Compressed bodies of mixed oxide of uranium and plutonium

Compressed bodies of a mixed oxide of uranium and plutonium (U, Pu)O2 are made from crushed sintered bodies of the mixed oxide (U, Pu)O2 having a particle size of less than or equal to 3 mm, by grinding, esp. in a ball mill, to give a fine powder having a mean particle size d50.3 less than or equal to 3 microns, and granulating the fine powder prod., compressing into pellets and sintering these into compressed bodies of the mixed oxide. The initial crushed material is pref. chosen from (i) sintered mixed oxide contg. a total of at most 40 wt.% unsintered UO2 and unsintered PuO2; (ii) sintered mixed oxide contg. a total of at most 15 wt.% unsintered UO2 and unsintered PuO2; and (iii) sintered mixed oxide contg. no unsintered UO2 or unsintered PuO2. 0.1-1.5 wt.% of a milling aid chosen e.g. from stearates, poly-alcohols and amines may be incorporated during milling of the starting material. Pref. milling assistants are Zn stearate, Al stearate and propanediol. A blowing agent such as the diamide of oxalic acid or the diamide of azodicarboxylic acid may be added to the fine powder obtd. by milling. A compression assistant such as Zn stearate and/or Al stearate may be added to the powder or to the granulated material prior to compression. On fabrique des comprimés d'oxyde mixte fritté de (U, Pu)O2 par broyage de pastilles en oxyde mixte qui ont une granulométrie inférieure à 3 mm. On broie très finement ce produit broyé en une poudre ayant une granulométrie moyenne d5 0 , 3 inférieure à 3 microns. On granule ensuite cette poudre et on la comprime en pastilles qui sont frittées en comprimés.