Redox potential evolution of nitric species and plutonium in HNO{sub 3}-HNO{sub 2} system

In France, the reprocessing process of spent fuel is carried out using the Purex process. The first chemical step of this process is the dissolution of the spent fuel in aqueous concentrated nitric acid. This dissolution solution is composed of many oxidizing species and it is necessary to understand the chemistry of these species to apprehend the behavior of structural materials. The redox potential is a useful discriminate variable to differentiate the effect of each species. In this framework, only the effect of NO{sub 3}{sup -}/HNO{sub 2} couple and PuO{sub 2}{sup 2+}/Pu{sup 4+} couple were investigated. These species were chosen because one is the main couple of medium and the other has a high standard potential. Their influence was investigated from the Nernst's equation. (authors)