Neutron activation of materials produces an energy release during the subsequent radioactive decay. In a fusion power plant this energy release is of the order of MWs. Accurate prediction of this decay heat is fundamental for the design of a fusion power plant, especially for the safety analysis. A very efficient detector system able to measure both electron and photon heats simultaneously and separately has been developed at ENEA Frascati and has been already used to validate the predictions of computer codes developed to calculate neutron activation energy release. In this paper we report measurements on some elements (tin, tantalum and lead) that have been irradiated with the D-T fusion neutrons produced by the Frascati Neutron Generator FNG. These elements could be present in ITER materials and give a significant contribution to the total radioactive inventory, especially if they produce long-live radionuclides. The scope of this study is to validate the general purpose code European Activation code System EASY-2007 comparing the results of the measurements with code predictions. The results are presented in terms of C/E (Calculation vs. Experiment) together with the associated uncertainties.