Gas Evolution Measurements on Reactor Irradiated Advanced Fusion Magnet Insulation Systems

Glass‐fiber reinforced plastics (GFRPs) are used as insulation materials for the superconducting magnet coils of the International Thermonuclear Experimental Reactor (ITER). The radiation environment present at the magnet location will lead to gas production, swelling and weight loss of the laminate, which may result in a pressure rise combined with undefined stresses on the magnet coil casing. Consequently, these effects are important parameters for the engineering and design criteria of superconducting magnet coil structures. In this study, newly developed epoxy and cyanate‐ester (CE) based S2‐glass fiber reinforced insulation systems were irradiated at ambient temperature in the TRIGA‐Mark II reactor (Vienna) to a fast neutron fluence of 1 and 5×1021 m−2 (E>0.1 MeV) prior to measurements of gas evolution, swelling and weight loss. The CE based laminates show increased radiation resistance, i.e. less gas evolution. The highest radiation hardness up to the highest dose was observed in a pure CE system. I...