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

Abstract

the coverage and temperature dependence of ZiRLo cladding with H 2 o 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 H 2 o adsorption, we determine the surface compositions of o 2− , hydroxyl oH − , chemisorbed H 2 o, zirconium carbide, adventitious carbon, Sn metal, and Sno 2 in ZiRLo. When ZiRLo is exposed to H 2 o molecules, the relative proportion of zirconium metal decreases, whereas that of the total zirconium oxides increases, suggesting the reaction between H 2 O and the zirconium metal in ZIRLO. On annealing a sample with 1000 L H 2 o on ZIRLO at 300 °C, Zr 2 o 3 and Zro 2 decompose, and oxygen diffuses into the bulk, thereby reducing the oxidation states of zirconium on the surface. Moreover, at this temperature, the excess H 2 o molecules on ZIRLO are thoroughly desorbed and tin element is diffused into the bulk in ZIRLO. 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 1-3. 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 4-7. Several commercial claddings such as ZIRLO, ZIRCALOY-4, ZIRCALOY-2, and M5 are utilized in nuclear reactors. In order to generate electrical energy, they are always contacted with water to transfer the heat energy produced from the nuclear fuels to water 8. Consequently, oxidation of the cladding surface by water is inevitable. Because this oxidation degrades the cladding performance, the reaction between the cladding and water should be studied to understand the oxidation phenomenon on the cladding surface. ZIRLO, which is a commercially available cladding material, is fabricated with small quantities of niobium, tin, and iron, which are minor alloying elements, to improve the corrosion resistance and mechanical strength 3,9. Although the oxidation of pure zirconium, ZIRCALOY-2, ZIRCALOY-4, and M5 are actively researched, studies focusing on the ZIRLO cladding are rare 1-3,8,10-18. 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 H 2 O adsorption using synchrotron-based high-resolution photoemission spectroscopy (HRPES), in this study. Because synchrotron-based HRPES renders it possible to change the photon energy, we can obtain

Decreasing Hydrogen Content within Zirconium Using Au and Pd Nanoparticles as Sacrificial Agents under Pressurized Water at High Temperature

“…Zirconium-based alloys consisting of 95% or more zirconium are typically used as nuclear fuel cladding materials in pressurized water reactors (PWRs) owing to their superior mechanical properties, corrosion resistance, chemical stability, heat transfer, and thermal absorption neutron cross-section compared to other alloys [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. During reactor operation, the cladding is constantly in contact with the primary circuit water to transfer the thermal energy produced by the nuclear fuel to the water for the generation of electrical energy [ 9 ].…”