Manufacture of sintered uranium dioxide

Claim 1

A PROCESS FOR THE MANUFACTURE OF HIGH DENSITY URANIUM DIOXIDE OF STOICHIOMETRIC COMPOSITION CONSISTING ESSENTIALLY OF THE STEPS OF PREPARING A URANIUM TRIOXIDE, REDUCTION OF THE URANIUM TRIOXIDE IN TWO STAGES OF TEMPERATURE, THE FIRST STAGE AT TEMPERATURE ON THE ORDER OF 350 TO 450*C. AND THE SECOND STAGE AT TEMPEATURES ON THE ORDER OF 600 TO 700*C., REOXIDATION OF THE REDUCED TRIOXIDE IN THE COLD IN A CURRENT OF NITROGEN CONTAINING OXYGEN, INCORPORATION OF MOULDING ADDITIVE THEREIN, THEN COMPRESSING THE RESULTING MIXTURE UNDER VACCUM, CRUSHING AND THEN SCREENING THE COMPRESSED PRODUCT, COMPRESSING THE CRUSHED AND SCREENED PRODUCT FOR MOULDING UNDER PRESSURE ON THE ORDER OF 2.5 TO 5 T./CM.2, THEN ELIMINATING THE MOULDING ADDITIVE UNDER VACUUM AT A TEMPERATURE LIMITED UPWARDLY FROM 600 TO 700*C. AND THEN SINTERING FOR APPROXIMATELY FIVE HOURS AT A TEMPERATURE ON THE ORDER OF 1250 TO 1400*C., THE URANIUM TRIOXIDE BEING OBTAINED BY CALCINATION OF AMMONIUM URANATE AT AT TEMPERATURE BETWEEN 350 AND 450*C. FOR FROM 5 TO 20 HOURS AND THE TWO STAGE REDUCTION STEP AND THE SINTERING STEP TAKING PLACE IN AN ATMOSPHERE OF DRY CRACKED AMMONIA.