On-line monitoring of oxygen potential and structure of oxide layer in liquid metals by electrochemical methods

Abstract

Lead lithium alloy is one of the candidate materials for the tritium breeders of fusion reactors. Lead bismuth eutectic alloy is one of the candidate materials for the coolant of fast reactors and the target of accelerator driven systems. The materials for unti-corrosion layer and tritium permeation barrier have been developed to be applied in these liquid metal systems. Some oxides such as Y₂O₃ and ZrO₂ are considered as the materials due to their excellent chemical stability. The corrosion monitoring of these layers in the liquid metals at high temperature is important issue. The purpose of the present study is to develop the on-line monitoring system for the corrosion of the oxide layers by means of electrochemical impedance spectroscopy (EIS) and solid electrolyte (SE) sensor. The YSZ type SE sensor and the specimen of pre-oxidized zirconium (Zr) were simultaneously immersed to liquid Pb at 698-898K. The responses of the sensor and the EIS were successfully obtained, and these signals indicated that the Zr oxide layer is stable in liquid Pb.