Tunnel Tests Span 35 years of Nevada Test Site
History
On August 10, 1957, a zero-yield safety experiment named "Saturn" was
detonated in C-Tunnel. Since then tests have been conducted in 16
different tunnels in Rainier Mesa on the Nevada Test Site. Today, there
is only one active tunnel used by the Defense Nuclear Agency (DNA).
The DNA evaluates the effects of nuclear weapons explosions, thermal
radiation, blast, shock, x-rays and gamma rays, on military hardware,
such as communication equipment, rocket nosecones, and satellites.
The typical Horizontal Line of Site (HLOS) test is primarily for
radiation effects research. Researchers attempt to minimize blast and
shock effects from the experiments. A large tunnel complex mined under
the mesa contains the HLOS pipe. The HLOS pipe is 1,500 to 1,800 feet
long and tapers from up to 30 feet in diameter at the test chamber to
several inches at the working point.
Experiments are placed in the HLOS pipe test chambers. At zero time
the nuclear device is fired, and radiation instantaneously flows down
the pipe, creating the necessary radiation environment.
To prevent bomb debris and blast from reaching and damaging the
experiments, three mechanisms are used to close the pipe. The first is
the Fast Acting Closure which is slammed shut by high explosives in
about one millisecond; the other two closures follow within 30 and 300
milliseconds.
Once the tunnel is declared safe by Radiological Safety personnel,
usually two days after the test, workers reenter the tunnel to recover
the experiments.
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