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Tanaka, Kazuya; Kanasashi, Tsutomu*; Takenaka, Chisato*; Takahashi, Yoshio*
Science of the Total Environment, 755(Part 2), p.142598_1 - 142598_8, 2021/02
Times Cited Count：5 Percentile：35.21(Environmental Sciences)In this study, we investigated coordination structures of Cs in 
Cs-doped bark, sapwood, heartwood, needle, and branch samples of trees collected in Fukushima by extended X-ray absorption fine structure (EXAFS) spectroscopy. We examined four representative tree species in Fukushima, 
, 
, 
, and 
. EXAFS spectra suggested that Cs was adsorbed as an outer-sphere complex on all parts of the four species, with electrostatic binding to negatively charged functional groups in components of tree tissues. These results were supported by extraction experiments where most of the sorbed Cs was desorbed from all parts of each tree species using 1 M CH
COONH
.
Sasa, Kimikazu*; Honda, Maki; Hosoya, Seiji*; Takahashi, Tsutomu*; Takano, Kenta*; Ochiai, Yuta*; Sakaguchi, Aya*; Kurita, Saori*; Satou, Yukihiko; Sueki, Keisuke*
Journal of Nuclear Science and Technology, 58(1), p.72 - 79, 2021/01
Times Cited Count：8 Percentile：71.58(Nuclear Science & Technology)Sugiura, Yuki; Tomura, Tsutomu*; Ishidera, Takamitsu; Doi, Reisuke; Francisco, P. C. M.; Shiwaku, Hideaki; Kobayashi, Toru; Matsumura, Daiju; Takahashi, Yoshio*; Tachi, Yukio
Journal of Radioanalytical and Nuclear Chemistry, 324(2), p.615 - 622, 2020/05
Times Cited Count：4 Percentile：45.45(Chemistry, Analytical)
C activities in tree rings near the Fukushima Dai-ichi Nuclear Power PlantMatsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*; Matsuzaki, Hiroyuki*
Radiocarbon, 61(6), p.1633 - 1642, 2019/12
Times Cited Count：2 Percentile：11.66(Geochemistry & Geophysics)
Cl in soil near the Fukushima Dai-ichi Nuclear Power PlantOta, Yuki*; Sueki, Keisuke*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsunaka, Tetsuya*; Matsumura, Masumi*; Tosaki, Yuki*; Honda, Maki*; Hosoya, Seiji*; Takano, Kenta*; et al.
JAEA-Conf 2018-002, p.99 - 102, 2019/02
no abstracts in English
Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Hosoya, Seiji*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*
Nuclear Instruments and Methods in Physics Research B, 439, p.64 - 69, 2019/01
Times Cited Count：2 Percentile：23.19(Instruments & Instrumentation)no abstracts in English
Kato, Masaji*; Nara, Yoshitaka*; Okazaki, Yuki*; Kono, Masanori*; Sato, Toshinori; Sato, Tsutomu*; Takahashi, Manabu*
Materials Transactions, 59(9), p.1427 - 1432, 2018/09
Times Cited Count：6 Percentile：32.61(Materials Science, Multidisciplinary)To ensure the safe geological disposal of radioactive waste, it is important to determine the permeability (hydraulic conductivity) of clays. The transient pulse method is suitable for low-permeability materials because it requires a relatively short time to determine their permeability. Upstream pore pressure typically increases in the measurement conducted via the transient pulse method. However, this procedure cannot be used to determine the permeability of clays due to the increase in pore pressure. Therefore, the transient pulse method has never been applied to determine clay permeability. In this study, we applied the transient pulse method to a clay sample to determine its permeability while decreasing the downstream pore pressure.
Sn strand during coolingSuwa, Tomone*; Hemmi, Tsutomu*; Saito, Toru*; Takahashi, Yoshikazu*; Koizumi, Norikiyo*; Luzin, V.*; Suzuki, Hiroshi; Harjo, S.
IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04
Times Cited Count：1 Percentile：7.59(Engineering, Electrical & Electronic)Nara, Yoshitaka*; Kato, Masaji*; Niri, Ryuhei*; Kono, Masanori*; Sato, Toshinori; Fukuda, Daisuke*; Sato, Tsutomu*; Takahashi, Manabu*
Pure and Applied Geophysics, 175(3), p.917 - 927, 2018/03
Times Cited Count：14 Percentile：58.67(Geochemistry & Geophysics)Information on the permeability of rock is essential for various geoengineering projects. It is especially important to investigate how fractures and pores influence the physical and transport properties of rock. Infiltration of groundwater through the damage zone fills fractures in granite with fine-grained minerals. However, the permeability of rock possessing a fracture naturally filled with fine-grained mineral grains has yet to be investigated. In this study, the permeabilities of granite samples, including a macro-fracture filled with clay and a mineral vein, are investigated. The permeability of granite with a fine-grained mineral vein agrees well with that of the intact sample, whereas the permeability of granite possessing a macro-fracture filled with clay is lower than that of the macro-fractured sample. The decrease in the permeability is due to the filling of fine-grained minerals and clay in the macro-fracture. It is concluded that the permeability of granite increases due to the existence of the fractures, but decreases upon filling them with fine-grained minerals.
