Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*
Tetsu To Hagane, 107(9), p.760 - 768, 2021/09
Times Cited Count：0 Percentile：0(Metallurgy & Metallurgical Engineering)no abstracts in English
Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*
ISIJ International, 61(4), p.1322 - 1329, 2021/04
Times Cited Count：3 Percentile：25.78(Metallurgy & Metallurgical Engineering)Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*
ISIJ International, 61(4), p.1170 - 1178, 2021/04
Times Cited Count：3 Percentile：25.78(Metallurgy & Metallurgical Engineering)Hojo, Tomohiko*; Akiyama, Eiji*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Kinugasa, Junichiro*; Yuse, Fumio*
Corrosion Science, 177, p.108957_1 - 108957_9, 2020/12
Times Cited Count：18 Percentile：76.44(Materials Science, Multidisciplinary)Hydrogen assisted cracking on hemispherically-stretch-formed specimens of transformation induced plasticity-aided martensitic steel was investigated. Hydrogen charging induced cracking around the foot of the impression formed on the steel sheet, and the cracks propagated along the radial direction toward the hillside and the plains. Distributions of stress, plastic strain and volume fraction of retained austenite were analyzed employing the energy-dispersive X-ray diffraction method utilizing the synchrotron X-ray radiation at SPring-8. It was notable that the crack initiation took place in the region where the measured tensile stress was the highest. Influences of plastic strain and resulted martensitic transformation were also suggested.
Hojo, Tomohiko*; Kumai, B.*; Koyama, Motomichi*; Akiyama, Eiji*; Waki, Hiroyuki*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Nagasawa, Akihiko*
International Journal of Fracture, 224(2), p.253 - 260, 2020/08
Times Cited Count：14 Percentile：67.28(Materials Science, Multidisciplinary)In the study, the pre-strain effect on hydrogen embrittlement property of the ultra-high-strength transformation-induced plasticity -aided bainitic ferrite steel was investigated towards application for automobile frame parts. 3-10% tensile pre-strain suppressed hydrogen-induced mechanical degradation relative to total elongation while 12-15% pre-strained specimen did not exhibit elongation after hydrogen charging. The advantageous effect of the 3-10% pre-strain was attributed to the suppression of crack initiation related to retained austenite. The TRIP by pre-straining decreased the volume fraction of retained austenite before hydrogen charging, thereby reducing existing probabilities of preferential crack initiation sites and propagation paths. Conversely, high pre-strain such as 12-15% does not effectively work due to work hardening resulting in increases in hydrogen embrittlement susceptibility and a significant increase in hydrogen content due to the multiplication of dislocations.
Akita, Koichi; Nakatani, Hayato*; Ogihara, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Igawa, Naoki; Shimojo, Yutaka
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 6(1), p.105 - 108, 2018/01
no abstracts in English
Jo, Takahisa; Goto, Takehiro; Yabuki, Kentaro; Ikegami, Kazunori; Miyagawa, Takayuki; Mori, Tetsuya; Kubo, Atsuhiko; Kitano, Akihiro; Nakagawa, Hiroki; Kawamura, Yoshiaki; et al.
JAEA-Technology 2010-052, 84 Pages, 2011/03
JAEA-Technology-2010-052.pdf:17.14MB
The prototype fast breeder reactor MONJU resumed the System Startup Test (SST) on May 6th 2010 after five months and fourteen years shutdown since the sodium leakage of the secondary heat transport system on December 1995. Core Confirmation Test (CCT) is the first step of SST, which consists of three steps. CCT was finished on July 22nd after 78 days tests. CCT is composed 20 test items including control rods' worth evaluation, radiation dose measurement etc..
Goto, Takehiro; Tsushima, Hiroyuki; Sakurai, Naoto; Jo, Takahisa
Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 13 Pages, 2006/07
MONJU is a prototype fast breeder reactor. Modification work commenced in March 2005. Since June 2004, MONJU has changed one-loop operation of the primary heat transport system with all of the secondary heat transport systems drained of sodium. Purposes of this change are to shorten the modification period and to reduce the cost incurred for circuit trace heating electrical consumption. Before changing condition, the following issues were investigated to show that this mode of operation was possible. The heat loss from the reactor vessel and the single primary loop must exceed the reactor core decay heat by an acceptable margin but the capacity of the preheater to keep the sodium within the primary vessel at about 200
C must be maintained. With regard to heat loss and core decay heat, the estimated heat loss in the primary system was in the range of 90-170kW in one-loop operation, and the calculated reactor decay heat was 21.2kW. Although the heat input of the primary pump was considered, it was clear that circuit heat loss greatly exceeded the core decay heat. As for the preheater, effective capacity was less than the heat loss. Therefore, the temperature of the reactor vessel room was raised to reduce the heat loss. One-loop operation of the primary heat transport system was able to be executed by means of these measures. The cost of electrical consumption in the power plant has been reduced by one-loop operation of the primary heat transport system. The modification period was shortened.
