Application of electrochemical methods in the development of models for fuel dissolution and container corrosion under nuclear waste disposal conditions

Abstract

The permanent disposal of nuclear fuel wastes requires the development of models that can assess the performance of a disposal vault over long periods of time. Models to assess the long-term stability of the nuclear fuel (UO2) and the corrosion performance of the waste container (either copper or titanium) have been based on electrochemical principles. Here we review the chemical/electrochemical performance of fuel and the two candidate container materials, and describe some of the electrochemical studies undertaken either to develop the mechanistic understanding upon which these models are based or to measure the values of parameters required to evaluate long-term performance. These include the following: the anodic dissolution of UO2; the reduction of O2 on various specimens of UO2; the crevice corrosion of various titanium alloys; the impedance characteristics of passive films on Ti alloys; the anodic dissolution of copper in chloride solutions; the reduction of O2 on copper; the effect of various transport barriers on the corrosion of copper; and the prediction of the corrosion potential of copper in aerated chloride solutions. Keywords: uranium dioxide, copper, titanium, nuclear waste, oxygen.