detonation. Analyses of the results of these tests are still proceeding but survival appears to be high (20 to 40 percent). See Section 3.3.3 for a further discussion of these tests. 3.2.2.2 Status In early January 1977, Aerospace issued a Request For Proposal to Westinghouse for the purchase of 2450 pounds of taggants. Their response in February 1977 included some exceptions to our standard terms and conditions. The effect of these exceptions was to limit any potential risk of loss on the part of Westinghouse to a figure not to exceed the value of the subcontract (approximately $200,000). Their intent was to limit their risk for any reason, including their own acts such as negligence or willful misconduct. This limitation was such that, if a circumstance arose wherein an innocent third party was wronged because of an act on the part of Westinghouse, that party would expect to collect from whomever agreed to permit Westinghouse to limit their liability. In an effort to achieve an acceptable modification of this limitation of liability, Aerospace agreed to inspect all taggant batches shipped by Westinghouse and to certify in writing that they met contractual specifications. On this basis, Westinghouse agreed to raise their assumption of risk level to $1 million. Aerospace would be subject to any shortfall and has no valid reason to assume this risk. Although Westinghouse has increased their liability, their continued refusal to accept responsibility for their own actions is the crucial issue. A contract for the purchase of the Westinghouse taggants could be issued if the Bureau of Alcohol, Tobacco and Firearms would indemnify Aerospace for the risk which Westinghouse wishes to avoid; however, it is unclear if any statutory provision exists which would permit the Bureau to assume that risk. Westinghouse has been given every opportunity through telephone conversations, correspondence, and meetings which invovled their technical, contractual, and legal personnel, and even a vice presidential contact, over a period of several months, to reappraise and reassess their position. These extended negotiations have caused a delay, in manufacture and delivery of taggants necessary for the pilot test program, and the delay would have had an adverse impact on projected completion dates. Because of the above factors, ATF authorized Aerospace to terminate any further efforts to negotiate a subcontract with the Westinghouse Electric Corporation for production of its taggants for identification of explosives. Since that time, efforts in this area have been limited to The rare-earth-doped compounds which are available, along with their emission peak wavelengths in nanometers for 325-nanometer excitation, are: Strontium Chlorophosphate: Europium 447 476 546 555 575 608-648 618 626 687 375 Yttrium Oxysulfide: Europium Strontium Fluoroborate: Europium, Samarium Strontium Fluoroborate: Europium Codes are not dependent upon emission peak intensities (or relative intensities) which could be varied by the concentration of the rare earths. Although the concentration levels are not a code parameter, they must be sufficiently controlled to permit a clear decision on the presence or absence of each compound in the coding scheme. With three available spotting phosphors, a single-particle coding capability of 3069 different configurations can be achieved. Additional coding rare earths have been considered. However, because of difficulties with availabilitly, cost, or interpreting the code (due to overlapping and masking spectra), only those listed earlier are deemed practical at present. Because of limitations in the total number of available codes, a twoparticle tagging scheme must be used. The two particles would be differentiated by the color of the spotting phosphor. The use of two particles expands the code capacity of the Westinghouse taggants to 1,046,529 codes. However, the need to restrict the number of actual combinations of particles to reduce readout ambiguity will reduce the number of available codes to approximately 600,000. The Westinghouse unencapusulated taggant particles have a specific gravity of approximately 3.4, are shaped like a grain of sand, and are about 0.2 mm in the largest dimension. After polyethylene encapsulation, the taggants are nearly spherical with an average diameter of 0.7 mm and have a specific gravity of about 1.0. In the postblast condition, due to fracture, they are, like the 3M Company taggants, without encapsulation and are smaller by a factor of between 2 and 10, depending on the blast environment. One quantity of taggants--20 batches, 2 pounds each--was purchased for analysis by Aerospace and for preliminary testing by the explosives industry. Dynamite, in four different formulations, and slurry, in two formulations, were tagged and tested by detonation. Analyses of the results of these tests are still proceeding but survival appears to be high (20 to 40 percent). See Section 3.3.3 for a further discussion of these tests. 