in the News
Human in the Mouse Mirror
NIF Target Chamber—Ready
for the Challenge
Testing Begins Soon at
Science and Technology
of the greatest challenges facing Lawrence Livermore is helping
to assure the safety and reliability of the nation's nuclear stockpile.
This effort, called stockpile stewardship, demands our best technologies
as well as our most creative thinking, especially in the absence
of nuclear testing.
Laboratory has been deeply involved in many aspects of stockpile
stewardship. One of them is the Enhanced Surveillance Campaign,
an effort to develop advanced diagnostic systems for the nondestructive
surveillance of stockpiled nuclear weapons. Nondestructive surveillance
is far more cost-effective and efficient than disassembling a weapon
and its many components.
of our most promising nondestructive surveillance technologies is
described in the article entitled Uncovering
Hidden Defects with Neutrons. The article details how a team
of Lawrence Livermore researchers is demonstrating the use of high-energy
neutrons as a way to inspect thick, heavily shielded objects such
as nuclear warheads. This technology is needed because current methods,
such as x-ray imaging, cannot easily reveal defects in materials
like plastics and ceramics when they are shielded by thick metal
parts such as uranium.
team has conducted experiments at Ohio University over the past
four years. Because of the experiments' highly promising results,
we hope to see a prototype system installed at Livermore that would
ultimately be transferred to other National Nuclear Security Administration
in operation, high-energy neutron radiography's primary mission
will be the surveillance of nuclear weapons. However, neutron imaging
could also be used to perform such tasks as identifying warheads
that need refurbishment or for inspecting refurbished warheads before
they are returned to the stockpile. In this manner, the technology
could serve as a valuable tool for carrying out any changes in the
size of the nation's stockpile by helping scientists to make informed
decisions based on the condition of weapons.
is important to note that neutron imaging is designed to complement,
not replace, existing nondestructive evaluation tools used in stockpile
surveillance. In analyzing the state of the U.S. stockpile, researchers
want as much data as they can possibly produce. Neutron imaging
may be the only way that researchers can learn anything about the
internal structure of some heavily shielded components. In this
respect, neutron imaging will simply help us do a better job of
success of high-energy neutron radiography demonstrates how we can
leverage our experience in underground nuclear testing, which stopped
in 1992. The initial idea for the project (that is, neutron imaging
in the 10- to 15-megaelectronvolt energy range) and basic details
of our current system design were derived from Monte Carlo simulations
that used advanced neutron and gamma-ray transport codes first developed
to support underground testing. Also, the design of the imaging
detector is based on technology Livermore scientists originally
developed for use at NNSA's Nevada Test Site.
neutron radiography is one of a number of enhanced nondestructive
evaluation technologies under development at Lawrence Livermore.
Another promising technology is high-energy x-ray tomography for
high-resolution imaging of a nuclear warhead's plutonium pit. Our
scientists are exploring other ideas as well, in response to high-level
requests for new diagnostics that support stockpile stewardship.
We hope these new ideas, like neutron radiography, will be successful
so that they will also serve the nation's stockpile stewardship
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