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Abstract: Fiber reinforced composites impregnated with mixtures of cyanate ester and epoxy resin demonstrated their excellent performance at the ITER design fluence and beyond. Slight modifications of the resin were necessary to extend the pot-life to more than 100h due to the complexity of the coil structure. Two CE blends were supplied by Huntsman, Switzerland, and CTD, USA, according to the ITER TF coil specification, in order to be qualified for ITER. Sets of test samples were produced under exactly the same conditions. The insulation systems consist of a wrapped R-glass/polyimide reinforcement, vacuum impregnated with the cyanate ester/epoxy blends. The mechanical properties were characterized prior to and after irradiation to a fast neutron fluence of 2×1022 m−2 (E >0.1MeV), i.e. twice the ITER design fluence, in tension and interlaminar shear at 77K. In addition, tension–tension fatigue measurements were carried out in order to simulate the pulsed operation of ITER. The results show that the mechanical properties of both materials are hardly affected by neutron irradiation. [Copyright &y& Elsevier]

Abstract: Insulation systems for fusion magnets have to operate in a harsh environment, especially also under intense radiation. Over the past years, cyanate ester (CE) resins have been playing an increasingly important role because of their enhanced temperature and radiation resistance compared to conventional epoxy resins. Blending CE with epoxy resins offers the possibility to manufacture radiation resistant insulations at a low price compared to pure CE materials. Therefore, it is of special interest to study the influence of the CE content and of the epoxy resin on the mechanical properties to find materials, which are suitable and economically reasonable for the specific demands of such magnets. In this study R-glass fiber/Kapton reinforced cyanate ester/epoxy blends with different CE content were investigated. Each material was exposed to conditions matching those expected for the ITER TF coil insulation as closely as possible. In order to characterize the mechanical properties, short-beam shear and static tensile tests were carried out at 77K prior to and after irradiation to fast neutron fluences of up to 5×1022 m−2 (E >0.1MeV), in the TRIGA reactor (Vienna) at ambient temperature (340K). In addition, tension–tension fatigue measurements were performed in the load-controlled mode to simulate the pulsed operation conditions of ITER. [Copyright &y& Elsevier]

Abstract: Fiber reinforced composites impregnated with mixtures of various cyanate ester and epoxy resins demonstrated their excellent performance at the ITER design fluence and beyond. The insulation systems consist of a wrapped R-glass/Kapton reinforcement, vacuum impregnated with a cyanate ester/epoxy blend. For the fabrication of the insulation a long pot-life of the resin is of great importance, which is mainly determined by the amount and the composition of the catalyst needed for curing the resin. However, the catalyst, which amounts to 1–2% of the resin, may also affect the mechanical properties as well as the radiation hardness of the material. In order to investigate these effects, two different composites were fabricated using a Mn- and a Co-catalyst, respectively. The mechanical properties are characterized prior to and after irradiation to a fast neutron fluence of 1×1022 m−2 (E >0.1MeV) in tension and interlaminar shear at 77K. [Copyright &y& Elsevier]

Abstract: To ensure secure operation of the magnet coils, the insulation system must keep its mechanical strength over the whole plant lifetime in a gamma and fast neutron radiation environment. Recent results on cyanate ester (CE)/epoxy blends demonstrated their mechanical integrity after irradiation to the ITER design fluence of 1×1022 m−2 (E >0.1MeV). For economic reasons, the cyanate ester content should be kept as low as possible due to the higher price compared to traditional epoxy resins. Therefore, the optimal composition of cyanate ester and epoxy is of great importance. In this study R-glass fiber/Kapton reinforced cyanate ester/epoxy blends with different epoxy resins and epoxy content were investigated. Short-beam shear and static tensile tests were carried out at 77K prior to and after irradiation to a fast neutron fluence of 1×1022 and 2×1022 m−2 (E >0.1MeV), which was done in the TRIGA reactor (Vienna) at ambient temperature (340K). In addition, tension–tension fatigue measurements were performed in the load- and strain- controlled mode to simulate the pulsed operation conditions of ITER. [Copyright &y& Elsevier]

Abstract: The application of glass-fiber reinforced plastics as insulation materials for fusion magnet coils (e.g. of ITER) requires a full mechanical material characterization under ITER relevant conditions. The tension–tension fatigue test is useful to simulate the pulsed tokamak operation of the ITER coils in the relevant range of 104–105 cycles. The fatigue process can be run under load or strain control, which may influence the material behavior under cyclic load conditions. Therefore, investigations were performed at 77K using an industrial glass-fiber reinforced composite impregnated with epoxy resin. For both the load and the strain controlled mode, R-values of 0.3 and 0.5 and a frequency of 10Hz were chosen. The results are discussed with respect to the lifetime performance of ITER. [Copyright &y& Elsevier]