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Liquid Explosive Detection

Since heightened security measures now require a near exclusive ban on any liquid in passenger luggage, airports face the sudden challenge of detecting this ubiquitous substance. With liquid being such a versatile substance, the ease to which prohibited substances, in this state, can be manipulated and concealed presents a disturbing risk.

There is further concern over airports’ ability to accommodate new security measures and procedures for passenger screening. The physical detection test of swiping a tape of cloth over the luggage, to pick up some residue from an explosive, is rendered useless, with this new threat. Arguably, this method has become an obsolete, futile and time consuming measure. Yet this is an established method, security staff are trained in. Whilst fears of terrorist groups developing nuclear or radioactive weapons are expressed and widely discussed, has the detection of the conventional explosive been disregarded? And what of staff training, using current technology, to identify this threat in it’s new format?

To address training requirements for liquid detection, Simfox customers can employ a widely used feature of Renful’s software. Simfox functions as a passenger screening X-Ray Simlator, but also provides many customizable features for the X-ray trainer. Renful is confident that Simfox’s ‘Item Categorization’ will prove invaluable to trainers, with the increasing demand on adequate training.

The Simfox Training program is used in locations across the world. Each institution has individual requirements for particular threat detection. For example: Mobile telephones can not be taken in to a prison but passengers can board a plane with one, dairy products like cheese are restricted items when traveling from Bulgaria to the UK but not from Finland. To accommodate these requirements, Renful included the ‘Item Categorization’ feature to Simfox. This allowed our customers to select which items students were required to prevent from passing through security. The Simfox database holds over 1000 x-ray items. Many are clearly threat items such as knives, guns, grenades, detonators, semtex e.t.c.

The Simfox database holds many hundreds of items that an organization may choose to class as restricted or not. The ‘Miscellaneous Item’ database includes containers holding liquids of all shapes, sizes and consistencies ranging from water to viscous substances like toothpaste, hand cream and shampoo.

In this example, the trainer has selected a 500 ml coke bottle, and re – classed it as a restricted item. They have then created a bag, with the coke bottle inside, and entered it in to their personal ‘Bag Database’ as a training bag that the student must choose to ‘hold’. When the student runs this bag as part of their X-ray training, they must select ‘hold» and identify the restricted item, in order to gain full marks. They can then review the bags and its contents after receiving their results.

This example had been chosen as the plotters of the August transatlantic flights were alleged to have planned to use a slurry explosive, concealed in a modified sports bottle. They planned to leave the top sealed and containing its original beverage. The modification was the addition of a false bottom, containing the gel explosive which was dyed red to blend in. For the detonator, there was a disposable camera flash.

" We know it can’t be detected by any security machines in use right now, and so it scared the hell out of everyone."

With respect to the array of improvised explosive devices (IEDs) currently being developed, training for the recognition and identification of their components under X-ray, is essential. The range of materials, which can be used for these components, is vast.

One of the most powerful explosives known, Nitroglycerine, can be a viscous liquid below 56°F, and its detonation generates gases that would occupy more than 1,200 times the original volume at room temperature. The clear liquid, Astrolite G, has a detonation velocity almost twice as powerful as TNT. Nitroglycerine has been in use since the 1930’s, by bank robbers distilling it from dynamite. Its propensity to explode with out warning, has now been widely tested, realized and controlled. The sensitivity of this liquid is now reduced by the addition of the explosive liquid nitromethane and compound trinitrotoluene.

Trinitrotoluene (TNT) is a solid explosive that is insensitive to friction, blows, and jarring and does not react with metals. It is also soluble in nitromethane which, on its own, is a powerful explosive. It is commercially available as a component of a binary or "two-part" product classified merely as a ‘Flammable liquid’ and is also used as a racing fuel. Its "Oxidizer" is also not classed as an explosive. Only when both elements are combined, is it classed as an explosive. Detonation can be achieved using a safety fuse with a non-electric detonator; by an electric detonator; or a Nonel detonator and shock tube initiator.

Due to concerns over Terrorists’ access to commercial explosives, regulations over their transportation have been reassessed and changed. It now works out more expensive to transport small amounts of Kinepak (commercial product using nitromethane) than bulk quantities, clearly intended for commercial uses. However, since Nitroglycerine was developed it has been in use for decades creating much documented experience of production and potential application.

Vincent Cannistraro, former executive director of the CIA’s counterterrorism center, views on nitroglycerin (plus the other materials used in the explosive concoction): ‘We know it can’t be detected by any security machines in use right now, and so it scared the hell out of everyone.’ www.globalsecurity.org

There are multiple components now available to terrorist groups or resourceful individuals. Much information regarding the chemical make up and production of highly explosive liquids is widely available on the internet. During house raids on the August UK bombing suspects, the chemical hydrogen peroxide was found. This is a cheap and highly available chemical and, if combined in a reaction with nail polish remover, creates the unstable crystalline powder triacetone triperoxide. This explosive is highly susceptible to heat, friction, shock and has been called the "Mother of Satan". Some experts believe, in the August transatlantic bombing attempt, the liquid equivalent of triacetone triperoxide would not have made an effective bomb. But it is not hard to imagine the existence of many groups, with easy access to our airports, working with these deadly liquids, intent on using them to cause maximum death, destruction and publicity. The longer they have to experiment, document and learn, the greater the chances of their success will be.