Polonium formation in Pb–55.5Bi under proton irradiation

Lead–bismuth eutectic (LBE) has been proposed both as spallation target and as coolant in a future accelerator driven system (ADS). The safety analyses require knowledge concerning the elements formed during proton irradiation, and their volatility. Discs of lead–bismuth eutectic (LBE) were irradiated with protons having 71 and 590 MeV energy resp. to analyse Po-isotopes formation. The generation of the isotopes Po 206 and 208 was clearly indicated. The ratio 206Po/208Po is dependent on the proton energy and as well on the beam intensity. In parallel to the analytical examinations calculations were carried out using the FLUKA Monte Carlo code to compare the analytical results with the calculations. The evaporation behaviour of irradiated LBE discs was examined as well whereby volatile Hg was found, but no Po evaporation was detected under the chosen conditions.