1
Introduction and Background

Description of the Chemical Agent and Munitions Stockpile

For more than 50 years, the United States has maintained a stockpile of chemical agents and munitions distributed among eight sites within the continental United States and at Johnston Atoll in the Pacific Ocean (Figure 1-1). Two basic types of chemical agents comprise the stockpile: neurotoxic (nerve) agents and mustard (blister) agents. Both types are frequently, and erroneously, referred to as "gases" even though they are liquids at normal temperature and pressure.

The nerve agents include the organic phosphorus compounds designated as VX, GB (Sarin), and GA (Tabun). These chemicals present a significant toxic hazard because of their action on the nervous systems of humans and animals through inhibition of the acetyl-cholinesterase enzyme. They are both considered extremely toxic. VX is more acutely toxic than GB, but the latter represents a greater potential hazard because of its higher volatility (about the same as water) and, thus, the greater likelihood of its being inhaled. Chronic health effects and cancer from low-level exposures have not been associated with nerve agents or with chemically (and toxicologically) similar commercially available organic phosphorus insecticides (Leffingwell, 1993). Only short-term symptoms have been documented in individuals who survive exposure to nerve agents.

The mustards (designated H [nondistilled mustard], HD [distilled mustard], and HT [thickened mustard]) do not present significant acute lethal hazards. Their principal effect is severe blistering of the skin and mucous membranes. They have been implicated as being carcinogenic, however, and may present a cancer hazard to individuals exposed acutely (Leffingwell, 1993; IOM, 1993). The estimates for induced cancers from accidental agent exposures (Chapter 2) only consider mustard agents.

Chemical agents, after being fully dispersed, do not tend to persist in the environment because their relatively simple chemical structures tend to undergo hydrolysis in humid climates. However, in extremely dry desert climates, they can remain for a considerable period of time (U.S. Army, 1988).

The chemical agents in the U.S. stockpile are stored in a variety of containment systems, including bulk (ton) containers, rockets, projectiles, mines, bombs, cartridges, and spray tanks. Figure 1-1 summarizes the stockpile configuration as of 1996 for the eight continental U.S. sites by agent, munition, and containment system (OTA, 1992; NRC, 1996a).

Call for Disposal

Chemical Stockpile Disposal Program

Because of the age of the chemical weapons stock-pile, their lack of utility as weapons or deterrents, the continuing costs of maintenance, and the potential for accidental release, there is now sufficient incentive for the United States (and other countries) to dispose of stored chemical weapons. In 1985, Congress enacted Public Law 99-145 to initiate the process of eliminating the U.S. chemical weapons stockpile, with an expedited program to dispose of M55 rockets, which raise



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1 Introduction and Background Description of the Chemical Agent and Munitions Stockpile For more than 50 years, the United States has maintained a stockpile of chemical agents and munitions distributed among eight sites within the continental United States and at Johnston Atoll in the Pacific Ocean (Figure 1-1). Two basic types of chemical agents comprise the stockpile: neurotoxic (nerve) agents and mustard (blister) agents. Both types are frequently, and erroneously, referred to as "gases" even though they are liquids at normal temperature and pressure. The nerve agents include the organic phosphorus compounds designated as VX, GB (Sarin), and GA (Tabun). These chemicals present a significant toxic hazard because of their action on the nervous systems of humans and animals through inhibition of the acetyl-cholinesterase enzyme. They are both considered extremely toxic. VX is more acutely toxic than GB, but the latter represents a greater potential hazard because of its higher volatility (about the same as water) and, thus, the greater likelihood of its being inhaled. Chronic health effects and cancer from low-level exposures have not been associated with nerve agents or with chemically (and toxicologically) similar commercially available organic phosphorus insecticides (Leffingwell, 1993). Only short-term symptoms have been documented in individuals who survive exposure to nerve agents. The mustards (designated H [nondistilled mustard], HD [distilled mustard], and HT [thickened mustard]) do not present significant acute lethal hazards. Their principal effect is severe blistering of the skin and mucous membranes. They have been implicated as being carcinogenic, however, and may present a cancer hazard to individuals exposed acutely (Leffingwell, 1993; IOM, 1993). The estimates for induced cancers from accidental agent exposures (Chapter 2) only consider mustard agents. Chemical agents, after being fully dispersed, do not tend to persist in the environment because their relatively simple chemical structures tend to undergo hydrolysis in humid climates. However, in extremely dry desert climates, they can remain for a considerable period of time (U.S. Army, 1988). The chemical agents in the U.S. stockpile are stored in a variety of containment systems, including bulk (ton) containers, rockets, projectiles, mines, bombs, cartridges, and spray tanks. Figure 1-1 summarizes the stockpile configuration as of 1996 for the eight continental U.S. sites by agent, munition, and containment system (OTA, 1992; NRC, 1996a). Call for Disposal Chemical Stockpile Disposal Program Because of the age of the chemical weapons stock-pile, their lack of utility as weapons or deterrents, the continuing costs of maintenance, and the potential for accidental release, there is now sufficient incentive for the United States (and other countries) to dispose of stored chemical weapons. In 1985, Congress enacted Public Law 99-145 to initiate the process of eliminating the U.S. chemical weapons stockpile, with an expedited program to dispose of M55 rockets, which raise

