Development of radiation distribution sensing method using one-dimensional optical fiber for Fukushima Daiichi NPS decommissioning

福島第一原子力発電所廃炉に向けた一次元光ファイバセンサを用いた放射線分布測定法の開発

寺阪 祐太   ; 渡辺 賢一*; 瓜谷 章*; 佐藤 優樹  ; 鳥居 建男  ; 若井田 育夫  

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

A significant amount of radionuclides were discharged into the environment as a result of the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, which occurred due to the large tsunami caused by the Great East Japan Earthquake on March 2011. To carry out the decommissioning operations of FDNPS, grasping the position of radioactive hotspots is essential. If the position of locally existing hotspots is clear, such information is extremely important for the establishment of the countermeasures for the reduction of external dose to the workers and the efficient decontamination. In this study, we focused on the radiation distribution sensing using optical fiber. Optical fiber can measure the radiation distribution one-dimensionally by detecting the scintillating light or Cherenkov light by photodetector. Due to the flexible characteristic of optical fiber as the sensor, it would be useful for the measurement under small and complex space in the decommissioning site of FDNPS. We introduce the R&D activities to apply the optical fiber-based radiation distribution sensor to the high dose rate environment, such as inside the FDNPS reactor buildings.