Morizono, Koji; Rekimoto, Masafumi; Jo, Takahisa; Miyakawa, Akira
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10
The construction program of the prototype FBR MONJU which has suspended since the sodium leak accident in 1995 has recently restarted and is under construction to implement various improvements. The test run program following the reconstruction work could roughly divided into two phases of Function test and System start-up test (SST). The requirements, test items and the schedule of the function test program of MONJU have been discussed.
Power up test(40% power)Miyakawa, Akira; Hattori, Kazuhiro; Jo, Takahisa
JNC TN2410 2005-002, 278 Pages, 2005/07
JNC-TN2410-2005-002.pdf:30.04MB
In December, 1992, the performance tests (System Startup Tests; SST) of Monju had been started after the integrated function tests. However, coolant leakage in secondary heat transport system occurred at 8th December, 1995. And so, the performance test was interrupted at the stage of the plant output about 40%. Then, it is also in a plant stop state now.In SST, the plant data was measured in all each stage of reactor power from fuel loading to rated power. And, based on the measurement data, the check of the system performance, the evaluation of appropriate design, and the consolidation of the measurement data for future etc. were carried out. There were about 130 test items in SST, 2/3 items of total were indispensable to starting of a plant (these are equivalent to starting test items of LWR), 1/3 items were R&D. Here, summary of past performance test result are organized.
Ito, Keisuke; Kawahara, Hirotaka; Mori, Takero; Jo, Takahisa; Ariyoshi, Masahiko; Isozaki, Kazunori
JNC TN9410 2005-008, 267 Pages, 2005/03
JNC-TN9410-2005-008.pdf:108.4MB
Control characteristic tests of reactor coolant temperature control system were carried out to confirm its controlling constant to make MK-III hear transport system control stably, and stability against actual disturbance to the plant. The control characteristic test consists of three kinds of tests. As a result, the optimum PI parameters of the reactor coolant temperature control system was confirmed that the proportional gain is between from 0.36 to 1.12(approximately half of MK-II), the integral time is 80 respectively. The gain margin of the control system was between from 7 to 19dB of through the vane opening range.
Kawahara, Hirotaka; Rekimoto, Masafumi; Jo, Takahisa; Ishida, Koichi; Ariyoshi, Masahiko; Isozaki, Kazunori
JNC TN9410 2005-002, 135 Pages, 2005/02
JNC-TN9410-2005-002.pdf:17.48MB
The manual shutdown tests and loss of electric power supply tests were carried out as the transient response test on anomaly condition at 70MWt and 140MWt operation. The decay heat removal tests by main cooling system were carried out after each transient response tests. It was confirmed that the plant protection system operates properly and the reactor can be shut down safely. These results confirmed that the thermal transients are less severe than the design conditions.
Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Hayashi, Nobuhiko; Urata, Kazuhiro*; Miura, Yushi; Kizu, Kaname; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Kudo, Yusuke; et al.
Plasma Science and Technology, 6(1), p.2141 - 2150, 2004/02
Times Cited Count：2 Percentile：6.49(Physics, Fluids & Plasmas)The dominant issue for the the modification program of JT-60 (JT-60SC) is to demonstrate the steady state reactor relevant plasma operation. Physics design on plasma parameters, operation scenarios, and the plasma control method are investigated for the achievement of high-
. Engineering design and the R&D on the superconducting magnet coils, radiation shield, and vacuum vessel are performed. Recent progress in such physics and technology developments is presented.
Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Chujo, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.
Nuclear Fusion, 43(7), p.606 - 613, 2003/07
no abstracts in English
Yamada, Fumiaki; Kimura, Koichi; Jo, Takahisa; Mori, Takero; Morizono, Koji; Tamayama, Kiyoshi; Miyakawa, Akira
no journal, ,
In this report that development plan of Monju plant dynamics analysis code.
Shobu, Takahisa; Tojo, Senta*; Suzuki, Junzo*; Sakaguchi, Yoshiki*
no journal, ,
no abstracts in English
Shobu, Takahisa; Tojo, Senta*; Suzuki, Junzo*; Sakaguchi, Yoshiki*
no journal, ,
Xu, P. G.; Morooka, Satoshi; Gong, W.; Suzuki, Tetsuya*; Harjo, S.; Shobu, Takahisa
no journal, ,
Xu, P. G.; Iwamoto, Chihiro*; Takamura, Masato*; Otake, Yoshie*; Kurihara, Ryo*; Ueno, Kota*; Kataoka, Minami*; Yamamoto, Kazuyoshi; Harjo, S.; Shobu, Takahisa
no journal, ,
Sato, Masami; Jo, Takahisa
no journal, ,
no abstracts in English
