Oxygen influence on ultrasonic Doppler velocimetry of lead–lithium flow using titanium transducer

• Ultrasonic Doppler velocimetry for lead–lithium flow is tested at different levels of ambient oxygen concentration.
• It is found that ultrasonic Doppler velocimetry does not work for lead–lithium flows in an oxygen-rich environment.
• Acoustic coupling between a titanium-tipped transducer and molten lead–lithium is deteriorated in the oxygen-rich environment.
• Thermodynamic consideration of lead–lithium is made to explain the UDV deterioration.

Ultrasonic Doppler velocimetry (UDV) with a titanium-tipped transducer has been successfully demonstrated for measuring a velocity profile of molten lead–lithium eutectic alloy (PbLi) with a concentration of oxygen and moisture lower than 1 ppm. In contrast, it is found that UDV does not work for PbLi flows in a more oxygen-rich environment. This paper presents UDV measurements of PbLi flows at different levels of ambient oxygen concentration, and then discusses the measurement deterioration, based on a thermodynamic consideration of oxides formation in molten PbLi. In summary, it can be concluded that in an oxygen-rich environment, titanium oxidation occurs and consequently deteriorates the acoustic coupling between the transducer tip and the molten PbLi.