EURISOL-DS Multi-MW Target Comparative Neutronic Performance of the Baseline Configuration vs. the Hg-Jet Option

This technical report summarises the comparative study between several design options for the Multi-MW target station performed within Task #2 of the European Isotope Separation On-Line Radioactive Ion Beam Facility Design Study (EURISOL DS) [1]. Previous analyses were carried out, using the Monte Carlo code FLUKA [2], to determine optimal values for relevant parameters in the target design [3] and to analyse a preliminary Multi-MW target assembly configuration [4]. The second report showed that the aimed fission rates, i.e. ~1015 fissions/s, could be achieved with such a configuration. Nevertheless, a preliminary study of the target assembly integration [5] suggested reducing some of the dimensions. Moreover, the yields of specific isotopes have yet to be assessed and compared to other target configurations. This note presents a detailed comparison of the baseline configuration and the Hg-jet option, in terms of primary and neutron distribution, power densities and fission product yields. A scaled-down version of the baseline configuration (i.e. reduced radius and length), is proposed and compared with the other designs. The results confirm the feasibility of the reduced target configuration, while obtaining fission product yields comparable to those of the Hg-jet layout, without the technical problems of the latter. Significant fission rates may be obtained with 4 MW of beam power and few one-litre UnatC3 targets. Moreover, the energy deposited in the liquid metal may be evacuated with reasonable flow rates.