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-CsOHRizaal, M.; Luu, V. N.; Nakajima, Kunihisa; Miwa, Shuhei
Proceedings of International Topical Workshop on Fukushima-Daiichi Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
Nakashima, Shinsuke*; Moro, A.*; Komatsu, Ren*; Faragasso, A.*; Matsuhira, Nobuto*; Woo, H.*; Kawabata, Kuniaki; Yamashita, Atsushi*; Asama, Hajime*
Proceedings of International Topical Workshop on Fukushima-Daiichi Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
Pshenichnikov, A.; Zubekhina, B.; Ogi, Hiroshi; Pham, V. H.
Proceedings of International Topical Workshop on Fukushima-Daiichi Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
Riyana, E. S.; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Okumura, Keisuke; Kanno, Ikuo
no journal, ,
Suzuki, Kenta; Yamada, Taichi; Kawabata, Kuniaki
no journal, ,
no abstracts in English
Tsubota, Yoichi; Laffolley, H.; Porcheron, E.*; Journeau, C.*; Delacroix, J.*; Gu
var, C.*; Brackx, E.*; Lallot, Y.*; Bouland, A.*
no journal, ,
In order to safely remove fuel debris from the Fukushima Daiichi Nuclear Power Station (1F), it is necessary to quantitatively evaluate radioactive airborne particulate generated by the cutting of nuclear fuel debris. We fabricated Uranium-bearing simulated fuel debris (SFD) with In/Ex-Vessel compositions and evaluated the physical and chemical properties of aerosols generated by heating the SFDs. Based on these results, we estimated the isotopic composition and radioactivity of aerosols produced when 1F-Unit2 fuel debris is laser cut, which is a typical example of a heating method. Plutonium, mainly 
Pu,
Am, and 
Cm were found to be the alpha nuclide, and Pu, 
Cs-Ba, and 
Sr-Y were found to be the beta nuclide of interest.
Yamada, Taichi; Imabuchi, Takashi; Kawabata, Kuniaki
no journal, ,
Guvar, C.*; Faure, J.*; Testud, V.*; Roger, J.*; Domenger, R.*; Valette, R.*; Brackx, E.*; Bouyer, V.*; Journeau, C.*; Berlemont, R.*; et al.
no journal, ,
The URASOL and the DA projects, respectively led by JAEA and CRIEPI in collaboration with ONET/CEA/IRSN, were proposed to obtain basic data on aerosols generation and characteristics from prototypic FD-simulants containing depleted uranium oxide cut by thermal or mechanical processing tools. The whole process developed by ONET/CEA/IRSN allows the manufacturing of specific compositions and supplying corium samples for cutting, the realization of cutting tests and the on-line dedicated aerosols measurements as well as sampling aerosols, to conduct initial FD simulants and aerosols post-trial analyses. This paper focuses on the initial FD simulant and aerosols chemical and microstructural analyses. Results on an ex-vessel composition of FD, named VF-U3, are given.
Takasaki, Koji
no journal, ,
In the decommissioning of Fukushima-Daiichi Nuclear Power Station, many radiation workers sometimes must work in contaminated areas with alpha and beta nuclide dust. In preparation for the future expansion of the scale of fuel debris removal, it is necessary to periodically check that there is no intake of alpha nuclides to ensure the safety of workers, and if radioactive materials are inhaled, to promptly evaluate the internal dose. Currently, the intake of alpha-nuclides such as plutonium is evaluated by measurement using a lung counter or bioassays, but the evaluation accuracy of the intake of alpha-nuclides in the body is not sufficient due to the difficulty of alpha-ray measurement. Therefore, we are studying the application of a superconducting transition edge sensor (TES)-type microcalorimeter, which is capable of nondestructive measurement with high resolution, to lung monitoring and analysis of bioassay samples to speed up and improve the internal dose assessment of plutonium.
