44 © The Containment of Underground Nuclear Explostons
Figure 3-7—Vessel | Closures
Mechanical closures
(MAC/GSAC)
“F~ 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 Nuciear Agency
the pipe ahead of the shock wave to prevent
enoughto squeezethe pipe shut. The stemming
e After 0.05 seconds (c), the ground shock moves
past the second closure andis no longer strong
® After 0.2 seconds (d), the cavity growth 1s
complete. The rebound from the explosion
early flow of high-velocity gas and debris into
the experiment chamber.
plug stops forming at about the distance where
the first mechanical pipe closure is located.