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Seki, Masakazu; Maekawa, Tomoyuki; Izawa, Kazuhiko; Sono, Hiroki
JAEA-Technology 2017-038, 52 Pages, 2018/03
JAEA-Technology-2017-038.pdf:4.6MB
The Japan Atomic Energy Agency is conducting a reactor modification project of the Static Experiment Critical Facility (STACY). In the modification, STACY is to be converted from a thermal reactor using solution fuel into that using fuel rods and light water moderator. Reactivity of the modified STACY core is controlled by the water level fed in the core tank as well as the present STACY. In order to verify the basic design of the water feed and drain system of the modified STACY, we constructed a mockup test apparatus with almost the same structure and specifications as the modified STACY. In the mockup test, performance checks were pursued regarding limitation of maximum flow of water feeding, adjustment of the flow rate of water feeding, stop of water feeding and others. This report describes the outline and results of the mock-up test of the water feed and drain system of the modified STACY.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Hatayama, Akiyoshi*; Shibata, Takanori*; Yamamoto, Takashi*; Akino, Noboru; Endo, Yasuei; et al.
Fusion Engineering and Design, 96-97, p.616 - 619, 2015/10
Times Cited Count：11 Percentile：67.3(Nuclear Science & Technology)In JT-60 Super Advanced for the fusion experiment, 22A, 100s negative ions are designed to be extracted from the world largest ion extraction area of 450 mm 
1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The original tent-shaped filter significantly improved the logitudunal uniformity of the extracted H
ion beams. The logitudinal uniform areas within a 
10 deviation of the beam intensity were improved from 45% to 70% of the ion extraction area. However, this improvement degrades a horizontal uniformity. For this, the uniform areas was no more than 55% of the total ion extraction area. In order to improve the horizontal uniformity, the filter strength has been reduced from 660 Gasus
cm to 400 Gasuscm. This reduction improved the horizontal uniform area from 75% to 90% without degrading the logitudinal uniformity. This resulted in the improvement of the uniform area from 45% of the total ion extraction areas. This improvement of the uniform area leads to the production of a 22A H ion beam from 450 mm 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.
Kojima, Atsushi; Umeda, Naotaka; Hanada, Masaya; Yoshida, Masafumi; Kashiwagi, Mieko; Tobari, Hiroyuki; Watanabe, Kazuhiro; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; et al.
Nuclear Fusion, 55(6), p.063006_1 - 063006_9, 2015/06
Times Cited Count：41 Percentile：89.45(Physics, Fluids & Plasmas)Significant progresses in the extension of pulse durations of powerful negative ion beams have been made to realize the neutral beam injectors for JT-60SA and ITER. In order to overcome common issues of the long pulse production/acceleration of negative ion beams in JT-60SA and ITER, the new technologies have been developed in the JT-60SA ion source and the MeV accelerator in Japan Atomic Energy Agency. As for the long pulse production of high-current negative ions for JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies the required pulse duration of 100 s and 70% of the rated beam current for JT-60SA. This progress was based on the R&D efforts for the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. Moreover, the each parameter of the required beam energy, current and pulse has been achieved individually by these R&D efforts. The developed techniques are useful to design the ITER ion source because the sustainment of the cesium coverage in large extraction area is one of the common issues between JT-60SA and ITER. As for the long pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 orders of magnitude by modifying the extraction grid with a high cooling capability and a high-transmission of negative ions. A long pulse acceleration of 60 s has been achieved at 70 MW/m
(683 keV, 100 A/m) which has reached to the power density of JT-60SA level of 65 MW/m.
Takada, Shoji; Shimizu, Atsushi; Kondo, Makoto; Shimazaki, Yosuke; Shinohara, Masanori; Seki, Tomokazu; Tochio, Daisuke; Iigaki, Kazuhiko; Nakagawa, Shigeaki; Sawa, Kazuhiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05
In the loss of forced core cooling test using High Temperature engineering Test Reactor (HTTR), the forced cooling of reactor core is stopped without inserting control rods into the core and cooling by Vessel Cooling System (VCS) to demonstrate the inherent safety of HTGR be secured by natural phenomena to make it possible to design a severe accident free reactor. In the test, the local temperature was supposed to exceed the limit from the viewpoint of long-term use at the uncovered water cooling tube by thermal reflectors in the VCS, although the safety of reactor is kept. The local higher temperature position was specified although the temperature was sufficiently lower than the maximum allowable working temperature, and natural circulation of water had insufficient cooling effect on the temperature of water cooling tube below 1
C. Then, a new safe and secured procedure for the loss of forced core cooling test was established, which will be carried out soon after the restart of HTTR.
