Simulation of helium and residue production in the Megapie target

This work is aimed at characterizing the Megapie spallation target in terms of main contributors to the activity, modification of the chemical composition as well as residue and volatile gas production. Calculations are performed with the nuclear transport code MNCPX2.5.0 coupled to the evolution code CINDER-90. In this work, we provide results for the lead-bismuth and its container. A sensitivity analysis with regards to the different models available in MCNPX2.5.0 as well as the effect of impurities is discussed.The results presented in this paper indicate that the activity of liquid metal target comes mainly from spallation residues. As for the container, it is found that the activity is driven by activation by low energy neutrons (energy less than 20 MeV). In this case, the main contributors found are 51Cr, 55Fe and 63Ni for period of times less than 27.7 days, between 27.7 days and 2.73 years, and above 2.73 years respectively