The Transient Behavior of Vipac and Pellet Thermal Reactor Oxide Fuels

The results of comparative transient tests performed in the Transient Reactor Test Facility (TREAT) indicate that the cladding failure threshold energy for nonirradiated vibrationally compacted and pellet-containing oxide fuel capsules is about 270 cal/g UO₂. At this energy input, general cladding melting and rapid deterioration due to reaction with water vapor occur for both fuel types. In vipac fuel capsules the cladding was penetrated by the ejection of molten UO₂ whereas in pellet-containing capsules the cladding rapidly deteriorated without the presence of molten fuel. When tested at near cladding failure threshold energies, the extent of metal-water reaction is comparable for the two fuel types.