Car-borne tracking of fissile material by covert search procedures

The recovery of fissile or radiological material illegally removed from its site of operation or storage is tremendously important in the context of the possible threat of nuclear terrorism. The material must be retrieved prior to its potential use in Radiological Dispersal Devices (RDD) or Improvised Nuclear Devices (IND). The process of tracking the material during transport or storage by means of a covert search is preferable to an open search as it does not draw the attention of civilians, thus preventing counter-productive reactions of panic by the general public or even early release by the terrorists. The Fraunhofer-INT has engineered a measurement system with an additional battery powered energy supply which can be integrated in a standard station wagon, featuring built-in gamma and neutron detection techniques as well as portable detection devices. It is therefore well-suited for covert search routines with respect to nuclear or radiological material which is transported across or stored in residential or industrial areas. Realistic case scenarios were investigated where nuclear or radioactive material was concealed on a test area, partly even inside buildings. At first, the rough location of the material was determined by means of the car's built-in detection system from inside the vehicle. Then the search for the exact location was continued on foot, using a portable detector which provides the opportunity to locate and subsequently identify the material in question. This way a thorough search of an area where such material is suspected was conducted. The search strategies as well as the results of these search procedures are presented.