Determination of oxygen-to-metal atomic ratio in mixed oxide fuel by non-dispersive infrared spectrophotometry after fusion in an inert gas atmosphere Original Research Article

A new method of analysis for the determination of the oxygen-to-metal atomic ratio (O/M) in a uranium–plutonium mixed oxide (MOX) fuel was developed. The sample and the nickel metal were fused in a graphite crucible in a resistance heating furnace under helium flowing through the system. The oxygen in the MOX fuel reacted quantitatively with the crucible graphite producing carbon monoxide, which was determined using non-dispersive infrared spectrophotometry (NDIR). The oxygen content in the MOX fuel was calculated from the analysis results of the carbon monoxide. The O/M ratios determined by the present method were in good agreement with those of the thermogravimetric method. The relative standard deviation was less than 0.20% for sintered MOX fuel. Only 30 mg of sample was required, and the analysis time takes about 10 min. No specific skills for glove-box work are necessary. The present method is applicable to sintered MOX fuels over a wide range of plutonium contents.