Influence of Alkali Metal Oxides and Alkaline Earth Metal Oxides on the Mitigation of Stress Corrosion Cracking in CANDU Fuel Sheathing

摘要

Stress corrosion cracking (SCC)can cause failures of CANDU~® Zircaloy-4 fuel sheathing. The process occurs when a corrosive element (i.e.,iodine) interacts with a susceptible material that is under sufficient strain at a high temperature. Currently, there is an ongoing effort to improve SCC mitigation strategies for future iterations of CANDU reactors. A potential mechanism forSCC mitigation involves utilizing alkali metal oxides and alkaline earth metal oxides that willsequester corrosive iodine while actively repairing a protective oxide layer on the sheath. SCC tests performed with sodium oxide (Na_2O) and calcium oxide (CaO) have shown to decrease significantly the sheath degradation.