Activities in a project aimed at the improvement of fuel elements for high flux test reactors are reported. The investigation of new fuel compositions, distributions, and geometries is being undertaken to increase fuel life, to improve the flux distribution, and to provide a means of safely reaching higher reactor operating power and power density in these reactors. The effects of nuclear irradiation on the fuel and structural materials is being studied to predict the performance of these materials in more advanced reactor designs. A summary of the past year's progress is given and the fabrication and irradiation of samples containing up to 50 wt % U--Al alloys, cermets of UO/sub 2/, U/sub 3/O/ sub 8/, UC, UN, U/sub 3/Si, and Al, clad in various Al an d Be--Al materials is described. The use of ThO/sub 2/ and Th cores, the addition of BeO to cermet cores and high density fuei cores of U--Al intermetailics produced by powder metallurgy techniques were studied during the year. High strength APM claddings involving Al/sub 2/O/sub 3/ contents from 8 to 10% were tested and indicate the need for improved quality control of the APM material. Duplex claddings involving burnable poison layers and APM clad …