Effects of Radial Hydrides on PWR Cladding Ductility following Drying and Storage

Abstract

The purpose of this research effort is to determine the effects of canister and/or cask drying, transfer and storage on radial hydride precipitation in, and potential embrittlement of, high-burnup (HBU) pressurized water reactor (PWR) cladding alloys during cooling for a range of peak drying-storage temperature (PCT) values and hoop stresses. Extensive radial-hydride precipitation could lower failure hoop stresses and strains, relative to limits established for as-irradiated cladding from discharged fuel rods, at temperatures below the ductility transition temperature (DTT), which has been referred to as the ductile-to-brittle transition temperature (DBTT) in previous reports. During post-storage transport, hoop stresses will be induced by "pinch-type" loading at grid spacers. Such loading is considered to be mild for normal conditions of transport and more severe for hypothetical accident conditions.