Preparation and evaluation of an ADU-derived ceramic grade UO2 powder.

The method and equipment used to prepare a ceramic grade uranium dioxide powder are described, together with relevant characteristics of the intermediate and final products. The method chosen followed the well established ammonium diuranate route involving continuous precipitation from uranyl nitrate solution using gaseous ammonia. Conversion of the ammonium diuranate to uranium dioxide was effected by heating in a hydrogen/nitrogen atmosphere and following this with a low temperature stabilisation treatment. Various physical tests were carried out on the resultant powder, and finally, specimens were pressed and sintered over a wide range of pressures and temperatures. The tests indicated that the powder was 'sinterable' and that the method of preparation produced a ceramic grade powder exhibiting consistent properties and behaviour