Hydrolysis of uranium nitrides

Studies were made on the hydrolysis of uranium nitrides (UN and cubic U₂N₃) by superheated steam. The resulting gaseous products were mainly hydrogen, though with U₂N₃ the hydrogen generation was replaced by that of nitrogen at higher temperatures. The condensed water contained ammonia, but not hydrazine. Both UN and U₂N₃ powders were ultimately converted to UO_2.1 after hydrolysis at temperatures up to 600℃; intermediate products (formed below 400℃) were presumably UO₂(N) or UN_1.7 in the case of UN and UN_1.8 with U₂N₃. The reaction mechanisms corresponding to the formation of such chemical species were estimated mainly from the behavior of nitrogen and hydrogen evolution and from the yield of ammonia. The effect brought by N₂ atmosphere on the ammonia formation and on the dissolution of nitrogen into solids were studied also by the hydrolysis under flowing N₂ gas. It was revealed that the yield of ammonia increased and the dissolution was inhibited by N₂ atmosphere. (author)