Systems Theoretic Process Analysis Tools for Nuclear Materials Safeguards Evaluation

Recent advancements in hazard analysis techniques and capabilities have proven insightful in a variety of industries and applications. One of these techniques is Systems Theoretic Process Analysis (STPA). This technique has been applied to evaluate complex systems in the aerospace, automotive, and nuclear power sectors. Recently, it has been applied to evaluate interfaces between safety, security and safeguards in the context of nuclear material transportation. From an evaluation of the literature, STPA has not been applied to evaluate the fundamental activities involved in nuclear material accountability and safeguards implementation for nuclear material process facilities. This work presents a first of a kind, STPA evaluation of the causes of nuclear material accountability and safeguards anomalies that might be encountered while operating a mixed oxide (MOX) reprocessing facility. The STPA evaluates potential upset conditions that could lead to false positive or false negative indications of diversion in a safeguards approach. A computational systems model of a hypothetical but representative MOX reprocessing facility was developed and used to facilitate quantitative evaluation of various process upsets identified through the STPA. Based on the results of the work, STPA shows promise as a technique for evaluating vulnerabilities in a safeguards approach or for identifying the causes of safeguards anomalies. Specifically, STPA could be used to resolve safeguards anomalies through a better understanding of signature patterns associated with specific process upsets.