New titrimetric method for oxygen to metal ratio in uranium oxide powders

O/U ratio is of high importance to both U₃O₈ and UO₂ powders for different reasons. In UO₂ powder it is a guiding parameter for sintering process where as for U₃O₈, it indicates efficiency of ammonium di-uranate (ADU) to U₃O₈ conversion process. In the present method for O/U determination, UO₂ and U₃O₈ powders are dissolved in 4.5 M sulphuric acid and little HF by heating on hot plate. Subsequently, optimized quantity of phosphoric acid is added on cooling, for getting sharp end point. The resultant solution is titrated with standard potassium dichromate using barium diphenylamine sulphonate (BDS) as an indicator. The expanded uncertainties calculated for UO₂ and U₃O₈ powders are ±0.004 and ±0.006 O/U ratio units respectively at 95 % confidence level. (author)