Patent ID: 7824640

Claim:
A multi-step process for producing nuclear grade, active uranium dioxide (UO 2 ) powder by: (1) reacting 1 mole of uranium hexafluoride gas (UF 6 ) with 2 to 10 moles of steam, plus inert gas, in a first stage flame reactor having at least one flame, to yield initial product uranyl fluoride particles (UO 2 F 2 ), HF gas and unreacted steam and inert gas, at a temperature of from 300° C. to 800° C.; (2) passing HF gas, unreacted steam and inert gas, as well as gas entrained initial product particles to a filter, where all HF, unreacted steam and inert gas pass through the filter and entrained particles do not; (3) passing the unentrained initial product uranyl fluoride particles through a positive valve means which passes powder, but prevents significant amounts of gaseous feedback from subsequent reactions into step (1); (4) passing the initial product particles that pass through the positive sealed valve means into a second stage rotary kiln reactor, having a kiln shell and a temperature range at its kiln shell of from an initial 400° C. to 700° C. to a final temperature between 100° C. to 300° C., where uranyl fluoride particles are passed along the rotary kiln countercurrent to steam, hydrogen, and inert gas, to react and remove fluoride as HF gas and to reduce uranyl fluoride particles, to form a sinterable, outlet, UO 2 powder; (5) passing the HF gas, steam, inert gas, and unreacted H 2 or steam and any entrained particles to a filter where all HF, steam, inert gas, and H 2 gases pass through the filter and entrained particles do not; (6) passing the particles that do not pass through the filters of steps (2) and (5) back into the flame reactor of step (1) or the kiln of step (4); (7) condensing HF and steam gas into liquid HF from the filtered off-gases; and (8) collecting UO 2 powder from an outlet of step (4).