Containing the Threat from Illegal Bombings An Integrated National Strategy for Marking, Tagging, Rendering Inert, and Licensing Explosives and Their Precursors (1998) / Chapter Skim
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2 Improving the Capability to Detect Explosives
2 Improving the Capability to Detect Explosives
Pages 40-71
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From page 40... ...
;i.,:j,:2:'~,;.: Tiff, iffy ~ Wreckage of Pan American World Airways flight 103, December 1988. Reprinted, by permission, from Archive Photos (Reuters/Rob Taggart)
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From page 41... ...
Local law enforcement or explosive ordnance disposal personnel who respond in such cases require a detection system that is easy to transport, easy to operate, and inexpensive. The number of systems that can be used to address the threat posed by a suspicious package is inversely proportional to the cost and logistics burden of the system.
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From page 42... ...
Two Strategic Approaches A wide range of explosives are available for use by a determined terrorist or criminal. In considering the need to enhance the detectability of concealed explosives, the committee decided that the costs and benefits of adding detection markers to explosives must be evaluated in the context of the existing and pro {On December 21, 1988, Pan Am flight 103 was blown up over the Scottish village of Lockerbie, killing 270 people, including 11 on the ground.
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From page 43... ...
For many reasons, improving the capability to detect unmarked explosives would be preferred if it could be shown to be technically and economically feasible. First, such a capability would save the expense of implementing a marking program.
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From page 44... ...
The ideal marker would not be common either in nature or in industrial use, so that the natural background would be low or nonexistent. The false alarm rate would be zero and the probability of detection would be 100 percent.
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From page 45... ...
If a single marker could be used for all explosives, detection would be simplified and the cost of the marker and the detection system would be reduced. Chemical Vapor Markers Rationale for Vapor Marking of Explosives Scientists noticed in the late 1970s that many commercial and military explosives were fortuitously contaminated with ethylene glycol dinitrate (EGDN)
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From page 46... ...
, the concealed C-4 can be detected easily and reliably by relatively low cost commercial explosive vapor detectors. Since DMNB has a much higher vapor pressure than does RDX (Table 2.2)
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From page 47... ...
IMPROVING THE CAPABILITY TO DETECT EXPLOSIVES TABLE 2.1 Abbreviations, Names, and Chemical Structures of International Civil Aviation Organization Vapor Markers 47 Abbreviation Name DMNB 2,3-dimethyl-2,3-dinitrobutane EGDN Ethylene glycol dinitrate o-MNT Ortho-mononitrotoluene p-MNT Para-mononitrotoluene Structure CH3 CH3 H C 1 1 CH NO2 NO2 H2l 1 H2 O2NO ONO2 H3 ¢~02 O2N~ CH3 TABLE 2.2 Vapor Pressures of Some Common Explosive Chemicals and International Civil Aviation Organization Vapor Markers Abbreviation Explosive Chemical AN NO PETN RDX TNT Marker DMNB EGDN o-MNT p-MNT Name Ammonium nitrate Nitroglycerine Pentaerythritol tetranitrate 1,3,5-Trinitro- 1,3,5-triazacyclohexane 2,4,6-Trinitrotoluene 2, 3 -Dimethyl-2, 3 -dinitrobutane Ethylene glycol dinitrate Ortho-mononitrotoluene Pa ra - mononitrotoluene Vapor Pressure (Torr, 25 °C) 5.0x 10-6 2.4x 10-5 3.8 x 10-1° 1.4x 10-9 3.0x 10-6 2.07 x 10-3 2.80 x 10-2 1.45 x 1o-l 4.12 x 10-2 SOURCE: Vapor pressures for DMNB, o-MNT, and p-MNT are from Elias (1991)
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From page 48... ...
This work has been carried out under the auspices of the United Nations, specifically within the Council of the ICAO (see Box 2.2~. A distinguishing feature of the post-1988 effort is the selection of vapor markers, detectable by existing explosives detectors, with appropriate vapor pressures to meet the requirement for a long lifetime.
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From page 49... ...
Thus, DMNB's toxicity is not an issue for marking plastic explosives, provided that adequate precautions are taken to deal with its higher vapor pressure. Because of DMNB's volatility, its use requires proper ventilation, as well as appropriate scrubber and personnel protection equipment, to reduce the permissible exposure limit (PEL)
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From page 50... ...
. In fact, several signatory states of the ICAO Convention have easily made production-sized batches of plastic explosives marked with DMNB.
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From page 51... ...
The committee observes that p-MNT has been used in the full-scale marking of a plastic explosive (Mostak and Stancl, 1995~. Detectability of ICAO Markers by Modified Commercial Explosives Detectors Recently, the detectability of each of the four listed ICAO markers incorporated into several plastic explosives was tested using commercial trace detection systems employing ICAO's standard box and suitcase tests (Malotky,1995~.
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From page 52... ...
It is anticipated that the cost of marking C-4 with DMNB will be reduced to about $0.20 per pound in the near future with the refinement of lower-cost methods for its synthesis. Use of ICAO Markers in Nonplastic Military and Industrial Explosives Although the Group of Specialists has focused on marking of plastic explosives, it has conducted some preliminary investigations on the marking of nonplastic military explosives and industrial explosive powders.
