Development of in-vessel components of the microfission chamber for ITER

Ishikawa, Masao; Kondoh, Takashi; Okawa, Kiyofumi*; Fujita, Kyoichi*; Yamauchi, Michinori*; Hayakawa, Atsuro*; Nishitani, Takeo; Kusama, Yoshinori

Microfission chambers (MFCs) will provide total neutron source strength in ITER. The MFC is a pencil-sized gas counter containing the fissile material, U. The MFCs will be installed behind blanket modules in the vacuum vessel (VV). Double coaxial mineral insulated (MI) cables will carry signals from the MFCs to the upper port. Though the MI cables will be installed at a factory of the vacuum vessel or ITER assembly hall, detectors with U will be installed to the vacuum vessel at the tokamak pit. Then, the MI cable should be connected in the vacuum vessel. In this work, the connection of the MI cable with the MFC was conceptually designed. The MI cable should be also installed with small curvature radius (R) of 100 200 mm to avoid the VV structure and other diagnostics. So, the vending test of the MI cable was conducted. As a result, damages leak, electrical disconnection and the change in insulation resistance have not been observed at R = 100 mm.