Oxidation and Hydriding of Zircaloy Fuel Cladding- The Inside (and Outside) Story

Abstract

Zirconium alloy fuel cladding corrodes, and absorbs hydrogen, both from the inside and the outside. The detailed mechanisms for oxide growth and hydrogen absorption are quite different, however, because of the different conditions ("protectiveness") of the oxide films formed in the two environments. Historical changes in the understanding of the processes in the two very different chemical environments on the two sides of the cladding are summarised, and current views of the hydrogen uptake process are summarised. The lack of protectiveness of the inside oxide also contributes to easy PCI corrosion