Electron microscopy and zirconium oxidation

Abstract

Zirconium-based alloys, namely Zircaloy-2 and Zr-2½ wt% Nb are heavily used in the CANDU (Canadian Deuterium and Uranium) system of nuclear energy generation. Although corrosion in heavy water at about 573 K is not a design limiting concern, corrosion does produce hydrogen which can result in hydride formation that embrittles reactor components. About twenty years ago, an effort was initiated at the Chalk River Nuclear laboratories (CRNL) designed to develop an understanding of the physical structure of the oxide films first, on reactor-grade zirconium, then on dilute zirconium alloys, and finally, on reactor materials. A great deal of this investigative work has been performed in the TEM, SEM and in a SAM.