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Journal Articles

Summary results of subsidy program for the "Project of Decommissioning, Contaminated Water and Treated Water Management (Development of Analysis and Estimation Technologies for Characterization of Fuel Debris (Development of Estimation Technologies of RPV Damaged Condition, etc.) in 2022JFY

Yamashita, Takuya; Shimomura, Kenta; Nagae, Yuji; Yamaji, Akifumi*; Mizokami, Shinya; Mitsugi, Takeshi; Koyama, Shinichi

Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 53 Pages, 2023/10

JAEA performed the subsidy program for the "Project of Decommissioning, Contaminated Water and Treated Water Management (Development of Analysis and Estimation Technologies for Characterization of Fuel Debris (Development of Estimation Technologies of RPV Damaged Condition, etc.) in 2022JFY. This presentation summarized briefly the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.

Journal Articles

Effect of magnesium silicate hydrate (M-S-H) formation on the local atomic arrangements and mechanical properties of calcium silicate hydrate (C-S-H); In situ X-ray scattering study

Kim, G.*; Im, S.*; Jee, H.*; Suh, H.*; Cho, S.*; Kanematsu, Manabu*; Morooka, Satoshi; Koyama, Taku*; Nishio, Yuhei*; Machida, Akihiko*; et al.

Cement and Concrete Research, 159, p.106869_1 - 106869_17, 2022/09

 Times Cited Count:3 Percentile:85.78(Construction & Building Technology)

Journal Articles

Oxidation mechanisms of hafnium overlayers deposited on an Si(111) substrate

Kakiuchi, Takuhiro*; Matoba, Tomoki*; Koyama, Daisuke*; Yamamoto, Yuki*; Yoshigoe, Akitaka

Langmuir, 38(8), p.2642 - 2650, 2022/03

 Times Cited Count:1 Percentile:16.24(Chemistry, Multidisciplinary)

0xidation processes at the interface and the surface of Si(111) substrate with thin Hf films were studied using photoelectron spectroscopy in conjunction with supersonic oxygen molecular beams (SOMB). The oxidation starts at the outermost Hf layers and produces stoichiometric HfO$$_{2}$$. Hf silicates (Hf-O-Si configuration) were generated in the vicinity of the HfO$$_{2}$$/Si interface in the case of the irradiation of 2.2 eV SOMB. The oxidation of the Si substrate takes place to generate SiO$$_{2}$$ compounds. Si atoms were emitted from the SiO$$_{2}$$/Si interface region underneath the HfO$$_{2}$$ overlayers to release the stress generated within the strained Si layers. The emitted Si atoms can pass through the HfO$$_{2}$$ overlayers and react with the impinging O$$_{2}$$ gas.

Journal Articles

Temperature effects on local structure, phase transformation, and mechanical properties of calcium silicate hydrates

Im, S.*; Jee, H.*; Suh, H.*; Kanematsu, Manabu*; Morooka, Satoshi; Koyama, Taku*; Nishio, Yuhei*; Machida, Akihiko*; Kim, J.*; Bae, S.*

Journal of the American Ceramic Society, 104(9), p.4803 - 4818, 2021/09

 Times Cited Count:8 Percentile:84.8(Materials Science, Ceramics)

Journal Articles

Data-driven derivation of partial differential equations using neural network model

Koyamada, Koji*; Yu, L.*; Kawamura, Takuma; Konishi, Katsumi*

International Journal of Modeling, Simulation, and Scientific Computing, 12(2), p.2140001_1 - 2140001_19, 2021/04

With the improvement of sensors technologies in various fields such as fluid dynamics, meteorology, and space observation, it is an important issue to derive explanatory models using partial differential equations (PDEs) for the big data obtained from them. In this paper, we propose a technique for estimating linear PDEs with higher-order derivatives for spatiotemporally discrete point cloud data. The technique calculates the time and space derivatives from a neural network (NN) trained on the point cloud data, and estimates the derivative term of the PDE using regression analysis techniques. In the experiment, we computed the error of the estimated PDEs for various meta-parameters for the PDEs with exact solutions. As a result, we found that increasing the hierarchy of NNs to match the order of the derivative terms in the exact solution PDEs and adopting L1 regularization with LASSO as the method of regression analysis increased the accuracy of the model.