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From page 53... ...
Marking of AN and ANFO with DMNB might also result in wide distribution of the marker in the environment, and consequent cross-contamination and false alarm problems with vapor detectors. Recently, work with marking emulsion and water gel explosives has received increasing attention.
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From page 54... ...
Pound for pound, bananas have three times the radioactivity of bulk explosives marked with 60Co.5 The main health risk for explosives workers would be handling the radioactive cobalt components before addition of 60Co to an explosive, blasting cap, or detonator. Although the isotope would be highly diluted before its incorporation into the manufacturing process, even the diluted 60Co mixture would be radioactive, and its use would require implementation of standard protocols for handling 5According to the JASON report, bananas have an activity of 3.3 nCi/kg due radioactive potassium, 40K, which is a beta emitter (JASON, 1994)
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From page 55... ...
In turn, some of these radon daughters produce coincident gamma rays. The second source of interference is the abundance of cosmic-ray muons, which are sufficiently penetrating that they can pass through a pair of scintillator panels and appear to produce a coincident event.
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From page 56... ...
Passive Markers Passive markers for detection of explosives have been discussed in great detail in several JASON reports (JASON, 1986, 1987, 1994~. None of the passive markers even approach the ideal marker the majority of concepts have flaws that make their implementation either virtually impossible or totally unacceptable.
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From page 57... ...
A serious disadvantage to this scheme is that although Er is a relatively good x-ray absorber, at reasonable levels of bulk doping it could not be detected among the clutter of low-, and medium-, materials. The proposed implementation is to paint the Er on the surface of detonators or plastic explosives in a distinctive checkerboard pattern (JASON, 1994~.
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From page 58... ...
Thermal neutron analysis has been used to detect unmarked explosives (Yeaple, 1991) , as discussed in the section below titled "Neutron-based Systems." This system is designed to detect nitrogen atoms (a component of many, but not all, explosives)
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From page 59... ...
If the requirement for high neutron opacity is relaxed, lower concentrations of boron are possible, but the marked explosive becomes harder to distinguish from other innocent neutron-absorbing materials, including water.
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From page 60... ...
DIRECT DETECTION OF UNMARKED EXPLOSIVES Since the initial signing on March 1, 1991, of the ICAO Convention on the Marking of Plastic Explosives for the Purpose of Detection (see Box 2.2) , considerable progress has been made in the development of technology to detect unmarked explosives as well.
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From page 61... ...
The energy of the gamma rays resulting from this scattering is characteristic of the elements encountered. Fast neutron analysis allows the operator to do an in situ elemental analysis.
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From page 62... ...
Computed Tomography In 1994 the Federal Aviation Administration (FAA) certified the ability of the InVision CTX-5000 as an automated explosives detection system (Ott, 1996~.
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From page 63... ...
airports.l2 Trace detection systems are in use in airports in Canada, Germany, and other locations and to protect selected federal installations. The same detection technology is being incorporated into walk-through portals in the United States and abroad to screen people for concealed explosives.
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From page 64... ...
However, compounds other than explosives are also electronegative. Despite its low cost and ability to detect the vapor markers, current commercial trace detection systems have moved away from electron capture for detection of explosives, primarily because of its lack of specificity and the resulting high rate of false alarms.l3 Chemiluminesence Chemiluminesence is a nitro-group-specific indicator.
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From page 65... ...
. Trace Detection of Explosives Versus Detection of International Civil Aviation Organization Markers Trace detection of an explosive is a less reliable indicator of the presence of a bomb than is detection of the bulk explosive itself.
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From page 66... ...
At the same time, producers of such trace detection systems should be encouraged to adjust their detection parameters to facilitate detection of the ICAO markers as well as traces of explosives. The resulting capability would enhance the probability of detecting bombs made with marked explosives, since it would provide two detection opportunities detection of the vapor or particulates from an explosive as well as detection of the marker rather than one.
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From page 67... ...
Anyone who makes, sells, transports, stores, or uses explosives detection markers, explosives detection equipment, or detectionmarked explosive materials may be sued for damages if these products or activities cause harm to others. Included within this group of possible defendants are private parties, like common carriers and building owners, as well as public entities, such as governments and law enforcement agencies.
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From page 68... ...
246-247~. In situations where the markers, detection equipment, or detection-marked explosive materials cause physical harm to persons or property, the victims may seek relief under the theory of negligence (pp.
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From page 69... ...
Local law enforcement agencies, typically the first responders to both hoax and real bombing incidents, possess extremely limited explosives detection equipment. Their budgets generally do not allow for procurement and use of existing detection devices.l6 Moreover, getting bulky detection equipment or even a bomb-sniffing dog on the scene quickly can be problematic.
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From page 70... ...
The addition of detection markers to any or all explosives would not address existing stocks of unmarked nonmilitary explosives diverted from the normal stream of commerce, unmarked military explosives, unmarked explosives provided by a state sponsor of terrorism, or unmarked improvised explosives. The technology available to detect unmarked explosives is improving rapidly, so that it is now increasingly possible to detect a broad range of explosives in many scenarios.
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From page 71... ...
2. The addition of detection markers to explosives beyond that required by the International Civil Aviation Organization Convention is not recommended at the present time.
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