During the middle third of the twentieth century, the United States developed and produced a wide range of weapons designed to disperse both nerve (GB and VX) and blister (sulfur mustard: H, HD, and HT) chemical agents at lethal concentrations. Although never used, 31,496 tons of chemical agents were produced after World War II, a large fraction of which was loaded into millions of individual munitions, with the rest stored in bulk containers. The agent-filled munitions and bulk containers that remained in the United States were stored in eight continental weapons depots, while chemical munitions that had been sent overseas were consolidated and stored on Johnson Atoll, southwest of the main Hawaiian islands.
In 1985, Congress directed the U.S. Army to start destruction of some elements in the chemical weapons stockpile (Public Law 99-145), and in 1991 Congress directed that all chemical weapons be destroyed (Public Law 102-484). In 1997 Congress ratified the Chemical Weapons Convention (CWC), an international treaty that specified all chemical weapons would be destroyed by April 29, 2012. What is now the Army’s Chemical Materials Agency (CMA) has built and operated chemical agent disposal facilities at Johnson Atoll and six of the eight continental U.S. storage depots, successfully destroying the agent-filled munitions and/or agent in bulk containers at all seven CMA sites. These activities have successfully destroyed 90 percent of the nation’s stockpiled chemical agents.
Congress assigned the job of destroying the stockpiled chemical weapons at the two remaining continental U.S. depots (in Lexington, Kentucky, and Pueblo, Colorado) to a separate U.S. Army Element, the Assembled Chemical Weapons Alternatives (ACWA) organization. This occurred after residents near these two facilities convinced their congressional representatives that they were seriously concerned about the safety and effectiveness of CMA’s technology selection for assembled weapons, based on robotic disassembly and separate incineration of the chemical agent and energetic materials in agent-filled munitions. The time required to define, assess, and develop alternative assembled weapons demilitarization technologies, coupled with serious budget constraints, has delayed chemical weapons destruction at Lexington and Pueblo; their demilitarization plants are still under construction.
All chemical weapon demilitarization technologies generate large amounts of potentially agent-contaminated secondary wastes as well as contaminated equipment, machinery, and plant structural elements. Chemical agent contamination levels for secondary waste, process machinery, and demilitarization equipment (tools, respirators, instruments, etc.) resulting from agent and energetics destruction processes have to be determined in order to develop safe decontamination strategies and/or disposal options. Furthermore, demilitarization plant structural elements may need to be decontaminated for maintenance activities required during disposal operations and agent changeover breaks in plant operations and during plant closure.
CMA has developed methods for determining whether waste materials, equipment, machinery, and even structural elements are contaminated by chemical agents. These methods generally involve (1) isolating the objects of interest in some sort of enclosure and (2) after a specified equilibration time, measuring vaporized agent concentrations in the enclosure’s headspace. In other cases, wipe samples of surfaces can be obtained and solvents may be used to extract chemical agent contaminants from wipe samples or waste stream materials and then analyzed with chromatographic techniques. These proven techniques are available and are planned for use in the two new ACWA demilitarization plants now being built.
While effective, these traditional methods can be time consuming and have to be repeated if initial decontamination efforts are not successful. A recent review, focused on technologies for quantifying agent vapor concentrations in CMA demilitarization facilities (NRC, 2005a), noted the potential of then newly developed ambient surface ionization mass spectrometry techniques to provide real-time measurements of chemical agent contamination on surfaces. Ambient ionization mass spectrometry involves sampling and ionization of chemical species in their native environment without, or with minimal, sample preparation. Objects sampled are usually solids, and the experiment is typically done at atmospheric pressure, with total analysis times on the order of a few seconds. Subsequent development of a wide range of ambient surface ionization techniques with mass spectrometric detection has been rapid and impressive. Significant improvements in sensitivity, response time, portability, and reliability have been demonstrated, and an increasing number of systems are or will soon be commercially available.
This study is focused on whether ambient surface ionization analytical techniques are sufficiently sensitive, specific, rapid, robust, and available to supplement current Army methods for screening materials, equipment, and structural elements for agent contamination. Considerable time and effort are spent characterizing and decontaminating secondary waste, process machinery, and equipment during both disposal operations and plant closure; this significantly extends the time needed for safe and effective chemical weapons destruction and prolongs plant closure. If robust, portable, real-time surface agent contamination analytical instrumentation is available and can shorten the time and effort required for tasks not directly contributing to chemical weapons destruction, they may be well worth deploying at the two new ACWA demilitarization plants.
The Committee on Assessment of Agent Monitoring Strategies for the Blue Grass and Pueblo Chemical Agent Destruction Pilot Plants (or ACWA Monitoring Committee) is made up of experts on analytical chemistry (including mass spectrometry and ion mobility measurements), plasma chemistry, environmental chemistry, environmental engineering, statistical sampling and experimental design, process chemical engineering, materials science, quantitative risk assessment, industrial engineering, and environmental regulations. Short biographies of the committee members are presented in Appendix A.
