Invoking Network & System Theory to Improve Security Risk Management in International Transport of Spent Nuclear Fuel

As international spent nuclear fuel (SNF) shipments become more frequent, inconsistent policies and resources along approved transportation routes will make managing transportation security increasingly complex. Motivated by an ongoing Sandia National Laboratories project evaluating the utility of system-theoretic analysis techniques on an integrated security, safety and safeguards (3S) assessment of international SNF transportation, this paper introduces a new approach for improving security risk management of international SNF transportation by offering a prioritization method for use with theoretic process analysis (STPA). System theoretic process analysis (STPA)—provides a framework for developing improved strategies capable of accounting for the increased complexity facing international SNF transportation risk management. STPA incorporates system and control theory to evaluate complex systems in terms of how system components interact to drive emergent, system-level behaviors. Developed to evaluate safety in complex systems, STPA is used across a wide range of industries— including the aerospace, nuclear power, and medical disciplines. This successful use initiated recent efforts to apply STPA to security, including for cyber, nuclear facility and port applications. STPA, based on a causality model represented as a hierarchical control structure (HCS), evaluates security in terms of maintaining control over desired actions of components within the system. This analysis process identifies undesired security control actions that could drive the system into a state of higher vulnerability. STPA offers the practical advantage of not requiring probability distributions for potential system failures in order to identify useful controls. However, STPA results do not currently have any prioritization scheme to focus on key areas for risk mitigation. The structure of an HCS is similar to a network in that it models pairwise relationships between different components of the system— suggesting that network theory might provide a mechanism for developing a prioritization scheme. Key tenets of network theory, such as connectedness, centrality and distance, merge well with STPA’s theoretical framework and could be used as metrics in the prioritization of its results. This paper offers a proof-of-concept argument for using network analysis to prioritize hazard controls generated with STPA toward the goal of prioritizing risk management decisions related to international SNF transportation.