SESSION III - Spallation Target Development and Coolant Technology

Abstract

The WEBEXPIR (Windowless target Electron Beam EXPerimental IRradiation) programme was set up as part of the MYRRHA/XT-ADS R&D efforts on the spallation target design, in order to answer different questions concerning the interaction of a proton beam with a liquid lead-bismuth eutectic (LBE) free surface. An experiment was conceived at the IBA TT-1000 Rhodotron, a 7-MeV electron accelerator which produces beam currents of up to 100 mA. Due to the small penetration depth of the 7-MeV electron beam and the high beam currents available, the TT-1000 allows to imitate the high power deposition at the MYRRHA/XT-ADS LBE free surface. The main goals of the experiment were to assess possible free surface distortion or shockwave effects under nominal conditions and during sudden beam on/off transient situations, as well as possible enhanced evaporation. The geometry and the LBE flow characteristics in the WEBEXPIR set-up were made as representative as possible of the actual situation in the MYRRHA/XT-ADS spallation target. Irradiation experiments were carried out at beam currents of up to 10 mA, corresponding to 40 times the nominal beam current necessary to reproduce the MYRRHA/XT-ADS conditions. As a preliminary general conclusion, it can be stated that the WEBEXPIR free surface flow was not disturbed by the interaction with the electron beam and that vacuum conditions stayed well within the design specifications.