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-ray analysisKinoshita, Norikazu*; Noto, Takuma*; Nakajima, Hitoshi*; Kosako, Kazuaki*; Kato, Takahiro*; Kuroiwa, Yoichi*; Kurabe, Misako*; Sasaki, Yuki*; Torii, Kazuyuki*; Maeda, Makoto; et al.
Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.479 - 486, 2023/02
Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*; Okihara, Mitsunobu*; Sato, Toshinori
45th Annual Waste Management Conference (WM 2019); Encouraging Young Men & Women to Achieve Their Goals in Radwaste Management, Vol.7, p.4749 - 4763, 2020/01
A rock excavation grouting technology has been recently studied as significant technology for reducing the ingress of water into the deep repository. However, it has not been studied for applying to the coastal region, where it is discussed to be a more suitable region for the geological disposal in Japan. The latest material called colloidal silica grout (CSG) is good for sealing narrow fractures but is known to be sensitive to the salinity of groundwater because of its gelling property with salt accelerator. Although the gelling of CSG can be controlled by adding an acidic pH adjuster, the methodology for delivering the appropriate grout is not well established for such conditions of saline groundwater. Therefore, this research project was established to enhance the existing rock grouting technology for deep repositories.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Saito, Akira*; Aoyagi, Kazuhei; Sato, Toshinori
Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.266 - 271, 2020/01
As engineering technique for geological disposal, a lot of advancement development of the grout technology has been performed. But the design, construction method in consideration of the properties of matter acquisition and mechanism of the hardening that assumed a seawater condition bottom is non-establishment. As we carried out the knowledge under saline water, the basic properties acquisition, the penetration properties acquisition, a study revue based on such situation.
Tsuji, Masakuni*; Aoyagi, Kazuhei; Nakashima, Hitoshi*; Okihara, Mitsunobu*; Sato, Toshinori
Proceedings of the Nordic Grouting Symposium 2019 (Internet), 15 Pages, 2019/09
This paper shows an overall result of the 3-year study on the characterisation of the colloidal silica grout (CSG) under saline groundwater, aiming to enhance the existing rock grouting technology, especially for the CSG under the saline groundwater. As a first step, we performed the survey of the latest grouting technology of CSG. We developed a feasible mixing methodology and have obtained the various CSG's properties impacted by the salty mixing water or submerged by saline water. Moreover, we proposed a theory for the grout penetration under saline water and performed the injection tests. In the second workshop in the final year, our overall findings in this study were recognised to attain some progress in the development of the grouting technology.
Martikainen, J.*; Tsuji, Masakuni*; Schatz, T.*; Nakashima, Hitoshi*; Okihara, Mitsunobu*; Aoyagi, Kazuhei; Sato, Toshinori
Proceedings of the Nordic Grouting Symposium 2019 (Internet), 13 Pages, 2019/09
This paper shows a result of the part of the study on characterisation of penetration of the colloidal silica grout (CSG) under saline groundwater, aiming to understand the impact of salinity on grout penetration by verifying the improved penetration theory with laboratory tests. This theory was proposed to add a time factor 
to the existing penetration theory of Funehag, especially under the saline groundwater conditions. A series of grout injection tests by the fracture test system were performed. The CSG of one European and Japanese were injected in the system, filled with the five different groundwater simulants. All no-flow tests were successful, resulting in the formation of relatively homogeneous gelled zones. Based on the analysis of acquired , it was found that as an alternative method, designing a longer gel time by multiplying the inverse value of can be proposed to attain the required penetration. Although the results were fruitful, further investigation is necessary to develop this penetration theory.
Toguri, Satohito*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Sugiyama, Hirokazu*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei; Masunaga, Kosuke
JAEA-Research 2017-013, 131 Pages, 2018/02
JAEA-Research-2017-013.pdf:8.49MB
The discussions on scientifically promising site for the geological disposal has been made at the council of studying group on techniques for geological disposal of radioactive wastes, which is held by Resources and Energy Agency. From the aspect of ensuring safety during the transportation of disposal waste, the coastal area is discussed to be a more suitable area. This report shows the result of the first year of this project as following items; Study on the state-of-art technology and remain tasks; laboratory tests on characterization of colloidal silica grout under sea water; Study on the development of grouting technology (design and the evaluation method of influence on the rock mass).
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Sato, Toshinori; Aoyagi, Kazuhei
Proceedings of 6th East Asia Forum on Radwaste Management Conference (EAFORM 2017) (Internet), 6 Pages, 2017/12
Regarding the engineering technology, the rock grouting has been recently studied as one of the most important technologies. Although the cement grout has not been reported to be affected by the sea water, the latest grouting material called colloidal silica grout is known to be sensitive to the saline water. The mechanism of its affection by sea water is not clear and its grouting methodology in such condition is not yet established either. Therefore, we studied on the latest grouting technologies for geological disposal in Nordic countries and Japan by article survey and a grouting workshop. As a result, it was found that the approach for countermeasures in grouting under sea water is different between Japan, Sweden, and Finland, which are based respectively on the mixture, on the design method, and on the controlling method. It seems that the best solution against this problem is to establish a hybrid and optimal grouting methodology under sea water by combining each country's developed grouting technology in the near future for saline condition, which is respectively based on mixing, design, and controlling method.
