Detection and monitoring systems for the prevention of illicit trafficking of radioactive and nuclear materials at sea ports in EU Member States

Illicit trafficking of radioactive and nuclear materials at sea ports may be considered as a serious problem. For this reason, a feasibility study has been carried out in order to investigate the detection possibilities of nuclear materials hidden in cargo which is handled at sea ports. Special attention is given to cargo packed in and transported with freight containers. Detection methods depend upon the measurement of gammas and neutrons, emitted by the nuclear material which is hidden. Detection limits of existing monitoring systems are unknown for geometrical configurations comparable to those specific at sea ports. For this reason calculations were carried out by means of the MCNP-4A Monte Carlo code in order to estimate these detection limits. These calculations are related to passive and active neutron assay, localised gamma sources and contaminated iron scrap. Results of this study are that radioactive materials can be detected without major problems. Passive neutron assay allows the detection of nuclear material in relative small quantities of plutonium in the absence of any deliberate neutron shielding, whereas in the case of dense neutron shielding, detection limits of several kilos of plutonium are obtained. A promising method appears to be a gamma- and neutron monitoring system in combination with an existing X-ray scan installation for cargo verification of container content. The detection probability is further increased when extra intelligence is applied about the origin and route of the cargo. (author)