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Figure 1-1 Location and size (percentage of remaining stockpile) of eight continental U.S. storage sites. Source: OTA, 1992; NRC, 1996a. special concerns because they are aging and because they contain agent, explosives, and propellant in an integrated configuration. Later, in 1992, Congress enacted Public Law 104-484, which directed the Army to dispose of the entire unitary1 chemical agent and munitions stockpile by December 31, 2004. Congress also directed that the Chemical Stockpile Disposal Program (CSDP) be implemented in a manner that ensured maximum protection of workers, the public, and the environment. Chemical Weapons Convention The CSDP has evolved in parallel with worldwide activities addressing questions of international control and the elimination of chemical agents and munitions. Over the course of several decades, a broad and complex agreement known as the Chemical Weapons Convention (CWC) was negotiated. Since 1993, the CWC has been signed by 165 countries and ratified by 89 countries. The convention was to go into effect six months after 65 countries had ratified it, which occurred on October 29, 1996. The CWC entered into force on April 29, 1997. The United States was actively involved in negotiating the CWC agreement and recently ratified it. Russia, the world's largest holder of chemical agents and munitions, has yet to ratify it. The CWC defines the destruction of chemical weapons as "a process by which chemicals are converted in an essentially irreversible way to a form unsuitable for production of chemical weapons, and which, in an irreversible manner, renders munitions and other devices unusable as such" (Smithson, 1993). The method of destruction is to be determined by each country, but the manner of destruction must ensure public safety and protect the environment. 1 The term unitary refers to a single chemical loaded in munitions or stored as a lethal material. More recently binary munitions have been produced, in which two relatively safe chemicals are loaded into separate compartments to be mixed to form a lethal agent after the munition is fired or released. The components of binary munitions are stockpiled separately, in separate states. They are not included in the present Chemical Stockpile Disposal Program. However, under the Chemical Weapons Convention of 1993, they are included in the munitions that will be destroyed.

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The CWC prohibits the development, production, acquisition, stockpiling, retention, transfer, or use of chemical weapons. Article IV of the CWC requires that signatories destroy chemical weapons and any special facilities for their manufacture within 10 years, i.e., by April 29, 2007. The date established by Congress for the destruction of the U.S. chemical stockpile remains December 31, 2004. Selection and Development of the Baseline Incineration System In the early 1980s, the Army investigated a number of technologies and strategies for the destruction or disposal of chemical weapons. Among these were chemical neutralization, ocean disposal (now banned by federal law), stockpile consolidation with subsequent destruction, and disassembly followed by component incineration. Incineration was selected by the Army as the preferred technology for stockpile disposal. The National Research Council (NRC) Committee on Demilitarizing Chemical Munitions and Agents was formed in August 1983 to review the status of the stockpile and to assess the available disposal technologies. In the committee's final report in 1984, incineration was endorsed as an adequate technology for the safe disposal of chemical warfare agents and munitions (NRC, 1984). Pursuant to the enactment of Public Law 99-145, the Army began development of components of the baseline incineration system at the Chemical Agent Munitions Disposal System (CAMDS) facility at Deseret Chemical Depot (DCD), formerly Tooele Army Depot South, Utah. Construction and systemization of the first fully integrated baseline incineration system, the Johnston Atoll Chemical Agent Disposal System (JACADS), was completed in July 1990 on Johnston Island, located in the Pacific Ocean approximately 700 miles southwest of Hawaii. The JACADS facility has a twofold mission: to destroy the chemical agents and munitions stored there to serve as a demonstration facility for the baseline incineration system Historical Risk Assessment by the Chemical Stockpile Disposal Program At a relatively early stage of the CSDP, a probabilistic risk assessment was performed in support of the Army's decision to use a baseline incineration system on site (U.S. Army, 1987). The PRA was documented in the Final Programmatic Environmental Impact Statement (FPEIS) (U.S. Army, 1988). The probabilistic risk assessment (PRA) done at that time was a less detailed version of the quantitative risk assessment (QRA). The FPEIS PRA evaluated accident sequences that could result in agent releases during the disposal process based upon the system design for JACADS. The PRA also examined risks for several disposal/transportation options at the eight continental U.S. storage sites. The JACADS analysis was modified slightly to account for major site-to-site differences. However, it was not site-specific in its treatment of design differences or local operating and maintenance practices, including disposal scheduling. The analyses of site-specific external-event hazards scenarios and the treatment of handling accidents, other particular accidents, and uncertainty were also less thorough. Role of the National Research Council Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program Concurrent with construction at JACADS, in 1987 the Army requested that the NRC review and evaluate the Army CSDP. The NRC established the Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program (Stockpile Committee) to perform these tasks over time and specifically to monitor operational verification testing (OVT) at JACADS, which began in July 1990 and was completed in March 1993. In July 1993, the NRC issued a preliminary short report (Part I) on OVT (NRC, 1993a) and in April 1994, a final report (Part II) on OVT at JACADS (NRC, 1994a). These reports concluded that the baseline incineration system was an adequate and safe means of disposing of the chemical weapons stockpile. Several subsequent reports have reaffirmed the committee's position. Construction of the first disposal facility in the

