Delayed hydride cracking in Zircaloy-2 with and without liner at various temperatures investigated by high-resolution neutron radiography

Delayed hydride cracking (DHC) remains an important phenomenon when considering cladding mechanical integrity during transport and storage of spent nuclear fuel. This work studies the hydrogen diffusion and precipitation patterns during DHC as a function of temperature via high-resolution neutron imaging. Zircaloy-2 cladding tubes with and without an inner liner were radially cracked from the outside-in direction within a temperature range of 210-360 degrees C. A quantitative analysis was performed on the neutron radiographs showing the average radial concentration of hydrogen around the crack tip. The results show the trend of an increase in local concentration of hydrogen precipitated around the crack tip with an in-crease in cracking temperature. The elevated local concentrations correlate with the amount of hydrogen in solid solution available to diffuse towards the crack tip as well as the tensile stresses at the crack tip.(c) 2022 The Authors. Published by Elsevier B.V.