A nuclear fuel sintered body is produced from a powder which contains at least one fissile heavy metal oxide. During the further treatment of the powder over the course of the process preceding the sintering operation, a dopant that contains at least 100 ppm of an iron oxide compound is added to the powder. The powder is a UO2-containing powder obtained from a dry-chemical conversion process, and if appropriate, a powder which contains further fissile heavy metal oxide (U3O8, PuO2, inter alia). As a result, the sintered body is provided with high plasticity combined, at the same time, with a large grain size. This advantageously reduces an interaction between the nuclear fuel sintered body and a fuel rod cladding tube during an operation of the reactor.