Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Luu, V. N.; 中島 邦久; Rizaal, M.; 三輪 周平
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
The trapping behavior of cesium (Cs) on concrete, such as pedestal and shield plugs, was assessed through multiple deposition tests of CsOH aerosols on concrete phase-CaCO within a temperature range of 170
C to 570C under humid conditions. The deposition rate of CsOH aerosols on CaCO as a function of temperature was examined. X-ray diffraction analysis revealed the presence of water-soluble Cs
CO on CaCO samples up to 420C, but negligible detection above this temperature. This finding is supported by quantitative analyses of Cs weight gain and chemical analysis, demonstrating an increase in deposition rate up to 420C, followed by a decline thereafter. The increased deposition rate is attributed to the chemical interaction between CsOH and CaCO, while the diminished rate beyond 420C may result from the decomposition of CaCO under steam, thereby reducing the available reactant for the chemical reaction with CsOH.
-CsOHRizaal, M.; Luu, V. N.; 中島 邦久; 三輪 周平
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
Thermochemistry prevailing between gaseous CsOH and concrete main chemical phase CaCO at temperatures up to 570C was investigated with various scenarios using the thermogravimetric method. The aim was to elucidate the decreasing behavior of cesium (Cs) trapping on CaCO observed in the transpiration method. A quasi-two-compartment platinum crucible was developed to realize co-measurements of both CsOH and CaCO during thermal treatment. Post-test X-ray diffraction was conducted to identify the chemical compound formed on the CaCO precursor. The early presence (timely sensitivity) of CsOH near the heated surface of CaCO was found to play a key role in the trapping (in the form of CsCO). Such a factor is crucial because, otherwise, the Ca(OH) would predominate the surface upon CaCO decomposition where leading to no reaction with CsOH.
谷藤 祐太; 羽成 敏秀; 川端 邦明
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 3 Pages, 2024/10
In this paper, we describe the results of a feasibility study of a noise reduction method from images using deep learning technology for decommissioning work. Currently, remotely operated robots have been used for the decommissioning work at the Fukushima Daiichi Nuclear Power Station (FDNPS) due to the high radiation environment. We have been conducting research and development for providing clear images during operations by removing only noise from images containing noise to contribute to safe and secure decommissioning work. Since we do a feasibility study of the noise reduction method using deep learning, the main target is not the video, but rather images, which are components of the video. We adopted the approach of building a learning model that can cope with various types of noise by training many noisy images in the deep learning process.
狩野 貴宏; 赤岡 克昭; 若井田 育夫
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 3 Pages, 2024/10
In decommissioning of Fukushima Daiichi Nuclear Power Station, only a small amount of the debris removed can actually be analyzed in detail. Therefore, we propose to analyze debris efficiently by performing a simple analysis in advance using Laser Induced Breakdown Spectroscopy (LIBS). LIBS is an elemental analysis method by using laser generated plasma. Plasma emission is measured by spectrometer and identifies the elements contained in the debris. LIBS analysis is suitable for measuring large amounts of debris because it does not require sample pretreatment and only a few seconds of laser irradiation. In addition, the composition ratio of elements can also be determined by analysis using a calibration curve prepared in advance. To create a calibration curve, the intensity ratio of the spectrum is used, but the intensity ratio is affected by the plasma temperature. For this reason, it is desirable that the plasma temperature does not change in LIBS. However, the spectrum changes depending on the measurement conditions. (For example, when the composition ratio changes.) In such cases, the plasma temperature may also change. Therefore, in this study, we did experiments under various conditions to verify whether the plasma temperature changes.
Pshenichnikov, A.; Zubekhina, B.; 多木 寛; Pham, V. H.
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
The CLADS-MADE-05 is the next test in the series of large-scale tests performed in JAEA with a purpose of understanding of mock-up assembly degradation and melt propagation behaviour accompanied by Cs and B containing aerosol release. A possibility of Cs and B aerosols interactions in RPV and formation of a new Cs bearing contaminating phase has been shown. This paper analyses the data on aerosol behaviour of Cs and B bearing aerosols when they interact in the gas line, and concentrates on the phenomenon of possible reactions on the liquid-liquid and liquid-gas interface when aerosols are interacting during the large-scale bundle degradation test.
岩田 圭弘; 宮部 昌文; Wells, S. R.*; 山元 祐太*; 長谷川 秀一*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
本研究では、(i)レーザー偏光に依存した選択則及び(ii)奇数同位体の持つリュードベリレベルの大きな同位体シフトに着目して、奇数同位体分離を目指したCa原子の3段階及び2段階共鳴イオン化スキームを開発した。レーザー偏光が直交条件となる場合に、奇数同位体の分離を確認した。イオン化領域の電場による
Caの非共鳴イオン化を抑制することで、さらなる
Caの光学的同位体選択性向上が期待される。
中島 慎介*; Moro, A.*; 小松 廉*; Faragasso, A.*; 松日楽 信人*; Woo, H.*; 川端 邦明; 山下 淳*; 淺間 一*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
Fuel debris retrieval at the bottom of the primary containment vessel (PCV) is one of the significant tasks for the decommissioning of the nuclear power plant and in particular for 1F. It is challenging for conventional manipulators to perform the retrieval process due to the presence of radiation, water leakage, and poor lighting conditions. We tackle those problems with the design and fabrication of a novel mechanical manipulator and its control and navigation algorithm. Continuous Variable Transmission (CVT)-based actuation improves the robot's shock resistance. AI-based navigation algorithm enables semiautonomous navigation and grasping in the cluttered environment inside the PCV.