Kato, Masaji*; Nara, Yoshitaka*; Okazaki, Yuki*; Kono, Masanori*; Sato, Toshinori; Sato, Tsutomu*; Takahashi, Manabu*
Zairyo, 67(3), p.318 - 323, 2018/03
To ensure the safe geological disposal of radioactive wastes, it is important to determine the permeability of clays. The transient pulse test is suitable to apply to the low permeability materials, because it takes relatively short term to determine the permeability. Usually we increase the upstream pore pressure in the measurement with the transient pulse test. However, it is impossible to determine the permeability of clay in this procedure because of the increase of pore pressure. Therefore, the transient pulse test has never been applied to the determination of permeability of clays. In this study, we tried to apply the transient pulse test to a clay obtained in Mizunami Underground Research Laboratory to determine the permeability with decreasing the downstream pore pressure. It was clarified that the transient pulse test with decreasing downstream pore pressure is appropriate from the measurements of granite and sandstone. It was shown that the permeability of a clay was determined by the transient pulse test with decreasing the downstream pore pressure, which agreed with the permeability determined from the falling head test. The measurement time of the transient pulse test is much shorter than that of the falling head test. It is concluded that the transient pulse test is appropriate for the determination of the permeability of clays.
Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Hosoya, Seiji*; Matsumura, Masumi*; Sueki, Keisuke*; Satou, Yukihiko
Dai-19-Kai AMS Shimpojiumu, 2016-Nendo "Jumoku Nenrin" Kenkyukai Kyodo Kaisai Shimpojiumu Hokokushu, p.76 - 79, 2017/06
To evaluate the radiological impact of the atmospheric C discharge from the Tokai nuclear facilities, a 80-year-old Japanese pine tree from Tokai, 1.8 km south-southwest of the Tokai Nuclear Power Plants (Tokai NPP and Tokai-2 NPP) and 1.4 km North-Northwest of the Tokai Reprocessing Plant (Tokai RP), was cored and each annual ring was measured for C. The C specific activities varied from 232.8 Bq kg
C to 403.3Bq kg C in the tree rings formed during the periods 1954-2013. The specific activities in 1967-2010 are significantly elevated compared with the ambient background values, clearly indicating C discharges from the nuclear facilities during their normal operation. The excess C activities of 0.5-70.0 Bq kg C in 1970-2011 are positively correlated with the estimated annual C discharges of 0.1-1.2 TBq from Tokai NPP and Tokai-2 NPP with R
of 0.66 (n = 38). These activity values of 
70.0 Bq kg C were corresponding to an additional annual effective dose of 3.9 uSv via the food ingestion pathway in the study location.
Kato, Masaji*; Nara, Yoshitaka*; Fukuda, Daisuke*; Kono, Masanori*; Sato, Toshinori; Sato, Tsutomu*; Takahashi, Manabu*
Zairyo, 65(7), p.489 - 495, 2016/07
Rock masses serve a vital function as natural barriers for geological disposal of radioactive waste; therefore, information on rock permeability is essential. Highly accurate measurement of permeability requires understanding of how temperature changes in the surrounding environment influence measurement results. We performed permeability measurement under conditions with dramatic changes of temperature in the surrounding environment to investigate the influence of such changes on the experimental results. Measurement of permeability with no temperature change was also conducted as reference. All measurements were conducted using the transient pulse method, and the sample material used was Toki granite obtained from Gifu Prefecture in central Japan. We found that temperature changes in the surrounding environment remarkably affected the pressure in reservoirs upstream and downstream, the pressure difference between them, and the confining pressure; all increased when temperature increased for our experimental system. Notably, pressure difference was affected immediately. This difference directly relates to estimation of permeability.
Takahashi, Yoshikazu; Suwa, Tomone; Nabara, Yoshihiro; Ozeki, Hidemasa; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; Kawano, Katsumi; Oshikiri, Masayuki; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4200904_1 - 4200904_4, 2015/06
Times Cited Count：3 Percentile：20.23(Engineering, Electrical & Electronic)The Japan Atomic Energy Agency (JAEA) is responsible for procuring all amounts of Central Solenoid (CS) Conductors for ITER, including CS jacket sections. The conductor is cable-in-conduit conductor (CICC) with a central spiral. A total of 576 NbSn strands and 288 copper strands are cabled around the central spiral. The maximum operating current is 40 kA at magnetic field of 13 T. CS jacket section is circular in square type tube made of JK2LB, which is high manganese stainless steel with boron added. Unit length of jacket sections is 7 m and 6,300 sections will be manufactured and inspected. Outer/inner dimension and weight are 51.3/35.3 mm and around 90 kg, respectively. Eddy Current Test (ECT) and Phased Array Ultrasonic Test (PAUT) were developed for non-destructive examination. The defects on inner and outer surfaces can be detected by ECT. The defects inside jacket section can be detected by PAUT. These technology and the inspected results are reported in this paper.
