METHOD OF PRODUCING GRANULES OF AT LEAST ONE METAL OXIDE Russian patent published in 2019 - IPC C04B35/50 C04B35/64 G21C3/62 

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for sintering a pressed powder of at least one metal oxide selected from actinides and lanthanides to produce nuclear fuel granules. Said method includes the following successive steps carried out in furnace in atmosphere containing inert gas, hydrogen and water: (a) increasing temperature from initial temperature T_I to temperature T_P holding, which is at level of 1400–1800 °C, (b) holding temperature at temperature T_P holding and (c) temperature reduction from temperature T_P holding to final temperature T_F. During step (a) of temperature T_I, until intermediate temperature T_i1 is achieved between 1000 °C and T_P, ratio of partial pressures P (H)₂/P(H₂O) is such that 500 < P(H₂)/P (H₂O) ≤ 50,000. During step (c) of second intermediate temperature T_i2 between T_P and 1000 °C until temperature T_F is reached, P (H₂)/P (H₂O) ≤ 500. Firing mode may include lowering temperature after holding at T_P to level of 20–500 °C with further temperature increase to T_P, holding and cooling.

EFFECT: technical result of invention is increase in specific weight to a level greater than or equal to 94,5 % of theoretical and higher thermal stability of this specific weight.

18 cl, 2 ex, 2 tbl, 7 dwg