Two methods for extrusion cladding were investigated and evaluated. In the coaxial method, the component parts of the extrusion assembly are concentric, and the fuel plate moves in the same direction as the hydraulicpress ram. In the right-angle method, the fuel-plate metion is perpendicular to that of the ram. Ribbed sheaths of aluminum were extruded satisfactorily on 3-in.-wide uranium plates in lengths up to about 10 ft. Lowest extrusion pressures were achieved with the most streamlined designs of mandrel tips, using flatfacod shear dies. Good results were obtained with billet and die temperatures of about 1050 deg F, at extrusion speeds up to 60 ipm. Extrusion pressures were 25,000 to 60,000 psi. End-cladding procedures were developed which involvod attaching end plates machined from aluminum powder-metallurgy products (12 to l8 wt. % Al/sub 2/O/sub 3/) to the core by means of T-shapod joints, and cladding the entire assembly with aluminum. Excellent bonds were achieved, on uranium as well as on the end plugs. The median values obtained by stud weld tests were 26,000 psi for uranium, and 12,000 psi for the end plugs. The importance of proper tool alignment and avoidance of imbalance of forces caused by pressure differentials within the extrusion container was demonstrated. (auth)