Multi-MW target station: Neutronic Calculations of the Baseline Design

This document summarises the study performed within the Task #2 of the European Isotope Separation On-Line Radioactive Ion Beam Facility Design Study (EURISOL DS) [1] to design the Multi-MW proton-to-neutron converter.A preliminary study [2] was carried out in order to understand the nature of the interactions taking place in the proton-to-neutron converter and their impact on the design of the facility. Namely, the target dimensions and material composition, type of incident particle, its energy and the beam profile were analysed in the aforementioned technical note, and their optimum values were suggested in the conclusions.The present work is based on the results of the previous study and uses the same methodology, namely Monte Carlo simulations with FLUKA [3]. This note describes the performance of a Hg target design and addresses more detailed issues, such as the composition of the fission target and use of a neutron reflector. It also attempts to integrate those components together and estimate the whole performance in terms of number of fissions, isotopic yields and power densities.The results of these calculations show the feasibility of this Multi-MW target design and the possibility of achieving the aimed fission rates with a reduced fission target. The assembly has been characterised in terms of neutronics and power densities, both key factors in the technical design, due to the high isotopic yields aimed and the large power densities foreseen.