Hydrogen Embrittlement Testing of a Zirconium Based Alloy

Nuclear fuel rods in power reactors are typically clad with zirconium based alloys. These materials undergo corrosion and consequent hydriding during reactor operation. Due to limited storage space in the utilities’ spent fuel pool for used and discharged fuel, many of the utilities are implementing dry cask storage. There is a concern that the relatively high temperature drying process for dry storage coupled with the nascent hydrides and internal gas pressures, may promote radial hydride reorientation that is favorably oriented to promote clad cracking clad breach during storage, transport and handling. Samples were charged with 200 and 800 wppm gaseous hydrogen and subjected to a radial hydride growth treatment at three stresses. These samples were characterized and tested using a simple ring compression test. Ductile to brittle transition temperatures were determined for these samples.