Taggants in Explosives (Part 5 Of

—. — Chapter Ill TAGGANT RESEARCH REVIEW —. .—— Chapter 111.–TAGGANT RESEARCH REVIEW **** **** *.*0 **** 9*** **** **** ***0 *0** **** **0 *****9 51 Taggant Development History ● **** **** **** 900* **4* *a **a********** 51 Identification Taggants. 51 Predetonation Only. 52 Radiological Tracers. 52 Chemical Assay. 53 Physical Taggants . 53 Summary. 56 Detection Taggants. 56 Vapor Taggants. 57 Summary. 58 Detection Taggant Sensor Systems. .......59 untagged Detectoin ● **** a*** **** **** e.** a*** **** *e* be********* 62 Vapor Detection. ..62 Differential Contrast Radiography . .. .....63 Excitation lnduced Emissions. .......64 Summary. .......65 Current BAFT/Aerospace Tagget ● **** 65 Program Status ... , . 65 Projected Schedule. ............ 68 Implementation Philosophy. ., . .......69 Identification Taggant Surviaval Teasting ● **0* **** **m* **09 *b** **em **0** 70 Boosters, Military Explosives . ., . .......71 Black and Smokeless Powders . .......72 Detonators and Detonating Cord . .......72 Summary. .......72 Chapter Ill TAGGANT RESEARCH REVIEW INTRODUCTION TAGGANT DEVELOPMENT HISTORY The idea of adding material to explosives to Identification Taggants enhance the predetonation detection and the postdetonation identification of explosives has Ideas for tagging materials to be used for been considered by various military and civil- identification of the source of explosives used ian agencies for at least 15 years. Some of the in criminal bombings and bombing attempts suggested material, such as radioactive iso- can be generally grouped into the following topes, would perform both functions, some four classes: could only perform one. A number of the con- 1. addition of materials that would not sur- cepts which have been proposed during that vive the detonation, but which would pro- time are briefly described in the following sub- vide information if a bomb were recov- sect ions. ered undetonated; 51 52 ● Taggants in Explosives 2. addition of materials that would physical- not legally usable in New York. This data is not ly survive the detonation and be recov- helpful to police in tracking bombers but does ered intact; assist in control of legal uses of dynamite 3. addition of materials to the explosives within New York. that would be detected in an assay of the The English apparently use a method some- debris; and what better than the date-shift code in that the 4. addition of radioactive isotopes. identifying code consists of colored threads within the explosives. The threads do not sur- Predetonation Only vive the detonation, but the information con- Since 1970, the date, shift, manufacturer, tent is not lost by discarding the cartridge, as is and product have been printed on the car- the case with the date-shift code; it may not be tridge of cap-sensitive high explosives. The possible, however, to encode sufficient infor- manufacturer keeps records, by that date-shift mation for U.S. needs by that method. code, and can tell to whom each batch of material was sold; distributors also are required to Radiological Tracers keep records of sale. It is possible, from the Addition of small amounts of radioactive date-shift code, to compile a list of last legal isotopes to explosives during the manufactur- purchasers of explosives from a lot with the ing process is particularly attractive as it pro- same date-shift code. I n fact, BATF maintains vides a mechanism for both identification of a National Explosives Tracing Center, whose the explosive materials from the postdetona- function is to coordinate that activity. A typi- tion debris and a simple detection mechanism. cal trace would start with the recovery of an There are a large number of radioisotopes, so undetonated bomb by a BATF special agent. an identification scheme could certainly be de- He would call into the tracing center with the veloped that would provide sufficient unique information, and the data would be forwarded code species. to the manufacturer who would provide the list of consumers or distributors; if explosives The two primary objections to this often- from that lot were sold to a distributor or dis- proposed solution are public reaction and tributors, they would be contacted for a list of safety. Given the present widespread antipathy retail purchasers. to anything involving radioactivity, it is doubt- ful if the public would accept such a solution, The date-shift code information has proven even if there were no safety hazards. useful in investigations of criminal bombings, although its utility is Iimited to instances Two potential safety hazards exist, one hav- where the explosive is recovered before deto- ing to do with sensitization of the explosive nation, or in some cases, where a low-order materials, and the other with the effects of