The committee’s statement of task is as follows:
The Program Manager for Assembled Chemical Weapons Alternatives (PMACWA) is currently in the process of constructing two chemical agent destruction facilities, the Blue Grass Chemical Agent Destruction Pilot Plant (BGCAPP) in Richmond, Kentucky and the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP) in Pueblo, Colorado. According to the current plant design, BGCAPP will dispose of mustard agent H, and nerve agents GB (sarin) and VX using chemical neutralization followed by supercritical water oxidation and PCAPP will dispose of mustard agent HD and HT, using chemical neutralization followed by biotreatment. In addition, the selection of an auxiliary explosive destruction technology (EDT) to handle leakers and reject munitions at PCAPP, and exploration of the use of this type of technology to possibly process M55 rocket motors and mustard agent munitions at BGCAPP is currently being investigated by ACWA.
Construction of BGCAPP and PCAPP is in the early stages and chemical agent monitoring strategies have not yet been finalized for these facilities. PMACWA will adopt monitoring methods for airborne agent at BGCAPP and PCAPP similar to those used by the U.S. Army Chemical Materials Agency (CMA) at its facilities. The current U.S. Army monitoring procedures have been considered to be sound and proven. However, PMACWA could benefit from a National Research Council (NRC) assessment of any technology advancements to monitor for agent contamination of solid waste materials as well as facility equipment and surfaces at BGCAPP and PCAPP using emerging technologies. Advancements in real-time and near real-time monitoring technology for chemical agents, agent simulants and similar semi-volatile chemicals are being regularly documented in the scientific literature and may present opportunities to build additional efficiencies into waste disposal and closure activities at BGCAPP and PCAPP.
The National Research Council will establish an ad hoc committee to:
• Review the process designs for both BGCAPP and PCAPP to evaluate the expected degree of contamination for facility solid wastes, equipment, and surfaces anticipated from agent destruction processes.
• Evaluate novel candidate technologies capable of real-time and near real-time quantification of chemical agents adsorbed onto or absorbed into materials relevant to chemical demilitarization operational and closure processes and identify specifications required for a new monitoring technology to improve BGCAPP and PCAPP waste disposal and plant closure activities.
• Using the specifications identified in bullet two, review and assess new and emerging technologies that enable rapid measurement of the degree of contamination of process equipment and waste, or if the degree of decontamination achieved is sufficient to meet established regulatory requirements, including requirements for off-site shipment of wastes. Specifically, promising novel technologies will be evaluated for detection and quantification of chemical agents adsorbed onto DPE suits, agents absorbed into activated charcoal, and agents adsorbed onto and/or absorbed into concrete surfaces.
The committee met in Aberdeen, Maryland (February 2011), Pueblo, Colorado (June 2011), Washington, D.C. (August 2011), and Irvine, California (October, 2011). Briefings on chemical demilitarization activities and technologies and ambient ionization analytical techniques were presented by the following organizations:
• Army Element Assembled Chemical Weapons Alternatives
• Army Chemical Materials Agency
• Army Edgewood Chemical Biological Center
• Battelle Memorial Institute
• Idaho National Laboratory
• Purdue University, Department of Chemistry
At these meetings, committee members also went over technical details, discussed, outlined, and wrote draft report sections, and reviewed report drafts. Additional information on the committee’s meetings is given in Appendix B.
Based on their respective expertise and experience, committee members were assigned to one or more of four working groups. These groups performed the bulk of the technical analyses and draft writing assignments. The four working groups were these:
• Plant Processes
• Current Waste and Structural Contamination Evaluation Practices
• Analytical Technologies
• Measurement Methodologies
Chapter 2 of this report describes the planned chemical weapons destruction processes to be employed at the two ACWA demilitarization facilities and analyzes the probable secondary waste streams and planned waste treatment and disposal activities. Current Army methods for monitoring chemical agent contamination of secondary waste materials as well as equipment, machinery, and structural components during agent changeout and plant closure activities are first presented in Chapter 2 and then elaborated on in Chapter 3. Chapter 3 also presents potential scenarios in which real-time surface or condensed phase agent measurements might be useful. Chapter 4 reviews the current state of the art of analytical ambient ionization mass spectrometry and discusses potential analysis tasks and technology implementations. An analysis of statistical sampling design methods and information on their application to chemical agent surface contamination measurements in relevant chemical demilitarization plant scenarios are presented in Chapter 5. The committee’s findings and recommendations are compiled in Chapter 6. As previously indicated, Appendix A contains short biographical sketches of the committee members and Appendix B provides details of committee meeting activities. Appendix C lists some known current sources of commercially available ambient ionization mass spectrometry equipment in support of the technical presentation in Chapter 4. Appendix D on statistical calibration and Appendix E on sampling variability and uncertainty analyses supplement the statistical presentation in Chapter 5.