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.