Hydride embrittlement and irradiation effects on the hoop mechanical properties of pressurized water reactor (PWR) and boiling-water reactor (BWR) ZIRCALOY cladding tubes: Part I. Hydride embrittlement in stress-relieved, annealed, and recrystallized ZIRCALOYs at 20 °C and 300 °C

Abstract

This series of articles on hydride embrittlement effect in ZIRCALOYs consists of three parts. Part I is concerned with the general influence of hydride on the mechanical properties of ZIRCALOYs at two temperatures (20 °C and 300 °C) and for hydrogen content up to 4500 ppm. The damage and fracture mechanisms were investigated by scanning electron microscopy (SEM) fracture surfaces and profiles observations. Special attention was paid to better understanding the ductile-brittle transition as a function of the hydrogen content at two temperatures. The macroscopical behavior of the hydrided ZIRCALOYs was then correlated to the damage and fracture mechanisms. In Part II, the morphology and crystallographic structure of hydrides in two ZIRCALOYs is examined at different magnifications and by different techniques (SEM, transmission electron microscopy (TEM), and X-ray diffraction) as a function of their pre-heat treatment and their hydrogen content. Part III, on the other hand, discusses the mechanical properties of the hydrides under the influence of several parameters based mainly on the SEM in-situ observations and the mechanical modeling.