| SOME FEATURES OF SEARCHING FOR EXPLOSIVES AND EXPLOSIVE OBJECTS WITH THE HELP OF DOGS, GAS ANALYTICAL INSTRUMENTS AND CHEMICAL RAPID TESTS.
PETRENKO Evgeny Sergeevich SOME FEATURES OF SEARCHING FOR EXPLOSIVES AND EXPLOSIVE OBJECTS WITH THE HELP OF DOGS, GAS ANALYTICAL INSTRUMENTS AND CHEMICAL RAPID TESTS. The problem of the rapid search for explosives, explosive devices and other explosive objects, unfortunately, will remain a serious problem for a long time. It is already obvious that there is no single universal means yet and none is expected, at least in the near future. The situation is further complicated by the fact that the tasks of searching for explosives and explosive devices, which have a sufficient variety of types and forms, have to be solved in various conditions (weather and climate, landscape and territorial), sometimes with obvious opposition, to put it mildly, from the opposite side. Nevertheless, there are real prerequisites for a successful solution to the problem of searching for explosives and explosive ordnance by direct and indirect signs using a number of technical means and technologies [1, 2]. This article will discuss some of the features of searching for explosives and explosive ordnance by direct signs, which are determined by the presence of the explosive substance itself or its individual components. Until recently, the bulk of work on searching for explosives and explosive ordnance in peacetime was assigned to specially trained dogs of the so-called mine detection service (MDS). The undoubted advantage of dogs is their ability to detect explosive vapors in extremely negligible concentrations — up to 10-16 g/cm 3 , which is still an unattainable result for gas analysis devices — explosive detectors, a kind of electronic analogues of a dog's nose. Such sensitivity of a dog's nose is its huge advantage and … a huge disadvantage. What is the advantage — it is clear: a dog is sometimes able to catch the smell of explosives from a distance of up to several meters. But what is the disadvantage? In addition to a large variety of distracting and irritating factors of external influence for a dog (odors, for example, oil products and paints and varnishes, odors of other animals and food, noise), especially in the conditions of modern megacities, there are numerous attempts at active counteraction by the organizers and perpetrators of terrorist acts using chemical or biological products. The result of such an impact can be either masking the smell of explosives or putting the dog out of action for a certain period of time, even to the point of death. In addition, weather and climate conditions, especially temperature and relative humidity and local turbulence, have a great influence on the work of dogs. Even the same type of explosives for dogs produced in different countries will still be completely different objects, since they will differ to one degree or another in specific odors caused by differences in the original raw material base, technological features of production and, to the greatest extent, specific additional components in the form of dyes, binders, phlegmatizers and sensitizers. The mechanism of the “functioning” of the dog’s nose has not been fully studied, and therefore the adjustment of the dog’s behavior for different search conditions is still possible to a limited extent. There are methods that significantly increase the safety of dogs in active counteraction conditions and the efficiency of their work in a wide range of search conditions. One of the most effective methods is working with special absorbent materials by preliminary air sampling. At the same time, the dog remains a living organism with all its functional features, which does not always give a signal about its inoperability (i.e. the green LED indicator, so characteristic of electronic equipment, is “missing”). Gas analytical devices for searching for explosives by vapors, represented by a fairly large class of drift spectrometers, have a significantly lower sensitivity compared to a dog — 10-9 … 10-13 g/cm 3 . This is their significant disadvantage and … a significant advantage. Such a comparatively low sensitivity limits the possibilities of searching for and detecting explosives and explosives that are characterized by low volatility and the ability to form vapors under normal conditions. Such explosives include hexogen, octogen TENH, tetryl and explosives based on them. To a greater extent, the operation of drift spectrometers is affected by air temperature (should be above +5 … +10 ° C to search for even such volatile explosives as TNT, EGDN, nitroglycerin and compounds based on them), relative humidity (should be less than 90%) and local air turbulence. Moreover, the degree of influence of these factors on the operation of devices is much higher than on the work of dogs. There are some tactical techniques that can significantly expand the capabilities of devices for searching for various explosives, for example, by using portable heat generators such as industrial and household hair dryers with an autonomous power source. Such heat generators can significantly improve the search conditions in a local area in a short time. At the same time, the relatively low sensitivity of the devices practically eliminates the possibility of actively counteracting their operation using chemical products and, especially, products of biological origin. Naturally, the presence of other animals and extraneous noises also does not affect the operation of the devices, which distinguishes them favorably from dogs. For gas analysis devices and dogs, there is a problem of searching for explosives in sealed containers and searching for long-buried explosives in concealing environments. If a sealed glass, metal or plastic container completely excludes the release of explosive vapors to the outside, then for a container based on polyethylene, paper and a number of other materials, the probability of explosive vapors to escape to the outside exists. Naturally, in this case, the content of explosive vapors in the air will be significantly lower than for unsealed volumes. And this will accordingly affect the probability of their detection. Today, the search for explosives in completely sealed containers can only be carried out using devices built on the use of nuclear-physical methods [1, 3]. With all this, it should be borne in mind that any container itself can be successfully detected using other methods and devices for searching for explosives based on indirect signs [2]. In