LIQUID LEAD-BISMUTH OXYGEN SENSORS PERFORMANCE STUDY

Liquid Lead-Bismuth Eutectic (LBE) has become the preferred coolant material for Lead Fast Reactors (LFR) due to its outstanding physical and chemical properties. However, the severe corrosion of structural materials by LBE restricts the development of Lead Fast Reactors. Research indicates that maintaining the dissolved oxygen concentration in LBE within the range of 10(-6) - 5x10(-8) wt.% effectively mitigates corrosion on structural materials. In this process, the measurement and control of oxygen concentration are crucial technologies that urgently need implementation. Oxygen sensors, as key devices for measuring internal oxygen concentration in LBE, are essential for dynamically adjusting the circuit's oxygen concentration. Based on the Nernst principle, oxygen sensors utilize the high oxygen ion conductivity and low electron conductivity of solid electrolytes, assembled into the form of an electrochemical cell for oxygen concentration measurement. Currently developed oxygen sensors are primarily designed for high-temperature environments, and the Pt/air and Bi/Bi2O3 oxygen sensors used exhibit shortcomings in low-temperature testing performance, making it challenging to meet the oxygen concentration measurement requirements below 300 degrees C in LFR's cold section. Therefore, there is an urgent need to develop wide-temperature-range LBE oxygen sensors suitable for lowtemperature operation. To meet low-temperature measurement requirements, we conducted tests on a water-cooled lead-bismuth platform to evaluate the performance of three reference electrode oxygen sensors: Cu/Cu2O, LSM/air, and LSCF/air. The applicable temperature lower limit of the oxygen sensor depends on the performance of the reference electrode. Experimental data indicate that, within the low-temperature range of 250 degrees C to 300 degrees C, Cu/Cu2O, LSCF/air, and LSM/air reference electrodes perform well, meeting the low-temperature measurement requirements of LFR. The Cu/Cu2O reference electrode exhibits good accuracy within the experimental temperature range after adding correction values. LSM/air and LSCF/air reference electrodes maintain good accuracy across the entire testing temperature range. Compared to metal/metal oxide reference electrodes, air-type reference electrode systems generally exhibit better accuracy. However, all three types of reference electrodes demonstrate excellent stability within the experimental temperature range.