2
The U.S. Chemical Weapons Stockpile

This chapter presents a brief description of the U.S. chemical weapons stockpile, covering the physical properties of chemical agents, their toxicities, associated weapons, and the nature and distribution of stockpile storage sites.

DESCRIPTION OF THE AGENTS

The U.S. chemical weapons stockpile contains nerve agents, or nerve gas, and blister, or mustard, agents. (Mustard was used extensively in World War I, whereas nerve agents were first used in war by Iraq in its war with Iran.) These two fundamental types of chemical warfare agents are contained in the U.S. stockpile in a variety of munitions and bulk containers.

Nerve agents in the U.S. stockpile include persistent VX, nonpersistent Sarin (GB), and a small quantity of Tabun (GA). All the nerve agents are organophosphonate compounds, which contain phosphorus double-bonded to an oxygen atom and single-bonded to a carbon atom. VX also contains sulfur in its chemical structure, GB contains fluorine, and GA contains the cyanide group (see Figure 2-1 for the chemical structures of major U.S. chemical agents and Table 2-1 for some of their physical properties).1

Nerve agents are highly toxic or lethal in both liquid and vapor forms.2 Although they are often referred to as gases, they are liquids at normal

1  

VX is O-ethyl-S-[2-diisopropyl aminoethyl]methylphosphonothiolate; GB is isopropyl methyl phosphonofluoridate, and GA is ethyl-N, N-dimethyl phosphoramidocyanidate.

2  

Terms used in the literature include: lethal, danger of quick death on exposure; toxic, serious impairment of health, or even death, on substantial exposure; poisonous, dangerous if not handled carefully (e.g., gasoline or household bleach); and hazardous, known or suspected to pose a risk to human health or the environment. In this report, the term toxic is sometimes used in a general sense, encompassing all levels of toxicity.



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Alternative Technologies for the Destruction of Chemical Agents and Munitions 2 The U.S. Chemical Weapons Stockpile This chapter presents a brief description of the U.S. chemical weapons stockpile, covering the physical properties of chemical agents, their toxicities, associated weapons, and the nature and distribution of stockpile storage sites. DESCRIPTION OF THE AGENTS The U.S. chemical weapons stockpile contains nerve agents, or nerve gas, and blister, or mustard, agents. (Mustard was used extensively in World War I, whereas nerve agents were first used in war by Iraq in its war with Iran.) These two fundamental types of chemical warfare agents are contained in the U.S. stockpile in a variety of munitions and bulk containers. Nerve agents in the U.S. stockpile include persistent VX, nonpersistent Sarin (GB), and a small quantity of Tabun (GA). All the nerve agents are organophosphonate compounds, which contain phosphorus double-bonded to an oxygen atom and single-bonded to a carbon atom. VX also contains sulfur in its chemical structure, GB contains fluorine, and GA contains the cyanide group (see Figure 2-1 for the chemical structures of major U.S. chemical agents and Table 2-1 for some of their physical properties).1 Nerve agents are highly toxic or lethal in both liquid and vapor forms.2 Although they are often referred to as gases, they are liquids at normal 1   VX is O-ethyl-S-[2-diisopropyl aminoethyl]methylphosphonothiolate; GB is isopropyl methyl phosphonofluoridate, and GA is ethyl-N, N-dimethyl phosphoramidocyanidate. 2   Terms used in the literature include: lethal, danger of quick death on exposure; toxic, serious impairment of health, or even death, on substantial exposure; poisonous, dangerous if not handled carefully (e.g., gasoline or household bleach); and hazardous, known or suspected to pose a risk to human health or the environment. In this report, the term toxic is sometimes used in a general sense, encompassing all levels of toxicity.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-1 Principal chemical wadare agents in the U.S. stockpile. temperatures and pressures. GB has a boiling point about 5°C lower than that for kerosene or diesel fuel. It evaporates at about the same rate as water and is relatively nonpersistent in the environment. VX evaporates much more slowly, and spills of liquid VX can persist for a long time under average weather conditions. Thus, GB presents mainly a vapor hazard, although contact with its liquid form can also be fatal. In contrast, VX presents mainly a contact hazard, although its vapor buildup in enclosed spaces can also reach lethal levels. In their pure form, all these nerve agents are nearly odorless and colorless. The blister agents include H, HD, and HT. The active ingredient in H and lid and a major component (60 percent) of HT is the same chemical substance, bis(2-chloroethyl)sulfide, or mustard.3 The agent H, sometimes called Levinstein mustard, contains 70 percent mustard and 30 percent 3   Mustard gas, sulfur mustard, yperite, and other names have also been applied to this agent. Although 'mustard gas' is often used, the chemical is a liquid at ordinary ambient temperatures; its initial boiling point is comparable with that of the more volatile parts of kerosene.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions TABLE 2-1 Physical Properties of Chemical Warfare Agents Agent Characteristic Nerve Agents Blister (Mustard) Agents GB (Sarin) VX H/HD HT Chemical formula (CH3)2CHO(CH3)FPO C11 H26NO2PS (ClCH2CH2)2S 60% (ClCH2CH2)2S, 40% sulfur and chlorine compounds Molecular weight 140.10 267.38 159.08 Not available Boiling point, °C 158 298 217 228 Freezing point, °C -56 < -51 14.45 0 to 1.3 Vapor pressure, mm Hg 2.9 @ 25°C 0.0007 @ 25°C 0.072@ 20°C Not available Volatility, mg/m3 4,100@ 0°C 22,000@ 25°C 10.5 @ 25°C 75 @ 0°C (solid) 610 @ 20°C (liquid) 831 @ 25°C Diffusion coefficient for vapor in air, cm2/sec 0.061@ 20°C 4 @ 20°C 0.060@ 20°C 0.05@ 25°C Surface tension, dynes/cm 26.5@ 20°C 32.0@ 20°C 43.2@ 20°C 44 @ 25°C Viscosity, cS 1.28@ 25°C 12.256@ 20°C 3.95 @ 20°C 6.05@ 20°C

