Satisfactory dense crack—free dispersions of spheroidal UO2 — ThO2 particles in BeO can be produced by "co-sintering", a process in which unsintered particles are hydrostatically pressed in BeO and the dispersion is sintered in one step, the large voids and cracks in dispersions of fully sintered particles in BeO following sintering are related to mismatched sintering shrinkage between the two phases; they are probably indicative of a high interfacial energy between the two phases. Co—sintering has been used for individual fabrication of specimens for irradiation testing, but is not immediately applicable to large scale fabrication of fuel element shapes, Possible modifications of the method are discussed.