Seki, Masakazu; Izawa, Kazuhiko; Sono, Hiroki
JAEA-Technology 2014-047, 22 Pages, 2015/03
JAEA-Technology-2014-047.pdf:2.33MB
The Japan Atomic Energy Agency is conducting a reactor modification project of the Static Experiment Critical Facility (STACY). In the modification, STACY is to be converted from a thermal reactor using solution fuel into that using fuel rods and light water moderator. Reactivity of the modified STACY is controlled by the water level fed in the core tank as well as the present STACY. Regarding water level detection, however, a float-type water-feed-stop switch is adopted in the modified STACY because the electro-conductivity-type switch of the present STACY for uranyl nitrate solution cannot detect demineralized water used in the modified STACY. For safety operation of the modified STACY, the float-type switch needs accurate and reliable detection of water level at any temperature. This report describes a mock-up test on accuracy verification of the float-type water-feed-stop switch in whole range of water temperature (room temperature 
70C) in the modified STACY operation.
Akino, Noboru; Endo, Yasuei; Hanada, Masaya; Kawai, Mikito*; Kazawa, Minoru; Kikuchi, Katsumi*; Kojima, Atsushi; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; et al.
JAEA-Technology 2014-042, 73 Pages, 2015/02
JAEA-Technology-2014-042.pdf:15.1MB
According to the project plan of JT-60 Super Advanced that is implemented as an international project between Japan and Europe, the neutral beam (NB) injectors have been disassembled. The disassembly of the NB injectors started in November, 2009 and finished in January, 2012 without any serious problems as scheduled. This reports the disassembly activities of the NB injectors.
Takada, Shoji; Shinohara, Masanori; Seki, Tomokazu; Shimazaki, Yosuke; Ono, Masato; Tochio, Daisuke; Iigaki, Kazuhiko; Sawa, Kazuhiro
JAEA-Technology 2014-001, 34 Pages, 2014/03
JAEA-Technology-2014-001.pdf:4.46MB
The loss of forced cooling with vessel cooling system inactive has been planned by using HTTR at the reactor power 9 MW. In this test, the forced cooling of reactor core is lost and the vessel cooling system which removes decay heat from core is tripped. In the test, the technical items such that the temperature of water cooling tubes is expected to be higher are considered. The methods to solve such technical items were proposed. The proposed methods were verified based on the test data of the cold test toward the proposal of test plan of safety demonstration test. In the cold test, the two water trains of vessel cooling system was tripped under the condition that the reactor was heated up without nuclear heating. The reactor inlet temperature was set at 120 and 150C.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; et al.
Review of Scientific Instruments, 85(2), p.02B314_1 - 02B314_4, 2014/02
Times Cited Count：14 Percentile：50.88(Instruments & Instrumentation)Non-uniformity of the negative ion beams in the JT-60 negative ion source was improved by modifying an external magnetic field to a tent-shaped magnetic field for reduction of the local heat loads in the source. Distributions of the source plasmas (H
ions and H
atoms) of the parents of H ions converted on the cesium covered plasma grids were measured by Langmuir probes and emission spectroscopy. Beam intensities of the H ions extracted from the plasma grids were measured by IR camera from the back of the beam target plate. The tent-shaped magnetic field prevented the source plasmas to be localized by B grad B drift of the primary electrons emitted from the filaments in the arc chamber. As a result, standard derivation of the H ions beams was reduced from 14% (the external magnetic field) to 10% (the tent-shaped magnetic field) without reduction of an activity of the H ion production.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.
Plasma and Fusion Research (Internet), 8(Sp.1), p.2405146_1 - 2405146_4, 2013/11
Distributions of H and H in the source plasmas produced at the end-plugs of JT-60 negative ions source were measured by Langmuir probes and emission spectroscopy in order to experimentally investigate the cause of lower density of the negative ions extracted from end-plugs in the source. Densities of H and H in end-plugs of the plasma grid in the source were compared with those in the center regions. As a result, lower density of the negative ion at the edge was caused by lower beam optics due to lower and higher density of the H and H.