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Alternative Technologies for the Destruction of Chemical Agents and Munitions Agent Characteristic Nerve Agents Blister (Mustard) Agents GB (Sarin) VX H/HD HT Liquid density, g/cm3 at 20°C 1.0887 1.0083 1.2685 Not available Latent heat of vaporization, cal/g 80 78.2 94 Not available Solubility, g/100 g of distilled water 100; soluble in organic solvents 5 @ 25°C; best solvents are dilute mineral acids 0.92 @ 22°C; soluble in acetone, CCl4, CH3Cl, tetrachloroethane, ethyl benzoate, ether   Heat of combustion, Btu/lb (cal/g) 10,000 (5.55) 15,000 (8.33) 8,100 (4.5) Not available   Source: Chemical Systems Laboratory (1983); Programmatic Environmental Impact Statement (PEIS) (1988). U.S. Departments of the Army and Air Force (1975).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions sulfur-containing impurities. HD, which is a distilled form of H, consists of nearly pure mustard. HT is a mixture of 60 percent HD with 40 percent other sulfur and chlorine compounds. I-IT is similar in appearance and biological activity to H and HD but is somewhat more active biologically. There is also the blister agent Lewisite (L), an arsenic compound, which is stored in only small amounts in the U.S. stockpile. Mustard has a garlic-like odor, with significant volatility at ordinary temperatures. It thus presents both vapor and contact hazards. Because mustard is nearly insoluble in water, it is very persistent in the environment and can contaminate soils and surfaces for long periods of time. All the chemical agents above are soluble in organic solvents; GB is also very soluble in water and VX is somewhat soluble. None of these chemical agents exists in pure form in either munitions or bulk containers. In munitions, GB and VX are stabilized with various compounds to prevent acid formation and decomposition of the agent. 4 Various impurities present at the time of manufacture and products of polymerization and decomposition (aging) are also present in the stockpiled agents. During Operational Verification Testing (OVT) at the Johnston Island storage site, for example, mustard agent was frequently been found in gel as well as liquid form. Toxicity of the Agents Nerve agents are the most lethal of the chemical warfare agents. VX is more toxic than GB, which is more toxic than GA. The peripheral nervous system of the human body uses either norepinephrine or acetylcholene (ACh) for neurotransrnission. The neurons of the sympathetic nervous system release norepinephrine to carry the final impulse to the end organs. Those of the parasympathetic system release acetylcholine. Acetylcholine also plays a vital role in the control of skeletal muscles autonomic ganglia and many structures within the central nervous system. The lethal effects of nerve agents result principally from inhibiting and inactivating of acetylcholinesterase (ACHE), an enzyme responsible for the normal breakdown of ACh.5 This inhibition results in the failure of the 4   For example, diisopropyl carbodiimide is used as a stabilizer for GB and VX and tributylamine is used as a stabilizer for GB. Trace metals such as nickel, copper, aluminum, and iron can also be found in stored agents. HD is often thickened by the addition of 5 to 10 percent polymer (Yang et al., 1992). 5   Once inside the body, VX not only inhibits AChE but also reacts directly with ACh receptors and other neurotransmitter receptors. The high toxicity of VX is also attributable to its high specificity for, and thus inhibition of, AChE.