Trace detection of explosive materials in air cargo containers

At the request of the National Coordinator for Counterterrorism in the Netherlands a research project called “Security through innovation - risk-oriented detection in a drive-through set-up” has been carried out by TNO Defense, Security and Safety (TNO) and by Dutch Customs. In 2009 and 2010, a group of TNO and Dutch Customs experts performed two experimental sessions involving air cargo containers, several trace detector systems and real explosive compounds at the cargo terminal of Amsterdam Airport Schiphol. Field experiments were designed in order to test the applicability of various commercially, off the shelf, trace detectors and promising newly-developed instruments with 6+ TRL levels for screening of air cargo containers and pallets. In order to select instruments suitable for cargo screening and trace detection of explosives hidden in cargo containers, a detailed market review and assessment of information acquired from diverse available sources has been performed during the initial phase of the project. In the subsequent stages a theoretical evaluation of the potential of these instruments or techniques was performed, followed by laboratory experiments and feasibility trials with selected devices and sampling tools. Preliminary investigation resulted in the final choice of devices/systems matched to the acknowledged threat list. Six different explosives – among them pure explosives as well as composites - characterized by differentiated physical and chemical properties were used during the experiments in two different scenarios. All explosives were packaged and concealed, such that large quantities of explosive were not visually exposed and possibly not readily available for sampling and analysis, with the aim of avoiding easy, visual detection. All experiments were designed and performed by TNO employees with particular attention paid to meticulous and well-structured sampling procedures. Logistic schemes were built to secure the best possible performance for all instruments tested. All trace detectors were applied according to the instructions provided by the many cooperating suppliers, enabling the equipment to achieve the best results for each detector. In particular cases, simple modifications to the sampling methods were carried out and/or additional sampling methods were introduced and tested. Both vapor and particle trace detectors were employed during the experiments. The results were analyzed directly after the sampling step or in more complicated cases the analysis was performed afterwards. The applicability of the particular set up or technique in a current scenario was evaluated. Functioning of the detectors used in a dedicated scenario was assessed in terms of the detection performance, observed false alarm rate and usage convenience. Also logistic issues and commercial aspects were taken into account. Research performed during the experimental sessions resulted in a vast amount of observations and findings and recommendations.