In situ investigation of pre-transition oxide films on zirconium alloy in simulated primary water condition

Abstract

The effect of oxidation time on the zirconium oxide phase under primary water chemistry of pressurized light water reactor was investigated using in situ Raman spectroscopy. The oxidation time of zirconium alloy was set to 100 days for investigating the pre-transition oxide characteristic of zirconium alloy. The in situ Raman spectra were obtained after 30, 50, 80, and 100 days from start-up. The Raman spectrum in a 30-day specimen represents the distinct tetragonal zirconium oxide peak. As oxidation time increases, the tetragonal zirconium oxide peak disappears and it is merged with monoclinic zirconium oxide peaks. Also, the monoclinic zirconium oxide peaks become sharper and the new peaks related to monoclinic oxide appear. The results of ex situ analyses, including those done with transmission electron microscopy and energy dispersive X-ray spectroscopy, were compared with those of in situ Raman spectra for the comprehensive understanding of the zirconium oxide phase and structure.