Seki, Masayuki; Kihara, Yoshiyuki; Kaito, Takeji; Tsukada, Tatsuya*; Motoki, Kazuhiko*; Hirako, Kazuhito*
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12
Oxide Dispersion Strengthened (ODS) steel has been developed as an advanced fuel cladding tube for sodium cooled fast reactors in Japan Atomic Energy Agency (JAEA) to attain the target burn up of 150 GWd/t in the bundle average because of its excellent swelling resistance and high mechanical strength in high temperature. If conventional TIG welding is applied to the ODS welding, it is difficult to obtain necessary mechanical strength at the weld zone because of the formation of porosity. It is formed by the argon bubbles which initially dissolve in the matrix and grow up under the high temperature during welding. Therefore JAEA has been conducted the development of pressurized resistance welding (PRW) technology for ODS cladding tube, which is one of the solid state welding methods. This paper describes in the development of PRW technology, an ultrasonic test method for detecting weld defects, the result of machine strength measurement examination in weld part and the result of fuel pin irradiation examination using nuclear reactor.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08
Times Cited Count：51 Percentile：88.4(Physics, Fluids & Plasmas)Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.
-iodobiphenyl molecular crystal on GeS(001)Sumii, Ryohei*; Sakamaki, Masako*; Matsumoto, Yoshihiro; Amemiya, Kenta*; Kanai, Kaname*; Seki, Kazuhiko*
Surface Science, 604(13-14), p.1100 - 1104, 2010/07
Times Cited Count：3 Percentile：17.17(Chemistry, Physical)Izawa, Kazuhiko; Seki, Masakazu; Hirose, Hideyuki; Kaminaga, Jota; Aoyama, Yasuo; Yoshida, Hiroshi; Sono, Hiroki; Ogawa, Kazuhiko; Sakuraba, Koichi
UTNL-R-0453, p.9_1 - 9_10, 2006/03
no abstracts in English
Kihara, Yoshiyuki; Seki, Masayuki; Fujio, Ishibashi,; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2005-002, 27 Pages, 2005/07
JNC-TN8430-2005-002.pdf:32.93MB
The irradiation test to gather the creep rupture data of the MARICO-2 test pieces manufactured from Oxide Dispersion Strengthened steel (ODS steel) cladding tube in JFY 2004. Therefore, to improve the reliability of the strength evaluation of the ODS steel cladding tube, it was planned to supplement the creep rupture data in that had been obtained so far. The strength evaluation test pieces supplied to this examination was manufactured by the request of the JNC OEC system nuclear fuel engineering group. This test pieces were manufactured by using Martensitic ODS and Ferritic ODS as well as MARICO-2 and CMIR-6. The specification of the test piece was same as two steel types. The problem did not occur for manufacturing the test pieces (20 pices of Martensitic ODS and 12 pices of Ferritic ODS) from April 5, 2005 to May 13, 2005. It was provided for JNC OEC System Division nuclear fuel group at the May, 2005.
Seki, Masayuki; Ishibashi, Fujio; Kihara, Yoshiyuki; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2004-003, 78 Pages, 2005/03
JNC-TN8430-2004-003.pdf:61.9MB
Irradiation test in BOR-60 at RIAR to judge practical use prospect of ODS cladding tube at early stage is planned as Japan-Russia a joint research. Irradiation test is done for five years from June, 2003 aiming at burn-up 15at%.The first stage irradiation test was achieved target burn-up 5at% in May, 2004.The second stage irradiation test begins in May, 2005. JNC Tokai welded martensitic ODS cladding tube and upper endplug by pressurizing resistance welding, and inspected, it was transported to RIAR. As well as last time, Use of long scale cladding tube caused problem that bending transformation occurred in cladding tube by welding pressure. However, we solved this problem by adopted a changeable pressurizing system. This system can suppress the transformation of the cladding tube because it can set the pressurizing power when beginning to connect it low. Manufacturing was enabled by using this system. A permissible value of the welding condition was expanded by having adopted the changeable pressurizing system, it has a advantage for the design of the hot device. The cladding tubes with upper endplug passed the inspection by OEC on 15 December 2004 were shipped on 13 January 2005 for RIAR.
