Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tsurumi, Miwa*; Enoto, Teruaki*; Ikkatai, Yuko*; Wu, T.*; Wang, D.*; Shinoda, Taro*; Nakazawa, Kazuhiro*; Tsuji, Naoki*; Diniz, G.*; Kataoka, Jun*; et al.
Geophysical Research Letters, 50(13), p.e2023GL103612_1 - e2023GL103612_9, 2023/07
Katsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
Times Cited Count:1 Percentile:7.13(Chemistry, Multidisciplinary)We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
Ogawa, Yusuke*; Suzuki, Satoru*; Taniguchi, Naoki; Kawasaki, Manabu*; Suzuki, Hiroyuki*; Takahashi, Rieko*
Materials and Corrosion, 72(1-2), p.52 - 66, 2021/01
Times Cited Count:2 Percentile:13.1(Materials Science, Multidisciplinary)Cast steel is one of the promising alternative to forged steel that is the current reference material for carbon steel overpack. In this study, the full-scale cast steel overpack was produced experimentally and the distribution of casting defects were investigated. The corrosion test regarding corrosion rate and stress corrosion cracking (SCC) susceptibility were also conducted using samples taken from the full-scale cast steel overpack and the corrosion resistance of cast steel was compared with that of forged steel. From above two corrosion tests, it can be said that the corrosion resistance of cast steel is mostly the same as that of forged steel.
Fujimoto, Shinji*; Tsuchiya, Hiroaki*; Ogawa, Soma*; Iida, Yoshihisa; Taniguchi, Naoki
Materials and Corrosion, 72(1-2), p.333 - 338, 2021/01
Times Cited Count:2 Percentile:13.1(Materials Science, Multidisciplinary)The stress corrosion cracking (SCC) of pure copper in bentonite was examined by a slow strain rate test (SSRT). The bentonite was swollen with pure water or aqueous solutions containing NH of 0.05 M and 0.1 M. The thick corrosion films and particulate deposits were formed on copper surface after SSRT. Typical tarnish rupture type SCC occurred on pure copper in swollen bentonite with and without NH. Crack propagation rate was enhanced by NH. It is confirmed thick oxide layer is formed on copper during plastic deformation which resulting in the tarnish crack type SCC. The many particulate deposits observed on the surface might be formed as a results of rapid dissolution of Cu to form porous CuO at locallized deformed sites.
Yamamoto, Masato*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Valo, M.*; Lambrecht, M.*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*
Small Specimen Test Techniques; 6th Volume (ASTM STP 1576), p.53 - 69, 2015/05
In order to ensure the robustness of the Master Curve technique, round-robin tests were performed using 0.16 inch-thick Mini-CT specimens by different investigators to see if consistent values can be obtained. All the specimens used were machined and pre-cracked by one fabricator from unique Japanese RPV material. Seven institutes participated in this exercise, and obtained valid values according to the ASTM E1921 standard. The scatter of values obtained was well within the uncertainty range defined in the standard, indicating the robustness of the Mini-CT specimen test technique. Throughout this activity, we could obtain 182 for a single material. We investigated the statistics of this large database, and found that there is no remarkable difference not only in the values but also in the fracture toughness distribution between the Mini-CT specimen and the standard size 1T-C(T) specimen results.
Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; Yin, Y.-G.; Iwasaki, Aya*; Ogawa, Kenichi*; Fujimaki, Shu
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 105, 2015/03
Watanabe, H.*; Lorusso, G.*; Nishimura, Shunji*; Otsuka, T.*; Ogawa, K.*; Xu, Z. Y.*; Sumikama, Toshiyuki*; Sderstrm, P.-A.*; Doornenbal, P.*; Li, Z.*; et al.
