A typical fuel pin in a fast reactor could be a ceramic fuel bonded within a metal cladding. Several varieties are possible, the main ones being helium- bonded U02 (enriched with Pu02) in stainless-steel cladding; and sodium — bonded UC pellet in stainless-steel cladding. The oxide and carbide can be fabricated in different ways (pelleted or vibro-compacted) and the cladding can be fabricated in different ways (solution-treated or cold-worked). Many other varieties are possible even in different configurations ranging from cermet fuels or silicon carbide-coated fuel particles (la). Each of these fuel elements has a different mode of failure depending on the circumstances and so different failure limits are required for each fuel element for each disturbance.