Determination of nitrogen in uranium-plutonium mixed oxide fuel by gas chromatography after fusion in an inert gas atmosphere

A gas chromatographic technique has been developed for the determination of nitrogen in uranium-plutonium mixed oxide fuel after fusion in an inert gas atmosphere. When the sample and pure iron powder in a graphite crucible were heated to approximately 2500°C by a resistance heating furnace, a large amount of carbon monoxide was evolved with a small amount of nitrogen and hydrogen. A gas chromatograph equipped with a pre-cut system was used for the separation of nitrogen from the carbon monoxide. Nitrogen separated by the gas chromatograph was determined by means of a thermal conductivity detector. Only 100 mg of the sample was used, and the analysis requires about 10 min. No specific skills for glove-box work are necessary. The relative standard deviation and detection limit (3σ-criterion)were less than 5% and 9μg g^-1, respectively. The present method is not only applicable to the analysis of research samples but also to the quality control of uranium-plutonium mixed oxide fuel production lines.