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Executive Summary MOTIVATION January 2012 saw the completion of the U.S. Army's Chemical Materials Agency's (CMA's) task to destroy 90 percent of the nation's stockpile of chemical weapons. CMA completed destruction of the chemical agents and associated munitions stored at six of eight continental U.S. storage facilities as well as chemical weapons deployed overseas, which were transported to Johnston Atoll, southwest of Hawaii, and demilitarized there. The remaining 10 percent of the nation's chemical weapons stockpile is stored at two remaining continental U.S. depots, in Lexington, Kentucky, and Pueblo, Colorado. Their destruction has been assigned to a separate U.S. Army organization, the Assembled Chemical Weapons Alternatives (ACWA) Element. ACWA is currently constructing the last two chemical weapons disposal facilities, the Pueblo and Blue Grass Chemical Agent Destruction Pilot Plants (denoted PCAPP and BGCAPP), with weapons destruction activities scheduled to start in 2015 and 2020, respectively. ACWA is charged with destroying the mustard agent stockpile at Pueblo and the nerve and mustard agent stockpile at Blue Grass without using the multiple incinerators and furnaces used at the five CMA demilitarization plants that dealt with assembled chemical weaponsmunitions containing both chemical agents and explosive/propulsive components. The two ACWA demilitarization facilities are congressionally mandated to employ noncombustion-based chemical neutralization processes to destroy chemical agents. Chapter 2 of this report reviews the disposal technologies designed to demilitarize chemical agents and other weapons components planned for use at the two ACWA facilities. ACWA will not have large furnaces to decontaminate or destroy munitions components and to process related secondary waste streams (which are cataloged in Chapter 3). This constraint has motivated an interest in analytical methods that can quickly and reliably identify and characterize agent- contaminated materials. Such methods could be useful in characterizing secondary waste materials during disposal operations at both sites, as well as during agent changeover operations (BGCAPP only) and especially during facility closure activities, when agent disposal facilities must be decontaminated before demolition (both BGCAPP and PCAPP). In order to safely operate its disposal plants, CMA developed methods and procedures to monitor chemical agent contamination of both secondary waste materials and plant structural components. ACWA currently plans to adopt these methods and procedures (described briefly in Chapter 2 and more thoroughly in Chapter 3) for use at 1
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2 ASSESSMENT OF AGENT MONITORING STRATEGIES FOR BGCAPP AND PCAPP these facilities. While these methods have allowed safe waste processing and closure activities, they are tedious and indirect, generally relying on vapor-phase agent measurements over confined surfaces rather than direct detection of surface contamination. Chapter 3 also develops and describes a half-dozen scenarios involving prospective ACWA secondary waste characterization, process equipment maintenance and changeover activities, and closure agent decontamination challenges, where direct, real-time agent contamination measurements on surfaces or in porous bulk materials might allow more efficient and possibly safer operations if suitable analytical technology is available and affordable. TECHNOLOGY OPPORTUNITY The last 5 years have produced very rapid development of ambient ionization mass spectrometric techniques capable of real-time surface and bulk material chemical analyses with little or no sample preparation. Two of these technologies, desorption electrospray ionization (DESI), first introduced in 2004, and direct analysis in real time (DART), introduced in 2005, are now commercially available and have widespread applications. Both DESI and DART, as well as a range of variations on each, are reviewed in Chapter 4, which also details their application to the detection and quantification of chemical agent and agent simulant compounds. The utility of various DESI and DART implementations to meet the chemical agent contamination characterization challenges identified in several of the ACWA operational and closure activity scenarios developed in Chapter 3 is addressed in Chapter 4. Chapter 4 also discusses the potential utility of real-time agent vapor concentration gradient measurement methods to locate specific contaminated surfaces. It concludes with a comparison of the strengths and weaknesses in (1) the current Army indirect methods to characterize chemical agent contamination adsorbed on solid surfaces and absorbed by porous materials and (2) direct measurements using ambient ionization techniques. Based on this comparison, the chapter presents findings and recommendations involving specific ambient ionization technology configurations that could guide specification, acquisition, and integration of this technology, if ACWA management determines that the ability to directly characterize the distribution of chemical agent concentrations on and in solid materials and the concentration gradients of airborne chemical agents is sufficiently useful to justify the effort and cost required to implement this type of technology. Efficient and effective use of any analytical technology must employ statistically robust measurement strategies. This is particularly true when dealing with the characterization of contamination by deadly substances like chemical agents. Chapter 5 briefly examines the published statistical basis of current Army chemical agent contamination characterization methods, presents a detailed analysis of recently published DART measurements of chemical agent concentrations in liquid solutions, and then examines the statistical basis of direct surface agent contamination characterization using various implementations of ambient ionization mass spectrometry techniques.
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EXECUTIVE SUMMARY 3 CONCLUSIONS A compilation of all of the findings and recommendations developed in Chapters 2-5 of this report is presented in Chapter 6. As reflected in those findings and recommendations, the committee concluded that ambient ionization mass spectrometry is a rapidly maturing and highly useful technology with specific available implementations capable of highly sensitive, real-time measurements of relative concentrations of chemical agents adsorbed on a variety of relevant surfaces and in some porous materials. Further, with suitable reference standards, absolute measurements of agent concentrations in ambient air and liquid solutions are feasible. If adopted, these capabilities might be very useful in supplementing the Army's traditional air and vapor headspace agent contamination measurements using current near-real-time agent monitors. A range of scenarios occurring during agent disposal operations and facility closure activities have been defined and developed by the committee to illustrate the potential utility of real-time ambient ionization mass spectrometric detection of chemical agent contamination. Although commercially available ambient ionization mass spectrometry instrumentation in the specific configurations recommended by the committee may not currently be available off the shelf, the major components have been commercialized, and a number of analytical instrument vendors are capable of designing, assembling, and demonstrating instruments meeting potential ACWA specifications. Given the current schedules for anticipated PCAPP and BGCAPP weapons disposal (beginning in 2015 and 2020, respectively) and facility closure activities, it is very likely that these instruments could be specified, tested, and deployed quickly enough to be used at PCAPP and BGCAPP, as suggested in this report. In addition, as demonstrated by their work as reviewed in Chapters 4 and 5, Army scientists at the Edgewood Chemical and Biological Center, sited near ACWA headquarters, have significant experience in the application of ambient ionization mass spectrometric measurements of chemical agent concentrations and distributions and could be a resource for developing and testing specific ambient ionization technology implementations for ACWA. Based on these considerations the committee's overarching finding and recommendation are as follows: Finding 6-1. Suitably specified ambient ionization mass spectrometry instrumentation could be utilized in a range of challenging activities at ACWA chemical weapons disposal facilities where real-time chemical agent contamination measurements may reduce the time and effort required to characterize the chemical agent contamination of waste materials, process equipment, and work areas. Recommendation 6-1. ACWA should carefully evaluate the capabilities of portable ambient ionization mass spectrometry and its potential to provide faster and more accurate characterization of chemical agent contamination, as detailed in this report, and determine if these likely benefits justify the effort and investment required to specify, acquire, and deploy suitable implementations of this technology.
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