Some features of the search for explosives and explosive objects using dogs, gas analysis devices and chemical rapid tests.
PETRENKO Evgeny Sergeevich
SOME FEATURES OF THE SEARCH FOR EXPLOSIVES AND EXPLOSIVE OBJECTS USING DOGS, GAS ANALYTICAL DEVICES AND CHEMICAL RAPID TESTS.
The problem of rapid search for explosives (HE), explosive devices and other explosive objects (EOD), unfortunately, will remain a serious problem for a long time.
It is already obvious that there is no single universal solution 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 hazards, which have a sufficient variety of types and forms, have to be solved in various conditions (weather-climatic, landscape-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 conditions was assigned to specially trained dogs of the so-called mine detection service (MDS).
The absolute advantage of dogs is their ability to detect explosive vapors in extremely low concentrations – up to 10-16 g/cm3, which is still an unattainable result for gas-analytical devices of explosive detectors, a kind of electronic analogue of a dog’s nose.
Such sensitivity of a dog’s nose is its great advantage and… great disadvantage.
The advantage is clear: a dog is sometimes able to detect the smell of explosives from a distance of up to several meters.
But what is the disadvantage?
In addition to a large variety of external factors that distract and irritate dogs (smells, for example, of petroleum products and paints and varnishes, smells of other animals and food products, noise), especially in the conditions of modern megacities, there are numerous attempts at active counteraction from 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 their efficiency in a wide range of search conditions. One of the most effective methods is working with special absorbent materials by preliminary air sampling.
With all this, the dog remains a living organism with all its functional features, which does not always give a signal about its inoperability (i.e. “there is no green LED indicator, so typical for electronic equipment).
Gas analytical devices for searching explosives by pairs, represented by a fairly large class of drift spectrometers, have significantly lower sensitivity compared to the dog — 10-9 … 10-13 g/cm 3 .
This is their significant disadvantage and … significant advantage.
Such a relatively low sensitivity limits the possibilities of searching for and detecting high explosives and explosives that are characterized by low volatility and the ability to form vapors under normal conditions.
Such explosives include hexogen, octogen PETN, tetryl and explosives based on them.
The operation of drift spectrometers is largely influenced 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 significantly higher than on the operation of dogs.
There are some tactical techniques that allow to 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 are capable of significantly improving the search conditions in a local area in a short time.
At the same time, the relatively low sensitivity of the devices practically excludes 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 eliminates the release of explosive vapors to the outside, then for a container made of polyethylene, paper and a number of other materials, the probability of explosive vapors escaping 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 directly 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 must 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 traces of them for quite a long time, days, months, and if such items are placed 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 explosives detected in one way or another. Gas chromatographs are rarely used for the rapid search for explosives and explosives in non-laboratory conditions.
Recently, fairly 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, the detection of explosives and explosive ordnance under 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 under conditions of a real threat of major terrorist attacks using explosives, as has repeatedly occurred 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, work only with their handlers) due to the limited financial resources and qualifications of law enforcement officers called in to participate 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 explosive devices to go off.
That is, we are talking about the serious danger that will accompany attempts to examine 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 can 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 arms 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 fuse 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 a large quantity, 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 explosive has ceased to contact the surface being examined, in conditions of subzero temperatures and high relative humidity.
There is another interesting aspect of the use of 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 the carrying or transportation of explosives and hazardous materials, especially if these explosives and hazardous materials are not clearly observed with him at the moment.
Traces of explosives on a person's hands and clothes in the event of contact persist 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.) or to hand over his objects (a driver's license, a passport, etc.).
Taking a sample from such items for subsequent examination using chemical express tests is carried out almost instantly.
The examination itself can be carried out either immediately on site or later in another location.
Chemical express tests for detecting explosives have become quite widespread throughout 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 foreign-made explosives 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 the tests. A similar picture will be for a fairly large family of ammonium nitrate explosives with the addition of TNT.
Some difficulties in using the 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 testing, if necessary, using, for example, gas chromatographs.
Attempts to conduct a test at the site of detection by igniting or detonating some of the substance may not yield results 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 propagates stably without attenuation.
With a smaller charge, 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 from a TNT block weighing 400 g 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:
1st group polynitroaromatic compounds (trinitrotoluene or TNT, picric acid, tetryl and a number of others);
2nd group – esters and nitroamines (PETN or PENT, hexogen, octogen and nitroglycerin);
3rd group – ammonium nitrate explosives and/or black powder.
Photo 1. Using a spray to detect explosives
Photo 2. A set of rapid tests
for detecting explosives “Mini ETK plus”
The 4th reagent-identifier of explosives, for example, from the Israeli kit “Mini ETK plus”, designed to detect chlorates, looks somewhat exotic.
The disadvantage of the express tests discussed above is, unfortunately, the insufficiently high reliability of detecting explosives of the 2nd and, especially, 3rd group.
This is due to the difficulty of standardized (strictly dosed) sequential application of explosive identification reagents to a sampler with a collected sample of the substance being studied in non-laboratory conditions and the possibility of the explosive 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 identification reagents of which are a rather aggressive environment under pressure 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 equipped with such a refrigerator (many still sincerely believe that the refrigerator is only needed to provide personnel 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 Lakmus-4 kit (photo 3), containing 3 reagents-identifiers of explosives for the first 3 groups of explosives (without the chlorate group).
Each explosive identification reagent 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 explosive identification reagents on the sample of the substance being tested and the absence of its erosion.
The kit includes 10 to 50 sets of 3 reagents-identifiers of explosives, which is another advantage of the kit.
Rapid tests can be provided to 10 to 50 people, respectively, to ensure the possibility of their simultaneous parallel work, unlike sprays, designed to carry out up to 50 tests under favorable storage and operating conditions, naturally by sequential use and only by one person.
Photo 3. A set of express tests
for detecting explosives “Litmus-4”
In general, I would like to note the fact that the problem of camouflaging explosives and explosive remnants is no less complex than the problem of finding these objects.
The possibility of disguising and covering explosives and explosive ordnance so that they cannot be detected by any means is highly questionable, but as already noted, one should not count on the creation of a single universal automatic search tool in the near future.
Under modern conditions, the success of searching for explosives and explosive ordnance will largely be determined by the availability of a range of special devices and equipment, 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.
2. Petrenko E.S. Means of searching for explosive objects by indirect signs.//Special equipment, 2002, No. 2.
3. Detector of explosives and other substances based on the nuclear quadrupole resonance (NQR) method.//Peace and Security, 2000, No. 4.