Mechanical properties of the ITER central solenoid model coil insulation under static and dynamic load after reactor irradiation

The candidate insulation system for the central solenoid (CS) model coil of the International Thermonuclear Experimental Reactor (ITER) is CTD-112P, an epoxy with a two-dimensionally woven S-glass-fiber reinforcement. Because of the pulsed operation of ITER, both the static and the fatigue behavior of the material have to be assessed under the actual operating conditions, including the appropriate radiation environment at the magnet location. To obtain information on the radiation-induced material degradation, the material was irradiated at ambient and low temperatures to neutron fluences of 5 × 1022 m−2 (E > 0.1 MeV). After measurements of swelling and weight loss, all experiments were carried out at 77 K. Half of the 5 K irradiated samples were subjected to a warm-up cycle to room temperature before testing. Tensile and short-beam-shear tests characterize the material in tension and interlaminar shear. Stress–lifetime diagrams of tensile and double-lap-shear specimens were assessed under tension–tension fatigue load up to 106 cycles.