METHODOLOGY TO OPTIMIZE AND INTEGRATE SAFEGUARDS SENSOR CONFIGURATIONS AND MEASUREMENTS IN LARGE NUCLEAR PROCESSING FACILITIES

Maintaining continuity-of-knowledge (COK) is an important monitoring strategy for complementing safeguards measures based on nuclear material accountability (NMA). This task is even more critical in large nuclear processing facilities due to technical difficulties in meeting NMA objectives and in detecting protracted diversions of one significant-quantity (SQ) of Pu, with prescribed probability. The notion of COK can be extended to the concept of nuclear operations accountability (NOA) in which the objective is not only to verify material transfers between two processing steps (i.e., a 1-step COK strategy) but also to detect overall facility misuse by supervising how these transfers have been conducted throughout the process (i.e., a multiple-step COK strategy). Yet, the main barriers for implementing NOA have been the overwhelming instrumentation, operational, and data-analysis burdens that this concept may entail. Current material tracking systems, with limited sensor infrastructures for automatically collecting and analyzing material tracking information, often exhibit inadequate intrusiveness and tamper-resistance properties. The sensor cost associated with NOA has led into the customary strategy of restricting safeguards monitoring at facility portals or at the boundaries of material balance areas. For its practical acceptance, the sensor requirements to implement NOA should be kept minimal. To this end, a rigorous, systematic methodology is presented that can be used to design optimal safeguards sensor configurations and monitoring systems for high throughput nuclear processing facilities. Given the operations or material flows anticipated for a fuel cycle facility, this methodology can be used to: i) assess the operations observability property of a given process-sensors arrangement and determine whether a given sensor configuration can be used for effectively implementing NOA; ii) identify optimal sensor configurations that guarantee observability of operational violations; iii) construct supervisory algorithms that can be incorporated in unattended safeguards monitoring systems to automatically integrate and analyze process tracking data. The theoretical and practical basis of this methodology, which has been implemented in software, are illustrated with examples.