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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.
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).
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Progress in Photovoltaics; Research and Applications, 21(7), p.1499 - 1506, 2013/11
Times Cited Count：6 Percentile：26.92(Energy & Fuels)Proton degradation behaviors of hydrogenated amorphous silicon (a-Si:H) solar cells irradiated with protons at 331 K are compared with that at 298 K (room temperature). Variations with time in the post-irradiation electrical properties are also investigated. It is found that the radiation degradation of the electrical properties at 331 K is significantly smaller than that at room temperature. Also, all the electrical properties (short-circuit current, open-circuit voltage, output maximum, and fill factor) recover with time after irradiation even at room temperature. The characteristic time of thermal annealing of short-circuit current is larger as the temperature is higher. These results indicate that temperature during irradiation and elapsed time from irradiation to measurement is an important parameter for radiation degradation of a-Si:H solar cells. Therefore, these parameters should be controlled in conducting the ground radiation tests.
Yabashi, Makina*; Tanaka, Hitoshi*; Tanaka, Takashi*; Tomizawa, Hiromitsu*; Togashi, Tadashi*; Nagasono, Mitsuru*; Ishikawa, Tetsuya*; Harries, J.; Hikosaka, Yasumasa*; Hishikawa, Akiyoshi*; et al.
Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164001_1 - 164001_19, 2013/08
Times Cited Count：71 Percentile：95.16(Optics)
ionsNarumi, Kazumasa; Naramoto, Hiroshi*; Yamada, Keisuke; Chiba, Atsuya; Saito, Yuichi; Maeda, Yoshihito
JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 166, 2013/01
no abstracts in English
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Journal of Non-Crystalline Solids, 358(17), p.2039 - 2043, 2012/09
Times Cited Count：5 Percentile：31.14(Materials Science, Ceramics)Electrical conductivity variations of undoped, n-type and p-type hydrogenated amorphous silicon (a-Si:H) thin films irradiated with various energy protons are systematically investigated in this study. Dark conductivity (DC) and photoconductivity (PC) of the undoped samples increased at first due to proton irradiation and then decrease dramatically with increasing proton fluence. However, increased PC was metastable and gradually decreased with time. Similar results were observed in the n-type a-Si:H, whereas the monotonic decrease was observed in the p-type one. The degrees of the DC and the PC decreases became lower as the irradiated proton energy was higher. The increases of both DC and PC are attributed to the temporal donor like center generation, although the additional proton irradiation decrease both the DC and PC by the accumulation of radiation-induced defects, which are act as deep traps and compensate carriers.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Nuclear Instruments and Methods in Physics Research B, 286, p.29 - 34, 2012/09
Times Cited Count：8 Percentile：52.49(Instruments & Instrumentation)Electric conductivity variations of undoped hydrogenated amorphous silicon (a-Si:H) semiconductors induced by swift protons are investigated. The results show that the conductivity drastically increases at first and then decreases on further irradiation. The conductivity enhancement observed only in the low fluence regime lasts for a prolonged period of time when proton irradiation stops in this fluence regime. On the other hand, the photosensitivity has a minimum value around the conductivity peak. This fact indicates that non-equilibrium carriers do not play a dominant role in the electric conduction in this fluence regime. It is found that the anomalous conductivity enhancement is dominated by donor center generation in the low fluence regime. At higher fluences the variation in electric conductivity becomes dominated by non-equilibrium carriers as the generated donor centers disappear. This is a general interpretation of radiation induced conductivity in semiconductors.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Nuclear Instruments and Methods in Physics Research B, 285, p.107 - 111, 2012/08
Times Cited Count：6 Percentile：43.52(Instruments & Instrumentation) ionsNarumi, Kazumasa; Naramoto, Hiroshi*; Yamada, Keisuke; Saito, Yuichi; Chiba, Atsuya; Takahashi, Yasuyuki*; Maeda, Yoshihito
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 155, 2012/01
no abstracts in English
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Applied Physics Express, 4(6), p.061401_1 - 061401_3, 2011/06
Times Cited Count：9 Percentile：38.03(Physics, Applied)Seebeck coefficient variations of undoped hydrogenated amorphous silicon (a-Si:H) semiconductors due to swift proton irradiation were investigated using an in-situ thermoelectric power measurement system. Undoped a-Si:H irradiated with 3.0 MeV protons at a fluence regime of 3.1
10
- 5.010
/cm
showed a negative Seebeck coefficient although the Seebeck effect was not observed at fluences above 5.310
