The Evolution of Criticality Safety Regulations for the Transport of Radioactive Fissile Material in Certified Packages - 22181

This paper describes the evolution of regulatory controls on the transport of fissile radioactive materials that began in the middle of the last century, particularly with early efforts in the US, the UK, Canada, and France. International efforts in this respect began at the IAEA in 1957. This multi-national effort led to the IAEA issuing its first internationally recognized regulations for the Transport Safety Regulations in 1961, which was then identified as SS-6. Since then, the Transport Safety Regulations have been updated multiple times, with the latest version being issued in 2018 as IAEA Specific Safety Requirements-6 (SSR-6), Regulations for the Safe Transport of Radioactive Material (2018 Edition). Supplementary guidance documents also have been issued by the IAEA over the years. The Transport Safety Regulations have the objective of protecting the workers, the public and the environment by requiring, for routine, normal and accident conditions of transport: (a) containment of the radioactive contents of packages, (b) control of excessive dose rates external to packages, (c) prevention of criticality when the contents of the packages are designated as having fissile material (FM), and (d) the prevention of damage to the packages by heat. This is accomplished first by applying a graded approach and by imposing a robust set of conditions on the design, testing and operation of the packages. As new generations enter the nuclear workforce, there is often a lack of understanding of the source and underlying logic behind the Transport Safety Regulations. To address this issue, Pacific Northwest National Laboratory (PNNL) initiated a knowledge management activity in 2020 to document the history and evolution of the Transport Safety Regulations. The knowledge management effort has two components. One component, which is discussed in this paper, covers the historical evolution of IAEA regulations related to the transport of fissile material (i.e., criticality safety) in certified transportation packages. The second component, which is discussed in a companion paper to be presented at this WM Conference, covers the evolution of the IAEA regulations related to the transport of non-fissile radioactive material in Type B and Type C certified transportation packages. Understanding the evolution of the IAEA's Transport Safety Regulations and their supplementary guidance documents is important because these regulations influence the development of the radioactive material transportation regulations in IAEA Member States, including in the U.S. (authors)