Experimental Investigation of Evaporation Behavior for Lead-Bismuth Eutectic and Its Impurity Tellurium

Evaporation behavior of lead-bismuth eutectic (LBE) and of tellurium in LBE pool is being investigated experimentally in order to obtain fundamental data on the coolant technology of an accelerator driven system and a fast reactor. The tellurium was used as a non-radioactive chemical surrogate of polonium which would generate and give radiological hazards in the above LBE cooled system. The experiments were conducted using the transpiration method in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. The LBE pool was about 500grams in mass and had a surface area of 4cm × 14cm. Two kinds of experiment were performed under the temperature condition in the range of 450 to 750°C to measure the collected vapor mass: LBE experiment without impurity and LBE-tellurium experiment. The paper presents experiment outline and several instructive results such as saturated vapor pressure of LBE, information on evaporation behavior of each element, and equilibrium partitioning behavior of tellurium from liquid to gas phase. These are also suggestive for understanding chemical behavior of polonium in LBE.