The implications of in-channel fuel plugging subsequent to a transient overpower accident in a liquid-metal fast breeder reactor have been investigated. The potential for cooling plugged coolant channels was examined by assuming the formation of a porous blockage in several adjacent subassemblies (from flat-to-flat) at axial locations near the upper plane of the active core. The results of a thermal-hydraulic analysis indicate that for this plugging pattern melting of the blockages with possible melting of the plugged subassemblies will occur. Molten blockages may reenter the active part of the core. Neutron transport calculations indicate that hydro-dynamic disassembly of the core as a direct result of gravity-driven reentry of molten blockages into the active core is unlikely. However, substantial melting and relocation of fuel in the plugged subassemblies could result in a power surge, causing pin failures in previously undamaged subassemblies, and raising again the possibility of hydrodynamic disassembly or whole core propagation. The possibility of fuel melting is directly dependent on the nature and amount of plugging. Further research is needed in this area, as the conditions for plugging are uncertain at the present time.