A Methodology for Evaluation of Containment and Surveillance Safeguards System Performance

A method is presented for evaluating the performance of containment and surveillance safeguards systems in detecting diversion of nuclear material from fuel cycle facilities. System performance is described by a probability of detection calculated as a function of diversion amount and the time over which it takes place. System performance is dependent on the performance of detection instrumentation and the strategy used in the diversion attempt. Instrument performance for each surveillance application is assumed available as input. The identification of diversion strategies is part of the evaluation method. The strategies of greatest interest for purposes of evaluation are those which, for any particular diversion amount and time, maximize the probability that the diversion will go undetected. These strategies are used as the basis for safeguards system evaluation because they provide worst-case bounds for system performance. Protracted diversion strategies involving uniform diversion of material are shown to be optimal for instrument performance of a particular mathematical form. System false alarm rate and instrument reliability are given explicit attention.