This book highlights the advances and trends in the safety analysis of sodium-cooled fast reactors, especially from the perspective of particle bed-related phenomena during core disruptive accidents. A sodium-cooled fast reactor (SFR) is an optimized candidate of the next-generation nuclear reactor systems. Its safety is a critical issue during its R&D process. The book elaborates on research progresses in particle bed-related phenomena in terms of the molten-pool mobility, the molten-pool sloshing motion, the debris bed formation behavior, and the debris bed self-leveling behavior. The book serves as a good reference for researchers, professionals, and postgraduate students interested in sodium-cooled fast reactors. Knowledge provided is also useful for those who are engaging in severe accident analysis for lead-cooled fast reactors and light water reactors.