research facility in the world by creating
conditions of extremely high temperatures and pressures,
100,000,000 C and 100 billion times atmospheric pressure.
ICF is the process of creating fusion in the laboratory using
short-pulse, high-energy lasers that are focused onto targets in
which the light energy implodes a small glass sphere, or
hohlraum, containing isotopes of hydrogen. If the hydrogen
atoms in the target are compressed for a sufficiently long period
of time at the required temperature, helium atoms are formed
and significant amounts of energy can be released. The laser
energy delivered by a fully operational NIF, which is shown in
Figure 1, will exceed the capacity of the currently largest laser
system at LLNL, Nova, by about fifty times. The primary NIF
missions are to achieve controlled thermonuclear fusion ignition
in the laboratory with modest gain and to support stockpile
stewardship, inertial fusion energy research, and high energy
The NIF laser system features 192 high-power laser beams
which will produce 1.8 MJ of laser energy in the near-ultraviolet
spectral region (about 0.35 micron wavelength). NIF uses
neodymium-doped glass in a laser architecture that groups the
192 independent beamlines into 24 bundles of eight beamlines.
An one omega (1.05 micron) laser pulse is first generated in the
Master Oscillator Room and then travels by fiber optics to the
Optical Pulse Generation system that consists of 48
Preamplifier Modules and several other front-end components.
The pulse is injected into the main laser cavity at the pinhole
plane of the Transport Spatial Filter (TSF), travels through the
periscope into the cavity region of the main laser cavity where it
is amplified by the Main Amplifier and conditioned by the Cavity
Spatial Filter with a four-pass configuration. After the Plasma-
Electrode Pockels Cell changes state, the pulse travels back
through the periscope into the transport region of the main laser
cavity where it is amplified by the Power Amplifier and
conditioned by the TSF with a single-pass configuration.
Finally, the pulse travels through the switchyard and target bay
by reflecting off turning mirrors, is frequency converted to three
omega (0.35 micron) light by the potassium dihydrogen
phosphate crystals in the Final Optics Assembly, and is focused
onto the hohlraum that is held by the target positioner.
Figure 1 The National Ignition Facility
The light from the NIF beams will be tightly focused onto a
very small target that is filled with cryogenic fusion fuel and
located inside a 10-meter diameter spherical chamber. When
NIF achieves ignition, the laser light will compress and heat the
fusion fuel to produce fusion reactions yielding up to 10 times
the laser energy delivered to the target.
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Sommer, S.C. & MacCalden, P.B. Development and implementation of seismic design and evaluation criteria for NIF, article, March 17, 1998; California. (digital.library.unt.edu/ark:/67531/metadc680795/m1/3/: accessed October 23, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.