Authors: A. Inoue
Affilation: Japan Atomic Energy Agency,Tokai, Japan
Pages: 576 - 578
Keywords: mediated electrochemical dissolution, plutonium dioxide, mechanism
The dissolution of plutonium dioxide (PuO2) is of a fundamental importance from the point of view of energy as well as environment. In this work the mechanism of the mediated electrochemical dissolution of semiconducting plutonium dioxide (PuO2) particles in nitric acid (HNO3) was studied on the basis of experimental kinetics published so far. It was found that the rate-controlling reaction is an interfacial electron transfer process between the solid tetravalent plutonium Pu4+(s) and an aqueous redox metal ion such as reductive U4+(aq) or oxidative Ce4+(aq) ion. The rupture of covalent bond of Pu-O of the possible [PuO4]4- cluster in the (110) plane of the cubic PuO2 lattice by electron transfer is decisive for the dissolution process. The role of HOMO and LUMO of the [PuO4]4- cluster is discussed with regards to the oxidative and reductive dissolution respectively.