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continental United States was begun in 1989 in Utah. This facility, the Tooele Chemical Agent Disposal Facility (TOCDF), is a ''second-generation'' baseline system, which has incorporated into its design and operating procedures many improvements and technological advances based on JACADS operating experience (NRC, 1996b). The recommendations of the Stockpile Committee have been a factor in the changes and improvements to the facility. Pre-operational testing (systemization) at the TOCDF began in August 1993. During systemization, several modifications were made to systems and procedures at the TOCDF, e.g., a new slag removal system was designed for the liquid incinerator to eliminate the need for frequent shutdowns of the unit for the manual removal of slag; the furnace feed system was reviewed in detail by MITRE Corporation, and changes were made to correct misfeed problems that had occurred at JACADS. In reviewing the FPEIS, the Stockpile Committee recognized the generic nature of the PRA and noted in a letter report (NRC, 1993b) that "the risk analysis as presented in the FPEIS was not directed at managing risk at any specific site." In the same letter report, the committee noted that the continental sites at which lethal chemical agents and munitions will be destroyed all differ substantially from Johnston Island, as well as from one another, with regard to terrain, weather, the density of nearby population, the transportation network, the size and variety of stored agents and munitions, other aspects, and, possibly, destruction technology" (NRC, 1993b). The committee specifically recommended in the letter report that "a site-specific, full-scope, scenario-based risk assessment should be performed for each continental U.S. facility, starting with the Tooele facility" and that "each site-specific risk assessment should include the case of continued storage without disposal as one scenario." The letter report laid out detailed technical specifications for the site-specific risk assessments (NRC, 1993b). Another NRC report, Recommendations for the Disposal of Chemical Agents and Munitions (NRC, 1994b), reiterated this recommendation and emphasized the importance of site-specific risk assessments to sound risk management practices. In response to the NRC' s recommendations, the Program Manager for Chemical Demilitarization (PMCD) directed that a QRA and a risk management program be developed for each continental site, beginning with DCD/TOCDF. Concurrently, the Army retained a five-member panel of experts to provide an independent review of the approach and methodology for the QRA. In the 1996 report, Review of Systemization of the Tooele Chemical Agent Disposal Facility, the Stock-pile Committee presented an evaluation of the methodology for the site-specific QRA for DCD/TOCDF (NRC, 1996b). The report described the QRA methodology and indicated the committee's approval of the methods used and satisfaction with the QRA team's response to questions and criticisms. The QRA team vigorously pursued gathering new information (new tests, new mechanistic calculations, and expert knowledge) whenever concerns were raised about aspects of their analysis. The Systemization report also cited risk-related recommendations from previous NRC reports and evaluated the Army's response up to that time. The committee was satisfied with the role of the Risk Assessment Expert Panel on the Tooele Chemical Agent Disposal Facility Quantitative Risk Assessment (Expert Panel) and the QRA team's diligent response to each comment from the Expert Panel. The report indicated the committee's satisfaction with the way in which the risk assessment addressed all the relevant recommendations, with three exceptions: (1) the analysis was not yet complete; therefore it would be necessary to ensure that the remaining work continued to meet the committee's recommendations; (2) public involvement in the QRA needed to be improved; and (3) there appeared to be a lack of coordination between the QRA and the health risk assessment (HRA). Therefore, the committee also advocated the preparation of a single risk assessment summary report for each site to present integrated results of the various risk studies being conducted as separate projects under diverse auspices. The first set of site-specific risk assessments for DCD/TOCDF and associated risk management documents have now been assembled and are the basis for this report. The committee has provided additional comments about public involvement relating to risk assessments in a recent report on community involvement (NRC, 1996c). The Army has recently published phase-one (first results) QRAs for five other sites (U.S.