Sn cable assembled with conduit for ITER central solenoidNabara, Yoshihiro; Suwa, Tomone; Takahashi, Yoshikazu; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4200305_1 - 4200305_5, 2015/06
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)
Sn conductors for toroidal field coils in ITERNabara, Yoshihiro; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Suwa, Tomone; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; Koizumi, Norikiyo; et al.
IEEE Transactions on Applied Superconductivity, 24(3), p.6000605_1 - 6000605_5, 2014/06
Times Cited Count：7 Percentile：39.51(Engineering, Electrical & Electronic)no abstracts in English
Sn conductor for ITER central solenoidTakahashi, Yoshikazu; Nabara, Yoshihiro; Ozeki, Hidemasa; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; Kawano, Katsumi; Oshikiri, Masayuki; Uno, Yasuhiro; et al.
IEEE Transactions on Applied Superconductivity, 24(3), p.4802404_1 - 4802404_4, 2014/06
Times Cited Count：25 Percentile：72.88(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) is procuring all amounts of NbSn conductors for Central Solenoid (CS) in the ITER project. Before start of mass-productions, the conductor should be tested to confirm superconducting performance in the SULTAN facility, Switzerland. The original design of cabling twist pitches is 45-85-145-250-450 mm, called normal twist pitch (NTP). The test results of the conductors with NTP was that current shearing temperature (Tcs) is decreasing due to electro-magnetic (EM) load cycles. On the other hand, the results of the conductors with short twist pitches (STP) of 25-45-80-150-450 mm show that the Tcs is stabilized during EM load cyclic tests. Because the conductors with STP have smaller void fraction, higher compaction ratio during cabling is required and possibility of damage on strands increases. The technology for the cables with STP was developed in Japanese cabling suppliers. The several key technologies will be described in this paper.
Hemmi, Tsutomu; Harjo, S.; Kajitani, Hideki; Nabara, Yoshihiro; Takahashi, Yoshikazu; Nunoya, Yoshihiko; Koizumi, Norikiyo; Abe, Jun; Gong, W.; Aizawa, Kazuya; et al.
KEK Progress Report 2013-4, p.45 - 47, 2013/11
The gradual degradation was observed in the results for ITER CS conductor samples. To investigate its origin, the internal strain in the sample after the testing was successfully measured using a neutron diffraction technique non-destructively. Up to now, the transverse electromagnetic loading has been considered as an origin of the degradation due to the local bending at the high loading side (HLS). However, as a result of the neutron diffraction measurement, the large bending at the LLS of the HFZ was found. The large bending was considered as an origin of the strand buckling due to the large void generated by the transverse electromagnetic loading and the thermally induced residual compressive strain. For the improvement of the conductor performance on the strand buckling, the shorter twisting pitch (STP) can be considered. The result of the SULTAN testing of the conductor sample with STP found very effective, and the performance degradation was negligible.
Sn conductors for ITER toroidal field coils in JapanTakahashi, Yoshikazu; Nabara, Yoshihiro; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Hamada, Kazuya; Matsui, Kunihiro; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.
IEEE Transactions on Applied Superconductivity, 23(3), p.4801504_1 - 4801504_4, 2013/06
Times Cited Count：11 Percentile：50.58(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) is the first to start the mass production of the TF conductors in March 2010 among the 6 parties who are procuring TF conductors in the ITER project. The height and width of the TF coils are 14 m and 9 m, respectively. The conductor is cable-in-conduit conductor (CICC) with a central spiral. A circular multistage superconducting cable is inserted into a circular stainless steel jacket with a thickness of 2 mm. A total of 900 NbSn strands and 522 copper strands are cabled around the central spiral and the cable is inserted into a round-in-round stainless steel jacket. It was observed that the cabling pitch of the destructive sample is longer than the original pitch at cabling. The JAEA carried out the tensile tests of the cable and the measurement of the cable rotation during the insertion to investigate the cause of the elongation. The cause of elongation was clarified and the results will be described in this paper.
Sn conductors for ITER central solenoidsNabara, Yoshihiro; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; Takahashi, Yoshikazu; Matsui, Kunihiro; Koizumi, Norikiyo; et al.
IEEE Transactions on Applied Superconductivity, 23(3), p.4801604_1 - 4801604_4, 2013/06
Times Cited Count：10 Percentile：48(Engineering, Electrical & Electronic)no abstracts in English
Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Koizumi, Norikiyo; Nakajima, Hideo
IEEE Transactions on Applied Superconductivity, 22(3), p.4803804_1 - 4803804_4, 2012/06
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)no abstracts in English
