Collaborative Laboratories for Advanced Decommissioning Science; Keio University*
JAEA-Review 2020-047, 63 Pages, 2021/01
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2019, this report summarizes the research results of the "Study of corrosion and degradation of the objects in the nuclear reactor by microorganisms" conducted in FY2019.
Takada, Hiroshi; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 28, p.081003_1 - 081003_7, 2020/02
At the Japan Proton Accelerator Research Complex (J-PARC), the pulsed spallation neutron source has been in operation with a redesigned mercury target vessel from October 2017 to July 2018, during which the operational beam power was restored to 500 kW and the operation with a 1-MW equivalent beam was demonstrated for one hour. The target vessel includes a gas-micro-bubbles injector and a 2-mm-wide narrow mercury flow channel at the front end as measures to suppress the cavitation damage. After the operating period, it was observed that the cavitation damage at the 3-mm-thick front end of the target vessel could be suppressed less than 17.5 m.
Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Furukawa, Masato; Natsume, Kyohei; Tsuchiya, Katsuhiko; Kamiya, Koji; Koide, Yoshihiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4201305_1 - 4201305_5, 2015/06
JT-60U magnet system will be upgraded to the superconducting coils in the JT-60SA programme of the Broader Approach activities. Terminal joint of Central Solenoid (CS) is wrap type NbSn-NbTi joint used for connecting CS (NbSn) and current feeder (NbTi). The terminal joints are placed at the top and the bottom of the CS systems. CS modules located at middle position of CS system need the lead extension from the modules to the terminal joint. The joint resistance measurement of terminal joint was performed in the test facility of National Institute for Fusion Science. The joint resistance was evaluated by the operating current and the voltage between both ends of the terminal joint part. Test results met the requirement of JT-60SA magnet system. The structural analysis of the lead extension and its support structure was conducted to confirm the support design. In this paper, the results of resistance test of joint and the structural analysis results of lead extension are reported.
Rouault, J.*; Le Coz, P.*; Garnier, J.-C.*; Hamy, J.-M.*; Hayafune, Hiroki; Iitsuka, Toru*; Mochida, Haruo*
Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.832 - 837, 2015/05
The French and international industrial partners already joined the project from 2010 to 2013 and many others are also effective in the Research and Development in support of ASTRID. A new partnership is now effective on both topics with Japan. This collaboration on the ASTRID Program and Sodium Fast Reactor is now fully integrated in the ASTRID program organization. In addition a specific Joint Team, CEA, AREVA, JAEA, MHI and MFBR, has been created to follow specifically Japanese contribution and develop evaluations of a common interest to orientate future work and contribute to ASTRID options confirmation and be of an interest for the future Japanese Fast Breeder reactor.
Takahashi, Hiroyuki*; Kudo, Yusuke; Tsuchiya, Katsuhiko; Kizu, Kaname; Ando, Toshinari*; Matsukawa, Makoto; Tamai, Hiroshi; Miura, Yukitoshi
Fusion Engineering and Design, 81(8-14), p.1005 - 1011, 2006/02
This paper presents dependence of the stress intensity factor, around the defect in the butt joint welding of a superconducting conductor conduit, on a geometrical factor estimated by fracture mechanics analysis. The stress intensity factor can be estimated by the Newman-Raju equation about CICC section, but the effect of the difference between the geometry assumed in the equation and CICC has not been clarified yet. Therefore, the three-dimensional finite element method (3D-FEM) is performed to estimate the geometrical factor. As a result, the Newman-Raju equation is considered to be available for the assessment of the fracture toughness of the conduit of rectangular shape because the maximum stress intensity factor by 3-D FEM is only 3% larger than that by the Newman-Raju equation in the maximum postulated defect.
JAERI-Research 2005-030, 182 Pages, 2005/09
It is difficult for Vacuum Vessel (VV) of ITER to apply a non-destructive in-service inspection (ISI) and then new safety concept is needed. Present fabrication standards are not applicable to the VV, because the access is limited to the backside of closure weld of double wall. Fabrication tolerance of VV is 5mm even the structure is huge as high as 10m. This accuracy requires a rational method on the estimation of welding deformation. In this report, an inherent safety feature of the tokamak is proved closing up a special characteristic of termination of fusion reaction due to tiny water leak. A rational concept not to require ISI without sacrificing safety is shown based on this result. A partial penetration T-welded joint is proposed to establish a rational fabrication method of double wall. Strength and susceptibility to crevice corrosion is evaluated for this joint and feasibility is confirmed. A rational method of estimation of welding deformation for large and complex structure is proposed and the efficiency is shown by comparing analysis experimental results of full-scale test.
