Progress in fuels and materials development is reported. Irradiation tests on powdered UAl/sub 3/ intermetallic compounds demonstrated good stability and fission gas retention capabilities. Developmental aluminum powder metal products showed good corrosion resistance at high temperatures while retaining excellent high temperature strength. All of the fuel compositions tested (UO/sub 2/, U/sub 3/O/sub 8/, and UAl/sub 3/ in aluminum matrices) exhibited density decreases under irradiation. Tensile tests on sandwich-type fuel plates at elevated temperatures indicated that the fuel plate strength is strongly influenced by the core material rather than dependent primarily on the cladding material as was found true of lower (MTR) temperatures. Three capsules containing beryllium were inserted in the ETR, in order to determine strength, gas release, and growth during a high-temperature (600--800 deg C) irradiation. An MTR fuel element employing advanced metallurgical techniques to optimize the hydraulic and heat transfer characteristics was fuily irradiated in the MTR. The fuel element consisted of 32 plates containing 250 g U/sup 235/ in a U/sub 3/O/ sub 8/--Al dispersion. A prototype ETR fuel element was made without side plates. (M.C.G.)