3.2.2.2 Status In early January 1977, Aerospace issued a Request For Proposal to Westinghouse for the purchase of 2450 pounds of taggants. Their response in February 1977 included some exceptions to our standard terms and conditions. The effect of these exceptions was to limit any potential risk of loss on the part of Westinghouse to a figure not to exceed the value of the subcontract (approximately $200,000). Their intent was to limit their risk for any reason, including their own acts such as negligence or willful misconduct. This limitation was such that, if a circumstance arose wherein an innocent third party was wronged because of an act on the part of Westinghouse, that party would expect to collect from whomever agreed to permit Westinghouse to limit their liability. In an effort to achieve an acceptable modification of this limitation of liability, Aerospace agreed to inspect all taggant batches shipped by Westinghouse and to certify in writing that they met contractual specifications. On this basis, Westinghouse agreed to raise their assumption of risk level to $1 million. Aerospace would be subject to any shortfall and has no valid reason to assume this risk. Although Westinghouse has increased their liability, their continued refusal to accept responsibility for their own actions is the crucial issue. A contract for the purchase of the Westinghouse taggants could be issued if the Bureau of Alcohol, Tobacco and Firearms would indemnify Aerospace for the risk which Westinghouse wishes to avoid; however, it is unclear if any statutory provision exists which would permit the Bureau to assume that risk. Westinghouse has been given every opportunity through telephone conversations, correspondence, and meetings which invovled their technical, contractual, and legal personnel, and even a vice presidential contact, over a period of several months, to reappraise and reassess their position. These extended negotiations have caused a delay, in manufacture and delivery of taggants necessary for the pilot test program, and the delay would have had an adverse impact on projected completion dates. Because of the above factors, ATF authorized Aerospace to terminate any further efforts to negotiate a subcontract with the Westinghouse Electric Corporation for production of its taggants for identification of explosives. Since that time, efforts in this area have been limited to completing the taggant-decoding effort from earlier tests. This will permit, for the record, an accurate characterization of the Westinghouse taggants in a variety of explosive environments. Curie point tagging was developed and patented by the General Electric Company for use in tagging bulk shipments of crude oil. The concept embodies the use of magnetic particles (ferrites) which possess fixed known Curie temperatures. The Curie point is the temperature at which ferromagnetic materials lose their magnetism and is easily detected as a drop in the magnetization of the sample. The Curie temperature itself is a physical property of the individual ferrite and is dependent only on the composition of the ferrite. Because ferrites are ceramic materials, they are quite stable at high temperatures and are not readily susceptible to heat damage. For use as a code, several ferrites would be mixed together with a binder and a spotting phosphor. Following polymer encapsulatoin, these formulated taggants would then be added to explosives as are other identificaton taggants. Figure 3-2 depicts the laboratory analysis of a particle containing five ferrites. Each of the step-like reductions in magnetization represents the Curie temperature of one of the constituents ferrites. In order to analyze a taggant, as depicted in the graph, a particle containing several ferrites is heated and its magnetization is simultaneously measured; a sharp drop in magnetization is indicative of a Curie point. The Curie point transitions are a permanent molecular property of ferrite materials. After the Curie point transitions have been measured at elevated temperatures, the original transitions are reinstated by cooling the material to room temperature. In general, the composition of ferrites is MOFe2O3, where M can be any divalent metal, such as manganese, zinc, nickel, etc. By manufacturing ferrites containing stoichiometric mixtures of divalent metals, thousands of ferrites can be formulated. Two examples of this type of ferrite are Nio. Zno.6Fe204 and Nio.6Zno.4 Fe204 The former has its Curie temperature at 190°C and the latter at 360°C. The analysis of the Curie point taggant can be accomplished by any sensitive magnetometer or by more elaborate means such as Mossbauer or electron spin resonance spectrometry. At the present time, Aerospace has entered into an agreement with General Electric whereby General Electric will manufacture several different ferrites for testing, provide consultation and access to necessary instrumentation. Some of these ferrites have already been formulated into Westinghouse-like potassium silicate taggants containing a fluorescent marker to assist in retrieval. These taggants are being tested for retrievability and readability by placing them in explosives and analyzing the postdetonation residue. Simultaneously, NCR Corporation has utilized its company-developed techniques to encapsulate the taggants with several different types of wall materials. These coatings will be tested for compatibilty with explosives and resistance to absorption of explosive oils and slurry liquids. An in-depth technical evaluation of Curie-temperature-measuring apparatus has been undertaken. This study indicated that a sensitive prototype portable instrument could be built for less than $10,000, and a production unit for about $3000. The Curie point taggants have substantial potential. The ferrites themselves would cost only a few dollars per pound and could provide more than 2 million possible codes with only five used at any one time. The detection apparatus could be readily fabricated and be made portable. 3.2.4 Identification Tagging Environmental Assessment An environmental assessment has been written in order to comply with the Environmental Protection Agency's regulations to evaluate the potential impact of explosive taggants on the environment. The assessment includes a synopsis of the background and development of the taggant particles and alternatives to their proposed use. It is agreed that the alternative of not implementing a Nationwide explosives tagging |