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Koizumi, Kenji; Suzuki, Masahiro; Aoki, Kazuhisa; Yamada, Susumu; Kim, M.; Suzuki, Kenta; Abe, Fumiaki; Machida, Masahiko; Okamoto, Koji
no journal, ,
In the 1F decommissioning, it is crucial to improve the environment of working spaces inside the reactor building. One of the most essential ones is to reduce the exposure of workers as much as possible by utilizing advanced safety planning and designing tools. JAEA has so far developed a digital software tool to reveal 3D distributions of air dose rates and perform virtual simulations to reduce worker's exposure inside working places. A core part is to inversely estimate radiation-source spatial distributions and their magnitudes even in limited monitoring results using a machine learning technique called LASSO. By measuring the point cloud data and air dose rate data using measuring devices mounted on remote-controlled robots, 3D distributions of the obtained contamination can be displayed, and decontamination evaluation and safety analysis for worker exposure reduction can be performed without radiation exposure on virtual digital space.
Ikeuchi, Hirotomo; Ogino, Hideki; Maeda, Koji; Kitagaki, Toru; Kobata, Masaaki; Kobayashi, Toru; Mizokami, Masato*; Mizokami, Shinya*
no journal, ,
Nishimura, Akihiko; Ide, Tsugio*; Ishihara, Nobuyuki*
no journal, ,
Nagao, Fumiya; Hagiwara, Hiroki; Oyama, Takuya; Watanabe, Yusuke; Sambongi, Mitsuru; Iijima, Kazuki
no journal, ,
In the decommissioning process of the Fukushima Daiichi Nuclear Power Plant, various types of solid radioactive waste are generated. For safe disposal of this waste, it is necessary to conduct safety assessments that account for and reduce currently existing uncertainties in input data, such as the characteristics of the generated waste, the properties of the waste packages, and the site environment. This presentation will introduce the efforts being undertaken by the Japan Atomic Energy Agency regarding disposal safety assessments, including the acquisition of parameters for waste and the biosphere, the examination of disposal concepts, and the development of safety assessment methodologies under quality assurance.
Shimomura, Kenta; Yamashita, Takuya; Nagai, Eiichi*
no journal, ,
no abstracts in English
Sambongi, Mitsuru; Ito, Azusa; Koma, Yoshikazu; Osugi, Takeshi; Okada, Takashi; Iijima, Kazuki
no journal, ,
This poster introduces interdisciplinary R&D conducted by Japan Atomic Energy Agency (JAEA) on the characterization, storage, processing and disposal of the solid radioactive waste generated by the TEPCO Fukushima Daiichi Nuclear Power Station (1F) decommissioning, with an example of R&D conducted in the storage for the volume reduction and recycling of 1F radioactive metal waste.
Ogi, Hiroshi
no journal, ,
Investigations inside Fukushima Dai-ichi Nuclear Power Station (1F) Unit 1 pedestal had revealed the concrete collapsing and the rebar exposure, indicative of the potential for Molten Core Concrete Interaction (MCCI) and the concrete melting under low-temperature conditions. Preliminary thermodynamic assessment using the TAF-ID database developed as OECD/NEA project suggested a solidus temperature of approximately 1050-1100 
C for the SiO
-based concretes. Assessment of the database through the detailed sim-concrete melting experiments is ongoing.
Sato, Takumi; Igarashi, Go*; Miura, Taito*; Aili, A.*; Maruyama, Ippei*; Miyamoto, Shintoro*; Nagae, Yuji; Li, X.; Sudo, Ayako
no journal, ,
In this study, we examined the mechanism of the collapse of only concrete with rebar remaining at the pedestal observed in the containment vessel (PCV) of the Fukushima Daiichi Nuclear Power Plant (1FNPP).