Laser remote analysis for decommissioning of Fukushima Daiichi Nuclear Power Station (1FNPS) and its application in the actual site

福島第一原子力発電所廃炉のためのレーザー遠隔分析技術とその現場適用

若井田 育夫  ; 大場 弘則  ; 中西 隆造; 赤岡 克昭 ; 柴田 卓弥  

Wakaida, Ikuo; Oba, Hironori; Nakanishi, Ryuzo; Akaoka, Katsuaki; Shibata, Takuya

In the decommissioning of 1FNPS, a large amount of fuel debris and radioactive wastes with extremely high radiation dose rate were existed, and a radiation resistant remote screening analysis has been strongly required. The combination of radioactive resistant optical fiber and LIBS will be one of the promising choices for the remote screening analysis under extremely high radiation condition, and basic performances of remote operability and radiation resistance has been demonstrated over 50 m long laser delivery and radiation resistance more than MGy under at a dose rate of 10 kGy/h. And especially, it has been successfully performed that the calibration curve will not change even under the radiative environment of 10 kGy/h. The challenging plan to install the LIBS system as a trial use in an actual working environment of 1FNPS has been currently approved for collected radioactive samples. A simple pollution protection unit with a cleaned air ventilation system has been installed to the previously developed portable LIBS system, and also the Remote controlled XYZ Sample Stage for LIBS Probe has been combined for the challenge at the actual working site in 1FNPS where air contamination is undeniable. The maximum surface dose rate of the sample was about 20 mSv/h.