addition, paints and varnishes and other materials that have had gas-air or direct contact with explosives can absorb explosives on their surface and retain their traces for quite a long time — days, months, and in the case of placing such objects in sealed containers — up to several years. And attempts to get rid of such traces do not always achieve their goal. The problem of searching for explosives and explosive ordnance of long standing in concealing environments can be considered not so unambiguously. Moreover, the concealing environment can exist both in open terrain (soils of various types) and in conditions of limited volumes of buildings, structures, baggage, etc. For open terrain with its characteristic precipitation, soil erosion and significant circulation of air masses, the consequences of the long presence of explosives and explosive ordnance, as a rule, contribute to a significant reduction in the possibility of their detection using dogs and gas analysis devices. In conditions of limited volume, it is possible not only to reduce the possibility of detecting explosives and explosive ordnance, but also to increase it due to the gradual spread of explosive particles and their absorption by the surfaces of surrounding objects. Gas chromatographs as a type of gas analytical devices, given their high cost and high requirements for operator qualifications, are used mainly in laboratory conditions to identify explosives in explosive ordnance detected in one way or another. Gas chromatographs are rarely used for the prompt search for explosives and explosive ordnance outside laboratory conditions. Recently, relatively cheap and accessible chemical express tests for the rapid detection and identification of explosives in non-laboratory conditions have become increasingly widespread all over the world [1]. Being a contact search tool, such tests allow detecting explosives in situations where attempts to search for explosives by their vapors in the air may lead to nothing. Some of these cases can be cited as examples. As noted above, at temperatures below +10 °C or relative air humidity over 90%, vaporization in explosives, including highly volatile ones such as TNT, nitroglycerin (dynamites, dynamons) and EGDN (ethylene glycol dinitrate), drops to a minimum or practically ceases. Naturally, detection of explosives and high explosives in such conditions using dogs and drift spectrometers becomes practically impossible without the use of special tactical techniques and technical means. Another advantage of chemical tests is due to the task of promptly inspecting large traffic flows or residential and industrial buildings with a large number of rooms in a limited time frame in the face of a real threat of major terrorist attacks using explosives, as has repeatedly happened in Russia and a number of other countries. Naturally, it is not possible to equip a large number of operators with relatively expensive gas analyzers and MRS dogs (which, moreover, only work with their handlers) due to the limited financial resources and qualifications of law enforcement officers involved in such operations on an emergency basis, who sometimes have a vague idea of the technologies for safely performing operations to search for explosives and explosive ordnance. It is well known that doorways and interior details are very often used for mining with the use of booby traps and other «surprises». There are very few specialists who are able to enter such premises or vehicles without allowing the explosive devices to go off. That is, we are talking about the serious danger that will accompany attempts to inspect various objects for the presence of explosives and explosive ordnance by untrained personnel, especially if the «surprise» is combined with a sufficiently powerful main explosive charge. An additional problem is posed by vehicles and premises equipped with locking devices and sealed with seals, the opening of which without the presence of all interested parties may cause, at a minimum, serious legal consequences (for example, objects sealed with State Customs Committee seals, which can only be opened in the presence of an authorized representative of the State Customs Committee). The presence of a small-scale inspection dog or a gas analyzer in the inspection group does not fundamentally solve the problem, since the distance from the entrance to the facility to the explosives and explosive devices can be tens of meters, and the drive of the sensor of the explosive device detonator can be located directly at the entrance. However, when carrying explosives to the facility, planting explosive devices, transporting them by transport, especially when we are talking about large quantities, some of the microparticles are likely to settle on locks, handles, steering wheel, keys, documents, etc. Since the surface of such microparticles is quite small, the vaporization will be quite small, which will not allow the effective use of MRS dogs and drift spectrometers. For chemical express tests, the detection of such microparticles of explosives based on the implementation of a color chemical reaction does not present any difficulties in a wide range of weather and climate conditions, including for a long time after the explosives have ceased to contact the surface being examined, in conditions of negative temperatures and high relative humidity. There is another interesting aspect of using chemical express tests. Sometimes, for operational or political reasons, it seems advisable to carry out a covert, hidden check of a person for involvement in carrying or transporting explosives and hazardous substances, especially if these explosives and hazardous substances are not clearly observed with him at the moment. Traces of explosives on a person’s hands and clothes in the event of contact can last for up to several hours. Even a single hand wash with soap cannot guarantee the removal of trace microquantities of explosives. Such a suspect may be asked, under one pretext or another, to briefly hold an object (a pen, a flashlight, a traffic controller’s baton, etc.) in his hands or to hand over his objects (a driver’s license, a passport, etc.). Samples from such objects for subsequent testing using chemical express tests are taken almost instantly. The testing itself can be carried out either immediately on site or later in another location. Chemical rapid tests for detecting explosives have become quite widespread all over the world and exist in various designs. The greatest success in their creation and