/cm. These results suggest that donor like centers are generated by low fluence proton irradiation, whereas the donor centers are compensated by radiation-induced defects or themselves disappear after high fluence proton irradiation. These effects decay with time, giving the donor centers a temporal nature.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 37th IEEE Photovoltaic Specialists Conference (PVSC-37) (CD-ROM), p.001615 - 001619, 2011/06
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.183 - 186, 2010/10
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Journal of Non-Crystalline Solids, 356(41-42), p.2114 - 2119, 2010/09
Times Cited Count：13 Percentile：57.27(Materials Science, Ceramics)Photoconductivity (PC) variations of device-grade a-Si:H thin films due to proton irradiation are investigated in this paper. We performed in-situ measurements of the PC variations induced by 0.10, 1.0 and 10 MeV proton irradiations. The irradiation initially caused an increase in PC in all sample. However, continued irradiation resulted in a dramatic decrease as the irradiation fluence increased. The results obtained in this study suggest that the PC increment is caused not by accumulation of displacement damage. The results of the temperature dependence of PC for a-Si:H before and after 10 MeV proton irradiation showed that such a proton-induced PC increment consisted of two components: one thermally stable and one metastable. The thermally metastable component disappeared in the temperature region of 300 to 340 K. On the contrary, radiation-induced defects were annealed above 340 K.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 35th IEEE Photovoltaic Specialists Conference (PVSC-35) (CD-ROM), p.002620 - 002624, 2010/06
Times Cited Count：2 Percentile：71.41(Energy & Fuels)
ionsTakahashi, Yasuyuki; Narumi, Kazumasa; Chiba, Atsuya; Saito, Yuichi; Yamada, Keisuke; Ishikawa, Norito; Sugai, Hiroyuki; Maeda, Yoshihito
EPL; A Letters Journal Exploring the Frontiers of Physics, 88(6), p.63001_1 - 63001_6, 2009/12
Times Cited Count：7 Percentile：45.5(Physics, Multidisciplinary)C and C
ions with 62.5-250 keV/u were incident on self-supporting amorphous carbon foils of 1.4-150 
g/cm
(70-7500 
). The secondary electrons emitted in the forward direction from a carbon foil were detected by a microchannel-plate detector placed at the exit side of the target. The vicinage effect on the secondary-electron yield was evaluated with the ratio of the secondary-electron yield R = 
/2, where and are the yields induced by the C and C ion with the same velocity, respectively. For the first time the disappearance of the vicinage effect on the secondary-electron yield from amorphous carbon foils bombarded with 62.5 keV/u C ions was observed for thick foils of 61-150 g/cm. The internuclear distance between the fragment ions at the exit of the target was evaluated by calculating trajectories of the fragment ions considering the Coulomb explosion. For a 62.5 keV/u C ion, we have determined the threshold internuclear distance where the vicinage effect disappears exits between 6 and 23 . It is expected that the vicinage effect on the energy loss (production process) in this velocity region disappears at the internuclear distance of a few . This result means that the transport or transmission process is important for the appearance of the vicinage effect. Moreover, the threshold internuclear distance depends on the velocity of the ion and increases as the velocity increases. The average charge of the ion increases with increase of the velocity of the ion. These mean that there is a possibility that a charge state plays an important role in the origin of the vicinage effect. In order to account for the experimental results, we discussed two models taking account of two kinds of potentials induced in response to the charge of the fragment ion in the transport process.
Sato, Shinichiro; Sai, Hitoshi*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*; Oshima, Takeshi
Proceedings of 34th IEEE Photovoltaic Specialists Conference (PVSC-34) (CD-ROM), p.002354 - 002358, 2009/06
Photoconductivity (PC) variations of a-Si:H thin films irradiated with 0.10, 1.0 or 10 MeV protons were investigated. According to the results, the PC values of all samples once increased and after that decreased dramatically. In order to obtain the knowledge about the anomalous PC increment, time dependence of the PC value increased by 10 MeV proton irradiation was also investigated. As a result, even the PC value after 270 hours was over twice higher than that before the irradiation, though the PC values decreased with time. However, the PC value became almost equivalent to the PC before the proton irradiation by applying light-soaking. These results mean that the anomalous PC increment is metastable.
Sai, Kazunori*; Suzuki, Yoshio; Araki, Fumiaki*; Uehara, Hitoshi*; Haginoya, Hirofumi*
Keisan Kogaku Koenkai Rombunshu, 8(2), p.761 - 764, 2003/05
no abstracts in English
ions with ion-beam analysis, 2Narumi, Kazumasa; Naramoto, Hiroshi*; Takahashi, Yasuyuki; Yamada, Keisuke; Saito, Yuichi; Chiba, Atsuya; Adachi, Masahiro; Maeda, Yoshihito
no journal, ,
no abstracts in English
Sato, Shinichiro; Sai, Hitoshi*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Oshima, Takeshi
no journal, ,
no abstracts in English
