BEHAVIOR OF PO-210 IN MOLTEN PB-17LI

The behavior of Po-210 in molten Pb-17Li was investigated in evaporation experiments. It was found that polonium evaporates in form of an intermetallic compound PbPo. Because of the low vapor pressure of this polonide, evaporation rates are small. The activity coefficient for Po in Pb-17Li is given by In gamma = -4.77 - (1329/T). Under conditions of a fusion reactor blanket with helium as cover gas, the evaporating fraction will be 10(6) times smaller than that estimated assuming ideal solution and vacuum. In agreement with observations at a Bi-inpile loop, only a very small fraction of the total polonium will be found in cover gas spaces.