Fusion energy sources have garnered private and public interest around the world in attempts to reach net-zero carbon emissions. Current fusion energy system designs involve solid or liquid blanket systems that serve the purposes of tritium (fuel) management, neutron multiplication, and heat removal for power conversion. The use of fluoride molten salts in fusion breeder blankets is an option worthy of investigation because molten salts such as FLiBe can serve all three major roles.

Although there have been past studies on FLiBe- and FLiNaBe-based breeder blankets, known as liquid immersion breeder blankets, there are no published designs or analyses of entire notional breeder blanket systems using molten salts. The existing public information on molten salt breeder blankets has mostly focused on the blanket vessel, with minimal information on the systems.

To address this issue, a preliminary design for a prototypical molten salt breeder blanket system was investigated using the U.S. Department of Energy’s Nuclear Energy Advanced Modeling and Simulation–developed SAM (System Analysis Module) code for heat exhaust/transport systems. Existing SAM capabilities involving thermal-hydraulic modeling were used to perform critical system design activities.

In this work, we present the performance of the heat removal system and identify potential gaps in research to further the liquid immersion breeder blanket system design. To address different major design aspects for liquid immersion systems, three transient cases are studied: minimum power transient, startup transient, and shutdown transient. For the three transient cases, two different materials, V-4Cr-4Ti and Inconel-718, are investigated to determine the impact on the temperature profile and operating limits of the loop. The data produced by this study will provide a foundation for future designs of molten salt-based fusion energy concepts, allowing for the deployment of a future fusion pilot plant.