Stability of complexed Rover dissolver solutions containing high concentrations of niobium, fluoride-ion, and aluminum

The processing of nuclear rocket (Rover) fuels requires high concentrations of hydrofluoric acid and nitric acid in the dissolver solution to dissolve the uranium and niobium. The resulting dissolver solutlon is highly corrosive and requires the addition of aluminum nitrate to complex the free fluoride'' and reduce corrosion on stainless steel processing equipment located downstream from the dissolver. The dissolver solution is very sensitive to aluminum nitrate addition; excessive aluminum nitrate results in precipitation of Nb/sub 2/O/sub 5/. Insufficient aluminum nitrate results in precipitation of AlF/ sub 3/, and the solution remains corrosive. The stability range of the complexed dissolver solution is narrow and time dependent. The stability range was determined expenimentally to vary from 24--30% for a 2-hr period and from 0-10% for a 24-hr period. The stability range is increased to 40% over a 5-day peniod when the solution is diluted and adjusted for solvent exrraction feed. (auth