Determination of plutonium in MOX fuel in the presence iron by controlled potential coulometry

A controlled potential coulometric method has been developed for the determination of plutonium in plutonium-uranium mixed oxide (MOX) fuel containing of iron. The coexisting iron in the dissolved MOX sample interferes with the determination of plutonium by coulometry, since the redox potential of iron is adjacent to the potential of plutonium. To avoid the interference of iron, the present method was developed under the consideration of the fact that o-phenanthroline reacts to iron to form the complex and then the redox potential of iron was shifted to the positive side. The added o-phenanthroline was more than 20 fold to the amount of iron. Uranium did not interfere at uranium to plutonium weight ratio of up to 10 fold. The relative standard deviation of the present method was less than 0.3% (n=7). (author)