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions nervous system to operate properly. The resulting accumulation of ACh profoundly interferes with the transmission of nerve impulses at cholinergic synapses. In cases of lethal intoxication, the immediate cause of death is asphyxiation, resulting from interference with the nervous control of the muscles of the diaphragm (U.S. Departments of the Army and Air Force, 1975). Mustard agents affect the eyes and lungs and blister the skin. They cause severe chemical burns and painful blisters, and are lethal at high dosages, especially if inhaled. Symptoms are generally delayed for several hours after exposure. Prolonged worker exposure in wartime mustard manufacturing facilities mused cancer in a significant percentage of those exposed (IARC, 1975; U.S. Department of the Army and Air Force, 1975). (See Chapter 4 for more detail on the toxicities and airborne exposure limits for both mustard and nerve agents.) More details on the medical, health, and physiological effects of exposure to agents and on treatment and therapy can be found in selected references (Compton, 1987; Goodman and Gilman, 1985; Namba, 1971; U.S. Departments of the Army and Air Force, 1975). DESCRIPTION OF THE MUNITIONS There are a number of munition types in the U.S. chemical weapons stockpile. Some contain, in addition to chemical agent, propellant or explosive components, or both (see Figures 2-2 to 2-5 and Tables 2-2 and 2-3). These munitions include 105-ram, 155-mm, and 8-inch artillery projectiles, mortar cartridges, land mines, and M55 115-mm rockets. The 155-ram artillery projectiles, for example, are filled with mustard, GB, or VX, and the 8-inch artillery projectiles are filled with GB or VX. Some munitions, such as aircraft-delivered nerve agent bombs, are stockpiled without explosives.6 In addition, about two-thirds of the chemical stockpile is stored in bulk liquid form in steel ton containers, including GA, GB, VX, mustard, and Lewisite (PEIS, 1988). GA and Lewisite are stored only at Tooele Army Depot (TEAD) in relatively small quantities. Lewisite will have to be handled separately from other agents and is not a major consideration here. 6   These include the MC-1 750-1b Air Force bomb, the MK-94 500-lb Navy bomb, the MK-116 (''weteye'') 525-1b Navy bomb (all GB-filled), and the TMU-28/B aerial spray tanks filled with VX.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-2 M55 rocket and M23 land mine. Source: USATHAMA (1982, 1983).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-3 105-mm, 155-mm, 8-inch, and 4.2-inch projectiles. Source: USATHAMA (1982, 1983).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-4 Bomb, spray tank, and ton container. Source: USATHAMA (1982, 1983).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-5 Physical envelopes of chemical munitions. Source: General Atomics (1982).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions TABLE 2-2 Composition of Munitions in the U.S. Chemical Stockpile Munition Type Agent Fuze Burster Propellant Dunnage M55 115-mm rocketsa GB, VX Yes Yes Yes Yes M23 land mines VX Yesb Yes No Yes 4.2-in. mortars Mustard Yes Yes Yes Yes 105-ram cartridges GB, mustard Yes Yes Yes Yes 105-ram projectiles GB, mustard Yesc Yesc No Yes 155-mm projectiles GB, VX, mustard No Yesc No Yes 8-in. projectiles GB, VX No Yesc No Yes Bombs (500-750 lb) GB No No No Yes Weteye bombs GB No No No No Spray tanks VX No No No No Ton containers GB, VX, GA, mustard, Lewisite No No No No a M55 rockets are processed in individual fiberglass shipping containers. b Fuze and land mines are stored together but not assembled. c Some projectiles have not been put into explosive configuration. Source: PEIS (1988).