production has been achieved in Russia, the USA, Israel and some other countries. Often, test manufacturers do not quite correctly talk about the possibility of identifying explosives in full. The maximum information that can be obtained is information about the presence of certain explosives in the substance being tested without specifying their percentage content and certainly without determining the brand of explosives. In particular, the compositions of the TG series (TG-20, TG-40, TG-60), TGA, TGAF, MS and similar explosives of foreign manufacture such as hexotols, which are a mixture of TNT and hexogen in various proportions with or without the addition of other components, will be indistinguishable for tests. A similar picture will be for a fairly large family of ammonium nitrate explosives with the addition of TNT. Some difficulties in using tests may arise when working with substances that are not explosives but contain ammonium nitrate without the presence of other explosives: mineral fertilizers and some detergents. Such substances may require additional studies, if necessary, using, for example, gas chromatographs. An attempt to conduct a test at the site of detection by igniting or detonating some of the substance may not give a result for a number of reasons. It is known that industrial ammonium nitrate explosives used for drilling and blasting operations can have a fairly significant critical detonation diameter (more than 200 … 300 mm). This is understood as the minimum size of the explosive charge along which the detonation wave spreads stably without attenuation. With a smaller charge size, detonation processes simply cannot develop. In addition, there are industrial explosives that are characterized by extremely low sensitivity to external initiating effects. To initiate detonation in such explosives, an intermediate detonator made from a 400 g TNT block is sometimes required. On the other hand, there are a number of substances that are not traditionally classified as explosives, but are capable of exploding under certain conditions, for example, when dispersed in the air in a certain concentration [1]. Such substances or products include sugar, legumes, wood chips and dust, soot, etc. There is no need to explain what consequences an attempt to test an unknown substance using fire can lead to for would-be testers. Returning to chemical express tests, it should be emphasized that until recently they were produced in the form of a set of sprays (photo 1) or droppers (photo 2) with explosive identification reagents and a set of samplers in the form of filter paper or paper, woven or non-woven materials with an adhesive layer. Various sets include from 2 to 4 explosive identification reagents for sequential use to identify the following groups of explosives: Group 1 — polynitroaromatic compounds (trinitrotoluene or TNT, picric acid, tetryl and a number of others);
The 4th reagent-identifier of explosives, for example, from the Israeli kit “Mini ETK plus”, designed to detect chlorates, looks somewhat exotic. Unfortunately, the disadvantage of the express tests considered above is their insufficiently high reliability in detecting explosives of the 2nd and, especially, 3rd group. This is due to the difficulty of standardized (strictly dosed) sequential application of explosive identifier reagents to a sampler with a collected sample of the substance being studied in non-laboratory conditions and the possibility of explosives being washed away over the surface of the sampler. The latter circumstance is especially important when working with microquantities of explosives at the level of their detection limit. For sprays, the explosive identifier reagents of which represent a rather aggressive environment under pressure of up to 6 atm, in addition, it is important to maintain their operability for some length of time, especially at temperatures above +35 ° C. Unfortunately, the possibility of storing such canisters in a refrigerator, especially for mobile groups in the summer in areas of local armed conflicts, seems unlikely. Special police units in the most developed countries usually have a specialized vehicle that has such a refrigerator (many still sincerely believe that the refrigerator is only there to provide the staff with chilled beer). In connection with the noted shortcomings of traditional express tests, the task arose of developing and producing a more advanced kit taking into account the specifics of Russian conditions. To date, there is only one successful development — the «Litmus-4» kit (photo 3), containing 3 reagents-identifiers of explosives for the first 3 groups of explosives (excluding the chlorate group). Each reagent-identifier of explosives is pre-applied in industrial conditions in a metered amount to its own sampler made of porous (woven or non-woven) material, each of which in turn is placed in a separate flat sealed container. Naturally, such a scheme for performing express tests ensures a guaranteed metered sequential effect of the reagents-identifiers of explosives on the sample of the substance being tested and the absence of its washouts. The kit includes from 10 to 50 sets of 3 reagents-identifiers of explosives, which is another advantage of the kit. Express tests can be provided to 10 to 50 people, respectively, to ensure the possibility of their simultaneous parallel work, unlike sprays, which are designed to carry out up to 50 tests under favorable storage and operating conditions, naturally by sequential use and only by one person.
In general, it should be noted that the problem of camouflaging explosives and explosive devices is no less complex than the problem of searching for these objects. The possibility of camouflaging and covering explosives and explosive devices so that they cannot be detected by any means is highly questionable, but as has already been noted, one should not count on the creation of a single universal automatic search tool in the near future. In modern conditions, the success of searching for explosives and explosive devices will largely depend on the availability of a set of special devices and tools, personnel qualifications, work incentives and a measure of responsibility. In addition, operational and preventive measures carried out by law enforcement agencies and aimed at preventing terrorist acts using explosives should play a significant role. Literature 1. Petrov S.I. On the assessment of the possibility of detecting explosives and devices containing them.//Special equipment, 2001, No. 4. |
