The LOTUS Swiss fusion fission hybrid test facility was used to investigate the influence of the self-shielding of resonance cross sections on the tritium breeding and on the thorium ratios. Nucleonic analyses were performed using some deterministic codes and the Monte Carlo method. It is shown that the self-shielding of resonance cross sections results in a decrease of the thorium capture rate and in an increase of the tritium breeding of about 6 %. Therefore for hybrid blanket calculations it is important to define an adequate energy group structure with many groups within the resonances of the fissile-fertile material and the self-shielding should be included in neutronics calculations.