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions TABLE 2-3 Composition of Selected Chemical Munition Types, by Weight   Chemical Weight (lb) Munition Type Agent Agent Explosive Propellant Metal M55 rocket VX, GB 10.5 3.2 19.3 23.8 155-mm projectile VX, GB, HD 6.3 2.4 ---a 92.6 Ton container VX, GB, HD 1,600 ---a ---a 1,400 a Not applicable. Source: PEIS (1988). Many of the chemical munitions contain explosives in the form of fuzes and bursters, as well as propellants. Fuzes are mechanically activated detonation devices that set off the bursting charge of a projectile, rocket, or land mine. The bursters axe explosive charges that, on detonation, disperse agent and metal fragments into the surrounding area. Propellants axe energetic materials necessary for the propulsion of the rockets and 105-ram artillery cartridges. In the following discussion, explosives and propellants will be referred to collectively as energetics. These munition components incorporate a variety of chemical compounds that must also be destroyed as part of chemical weapons destruction.7 Disposal requires consideration of other chemical compounds and materials as well. For example, the fiberglass shipping and firing tubes for 7   Fuzes include cyclonite, lead styphnate, lead oxide, barium nitrate, antimony sulfide, tetracine, and potassium chlorate. Bursters include tetryl, tetrytol (tetryl plus trinitrotoluene [TNT]), or Composition B (cyclonite plus TNT). Propellants include nitrocellulose, dinitrotoluene, lead stearate, triacetin, dibutylphthalate, and diphenylamine.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions M55 rockets were found to contain small quantities of polychlorinated biphenyls (PCBs). Munitions are often stored in configurations suitable for transport during wartime, such as in boxes or protective robes. Such packing and handling materials are referred to as dunnage. For chemical munitions, dunnage includes wood pallets (some treated with pentachlorophenol [PCP]), metal fasteners, steel drums, and polystyrene packing. Used protective suits and spent decontamination solution also require disposal. All these materials must be covered in any program for chemical weapons destruction. However, dunnage may be handled by disposal in a hazardous waste site. GEOGRAPHICAL DISTRIBUTION OF THE STOCKPILE The U.S. chemical weapons stockpile is distributed among Army bases at eight continental U.S. sites and at Johnston Island in the Pacific Ocean (Figure 2-6 and Table 2-4). Some of these storage locations are quite remote; others, such as Aberdeen Proving Ground, Newport Army Ammunition Plant, and Lexington Blue Grass Army Depot, are close to populated areas. Chemical agents at all these sites total about 25,000 metric tons, with 40 percent stored in Utah at TEAD (Ember, 1992; Picardi et al., 1991). Quantifies at other locations range from 1.6 percent of the stockpile, at Bluegrass Army Depot, to 12 percent, at Pine Bluff Arsenal. The character of the stockpile also differs among storage sites. Aberdeen Proving Ground and Newport Army Ammunition Plant store only ton containers of HD and VX, respectively. Pueblo Army Depot maintains only mustard agents (HD) and HT) in cartridges and projectiles. The other locations store both nerve and mustard agents as well as a variety of munition types. Johnston Island has approximately 100,000 artillery projectiles filled with nerve agent that were removed ("retrograded") from West Germany in 1990. (Some weapons stored at Johnston Island will be destroyed during OVT of the baseline technology.) Table 2-5 indicates the differences among sites in the amounts of metals, explosives, propellants, and agents stored. At all sites, containers of agents and weapons containing agents must be prepared for destruction. These operations produce contaminated or hazardous waste streams that must also be dealt with in the disposal process (see Chapter 4 for further details on the requirements of disposal).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions FIGURE 2-6 Types of agent and munitions anti percentage of total agent stockpile (by weight of agent) at each storage site. Source: OTA (1992).

