Thermal Compatibility Studies of Unirradiated Uranium Silicide Dispersed in Aluminum

Powder metallurgy dispersions of uranium silicides in an aluminum matrix have been developed by the international Reduced Enrichment for Research and Test Reactors program as a new generation of proliferation-resistant fuels. A major issue of concern is the compatibility of the fuel with the matrix material and the dimensional stability of this fuel type. A total of 45 miniplate-type fuel plates were annealed at 400°C for up to 1981 h. A data base for the thermal compatibility of unirradiated uranium silicide dispersed in aluminum was established. No tested modification of a standard fuel plate showed any significant reduction in plate swelling. The cause of the thermal growth of silicide fuel plates was determined to be a two-step process: (a) the reaction of the uranium silicide with aluminum to form U(AlSi)₃ and (b) the release of hydrogen and subsequent creep and pillowing of the fuel plate.