Radiation damage analysis for the liquid metal target META:LIC

Neutronic calculations were performed with the MCNPX Monte Carlo code for an advanced target geometry of the META:LIC (MEgawatt TArget:Lead bIsmuth Cooled) project which was integrated into a target-moderator-reflector system. For this target station setup radiation damage calculations were performed using the standard Norgett-Robinson-Torrens methodology. The analysis showed high values of up to 55 dpa over 5000 operation hours for the beam entrance window of the target module steel frame. Changing the conservative assumption of a Gaussian beam profile, used in this analysis, to a more realistic parabolic profile reduce the maximal displacement damage in the window to about 53 dpa/ 5000 h. According to ESS specification for the chosen reference target this value defines the targets lifetime to about 3 month. Contrary to the reference target, the META:LIC target works under ambient pressure, therefore the estimated lifetime only yields a lower limit to the lifetime. Furthermore, the target was especially designed such that the window wall is neglectable for the performance of the target. The worst case scenario can be assumed to be the burning of a hole into the window which will result in a small loss of LBE into the proton beam guide. Thus, defining the end of the lifetime of the target by the detection of LBE in the proton beam guide will yield a much longer lifetime, here additional care has to be put into safety considerations.