A detailed analysis of integral benchmark experiments using the latest evaluated nuclear data files from FENDL-2.0, ENDF/B-VI, JEF-2.2, JENDL-3.2, BROND-2.1 and CENDL-2.0 is performed to calculate the tri tium breeding ratio in Li, Pb-Li, Pb-Li-C, Be-Li and Be-Li-C spheres using a Monte Carlo technique. Tritium breeding mechanism in each of these spherical shell configurations is analysed and explained by comparing the tritium breeding reaction cross section in ⁷Li and ⁶Li from all the evaluated nuclear data files.