Seki, Masayuki; Ishibashi, Fujio; Kihara, Yoshiyuki; Tsukada, Tatsuya*; Hirako, Kazuhiko*
JNC TN8430 2004-002, 49 Pages, 2005/03
JNC-TN8430-2004-002.pdf:72.34MB
The irradiation test by MARICO-2 and CMIR-6 is planned aiming to the irradiation characteristic of ODS cladding tube. The test pieces of MARICO-2 and CMIR-6 were manufactured by using Martensitic ODS cladding tube and Ferritic ODS cladding tube. The specification of the test pieces was same as two steel type. The test pieces of Martensitic ODS were manufactured from February 19, 2004 to March 11, 2004.(MARICO-2:38test pieces (in clueded 11pieces reserve and QA sample) and CMIR-6:6 test pieces). The test pieces of Ferritic ODS was manufactured from August 17, 2004 and September 22, 2004.(MARICO-2:32test pieces(in clueded 11pieces reserve and QA sample) and CMIR-6:6 test pieces). The problem did not occur for manufacturing the test pieces. Martensitic ODS test pieces was provided for JNC OEC System Division Nuclear fuel group at the May 2004 and Ferritic ODS test pieces was provided for JNC OEC System Division Nuclear fuel group at the October 2004.
Ebisawa, Noboru; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Seki, Norikazu*; Oga, Tokumichi; Ikeda, Yoshitaka
Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03
no abstracts in English
Seki, Masayuki; Kono, Shusaku; Kihara, Yoshiyuki; Kaito, Takeji; Ukai, Shigeharu; Hirako, Kazuhiko*
Journal of Nuclear Materials, 329-333, p.1534 - 1538, 2004/00
Times Cited Count：33 Percentile：87.58(Materials Science, Multidisciplinary)Welding technology for fuel cladding and end-plugs made of ODS steel has been developed to apply for the fast reactor fuel pin fabrication at Tokai-works of JNC. A pressurized resistance welding (PRW) method is utilized as solid phase welding. The method is based on electrical resistance heating of the components while maintaining a continuous force sufficient to forge weld without melting of the components. The contact force between cladding and end-plug is given by pneumatic-hydraulic system. The welding parameters, e.g. electric current, voltage and contact force, are controlled by a programmable system. The appropriate conditions are selected to be a 700 Kgf contact load with 16 kA current for 20 ms after holding for pre-heating by 6 kA current. For relieving the residual stress, the post-welded heat-treatment is performed in the condition of tempering at 1053 K for 10 min. A metallugically bonded welds has been formed by the PRW method, keeping the original dispersed distributio
Kono, Shusaku; Seki, Masayuki; Fujio, Ishibashi,; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2003-010, 28 Pages, 2003/07
JNC-TN8430-2003-010.pdf:2.18MB
The defect occurred at the resistance welding zone is very minute and therefore cannot be identified by X-ray inspection. Then, the ultrasonic examination method, in which the resolution of the defect is higher than that of the X-ray inspection method, has been developed. The ultrasonic wave sounds straight easier in the material than X rays, excels in defecting the micro defect. However, the pulse amplitude of ultrasonic wave is influenced by the shape and direction of the defect. Then, the ultrasonic inspection equipement, in which the ultrasonic probe and the sample rotation axis are controlled to drive with the pulse motor and the defect data (position and size)are analized by image processing ultrasonic signal, was developed to measure the shape and the position of defect accurately. However, an ultrasonic examination method is the comparative inspection method. Therefore, the standard test block or the reference block is indispensable to guarantee the defectability and the ultrasonic echo sensibility of the inspection device. The standard test block is provided in JIS etc, it is needed to defect the peculiar defect occurred at the resistance welding zone. Then, the method of processing a standard test block is examined, the standard test block was made experimentally by electric discharge processing and diffusion junction method. The ultrasonic echo sensitivity and the threshold for image processing were proofread by using the standard test block, the ultrasonic inspection and metallographic inspection were executed. Comparing the ultrasonic inspection results with the metallographic inspection results, the detectability of defect depth and the measurement accuracy were proved to be 3
m and with errors less than 10m respectively. From these results, the effectireness of proofreading the ultrasonic inspection condition by the standard test block was confirmed. Moreover, it was confirmed that there was a peculiar relationship between the depth ...
