Influence of water radiolysis products on passive film formation and reduction in a mixed radiation environment

Abstract

Spallation neutron sources generate a mixed radiation environment when a beam of high energy particles (e.g. protons or deuterons) hits a heavy metal target. Radiolysis results when these primary and secondary (spallation) particles lose energy by Coulomb interaction with the electrons in the hydrogen and oxygen atoms of water. The results of cyclic voltammetry experiments on gold in sulphuric acid (pH 1.6) and exposed to a spallation environment were consistent with the presence of water radiolysis products. However, no changes in the Au OA1 - OA4 oxidation peaks or the OCIII reduction peak were observed in irradiated specimens. These findings indicate that proton irradiation and the resulting water radiolysis products do not influence passive film formation and reduction. Cyclic voltammetry experiments have also shown that a modest quantity of hydrogen bubbled into the solution had little influence on the concentration of radiolysis products that are produced during spallation near the electrochemical double layer.