Hand-held devices for the detection of clandestine nuclear material on-site

The possible threat of nuclear material out of legal control has become an increasingly important issue for the international community in the last years. Improvised Nuclear Devices (IND) and Dirty Bombs may have far reaching consequences, e.g., contaminating vast areas and even killing people, when successfully detonated by terrorists or terrorist groups. Whereas the declared nuclear material in the nuclear fuel cycle is under good control by international safeguards it is difficult to cope with undeclared or stolen nuclear material. The best detectors and sophisticated methods have to be used to reveal undeclared as well as clandestine nuclear material or activities. Important means for detecting such material are portal monitors and other fixed installations at state boarders and gateways of nuclear and industrial facilities. In addition mobile measuring systems are of great importance. These fixed installations and mobile measuring systems have to be supplemented by reliable and easy to use hand-held devices for the detection of gamma and neutron radiation emitted by the material. Hand-held devices may not only be used in combination with fixed installations and mobile systems but may also support police men or fire fighters to detect illicit radioactive and nuclear material. We tested a variety of advanced hand-held devices with respect to reliability, ease of use, quality of the user interface, false alarm rate and the generation of wrong results. Another important issue is the necessary skill and operating experience of the operational staff in their work. As many users will not be specialist in the area of measurement of radiation the utilization of hand-held devices must be simple and to a great extend fool proof. In this respect we investigated gamma dosimeters and pagers as well as spectroscopic devices, gamma detection systems equipped additionally with a small neutron detector and dedicated neutron devices also. Hand-held devices are an inevitable means for detecting undeclared nuclear material and activities onsite. It is not sufficient to have measuring devices at hand with the best and most advanced technology but it is at least of the same importance to apply them correctly and in best manner.