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Army, 1995a, 1996a, 1996b, 1997a, 1997b). Although evaluations of these QRAs are not included in this report, they show that the site-specific risk varies widely from site to site with the nature of the stockpile, the demographics near the site boundary, and the potential for external events. Composition of the Stockpile Committee The experience and familiarity from advisory and oversight activities, and from report development by the Stockpile Committee since its inception, provide a sound basis upon which to evaluate the present state of the Army's risk management activities for the Tooele storage and disposal facilities. Over the years, the Stockpile Committee has adjusted the composition of its membership to maintain a balance of disciplines necessary to meet the task at hand. Of the 15 current members, two are long-standing, recognized experts in the field of risk assessment and risk management. Other members of the Stockpile Committee have expertise in risk communications, public involvement, chemical engineering, mechanical engineering, combustion technology, biochemical engineering, chemical process design and control, analytical chemistry, toxicology, emergency response, human systems, and environmental law and sciences. The Stockpile Committee has prepared 16 NRC reports on various aspects of the overall CSDP, the development of the baseline incineration system, the systemization of the TOCDF, and the importance of public involvement. Appendix C is a list of these reports. The baseline incineration system at the TOCDF has evolved over the past decade through refinement of the prototype facilities at CAMDS and JACADS. The Stockpile Committee has tracked developments at these facilities and at the TOCDF and has commented extensively on progress at all of them through the construction, systemization, OVT, and agent destruction phases. Purpose of the Report This report continues the oversight of risk considerations begun in previous Stockpile Committee reports. It encompasses the program-wide and site-specific definition of the documented CSDP risk management process and evaluates the results of risk assessments performed for the Tooele storage and disposal facilities and the overall risk management process being implemented for the TOCDF, the first full-scale chemical agent and munitions disposal facility in the continental United States. In this evaluation, the committee focuses on five areas: (1) the quality of the risk assessments conducted for DCD/TOCDF; (2) the significance and interpretation of results and conclusions; (3) the integration (or lack thereof) of results from separate risk assessments; (4) the utilization of risk assessments in a comprehensive risk management plan for the TOCDF as well as the CSDP; and (5) the implementation of risk management practices. Characterizing effective risk management processes is the central theme of this report. The emphasis is on the utility of thorough, high quality, technically sound risk assessments as a basis for risk management practices. This report covers both major risk assessments, namely, the QRA (a quantitative evaluation of risks from accidental releases of agent), and the HRA (health risk assessment, which approximates worst case analyses of stack emissions for normal and upset operations). Other data being gathered by the Army at Tooele could be used to decide if a separate agricultural risk assessment will be needed in the future. As for the QRA and the HRA, this report considers the methodology, scope, and technical quality of the analyses; the treatment of acute and latent risks resulting from accidents; the risks from normal and upset operations; and the use of the results for the purpose of risk management. The report also addresses the integration of results of various assessments and how they can be communicated effectively, both within the CSDP and externally, to involve the local community in decisions pertaining to storage and disposal operations. The assessments of risk at the Tooele site involve a chemical agent and munitions storage and disposal system that includes sophisticated technology, procedural regimes, and contingency plans. Although the committee intends this commentary to assist the Army with the ongoing implementation of an effective risk management program at the Tooele site, a broader goal is to improve the risk assessment and management process at future sites, at both the programmatic and site-specific levels.

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The committee hopes that by reporting on the Army's CSDP risk management program at Tooele, the public may come to a better understanding of the risks, the thoroughness with which these risks have been analyzed, and the ways risk analyses have been used to reduce and manage risk. Consequently, in addition to the U.S. Army, the public is viewed as a primary audience for this report. Chapter 2 assumes the reader's familiarity with the methodology and terminology of risk analysis and assessment. Readers who are not familiar with the subject may wish to begin with Appendix A, which presents an introduction to the subject, starting with the simple example of a person tripping over a crack in the sidewalk. The example is then expanded to include some of the complications and refinements required in a real risk assessment of complex facilities like DCD/TOCDF. A final section of Appendix A discusses the process of risk management for the CSDP.