A New Look at Transportation Security: A Complex Risk Mitigation Framework for the Security of International Spent Nuclear Fuel Transportation

Growing interest in nuclear energy programs worldwide and the high cost of managing spent nuclear fuel (SNF) introduces additional complexity into traditional nuclear material transportation operations. New elements of complexity facing securing such transports include, but are not limited to: • an increasing number of SNF cask transfers between transportation modes (e.g., road to rail to water); • an increasing number of geopolitical or maritime borders crossed by SNF casks; and, • the higher potential for inconsistent security requirements, resources and regulations along approved international SNF transportation routes. Combining the expected increase in SNF shipments with the emergence of multimodal transportation routes illustrates increases in risk complexity for SNF transportation. Further, this increase in risk complexity directly challenges traditional approaches to SNF transportation security that build off of decades of transportation safety analyses, which themselves are derived from technical cask design, acceptable dose rates, defense-in depth strategies and probabilistic hazard estimates. Recent work in risk mitigation and SNF transportation studies suggest that applying a complex risk mitigation perspective built on the interdependence of security, safety and safeguards (3S) can improve the security design and analysis of international SNF transportation. More specifically, such a paradigm shift helps identify solutions more aligned with complex realities and potential real world hazards than traditional approaches driven by safety regulations determined from SNF cask degradation laboratory experiments. The evaluation of two novel, system-level analysis techniques against a hypothetical, international SNF transportation case demonstrates such benefits. First, dynamic probabilistic risk assessment (DPRA) builds on traditional probabilistic-based methods to provide a unified framework to account for the joint effects of aleatory and epistemic uncertainties on SNF transportation risk for a more complete set of identified event sequences leading to undesirable consequences. Similarly, system theoretic process analysis (STPA) combines the concepts of hierarchy, emergence, control, and communication to model SNF transportation as a complex socio-technical system where system-level risk is managed by ensuring the control of interactions between technologies, organizational influences and environmental pressures. The paper will discuss how an integrated complex risk mitigation framework offers several benefits to reducing security vulnerabilities—especially in the face of the expected increase in international SNF shipments in the near future. In addition to expanding the solution space for transportation security, this framework also provides opportunities to enhance safeguards on SNF in transit as well as discusses options to increase coordination between security, safeguards and safety—ultimately mitigating and managing the increasingly complex risks from the international transportation of SNF. (author)