-FeSi
nanocrystalsMaeda, Yoshihito; Nishimura, Kentaro*; Nakajima, Takahito*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji
Physica Status Solidi (C), 9(10-11), p.1884 - 1887, 2012/10
Times Cited Count：4 Percentile：88.36(Materials Science, Multidisciplinary)We report enhancement of intrinsic photoluminescence (PL) from -FeSi nanocrystals by doping carbon. In the appropriate dose of C
ion implantation into the average nanocrystal size of 14 nm, the PL intensity was enhanced by 260% and increase of the exciton binding energy of 1.8 meV in comparison with that of the non-doped nanocrystal. Furthermore, we found that there was a clear correlation between the PL enhancement and increase of the exciton binding energy. This important result suggests that carbon atoms doped in the silicide lattice may play as an isoelectronic trap and probably form bound excitons with stable states as predicted theoretically. We found a new mechanism of the PL enhancement for -FeSi nanocrystals.
-FeSi nanocrystals embedded in SiMaeda, Yoshihito; Nishimura, Kentaro*; Nakajima, Takahito*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji
Physica Status Solidi (C), 9(10-11), p.1888 - 1891, 2012/10
Times Cited Count：3 Percentile：83.1(Materials Science, Multidisciplinary)We have systematically investigated photoluminescence (PL) properties of -phase nanocrystals which are formed by a phase transition from metastable -FeSi with a Fluorite structure to -FeSi, and succeeded in enhancement of the PL intensity in the optimum conditions of double annealing process. For the PL enhancement, the time of postannealing at 800
C is dominated by the time of the preannealing at 400 or 500C which is related to amount of the -phase. After discussing some possible factors, we speculate that the PL enhancement observed in this study may be attributed mainly to improvement of the interface condition between the nanocrystal and Si, because the crystallographic epitaxial relationship among the phases, Si(111)//(111)//(202)/(220) can be maintained during precipitation of the nanocrystal on Si(111).
Terada, Atsuhiko; Hino, Ryutaro; Hirayama, Toshio; Nakajima, Norihiro; Sugiyama, Hitoshi*
Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04
The Japan Atomic Energy Agency has been conducting study on thermochemical IS process for water splitting hydrogen production. Based on the test results and know-how obtained through the bench-scale test, a pilot test plant, which has a hydrogen production performance of 30 Nm
/h, is being designed conceptually as the next step of the IS process development. In design of the IS pilot plant, it is important to make chemical reactors compact with high performance from the viewpoint of plant cost reduction. A new hydraulic analytical code has been developed for optimizing mixing performance of multi-phase flow involving chemical reactions especially in the Bunsen reactor. Preliminary analytical results obtained with above mentioned code, especially flow patterns induced by swirling flow agreed well with that measured by water experiments, which showed vortex breakdown pattern in a simplified Bunsen reactor.
Takizawa, Daichi*; Takagi, Hitoshi*; Makita, Chikako*; Nakajima, Yuka*; Saito, Etsuko*; Oyama, Tatsuya*; Ichikawa, Takeshi*; Kakizaki, Akira*; Sato, Ken*; Mori, Masatomo*; et al.
no journal, ,
no abstracts in English
Matsukura, Bui*; Nakajima, Takahito*; Maeda, Yoshihito; Narumi, Kazumasa; Terai, Yoshikazu*; Sado, Taizo*; Hamaya, Kohei*; Miyao, Masanobu*
no journal, ,
no abstracts in English
MnSi/Ge(111) interfacesMatsukura, Bui*; Nakajima, Takahito*; Nishimura, Kentaro*; Narumi, Kazumasa; Sakai, Seiji; Maeda, Yoshihito
no journal, ,
no abstracts in English
ion implanted -FeSi with different crystal morphologiesNakajima, Takahito*; Nishimura, Kentaro*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji; Maeda, Yoshihito
no journal, ,
no abstracts in English
-FeSi nanocrystals by phase transition and enhancement of light emission propertyNishimura, Kentaro*; Nakajima, Takahito*; Nagasawa, Yoshiyuki*; Narumi, Kazumasa; Maeda, Yoshihito*
no journal, ,
Masunaga, Kosuke; Sato, Toshinori; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed for the countermeasures against water inflow in the underground construction. This report shows the outline of this study.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed. Status of technology for grouting in the field of geological disposal in foreign countries has been understood by literature survey and site inspection.
Nakashima, Hitoshi*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Saito, Akira*; Sato, Toshinori; Masunaga, Kosuke
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed. This report shows the results of laboratory tests.
Nakashima, Hitoshi*; Saito, Akira*; Tsuji, Masakuni*; Sato, Toshinori; Aoyagi, Kazuhei; Masunaga, Kosuke*
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed. This report shows the results of laboratory tests.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Sato, Toshinori; Masunaga, Kosuke*
no journal, ,
Study on characterisation of colloidal silica grout under sea water including developing theoretical model and numerical simulation applicable to sea water has been performed.
