Study of electrochemical breakdown of anodic oxide films on zirconium. Application to decontamination

Zircaloy-4 constitutes the jacket material of the fuel elements. In order to decontaminate radioactive isotopes trapped in the zirconia film, electrochemical cracking is used in a nitric acid environment to produce the fracture and scaling of the oxide film. The physicochemical conditions of cracking are determined, as well as the role played by internal stresses in the layer. This work is completed by surface analyses (SEM) and y impedance measurements in order to determine the evolution of the film resistance during cracking. (authors)