Neutronics of the MEGAPIE Liquid PbBi Spallation Target: Inner Flux Measures and Simulations

The MEGAPIE project, a 1-MW liquid lead-bismuth spallation target, has operated successfully at Paul Scherrer Institute in Switzerland. It constitutes the first step in demonstrating the feasibility of heavy liquid-metal target technologies for accelerator driven systems. With the 4-month irradiation phase now concluded, the experiment has provided unique data for a better understanding of the behavior of the target under realistic irradiation conditions. A complex neutron detector, which has journeyed throughout all of the irradiation inside the target and close to the proton beam, has been extracted along with metallic foil monitors. These have provided a measure of the total inner neutron flux. This paper aims to present the current developments in this analysis and in the Monte Carlo simulations that have been performed.