Irradiation effects on the fatigue behaviour of an ITER candidate magnet insulation material in tension and interlaminar shear

The magnets of ITER and future fusion plants will be subjected to fast neutron and γ-radiation over their lifetime, which influences the mechanical properties of the magnet insulation materials. The ITER candidate material CTD-112P, a two-dimensionally woven S2-glass-fibre reinforced epoxy, was investigated at 77 K in the static and fatigue modes in tension and interlaminar shear. The material was irradiated in the TRIGA reactor (Vienna) with several neutron fluences and by a 60Co-source (Madrid) up to 107 Gy. The results of the tensile tests show a minor reduction (∼5%) in the ultimate tensile strength caused by irradiation and a reduction in the tensile fatigue lifetime only at the highest neutron fluence (2×1022 m−2, E>0.1 MeV). The shear properties of the material are affected neither in the static nor in the fatigue mode up to a fast neutron fluence of 5×1021 m−2, i.e. a total absorbed dose of 2.8×107 Gy.