AbstractThe release of 210Po from 17Li83Pb eutectic was experimentally investigated up to 450 °C in flows of noble gases and atmospheric air at different humidity. Aerosol and sorption filters were applied for the quantitative determination of releasing polonium aerosol and gaseous fractions.The experimental results reveal the strong dependence of 210Po release rate on temperature and the state of the eutectic surface. In the eutectic temperature range from 350 to 450 °C the polonium release rate in argon is increasing from 10−11 to 10−9 Ci cm−2 h−1.In all tests the 210Po activity in the carrier gas was determined in aerosol and gaseous forms. Polonium in the gaseous phase was found to be in the range from 5% to 80% of the overall concentration. The total 210Po concentration in the carrier gas near the melted eutectic surface at the temperature 450 °C reached 2.7 × 10−10 Ci 1−1, which exceeds the permissible level by three orders of magnitude.Comparison of experimental data with estimates based on metallic polonium evaporation indicates the formation of chemical compounds of polonium with lead and in some cases with hydroxide.