Final Results from a System-Theoretic Framework for Mitigating Complex Risks in International Transport of Spent Nuclear Fuel

In response to the expansion of nuclear fuel cycle (NFC) activities—and the associated suite of risks—around the world, a recently completed Laboratory Directed Research and Development (LDRD) project at Sandia National Laboratories (SNL) evaluated systems-based solutions for managing such risk complexity in multimodal and multi-jurisdictional international spent nuclear fuel (SNF) transportation. By better understanding systemic risks in SNF transportation, developing SNF transportation risk assessment frameworks, and evaluating these systems-based risk assessment frameworks, this research illustrated interdependency between safety, security, and safeguards risks is inherent in NFC activities and can go unidentified when each “S” is independently evaluated.This research used two novel analysis techniques—dynamic probabilistic risk assessment (DPRA) and system-theoretic process analysis (STPA)—to evaluate the gaps, interdependencies, conflicts and leverage points of an integrated “3S” analysis for international SNF transportation. These novel analysis techniques provided the basis for a robust, technically rigorous evaluation of the potential benefit of integrated 3S approaches over traditional methods that rely on analyzing each ‘S’ in isolation to mitigate complex risk. More specifically, this LDRD project explored the followingresearch goal:Understand systemic threats and risks related to SNF transportation;Develop an SNF transportation risk assessment framework; and,Evaluate the effectiveness of SNF system model and risk assessment frameworks.This paper summarizes the final project results for both the DPRA and STPA analyses, including explanations of how each analysis technique was used to develop an integrated 3S technique and the process by which the isolated and integrated analyses were conducted. Then, the rubric for comparing isolated and integrated analysis approaches is explained. The final research results met the research goals and concluded that (1) new system state-based concept is a helpful start for managing risk complexity; (2) DPRA and STPA offer system-theoretic frameworks better able to mitigate the growing risk complexity; and (3) integrated 3S approaches do offer enhancements to mitigating the complex risk associated with international SNF transportation. These results suggest a need—and provide a way—to reprioritize efforts to reduce complex risk and develop technical advances to reduce global nuclear dangers across the NFC.