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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
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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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