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眞田 幸尚
no journal, ,
東京電力福島第一原子力発電所事故以降、各研究機関によって放射線モニタリング及び同結果解析が続けられている。本発表ではそれにより導かれる知見と現況について解説する。
寺阪 祐太; 渡辺 賢一*; 瓜谷 章*; 佐藤 優樹; 鳥居 建男; 若井田 育夫
no journal, ,
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.
西村 昭彦; 金井 昭夫*; 吉田 稔*
no journal, ,
福島第一原子力発電所の廃止措置に関して、文部科学省より英知事業の推進が進められている。原子力機構の福島研究開発部門廃炉環境国際共同研究センターは本事業の取りまとめと連携協力を行っている。2019年に国際協力の推進として日露共研分野において、研究テーマ「微生物生態系による原子炉内物体の腐食・変質に関する評価研究」が採択され、2020年12月末まで実施される。ここでは、炉内に流入する地下水に含まれる微生物が、原子炉構造体の劣化・腐食の促進の一因となる可能性の有無を明らかとする。この研究テーマの発展として、連携重点研究として令和2年度より3年間、研究テーマ「廃止措置のリスク要因低下手法に関する研究」が採択された。ここでも、日露の国際協力の推進の一助を実施する。発表では、連携重点研究として実施する小テーマ8課題を紹介する。併せて、微生物腐食の抑制方法についての提案を行う。
冠城 雅晃; 島添 健次*; 大鷹 豊*; 上ノ町 水紀*; 鎌田 圭*; Kim, J.*; 吉野 将生*; 庄司 育宏*; 吉川 彰*; 高橋 浩之*; et al.
no journal, ,
Nine years have been passed since the accident of Fukushima Daiichi Nuclear Power Station (FDNPS), and the retrieval of nuclear fuel debris will be planned to start from 2021 fiscal year. But these retrieval samples will include not only nuclear fuel debris, but also the other materials. To accelerate the decommissioning, non-destructive assessments (NDA) for the nuclear fuel debris are required for the quick disposals. We are developing a high energy gamma-ray spectrometer under high dose-rate environments using CeBr
scintillator. The goal of this research is to realize gamma-ray spectrometry at dose rates of over 1 Sv/h. Then, we first developed a small cubic CeBr scintillator, and we studied the high dose-rate performance at dose rates of up to 790 mSv/h in a 
Co field. In this presentation, we will introduce the concept of Multi Cubic high energy gamma-ray spectrometer, and show the high dose-rate performance in a standard radiation field.
大道 博行*; 山田 知典; 伊藤 主税; 宮部 昌文; 柴田 卓弥; 古河 裕之*; 長谷川 秀一*
no journal, ,
Nine years are past after the serious accident at Fukushima Daiichi Nuclear Power Station held in March 2011. A lot of efforts have been paid for retrieval of nuclear debris retrieval such as improvement of mechanical, thermal and water jet techniques. In order to characterize the phenomena for evaluate the applicability of laser processing technique for the decommissioning of Fukushima Daiichi which is one of the key issues listed by NDF corporation, we investigate the processes. We have performed characterization of fine particle and fragment production from laser irradiated ceramics and concrete samples during a processing to make useful information for the activities of the decommissioning of Fukushima.