Production and investigation of thorium-containing fuel compositions

A technology has been developed for obtaining fuel tablets with the composi tions (U, Th)O-2, (U, Th, Ca)O-2, and (U, Th)O-2 + MgO by combined precipit ation of uranium, thorium, magnesium, or calcium components from inert solu tions, followed by heat treatment of the powders, compression into pellets, and sintering of the pellets. Work on optimizing the technological process es for obtaining fuel pellets so as to obtain good pellet quality was perfo rmed. The effect of the properties of the precipitates and powders fabricat ed using different technological regimes on the properties of the finished objects was studied. The work includes detailed investigations of powders ( x-ray phase analysis, electron-microscopic investigation) and sintered fuel tablets (change in the geometric dimensions as a result of sintering, dete rmination of the density, and study of the microstructure). The behavior of fuel compositions (U, Th)O-2 and (U, Th)O-2 + MgO in contac t with coolants under conditions where the fuel elements become unsealed wa s studied: with water at 300 degreesC and sodium at 700 degreesC. 3 figures , 3 tables, 6 references.