Exploring diversion-pathway analysis of a generic molten-salt fast reactor using multiphysics informed signatures

Multiple commercial ventures are exploring molten-salt reactors due to their inherent safety features, flexibility in fuel sources, high fuel utilization, and thermal efficiency. The continual flow of fuel salt, large quantities of fissile material, and the ability to add or divert material due to the liquid nature of fuel salts introduces new challenges for international safeguards. To understand how international safeguards could most efficiently and effectively be applied, it is important to capture the inherent multiphysics nature of a molten-salt reactor. This work examines a generic molten-salt fast reactor to understand how potential diversion scenarios would affect the concentration of radionuclides in the primary and auxiliary systems. Three types of diversion were examined: protracted uranium diversion of fuel salt, gaseous plutonium extraction, and uranium-metal plating. Five isotopes (with corresponding gamma signatures) were found to be statistically different between the various diversion cases and nominal operations. These isotopes are present during the diversion scenarios and continue to be present during operations afterwards indicating that diversion could be detected throughout operations.