44 « The Containment of Underground Nuclear Explosions
Figure 3-7—Vessel | Closures
Mechanical closures
(MAC/GSAC)
~*~ Mechanical closure
(TAPS)
Pre-fire geometry
Approximate closed FAC geometry
Fast acting closure
(FAC)
A) Mechanical Closures (MAC/GSAC)
B) Tunnel and Pipe Seal (TAPS)
C) Fast Acting Closure (FAC)
SOURCE: Modified from Defense Nuclear Agency
the pipe ahead of the shock wave to prevent
early flow of high-velocity gas and debris into
the experiment chamber.
enoughto squeeze the pipe shut. The stemming
plug stops forming at about the distance where
the first mechanical pipe closure is located.
e After 0.05 seconds(c), the ground shock moves
e After 0.2 seconds (d), the cavity growth is
past the second closure andis no longer strong
complete. The rebound from the explosion