Irradiation tests have been conducted in the ORR, ETR, and LITR for evaluating fuel materials for the EGCR. Time limitations imposed by the reactor construction schedule restricted material choices and test conditions to those immediately appropriate for the EGCR and necessitated some replication. Fifty-nine assemblies were irradiated at stainless steel cladding surface temperatures of 1300 to 1600°F and power densities both above and below 30,000 Btu/hr per foot of UO2 fuel length. NaK-filled containers were employed to test prototype-size fuel capsules, and air-cooled capsules of reduced size were used for fission-gas-release studies. External pressurization of 315 psia was applied to fuel assemblies of prototype size. Preliminary results appear to affirm the adequacy of the fuel element design.