detonation does not destroy the cartridge. In low-level radiation. Addition of foreign materi- addition, the information is only on cap-sensi- als to explosives poses a potential sensitivity tive high explosives, and on the packages of hazard. However, the amount of radioisotopes detonators, black powder, and detonating required would be far smalIer than the mate- cord. No trace data is available for other ex- rial necessary for other tagging mechanisms, plosive material, such as smokeless powder, in- so explosive sensitization would probably be dividual detonators, or even cap-sensitive high no more of a problem than with other types of explosives that have been removed from the taggants. cartridge. The hazards of low-level exposure to radia- Smaller amounts of information are given by tion are not well-defined; the current trend is other systems that do not survive the detona- toward severe limitation of exposure. Thou- tion. For instance, all dynamite legally coming sands of people come into direct contact with into New York must be red. I f dynamite is re- explosives every day at the manufacturers, dis- covered that is not red, it indicates a purchase tributors, and users level, so a large number of Ch. 111—Taggant Research Review . 53 people would have some exposure. Primary ethanol solutions. By using several rare earths concern would be at the manufacturing level, and by varying concentrations, a sufficient where workers would have more continuous number of unique codes could be constructed. exposure than, for instance, a user. Aside from The taggants were recovered from the debris the adverse psychological effect the use of with ethanol-dampened cotton swabs. The tracers might have on such workers, and the swabs were then assayed in the laboratory by possible long-term effects of low-level expo- ion-exchange methods; analysis was accom- sure, there would be a large cost impact due to plished by X-ray excited optical luminescence the need for specially trained personnel, as techniques. welI as storage, handling, and decontaminat- ing equipment. If it were necessary for the Drawbacks to the Ames taggants included Nuclear Regulatory Commission to control the sensitization of the explosives by the ethanol shipment of the explosives and to license and carrier, a high background level, particularly otherwise supervise all explosive users, addi- for detonations taking place near or on the tional major costs and inconvenience would ground, and a rather specialized laboratory occur. procedure necessary for the taggant assay and identification. A final drawback is that reading of the information encoded in the postdetonation de- Physical Taggants bris would be a fairly complicated laboratory procedure involving sample preparation, radia- This class of taggants is designed to survive tion counting, and radioisotope identification. the detonation in its original physical form, to Only a limited number of laboratories in the be separated from the debris, and to be de- country have the trained personnel and facili- coded, either in the field or in the laboratory. ties; police forensic laboratories are not Several types of materials have been sug- among them. gested. Physical taggants must meet the same requirements as the chemical taggants, how- Chemical Assay ever, in addition to physical survival, so the number of serious candidates is somewhat lim- A number of approaches have been pro- ited. Three taggants remain promising candi- posed that have in common the addition of dates. chemicals to the explosives that would be recovered from the postdetonation debris and be 3M COLOR-CODED TAGGANT identified by a laboratory assay of the debris. More research has been conducted with the While the number of chemical materials is al- 3M identification taggant than with any other. most limitless, a successful chemical taggant It is the baseline taggant proposed by BATF for must have the following properties: implementation if a taggant program is legis- ● inertness, lated, and is the taggant used for the OTA cost, ● nonsensitization of the explosives, safety, and utility analyses. ● not present in background material, The taggant consists of an irregular chip of ● able to survive the detonation, thermosetting melamine alkyd, approximately ● long-term stability, 0.12 mm thick and about 0.40 mm in its great- ● not a health hazard, and est dimension. Figure 6 shows the eight-layer ● sufficient variation must be possible to construction; variation of the sequence colors form a large number of unique codes. provides the necessary library of codes. A total The chemical taggant with which the great- of approximately 6 million unique codes is est amount of research has been conducted available, when al Iowances are made for

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