Oxidation of Technetium Metal as Simulated by First Principles

Abstract

Advanced models for alloy corrosion should take into account the properties of the oxide film that provides the first line of corrosion resistance. Predictive models for alloy corrosion are particularly desirable for the evaluation of candidate alloy forms for the disposition of spent nuclear fuel. Since technetium is one of the long-lived fission products generated in a nuclear reactor, we consider herein the mechanism of technetium oxidation, beginning with computing the properties of the oxide using a number of first-principles approaches, and then moving to oxygen chemisorption and multilayer oxide growth. For TcO2, electronic structure elements were improved with the use of the Hubbard U method, but this choice led to poor structural predictions. Conventional GGA, on the other hand, gave good structural and mechanical agreement with the hybrid density functional calculations. We examined a number of surface terminations for this oxide phase and found that the “striped” nonpolar surface termination wa...