Process for preparing a powder comprising a solid solution of uranium dioxide and of a dioxide of at least one other actinide and/or lanthanide element

A method for preparing a powder of a solid solution of dioxide of uranium and of at least one other actinide and/or lanthanide element comprising:

• combusting a solution comprising uranyl nitrate and at least one nitrate of the other actinide and/or lanthanide element and a nitrogen-containing fuel, which is glycine, said nitrogen-containing fuel being used according to a predetermined amount in order to form, at the end of combusting, said solid solution, this predetermined amount being an over-stoichiometric amount of nitrogen-containing fuel relative to the uranyl nitrate obtained by:
• a) determining the combustion equation of uranyl nitrate, to which a factor φU is assigned to the stoichiometric coefficient of the nitrogen-containing fuel;
• b) determining an over-stoichiometric amount of the nitrogen-containing fuel, QU, by multiplying the known amount of uranyl nitrate by the stoichiometric coefficient of the nitrogen-containing fuel and by the factor φU, the latter being set to a value greater than 1;
• c) determining the combustion equation of the nitrate of other actinide and/or lanthanide element, to which a factor φAn/Ln is assigned to the stoichiometric coefficient of the nitrogen-containing fuel;
• d) determining an amount of the nitrogen-containing fuel, QAn/Ln, by multiplying the known amount of the nitrate of the other element by the stoichiometric coefficient of the nitrogen-containing fuel and by the factor φAn/Ln, the latter being set to a value below 2;
• e) obtaining the aforementioned predetermined amount by adding at least the amounts of nitrogen-containing fuel determined in b) and d), respectively, QU and QAn/Ln.