Journal Articles

Determination of atomistic deformation of tricalcium silicate paste with high-volume fly ash

Jee, H.*; Im, S.*; Kanematsu, Manabu*; Suzuki, Hiroshi; Morooka, Satoshi; Koyama, Taku*; Machida, Akihiko*; Bae, S.*

Journal of the American Ceramic Society, 103(12), p.7188 - 7201, 2020/12

 Times Cited Count:8 Percentile:66.5(Materials Science, Ceramics)

Journal Articles

Precise chemical state analyses of ultrathin hafnium films deposited on clean Si(111)-7$$times$$7 surface using high-resolution core-level photoelectron spectroscopy

Kakiuchi, Takuhiro*; Matoba, Tomoki*; Koyama, Daisuke*; Yamamoto, Yuki*; Kato, Daiki*; Yoshigoe, Akitaka

Surface Science, 701, p.121691_1 - 121691_8, 2020/11

 Times Cited Count:1 Percentile:6.21(Chemistry, Physical)

Ultrathin hafnium films on Si(111)-7$$times$$7 were studied using synchrotron radiation photoelectron spectroscopies to reveal the chemical states at interface and surface. Ultrathin Hf layers grow on clean Si(111)-7$$times$$7 surface by lever rule. Surface and interface of Hf/Si(111) contain three components (metallic Hf layers, Hf monosilicide (HfSi) and Si-rich Hf silicide). Ultrathin Hf layers changes HfSi$$_{2}$$ islands on bared Si(111)-7$$times$$7 surface after annealing at 1073 K. It was found that the long axes of the rectangle islands expand the direction connecting the corner holes in DAS model of clean Si(111)-7$$times$$7 surface.

Journal Articles

The Effect of rehydration on bond strength of reinforced concrete subjected to high temperature

Miyabe, Azusa*; Koyama, Taku*; Nishio, Yuhei*; Suzuki, Hiroshi; Kanematsu, Manabu*

Konkurito Kozobutsu No Hoshu, Hokyo, Appuguredo Rombun Hokokushu (CD-ROM), 19, p.59 - 64, 2019/10

no abstracts in English

Journal Articles

Evaluation of deformation and fracture behavior of reinforced concrete using neutron beam technique

Ueno, Kazuki*; Suzuki, Hiroshi; Koyama, Taku*; Nishio, Yuhei*; Kanematsu, Manabu*

Konkurito Kozobutsu No Hoshu, Hokyo, Appuguredo Rombun Hokokushu (CD-ROM), 18, p.647 - 650, 2018/10

no abstracts in English

Journal Articles

Deformation analysis of reinforced concrete using neutron imaging technique

Koyama, Taku*; Ueno, Kazuki*; Sekine, Mariko*; Matsumoto, Yoshihiro*; Kai, Tetsuya; Shinohara, Takenao; Iikura, Hiroshi; Suzuki, Hiroshi; Kanematsu, Manabu*

Materials Research Proceedings, Vol.4, p.155 - 160, 2018/05

 Times Cited Count:0 Percentile:0.18

Journal Articles

Non-destructive bond stress evaluation of bending and shear deformed reinforced concrete structure using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Satake, Kosuke*; Kanematsu, Manabu*; Koyama, Taku*; Niwa, Akinobu*; Kabayama, Kenji*; Mukai, Tomohisa*; Kawasaki, Takuro; Harjo, S.

Hihakai Kensa, 67(4), p.180 - 186, 2018/04

The bond behavior between rebar and concrete under bending moment was investigated by measuring the stress distribution in the two-dimensionally distributed rebars embedded in the reinforced concrete (RC) beam using neutron diffraction. The stress distributions in both of the main rebar and the transverse stirrups embedded in concrete were successfully measured at the fixed measurement configuration without any sample rotations, by suggesting a simple measurement technique on the premise that the transverse restriction from the surrounding concrete to the main rebar is negligible. The bending and shear fracture behavior of the RC beam specimen was predicted by comparing changes in the stress distribution in the rebars measured by neutron diffraction with respect to the applied stress, with the macroscopic deformation measured by strain gauges fixed on the concrete surface. In this study, it was found that the neutron diffraction technique can be a useful technique to evaluate not only the anchorage performance but also the bending behavior of the RC beam.

Journal Articles

Development of a high power wideband polarizer for electron cyclotron current drive system in JT-60SA

Saigusa, Mikio*; Oyama, Gaku*; Matsubara, Fumiaki*; Takii, Keita*; Sai, Takuma*; Kobayashi, Takayuki; Moriyama, Shinichi

Fusion Engineering and Design, 96-97, p.577 - 582, 2015/10

 Times Cited Count:6 Percentile:46.16(Nuclear Science & Technology)

A wideband polarizer has been developed for an ECCD system in JT-60SA. The groove depth of the mirrors installed in miter bends were optimized for two frequencies (110 GHz and 138 GHz) by numerical simulations. All surfaces of Poincare spheres were covered at both of the frequencies in low power test. The thermal stress of polarizer were estimated by the numerical simulations. The twister polarizer has been tested up to 0.24 MW during 3 s at 110 GHz.

