This invention relates to a process for manufacturing a dense material containing UO2, comprising: a) introducing at least two powders each comprising uranium dioxide UO2 into a vibrating grinder, wherein at least two powders are provided by two different synthesis routes and each powder has a specific surface area close to that of any other uranium-dioxide containing powder introduced into said grinder; b) shaking said powders by means of said vibrating grinder so as to form a particulate material, the grinding intensity being sufficient to break up the agglomerates and the aggregates in the powders without at the same time breaking up the crystallites in the powders, and the grinding energy provided to the powders being such that substantially all of the agglomerates and aggregates are destroyed; c) introducing said particulate material into a mould; d) applying a shaping stress to said particulate material in order to obtain a compacted material; e) carrying out the sintering of said compacted material so as to obtain the dense material.