AbstractAn overview is presented of the R&D work conducted at Forschungszentrum Karlsruhe in co-operation with the Institute of Nuclear Power Engineering, Obninsk, and the University of Wisconsin (UW), Madison, on the development of neutronic computational tools and nuclear data for the International Fusion Material Irradiation Facility intense D–Li neutron source. The focus is on the progress achieved recently for the D–Li neutron source term modelling with an advanced Monte Carlo procedure making use of newly evaluated double-differential data for the 6,7Li(d, xn) reactions, and the creation of the Intermediate Energy Activation File IEAF-2001, an activation data library comprising 679 target nuclides from Z=1 (hydrogen) to 84 (polonium) with neutron induced activation reactions up to 150 MeV.