Uranium aluminide powder production, fuel plate fabrication development, and irradiation performance of more than 1700 fuel elements during 10 yr of operational service at Idaho National Engineering Laboratory are discussed. The UAlx dispersion fuel system has performed well in extended service in the high flux test reactors. The anticipated benefits of the powder dispersion form—accommodation of fission products in deliberate voidage, structural tolerance of fission gas, and dispersion of burnable poisons—have been realized. The operating limit for the Advanced Test Reactor fuel elements is presently set at 2.3 × 1021 fiss/cm3 of core—a burnup of >500 000 MWd/MTU. The growth or swelling of uranium aluminide fuel plates at up to 2.4 × 1021 fiss/cm3 is proportional to the fission density, but the proportionality constant depends on the temperature, core porosity, and fuel loading with 93% enriched uranium. For a fuel loading of 4.3 × 1021 U atoms /cm3, the growth corresponds to 0.11% per % burnup. The blister test as a criterion for impending fuel plate failure due to swelling appears adequate, and the blister temperature at fission densities of 2.7 × 1021 fiss/cm3 of core is ∼720 K.