High-temperature absolute hydrogen desorption kinetics of zirconium hydride under clean and oxidized surface conditions

Abstract

High-temperature absolute hydrogen desorption kinetics of zirconium hydride specimens with H/Zr ratio from 1.7 to 0 with no hydrogen backpressure for oxidized and clean surface conditions were discussed. The temperature under study was in the range of 750–820 °C in order to create a hypothetical reactor accident condition manageable by the experimental setup. For the case of the clean surface state, hydrogen release was so rapid that most of hydrogen had escaped from zirconium hydride specimens over the course of only 10 min in the temperature range of ∼600–700 °C. For the case of the oxidized surface condition, the release rate was much slower and exhibited a strange and unexplainable linear fashion regardless of the temperature and H/Zr ratio. The zeroth-order absolute dehydriding rate was determined with an activation energy of 313 ± 17 kJ mol −1.