Analysis of sequential charged particle reaction experiments for fusion reactors

Sequential charged particle reactions, that is, reactions induced by secondary charged particles generated due to neutron reactions, may cause non-negligible radioactivity in low activation material. A computer code ACT4, which had been developed to calculate radioactivity, decay heat and gamma ray source for fusion reactors was supplemented an ability to deal with the reactions. Experiments conducted with Fusion Neutronics Source in Japan Atomic Energy Research Institute for the radioactivity by sequential charged particle reactions were analyzed with the newly revised code of ACT4. As the result, the activations via sequential reaction in LiF showed reasonable agreement with experimental data, which means that the ACT4 program will work well. However, the other activations in vanadium and low activation ferritic steel did not. The disagreement must be caused by incorrectness in neutron cross sections, charged particle cross sections, charged particle emission spectra, etc., and they need to be fully reviewed for the detailed and reliable design analysis of fusion reactors.