Prediction of the radionuclide inventory in the European Spallation Source target using FLUKA

The FLUKA code was applied to a simplified model of the tungsten target of the European Spallation Source (ESS) and shown to be suitable for modelling the radionuclide inventory of the ESS target. Two groups of radionuclides were selected based on dose factors and total predicted activities, one immediately after 5 years (designed lifetime of the target) of operation, and the other 10 years after shutdown. The predicted radionuclide production was higher than estimated by other authors for most of the radionuclides considered. The calculated H-3 activity was close to the highest values obtained with other spallation models. Particular attention was paid to the evaluation of the production of one of the most toxic radionuclides, Gd-148. Differences in the predicted activities of Gd-148 were mainly attributed to differences in the spallation and nuclear evaporation models used.