Study of the zirconium oxidation under heavy ion irradiation

The objective of the present paper is to put in evidence the influence of damages due to the collision cascades which take place at the end of the heavy ion micrometer range, on the zirconium surface oxidation. A comparison between two zirconium oxidation experiments under heavy ion irradiation performed in the same temperature and pressure conditions is presented. In the first experiment, a 6 $\mu$m thick zirconium foil is irradiated with a 50 MeV $^{129}$Xe beam which stops in the Zr foil. In the second one, a 2 $\mu$m thick zirconium foil is crossed by the whole fission fragment distribution emitted in the $^{235}$U fission. In order to explain the unexpected increase of the oxidation rate observed in the first case, MeV argon irradiation experiments have been performed at IPNL. Results show that collision cascades created in the Zr foil, far from the surface, increase significantly the Zr oxidation.