Synchrotron-based high-resolution photoemission spectroscopy study of ZIRLO cladding with H2O adsorption: Coverage and temperature dependence

Sangjune Park,Jong-Yun Kim,Sang Ho Lim,Ki-Jeong Kim,Young-Sang Youn,Jeongmook Lee,Dong Woo Lee

doi:10.1038/s41598-020-63585-5

Abstract

The coverage and temperature dependence of ZIRLO cladding with H2O adsorption are studied using synchrotron-based high-resolution photoemission spectroscopy (HRPES). Based on the analytical results of the Zr 3d, O 1 s, C 1 s, and Sn 3d HRPES profiles prior to H2O adsorption, we determine the surface compositions of O2−, hydroxyl OH−, chemisorbed H2O, zirconium carbide, adventitious carbon, Sn metal, and SnO2 in ZIRLO. When ZIRLO is exposed to H2O molecules, the relative proportion of zirconium metal decreases, whereas that of the total zirconium oxides increases, suggesting the reaction between H2O and the zirconium metal in ZIRLO. On annealing a sample with 1000 L H2O on ZIRLO at 300 °C, Zr2O3 and ZrO2 decompose, and oxygen diffuses into the bulk, thereby reducing the oxidation states of zirconium on the surface. Moreover, at this temperature, the excess H2O molecules on ZIRLO are thoroughly desorbed and tin element is diffused into the bulk in ZIRLO.

Highlights

Zirconium and its alloys have been extensively used as cladding and structural materials in the nuclear industry because they possess several advantages over other materials, a low thermal neutron absorption cross-section, and good corrosion resistance, in particular[1,2,3]
When we performed preliminary experiments using commercial X-ray photoelectron spectroscopy (XPS) (VG Scientific ESCALAB 220i-XL), the Fe 2p and Nb 3d peaks were not observed in ZIRLO; the Nb 3d signal was not detected in our high-resolution photoemission spectroscopy (HRPES) spectrum
As the primary analysis in this study involves the Zr 3d spectra, we reduced the photon energy up to 400 eV to obtain the most sensitive Zr 3d HRPES profiles

Summary

Introduction

Zirconium and its alloys have been extensively used as cladding and structural materials in the nuclear industry because they possess several advantages over other materials, a low thermal neutron absorption cross-section, and good corrosion resistance, in particular[1,2,3]. Cladding is mainly composed of 95% or more zirconium, and serves to completely seal the nuclear fuels in the fuel rod to prevent the external release of fission products generated from nuclear fuels by irradiation[4,5,6,7] Several commercial claddings such as ZIRLO, ZIRCALOY-4, ZIRCALOY-2, and M5 are utilized in nuclear reactors. As ZIRLO is the most commonly used cladding material in the pressurized water reactors (PWRs), currently, investigating the oxidation behavior of ZIRLO by water is crucial to comprehend the oxidation behavior in current PWRs. In view of the above, we performed experiments on the coverage and temperature dependence of ZIRLO cladding with H2O adsorption using synchrotron-based high-resolution photoemission spectroscopy (HRPES), in this study. To the best of our knowledge, the coverage and temperature dependence of ZIRLO cladding with H2O adsorption have not been systematically studied using synchrotron-based HRPES

Methods

Results

Conclusion