Patent Number: 046719040
Section: claims

1. Method for producing sintered oxidic nuclear fuel bodies by mixing a base powder of UO.sub.2 or a mixture of UO.sub.2 and PuO.sub.2 and powder containing rare-earth oxide designated SE.sub.2 O.sub.3 -containing powder, subsequent compacting of the powder mixture to form compacts and densifing these compacts by sintering in a gas atmosphere with reducing action at a temperature in the range from 1500.degree. to 1750.degree. C., the combination therewith of mixing with the base powder, a rare-earth-oxide-containing powder with powder particles which exhibit, at least in one surface layer, a crystal lattice of the fluorite type with the stoichiometric composition (SE.sub.0.5, U.sub.0.5) O.sub.2.00, wherein the rare-earth-oxide-containing powder exhibiting a crystal lattice of the fluorite type with the stoichiometric composition (SE.sub.0.5, U.sub.0.5) O.sub.2.00 is generated by coating a starting powder containing a rare earth oxide with an UO.sub.2 coating on the starting powder particles and annealing the UO.sub.2 - coated powder. 2. Method for producing sintered oxidic nuclear fuel bodies by mixing a base powder of UO.sub.2 or a mixture of UO.sub.2 and PuO.sub.2 and powder containing rare-earth oxide designated SE.sub.2 O.sub.3 -containing powder, subsequent compacting of the powder mixture to form compacts and densifying these compacts by sintering in a gas atmosphere with reducing action at a temperature in the range from 1500.degree. to 1750.degree. C., the combination therewith of mixing wiht the base powder, a rare-earth-oxide-containing powder with powder particles which exhibit, at least in one surface layer, a crystal lattice of the fluorite type with the stoichiometric composition (SE.sub.0.5, U.sub.0.5) O.sub.2.00, wherein the rare-earth-oxide-containing powder for mixing with said base powder is produced from a mixture of rare earth oxide-containing starting powder and UO.sub.2 powder in approximately equimolar proportions by milling and the crystal lattice of the fluorite type with the stoichiometric composition (SE.sub.0.5 . U.sub.0.5) O.sub.2.00 is formed during said sintering. 3. Method for producing sintered oxidic nuclear fuel bodies by mixing a base powder UO.sub.2 or a mixture of UO.sub.2 and PuO.sub.2 and powder containing rare-earth oxide designated SE.sub.2 O.sub.3 -containing powder, subsequent compacting of the powder mixture to form compacts and densifying these compacts by sintering in a gas atmosphere with reducing action at a temperature in the range from 1500.degree. to 1750.degree. C., the combination therewith of mixing with the base powder, a rare-earth-oxide-containing powder with powder particles which exhibit, at least in one surface layer, a crystal lattice of the fluorite type wiht the stoichiometric composition (SE.sub.0.5, U.sub.0.5) O.sub.2.00, wherein the rare-earth-oxide-containing powder is generated by common precipitation from a solution, in which uranium and the rare earth are dissolved in approximately equimolar proportions and the precipitate calcined to produce the rare-earth-oxide-containing powder exhibiting a crystal lattice of the fluorite type with the stoichiometric composition (SE.sub.0.5, U.sub.0.5) O.sub.2.00. 4. Method according to claim 1, wherein the powder containing rare-earth oxide is Gd.sub.2 O.sub.3 -containing powder. 5. Method according to claim 2, wherein the powder containing rare-earth oxide is Gd.sub.2 O.sub.3 -containing powder. 6. Method according to claim 3, wherein the powder containing rare-earth oxide is Gd.sub.2 O.sub.3 -containing powder.