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Alternative Technologies for the Destruction of Chemical Agents and Munitions TABLE 2-4 Chemical Munitions Stored in the Continental United States Chemical munitions (Agent) APG ANAD LBAD NAAP PBA PUDA TEADa UMDA Mustard agent (H, HD, or HT)                 105-mm projectile (HD)   X       X     155-mm projectile (H, HD)   X X     X X   4.2-in. mortar (HD, HT)   X       X X   Ton container (HD) X X     X Xb X X Ton container (HT)         X       Agent GB                 105-mm projectile   X         X   155-mm projectile   X         X X 8-in. projectile   X X       X X M55 rocket   X X   X   X X 500-lb bomb               X 750-1b bomb             X X Weteye bomb             X   Ton container   Xb Xb   Xb   X X Agent VX                 155-mm projectile   X X       X X 8-in. projectile             X X M55 rocket   X X   X   X X M23 land mine   X     X   X X Spray tank             X X Ton container       X       X a Small quantities of Lewisite and Tabun (GA) are stored in ton containers at TEAD. b Small quantities of agent drained as part of the Drill and Transfer system assessment for the M55 rockets. APG, Aberdeen Proving Ground, Md.; AMAD, Anniston Army Depot, Ala.; LBAD, Lexington/Blue Grass Army Depot, Ky.; NAAP, Newport Annex Army Depot, Ind.; PBA, Pine Bluff Arsenal, Ark.; PUDA, Pueblo Depot Activity, Colo.; TEAD, Tooele Depot Activity, Utah; and UMDA, Umatilla Depot Activity, Ore.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions TABLE 2-5 Approximate Amounts of Metals, Energetics, and Agent Contained in the Chemical Weapons Stockpile (tons), by Site Site Ferrous Metal Aluminum Explosive Propellant Agenta Tooele 22,000 570 350 175 10,500(?) Annieton 13,700 1,020 451 757 1,800 (?) Umatilla 7,930 1,380 338 1,030 2,900 (?) Pine Bluff 2,644 1,431 180 1,060 3000 (?) Lexington 1,631 904 115 670 400 (?) Pueblo 10,910 0 124 0 2,500(?) Newport 2,455 0 0 ? 1000 (?) Aberdeen ? 0 0 0 1,300 (?) JACADS ? ? ? ? 1,700(?) TOTAL 71,270(?) 5,305(?) 1,558(?) 3,692(?) 24,800 (?) a Estimated values, based on percentages of the total stockpile at each site, multiplied by 25,000 tons. Source: Information supplied by the Program Manager for Chemical Demilitarization at a meeting of the Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, March 9-10, 1992, National Academy of Sciences.

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Alternative Technologies for the Destruction of Chemical Agents and Munitions SUMMARY In summary, the U.S. chemical weapons stockpile consists of a diverse assemblage of lethal chemical agents and associated munitions, representing a complex disposal task, regardless of the technology used. Amounts and types of agents and munitions vary greatly among storage sites. In particular, Aberdeen Proving Ground and Newport Army Ammunition Plant have only ton containers of HI) and VX, respectively, while other storage sites maintain a variety of other agent-containing weapons.