On the wettability change of oxidized and gamma irradiated Zircaloy

In order to understand the mechanism of the enhancement of wettability of Zircaloy surface by gamma irradiation, we have examined wettability changes on the Zircaloy surface by surface oxidation as well as the gamma irradiation. Without the irradiation, a high surface energy brought by a simple oxidation increased the wettability. In the case of the gamma irradiation, it is found that local nano or atomic scales roughness enhanced the wettability. All these suggest that the enhancement of the wettability of the oxidized Zircaloy surface by the gamma irradiation includes changes of surface nature owing to chemical interactions between the oxidized surface and some reactive species produced by water radiolysis, which automatically bring the modification of geometrical structure in nm scale. (author)