Sato, Takumi; Sudo, Ayako; Nagae, Yuji
no journal, ,
Terashima, Kenichi; Sakamoto, Masahiro; Matsumura, Taichi; Riyana, E. S.; Kanno, Ikuo; Okumura, Keisuke
no journal, ,
Ikeuchi, Hirotomo
no journal, ,
no abstracts in English
Hanari, Toshihide; Kawabata, Kuniaki; Imabuchi, Takashi
no journal, ,
This presentation describes the results of 3D reconstruction based on images, introducing a robust image selection method by multi-modal detection for a remote operation on decommissioning tasks at the Fukushima Daiichi Nuclear Power Station. We have been developing a 3D reconstruction method based on images to improve the spatial awareness of the robot operators during the decommissioning tasks. For the display of 3D reconstruction models on demand of the operators, a reduction of the computational cost of 3D reconstruction is required. Thus, we tried to introduce an image selection process in the 3D reconstruction. We performed a verification of the 3D reconstruction introducing the proposed method to the image sequence. The results suggest that adequate images can be selected from the image sequence to reduce the computational cost of the 3D reconstruction, and the speed-up of the 3D reconstruction processes can be achieved for displaying the 3D model on demand of the operators.
Nishimura, Akihiko; Akaoka, Katsuaki; Okumura, Keisuke
no journal, ,
We propose incorporating developed laser technologies into a robotic arm working in 1F-PVC (Platinum stage). These technologies will be also used for in monitoring working environment and analyzing in radiation-controlled areas (Gold stage). Furthermore, we will apply them to categorize packing containers post debris removal (Silver stage). In addition, we will proceed them in order to revitalize local economy of Fukushima prefecture, being effective in advancing decommissioning (Bronze stage). These four stages, Mandala from Bronze to Platinum, are being carried out in parallel and in sequence. As for laser application technologies, we propose combining laser spectroscopic analysis technology and remote strain measurement technology with a robot arm.
Miwa, Shuhei; Nakajima, Kunihisa; Karasawa, Hidetoshi; Rizaal, M.; Luu, V. N.; Mohamad, A. B.
no journal, ,
no abstracts in English
Sato, Ikken*; Yamaji, Akifumi*; Li, X.; Yamashita, Takuya; Mizokami, Shinya*
no journal, ,
Morishita, Yuki; Yamada, Tsutomu*; Nakasone, Takamasa*; Kanno, Marina*; Sasaki, Miyuki; Sanada, Yukihisa; Torii, Tatsuo*
no journal, ,
We have tried to create a novel compact alpha/beta detector capable of direct insertion into piping for the immediate assessment of alpha and beta contamination. The detector, a phoswich detector, comprises scintillators for alpha and beta particles. For alpha particles, a ZnS(Ag) scintillator with a thickness of 3.25 mg/cm
was used as the initial layer, while a cerium-doped GdGaAl
O
(GGAG) scintillator measuring 6 mm 
6 mm 6 mm served as the scintillator for the secondary layer for beta particles. The bottom of the GAGG scintillator was coupled with optical grease to a compact photomultiplier tube (H14603, Hamamatsu Photonics K.K.), with an effective diameter of 8 mm
. The signal was amplified by a preamplifier embedded in the compact photomultiplier tube and then the signal was input to a digitizer (DT5730S, CAEN). to confirm the alpha/beta discrimination performance. Subsequently, a thorium source emitting alpha and beta particles concurrently conducted measurement. A charge integration (CI) method was employed to distinguish the alpha and beta waveforms. A 2-dimensional Pulse Shape Discrimination (PSD) map showed the distribution of two clusters of alpha and beta particles, both of which were effectively discriminated. The detector has outer dimensions of 22.0 mm 22.0 mm 30.0 mm, facilitating direct insertion into a pipe for measurement purposes. As a future endeavor, we aim to optimize the discrimination between alpha and beta particles by modifying the combination of scintillators.