Imaging and hydrogen analysis by SIMS in zirconium alloy cladding: a dual ion beam approach



Zirconium-based alloys are used as fuel cladding material in nuclear power plants. During the reactor operation, the material is oxidized by the water (reactor coolant), and hydrogen gas is formed. The released hydrogen gas, which partly diffuses into the zirconium alloy, forms hydrides when the hydrogen solubility limit is exceeded. This may result in blistering and cracking of the cladding – a phenomenon commonly known as hydrogen embrittlement. Both corrosion and H-uptake phenomena are limiting factors, which can reduce the time of life of cladding under irradiation in a power plant. This study concerns a preliminary investigation of hydrogen by SIMS in a hydrogenated but not-irradiated Zircaloy-4 sample in order to develop a better understanding of hydrogen ingression in high burn up irradiated cladding tubes. Although hydrogen can be easily detected using the SIMS technique, any contamination source of hydrogen must be well identified and minimized during the SIMS measurements. In this work, we have analyzed a hydrogenated (135 wppm in bulk) Zircaloy-4 cladding specimen. In the first step, the sample's surface has been presputtered with cesium ions. Thereafter, H ions yield images have been acquired analyzing the sample with a gallium primary ion beam. Using this dual beam approach, the hydride precipitates present in the sample have been clearly identified and analyzed. Copyright © 2014 John Wiley & Sons, Ltd.