Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kuwabara, Ryota; Yanai, Tomohiro; Kagi, Takumi; Watahiki, Shunsuke
Nihon Hozen Gakkai Dai-21-Kai Gakujutsu Koenkai Yoshishu, 2 Pages, 2025/07
The blower shaft, which is part of the ventilation system in the JMTR reactor building, was refurbished using a thermal spraying technique to address wear damage. By applying this method, the repair was successfully conducted on-site within a short time frame. The results demonstrate that thermal spraying is an effective maintenance technique for equipment and components in aging decommissioning facilities.
Kagi, Takumi; Araki, Daisuke; Yanai, Tomohiro; Kuwabara, Ryota; Sugaya, Naoto; Nishimura, Arashi; Ebisawa, Hiroyuki; Watahiki, Shunsuke; Tanimoto, Masataka
JAEA-Testing 2024-005, 24 Pages, 2025/03
JAEA-Testing-2024-005.pdf:6.92MB
On September 9, 2019, the strong winds of Typhoon No. 15 caused the secondary cooling system cooling tower of the Japan Materials Testing Reactor (JMTR) to collapse. The cooling tower collapsed from east to west, and four secondary cooling system pipes connected to it also pulled down, and all four pipes were damaged at their riser sections. Because the exterior wall slate material (asbestos slate) covering the collapsed cooling tower contained asbestos, it was necessary to ensure the safety of the workers and to minimize the impact of asbestos on the surrounding environment during the removal work. This report describes the work plan devised while complying with the relevant laws and the results of its implementation to ensure worker safety and reduce the environmental impact of asbestos during the removal work, storage management, and transportation of the asbestos slate material from the cooling tower of the secondary cooling system.
Yoon, J.-Y.*; Takeuchi, Yutaro*; Takechi, Ryota*; Han, J.*; Uchimura, Tomohiro*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
Nature Communications (Internet), 16, p.1171_1 - 1171_8, 2025/02
Times Cited Count：1 Percentile：77.58(Multidisciplinary Sciences)Kuwabara, Ryota; Yanai, Tomohiro; Kagi, Takumi; Tanimoto, Masataka
JAEA-Review 2024-036, 43 Pages, 2024/09
JAEA-Review-2024-036.pdf:4.18MB
The Japan Materials Testing Reactor (JMTR) has a main facility and a specified facility, and construction began in 1967. Therefore, there is concern that asbestos was used in various parts of the facility since it was built before asbestos was regulated. Asbestos has very good properties such as durability, heat resistance, chemical resistance, and electrical insulation, and there is a high probability that asbestos was contained in components and building materials at that time. Therefore, the investigation was focused on specified facilities outside the controlled areas, and an investigation was conducted on heat insulators wrapped around piping installed in the facilities. Of the various systems of piping installed in the facilities, we investigated the presence or absence of asbestos in the heat insulators, especially in piping that had been installed for a long period of time. Inhalation of asbestos can cause diseases such as lung cancer and mesothelioma, so when buildings are demolished or renovated, there is a legal requirement to conduct a preliminary investigation to determine the presence of asbestos. Therefore, it is important to understand the status of asbestos usage within the facility in advance, and we believe that it can also be applied to the formulation of plans for the dismantling and removal of equipment and devices during future decommissioning. As a result of the investigations, asbestos was found in the thermal insulation, especially in the elbow where the piping is bent. The results of these investigations are presented in this report.
7Kakiuchi, Takuhiro*; Anai, Ryota*; Saiki, Taiju*; Tsuda, Yasutaka; Yoshigoe, Akitaka
Journal of Physical Chemistry C, 128(31), p.13052 - 13063, 2024/08
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)0xidation at the interface and the surface of Si(111) substrate with thin Hf films were studied using synchrotron radiation photoelectron spectroscopy in conjunction with supersonic oxygen molecular beams (SOMB). An Hf/Si(111) with a coverage of 0.5 monolayer (ML) included HfSi and HfSi
. Following exposures to thermal oxygen molecules with a translational energy (Et) of 0.03 eV, HfSi was oxidized into Hf
valence. Following SOMB irradiation with Et of 0.39 eV, the other HfSi could be oxidized into the Hf
. Following the thermal O
exposures, the metallic Hf was nonlocally oxidized to HfO via trapping-mediated dissociative adsorption. Meanwhile, the segregated Si atoms were oxidized by SOMB irradiation with 2.2 eV and SiO was generated on the surface.
Sn thin films by magneto-optical Kerr effectUchimura, Tomohiro*; Yoon, J.-Y.*; Sato, Yuma*; Takeuchi, Yutaro*; Kanai, Shun*; Takechi, Ryota*; Kishi, Keisuke*; Yamane, Yuta*; DuttaGupta, S.*; Ieda, Junichi; et al.
Applied Physics Letters, 120(17), p.172405_1 - 172405_5, 2022/04
Times Cited Count：26 Percentile：87.58(Physics, Applied)Kakiuchi, Takuhiro*; Anai, Ryota*; Saiki, Taiju*; Tsuda, Yasutaka; Yoshigoe, Akitaka
no journal, ,
Initial oxidation mechanism of hafnium adsorbed Si(111)-77 [Hf-Si(111), the thickness of Hf:0.5 monolayer] was studied by synchrotron radiation X-ray photoelectron spectroscopy. The individual Hf atoms were associated with the back bonds of Si rest atoms or Si adatoms on Si(111)-77, and the Hf monosilicide HfSi) unit was formed on the outermost surface. Following the HfSi units immediately reacted with the thermal O molecules [translational energy (Et=0.03eV], Hf silicates (Hf-O-Si) were produced. In addition, some dissociated O atoms were inserted between the adsorbed Hf atoms. As a result, Hf sub-oxides/silicates up to 3+ states were formed. When a non-equilibrium condition was induced by irradiation of the supersonic O molecular beam of Et = 0.39 eV, the Hf4+ state was confirmed along with and the oxidation of Si bulk. This indicates that there is an activation energy to oxidize the Hf-Si bonds of the bulk side.
-Lactamase TOHO-1 determined by combined high-resolution neutron and X-ray crystallographyKurihara, Kazuo; Sunami, Tomoko; Yamada, Mitsugu; Nitanai, Yasushi*; Okazaki, Nobuo; Adachi, Motoyasu; Tamada, Taro; Shimamura, Tatsuro*; Miyano, Masashi*; Ishii, Yoshikazu*; et al.
no journal, ,
To help resolve questions regarding the catalytic activity of -lactamase, the crystal structure of an unliganded form of the -lactamase Toho-1 with double mutation R274N/R276N (Toho-1/NN) has been determined by the use of high-resolution neutron and X-ray diffraction data. A large single crystal of Toho-1/NN with a dimension of 2.6 2.5 1.3 mm
was used to collect 100 K neutron diffraction data to 1.5 
resolution and X-ray diffraction data to 1.4 resolution. The structural model of Toho-1/NN was refined to an R-factor of 19.7% using a program PHENIX. The structure showed that Glu166, a catalytic residue of Toho-1, was protonated even at pH 7 nonetheless for the close location to the positively charged side chain amino group (-NH3
) of Lys73. It is also found that there is a hydration water network bridging between the protonated Glu166 and the oxyanion hole comprising two main chain nitrogen atoms of Ser70 and Ser237. The neutron structure analysis also revealed the clear configuration of the proposed catalytic water molecule bridging Glu166 and Ser70. These observations are important to understand the catalytic action of -lactamase Toho-1.
