20 Years of Nuclear Forensics at ITU – Highlights and Recent Advances

Nuclear Material is kept under a stringent system of national control and international verification. This includes physical protection and safeguards measures. Still, in early 1992 the first case of \"nuclear smuggling\" was detected with the seizure of a number of uranium fuel pellets. Those pellets were taken to the Institute for Transuranium Elements (ITU) for closer examination. Since then, more such incidents have been reported and the phenomenon has been understood in a broader sense and referred to as \"illicit trafficking\". The methodology applied for the examination of the nuclear material (and any associated material) and the respective interpretation of data is referred to as \"nuclear forensic science\". During the two decades of \"Illicit trafficking\" the phenomenon had changed and also the analytical and interpretational methods have evolved. In more than two decades of involvement in nuclear forensic investigations at ITU, the analytical techniques were developed further, adapted to the specific needs and perfected with regard to timeliness and reliability of results. Collaboration with authorities involved in the response process was strengthened and their specific needs have been included in the nuclear forensics methodologies. A systematic approach was developed for investigating samples of seized material, and a comprehensive, though efficient, process for conducting the various analyses was implemented. Taking into account that nuclear forensic samples are always unique in terms of the circumstances of the incidents, of the nature of the material and of the objectives of the investigation, the scientific investigations on the actual nuclear material are carried out under the same boundary conditions. On the other hand, we have to include in our considerations also the fact that illicit nuclear trafficking is a border crossing problem. In consequence, also the nuclear forensic investigations need to take this aspect into account. As can be seen, nuclear forensics is not only a multi-disciplinary branch of science; it involves further dimensions such as law enforcement, international safeguards, radiation protection etc. The paper will present selected examples of casework conducted during the past 20 years and illuminate recent methodological developments.