Journal Articles

Remote visualization system based on particle based volume rendering

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi; Sakamoto, Naohisa*; Koyamada, Koji*

Visualization and Data Analysis 2015 (Proceedings of SPIE Vol.9397) (Internet), p.93970S_1 - 93970S_8, 2015/02

 Times Cited Count:4 Percentile:87.65

In this paper, we propose a novel remote visualization system based on particle-based volume rendering (PBVR), which enables interactive analyses of extreme scale volume data located on remote computing systems. The remote PBVR system consists of Server, which generates particles for rendering, and Client, which processes volume rendering, and the particle data size becomes significantly smaller than the original volume data. Depending on network bandwidth, the level of detail of images is flexibly controlled to attain high frame rates. Server is highly parallelized on various parallel platforms with hybrid programing model. The mapping process is accelerated by two orders of magnitudes compared with a single CPU. The structured and unstructured volume data with 100 millions of cells is processed within a few seconds. Compared with commodity Client/Server visualization tools, the total processing cost is dramatically reduced by using proposed system.

Journal Articles

Operation of the electron accelerators and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Hanaya, Hiroaki; Haneda, Noriyuki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Koyama, Shigeru*; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 209, 2008/03

The accelerator served mainly for graft-polymerization for new material development, radiation effect study on semiconductors, and various experiments of outside users. The annual operation time for the electron accelerator is 597.4h(517h for vertical beams, 80.4h for horizontal beams) The Co-60 $$gamma$$-ray irradiation facilities consist of three buildings (8 rooms) and cover a wide dose-rate range from 0.04Gy/h to 20kGy/h with eight irradiation cells. The annual operation time for the cobalt first, second irradiation facilities and food irradiation facility is 20,844 h, 6,335 h and 3,150 h.

Journal Articles

Utilization of the electron accelerator and $$gamma$$-ray irradiation facilities

Kojima, Takuji; Kaneko, Hirohisa; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Koyama, Shigeru*; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 208, 2008/03

An electron accelerator and three $$gamma$$ ray irradiation facilities were operated for various research subjects as operation plan in FY 2006 without serious trouble. The number of research subjects for the No.1 accelerator, the Cobalt No.1 facility, the Cobalt No.2 facility, and the Food irradiation facility, is 544, 159, 622, and 357, respectively.

Oral presentation

Research and development of wide band polarizer for high power millimeter waves

Sai, Takuma*; Matsubara, Fumiaki*; Takii, Keita*; Oyama, Gaku*; Saigusa, Mikio*; Kobayashi, Takayuki; Moriyama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Bending bond stress evaluation of RC member using TOF neutron diffraction

Satake, Kosuke*; Kusunoki, Koichi*; Mukai, Tomohisa*; Kanematsu, Manabu*; Koyama, Taku*; Suzuki, Hiroshi

no journal, , 

no abstracts in English

Oral presentation

Evaluation of deformation behavior of reinforced concrete using neutron beam techniques

Ueno, Kazuki*; Suzuki, Hiroshi; Koyama, Taku*; Sekine, Mariko*; Nishio, Yuhei*; Kanematsu, Manabu*

no journal, , 

no abstracts in English

Oral presentation

Experimental study on stress evaluation of rebar in repaired reinforced concrete by neutron diffraction

Sekine, Mariko*; Suzuki, Hiroshi; Koyama, Taku*; Ueno, Kazuki*; Nishio, Yuhei*; Kanematsu, Manabu*

no journal, , 

no abstracts in English

Oral presentation

Research and development on preceding processing methods for contaminated water management waste at Fukushima Daiichi Nuclear Power Station, 2; Investigation of approach for selecting solidification techniques applied to contaminated water management waste

Furukawa, Shizue*; Koyama, Tadafumi*; Kikuchi, Michio*; Otsuka, Taku*; Yamamoto, Takeshi*; Imaizumi, Ken*; Osugi, Takeshi; Nakazawa, Osamu; Kuroki, Ryoichiro

no journal, , 

In order to evaluate the application to the solidification of the water treatment secondary waste generated from Fukushima Daiichi Nuclear Power Station, research concerning the approach of applicability evaluation was conducted for solidification technology of practical scale.

22 (Records 1-20 displayed on this page)