Gas evolution from insulating materials for superconducting coil of ITER by gamma ray irradiation at liquid nitrogen temperature

Idesaki, Akira; Koizumi, Norikiyo; Sugimoto, Makoto; Morishita, Norio; Oshima, Takeshi; Okuno, Kiyoshi

A laminated material composed of glass cloth/polyimide film/epoxy resin will be used as an insulating material for superconducting coil of ITER. In order to keep safe and stable operation of the superconducting coil system, it is indispensable to evaluate radiation resistance of the material, because the material is exposed to high radiation field of 10 MGy at low temperature of 4 K. In this work, the gas evolution from the laminated material by gamma ray irradiation at liquid nitrogen temperature (77 K) was investigated, and the difference of gas evolution behavior due to difference of components in the epoxy resin was discussed. As a result, it was found that the main gases from the epoxy resin by the irradiation were hydrogen, carbon monoxide and carbon dioxide, and that the amount of the gases from epoxy resin containing cyanate ester was 30-40% less than that from the epoxy resin containing tetraglycidyl-diaminophenylmethane (TGDDM).