AbstractThe neutronic performance of both a ceramic breeder and a liquid metal blanket developed at the Nuclear Research Centre Karlsruhe for NET (Next European Torus), has been studied in a three-dimensional analysis of NET in the double null configuration. The analysis has been performed with the help of the Monte Carlo code MCNP. The main concern of the study has been the assessment of the global tritium breeding ratio, the determination of the total power production, and a complete evaluation of the spatial distribution of the power density. One-dimensional calculations have also been performed to assess their potential and limitations. Typically they overestimate the breeding ratio by about 30%. However, for the NET double null configuration they are able to reproduce correctly the total power production and the power peaking in the torus mid-plane.