Method for the control of the composition and physical properties of solid uranium oxides

A method for controlling the composition and physical properties of uranium oxides formed in a high temperature chemical reactor having a reaction zone for the dry thermal conversion of UF.sub.6 comprising the steps of:

• 1) preheating gaseous reactant streams necessary for the conversion of UF.sub.6 to uranium oxides and HF comprising two or more gas streams wherein at least one of the streams is preheated to a temperature of 700.degree.-1000.degree. C. including
• a) a first stream formed of a gaseous mixture of UF.sub.6 and O.sub.2, and
• b) a second stream formed of a combination of gases containing hydrogen selected from the group consisting of H.sub.2, H.sub.2 O, NH.sub.3 and CH.sub.4 and oxygen in a combined form selected from the group consisting of H.sub.2 O and CO.sub.2 ;
• said reactant streams being of a preselected feed composition for control of reaction heat and to favor the formation of predominately one of said uranium oxides;
• 2) then mixing said heated streams;
• and
• 3) injecting the mixed reactant streams directly into said reaction zone while maintaining the temperature and pressure to optimally produce one of said uranium oxides with the desired physical properties.