Chemical Weapons and Dissemination
Chemical warfare agents in the United States stockpile are stored either in the chemical weapons themselves, or in bulk storage containers. Chemical weapons were generally designed with two objectives in mind:
- compatibility with existing weapons systems, i.e., chemical artillery shells could have been fired from the same guns as conventional artillery shells, chemical bombs could have been dropped from the same airplanes as conventional bombs, etc.
- efficient generation of an aerosol of chemical weapons agent at the target
Artillery Shells
Chemical artillery shells (or "projectiles") contain a reservoir filled with chemical agent surrounding an axial explosive charge. The nose of some (but not all) shells has a lifting lug screwed in place. In order to fire the shell, the lifting lug is replaced with a fuze; in some cases the fuze is permanently affixed to the nose of the nose of the shell. When the shell is fired, the fuze is armed. When the shell arrives at its target, the fuze detonates the axial explosive charge, or burster. The burster shatters the shell casing and causes the chemical agent to disperse as an aerosol.
In the past, the US has used several munitions that have the same configuration(s) and use identical shell bodies, bursters, and fuzes as chemical weapons, but contain different fills of flame or smoke-generating chemicals.
Land Mines
The M23 chemical agent land mine contain a reservoir filled with chemical agent surrounding an explosive charge. The top of the land mine has a pressure plate; when the pressure plate is depressed, the fuze detonates the explosive charge, or burster. The burster shatters the mine casing, blows away the soil covering the mine, and causes the chemical agent to disperse as an aerosol.
Rockets
The M55 chemical agent rocket is stored in a fiberglass shipping and firing tube. The rocket includes (from the rear forward) a set of spring loaded guidance fins, an M28 double-base rocket propellant, a reservoir filled with chemical agent surrounding an axial explosive charge, and a fuze. When the rocket is fired, the propellant ignites and thrusts the rocket out of the shipping and firing tube. The guidance fins extend and the rocket flies off to its target; the fuze is armed in flight. When the rocket arrives at its target, the fuze detonates the axial explosive charge, or burster. The burster shatters the rocket casing and causes the chemical agent to disperse as an aerosol.
The M55 rocket is probably the most hazardous chemical weapon in the US stockpile from a safety standpoint. The rocket manufacturing process coupled with the age of these weapons effectively prevents the separation of the energetic materials (propellant and explosives) from the chemical warfare agent fills; this complicates the destruction of rockets as compared to all other chemical munitions. As the rocket propellant ages, it becomes unstable; all M55 chemical rockets contain 40 year-old propellant. In addition, the rocket is made of light aluminum rather than the heavy gauge steel of other chemical weapons. Sarin-containing rockets poses a particular hazard because the traces of fluoride ion in the aging Sarin increase the corrosion of the aluminum body of the rocket. Sarin-containing M55 rockets account for the largest proportion of leaking chemical munitions in the US stockpile.
Bombs
Chemical bombs contain a reservoir filled with chemical agent surrounding an axial explosive charge. Chemical bombs are generally stored without the tail fins and the detonating fuze. These items would be attached immediately before the bomb is loaded onto an aircraft. After the bomb is dropped, the fuze is armed. When the bomb arrives on its target, the fuze detonates the axial explosive charge, or burster. The burster shatters the bomb casing and causes the chemical agent to disperse as an aerosol.
Bulk Storage Items
Chemical agent that is not stored in weapons is stored in bulk containers. These containers are similar to containers in general use in the chemical industry. They are probably the least hazardous way to store chemical agent because they do not contain any explosive or energetic components.