Physical Review Letters, 113(4), p.042502_1 - 042502_6, 2014/07
Times Cited Count:24 Percentile:77.04(Physics, Multidisciplinary)Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*
Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 7 Pages, 2014/07
The Master Curve (MC) approach for the fracture toughness reference temperature To is expected to be a powerful tool to ensure the reliability of long-term used RPV steels. In order to get sufficient number of data for the MC approach related to the present surveillance program for RPVs, the use of miniature specimens is important. The test technique for the miniature specimens (Mini-CT) of 4 mm thick had been verified the basic applicability of MC approach by means of Mini-CT for the determination of fracture toughness of typical Japanese RPV steels. A round robin (RR) program was organized to assure the robustness of the technique. As the third step of RR program, blinded tests were carried out. Precise material information was not provided to the participants. From the results obtained, the scatter range in was within the acceptable scatter range specified in the testing standard. The selection of testing temperature seems to give limited effect like that in larger specimens.
Yamamoto, Masato*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Miura, Naoki*
Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 8 Pages, 2013/07
Master Curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data by the MC approach from used specimens of surveillance tests for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach was launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out technical issues to be solved. As the second step of this program, the effect of loading rate (d/d) was evaluated based on enlarged database. Despite of the difference in d/d, no specific difference in scatter band of was found in d/d - relationships. D/d seems not to be sensitive on scatter band of To in the present results.
Kawachi, Naoki; Koyanagi, Atsushi*; Suzui, Nobuo; Ishii, Satomi; Yin, Y.-G.; Yamazaki, Haruaki; Iwasaki, Aya*; Ogawa, Kenichi*; Fujimaki, Shu
JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 93, 2013/01
Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Chiba, Atsushi*; Hirano, Takashi*; Sugihara, Takuji*; Sugiyama, Masanari*; Miura, Naoki*; et al.
Proceedings of 2012 ASME Pressure Vessels and Piping Conference (PVP 2012) (DVD-ROM), 7 Pages, 2012/07
Master curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data for the MC approach from broken halves of surveillance test specimens for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach of a Japanese RPV steel has been launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out further investigation items to be solved. As the first step of this program, four institutes carried out MC testing and evaluation using common test procedure and specimens. Valid reference temperature T was successfully obtained in each institute. However, the T values showed large differences with maximum of 34C. It was indicated on the reason of difference that there is a strong correlation between the T values and loading rate, which was selected by each institute per test standard.
Kawachi, Naoki; Suzui, Nobuo; Ishii, Satomi; Yamazaki, Haruaki; Iwasaki, Aya*; Ogawa, Kenichi*; Fujimaki, Shu
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 93, 2012/01
Kawachi, Naoki; Suzui, Nobuo; Ishii, Satomi; Ito, Sayuri; Ishioka, Noriko; Yamazaki, Haruaki; Iwasaki, Aya*; Ogawa, Kenichi*; Fujimaki, Shu
Nuclear Instruments and Methods in Physics Research A, 648(Suppl.1), p.S317 - S320, 2011/08
Times Cited Count:19 Percentile:80.33(Instruments & Instrumentation)Kawachi, Naoki; Suzui, Nobuo; Ishii, Satomi; Ito, Sayuri; Ishioka, Noriko; Yamazaki, Haruaki; Iwasaki, Aya*; Ogawa, Kenichi*; Fujimaki, Shu
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 101, 2011/01
Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko
Journal of Oceanography, 66(5), p.649 - 662, 2010/10
Times Cited Count:2 Percentile:6.23(Oceanography)A numerical experiment is performed to reproduce a distribution of concentrations of Sr and Cs and estimate their total amounts in the Japan Sea. The concentrations of Sr and Cs in the surface layer is in the range of 1.0-1.5 Bq/m and 2.0-2.5 Bq/m. The concentrations in the intermediate and deep layer are higher than those observed in the northwestern Pacific Ocean, indicating active winter convection in the Japan Sea. The total amounts of Sr and Cs in the seawater is evaluated to be 1.34 PBq (1 PBq = 10 Bq) and 2.02 PBq, which demonstrates an estimation by observational data in the Japan Sea expeditions between 1997 and 2002 by Japan Atomic Energy Agency. The total amounts of Sr and Cs vary corresponding to deposition at the sea surface with the maximums of 4.86 PBq for Sr and 7.33 PBq for Cs in the mid-1960s.
Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10
This study aims to demonstrate many findings in the Japan Sea expeditions by Japan Atomic Energy Agency between 1997 and 2002 making use of an ocean general circulation model. A numerical experiment is performed between 1945 and 2000 with deposition at the sea surface by global fallout as main source of anthropogenic radionuclides. The concentrations of Sr and Cs in the surface layer are approximately in the range of 1.0-1.5 Bq/m and 2.0-2.5 Bq/m and they exponentially decrease with depth from the sea surface to the sea bottom. Total amounts of Sr and Cs in the seawater of the Japan Sea are estimated to be about 1.34 PBq (1 PBq = 10 Bq) and 2.02 PBq in the numerical experiment, which demonstrates observational estimations in the Japan Sea expeditions. Time series of the total amounts show that they attain the maximums of 4.86 PBq for Sr and 7.33 PBq for Cs in 1964.
Takahashi, Kuniaki; Meguro, Yoshihiro; Kawato, Yoshimi; Kuroda, Kazuhiko*; Ogawa, Naoki*
JAEA-Technology 2008-084, 12 Pages, 2009/02
Low level liquid waste discharged from a Reprocessing Facility includes sodium nitrate. In the case that it is directly solidified with cement and so on and then the solidified waste are disposed under the ground, sodium nitrate soaks into the environment through underground water layer. We planned to apply the biological treatment system that many ordinary industrial plants are running in the field of waste water treatment to reduce nitrate. We carried out degradation experiments of nitrate for 4wt% sodium nitrate solution by biological method. To solve the assignments that biological treatment technology has, we tested and obtained the results as shown below; (1) The amount of sludge ash could be cut down a tenth as much as usual. The disposal cost reduction of secondary waste is just in sight. (2) Treatment performance could be improved up to 7 kg-N/m/d from 4 kg-N/m/d. It could be expected the more compact system by improvement of the membrane set into the biological treatment tanks.
Suzuki, Takashi; Kabuto, Shoji; Kinoshita, Naoki; Amano, Hikaru; Togawa, Orihiko
JAEA-Conf 2008-003, p.24 - 27, 2008/04
no abstracts in English
Taniguchi, Naoki; Kogawa, Noritaka*; Maeda, Kazuto*
JAEA-Research 2006-051, 60 Pages, 2006/08
It is necessary to understand the corrosion behavior of candidate overpack materials to plan the in-situ engineered barrier test at underground laboratory constructing at Horonobe and to design the overpacks suitable to Horonobe environment. The preliminary corrosion tests of carbon steel which is a candidate material for overpacks were carried out using artificial groundwater and actual groundwater sampled at Horonobe. As the results of anodic polarization experiments, the anodic polarization curves of carbon steel in buffer material were active dissolution type, and the corrosion type of carbon steel in Horonobe groundwater environment was expected to be general corrosion. The results of immersion test under air equilibrium condition and anaerobic condition showed that the corrosion rate and the degree of corrosion localization were not exceeded the data obtained in previous studies. Based on the experimental results, it was confirmed that the corrosion assessment model and assumed corrosion rate in second progress report (H12 report) can be applied to the assessment for Horonobe groundwater condition.
Suzuki, Takashi; Kitamura, Toshikatsu; Kabuto, Shoji; Togawa, Orihiko; Kinoshita, Naoki; Amano, Hikaru
JAEA-Technology 2006-018, 40 Pages, 2006/03
An accelerator mass spectrometry has been set up at the Mutsu Establishment of Japan Atomic Energy Agency. This AMS has two independent beam lines, optimized for C and I measurements. For the I measurement, precision and reproducibility was 2.0 - 1.5% and 1.5 - 0.7%, respectively at the acceptance test in July 2000, and after that, exchange of MCP and re-alignment improved precision and reproducibility to 0.6% and 0.26%, respectively. The results of testing standard materials, which have a variety of iodine isotopic ratios (I/I), showed that this beam line has excellent measurement accuracy between 10 and 10 iodine isotopic ratios, and the detection limit is substantially below the 10 iodine isotopic ratio. Sub-standard samples were normalized to NIST SRM 3230 standard reference material, and the iodine isotopic ratio was (1.210.01)10 for Iso Trace Lab. Standard, (7.220.03)10 for Standard No. 3K and (2.770.03)10 for Standard No. 3i.