Journal of Nuclear Materials, 329-333(Part2), p.1567 - 1570, 2004/08
Elastic-plastic finite element analysis was performed for low cycle fatigue behavior of stainless steel/alumina-dispersion-strengthened copper (DS Cu) joint in order to investigate the fatigue life and the fracture behavior of the joint. As the results, a strain concentration was occurred near the interface of DS Cu for small strain range, however, in the DS Cu for large strain range. The fatigue life and fracture point were evaluated taking account for the strain concentration. The fatigue life and fracture point were consistent with those of the low cycle fatigue test.
Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*; Bessette, D.*; Nunoya, Yoshihiko; Matsui, Kunihiro; Koizumi, Norikiyo; Isono, Takaaki; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 14(2), p.1410 - 1413, 2004/06
Cable-in-conduit conductors that consist of about 1,000 NbSn strands with an outer diameter of about 0.8mm, have been designed for the TF and CS coils of the ITER. The rated current of these coils is 40 -68kA. Two joint types (Butt and Lap) were developed during the CS Model Coil project. The performance of these joints was evaluated during the operating tests and the satisfied results were obtained. The joints of the TF coils are located outside of the winding in a region where the magnetic field is about 2.1T, a very low value as compared to the maximum field of 11.8T at the winding. The CS joints are located at the coil outer diameter and embedded within the winding pack due to the lack of the space. The maximum fields at the CS joint and winding are 3.5 and 13T, respectively. For the TF coils and the CS, the joints are cooled in series with the conductor at the outlet. The maximum temperature increase due to the joule heating in the joints is set at 0.15K to limit the heat load on the refrigerator. It is shown that both joint types are applicable to the ITER coils.
Committee for the Joint Research Project between JAERI and Universities; Committee for the Universities' JAERI Collaborative Research
JAERI-Conf 2003-015, 103 Pages, 2003/11
The present report describes the Proceedings of the Symposium on the Joint Research Project between JAERI and Universities - Results of the 4th Phase Joint Research Project and the Future Plan -, held at the University of Tokyo on February 18, 2003. The joint research project composed of the backend chemistry project and the advanced radiation application project was to be concluded in the end of March 2003. Hence the symposium was held in order to review the results obtained in the 4th phase project and to exchange ideas on the effective measures for the future joint collaboration in view of the past activities.
Journal of Nuclear Science and Technology, 40(9), p.687 - 694, 2003/09
The ITER vacuum vessel is a double-walled torus with large-sized quadrilateral ports and is required to provide a quite high degree of vacuum for deutrium - tritium fusion reaction. The vacuum vessel is required to install after assembled with toroidal field coils. From a radiological safety aspect, the vacuum vessel is functioned as a physical barrier to enclose radioactive materials. Therefore, construction of the vacuum vessel needs application of newly developed technologies on design, fabrication and examination. The technologies include design approach by finite element analysis, and partial penetration T welded joints to join ribs to outer shell. Several issues have to be resolved for applying those technologies to the vacuum vessel. This paper describes several newly developed technologies and key issues for applying to the vacuum vessel and then their resolutions.
Committee for the Joint Research Project on Backend Chemistry; Committee for the Collaborative Research on the Advanced Radiation Technology
JAERI-Review 2003-001, 97 Pages, 2003/02
no abstracts in English
AIP Conference Proceedings 680, p.229 - 236, 2003/00
JAERI and KEK-Institute of Particle and Nuclear Studies are collabarating to build an ISOL-type radioactive ion beam(RIB) acceleration system in the JAERI-Tokai tandem accelerator lab. In this project, the tandem accelerator is used as a proton beam driver to create RIB from fission products of a uranium target and a RIB accelerator already built by KEK will be installed in an old target room of the tandem accelerator lab. The beam energy is 1.1 MeV/nucleon, which is not sufficient for experiments related to nuclear reactions. They have a plan to boost the beams to 5 - 9 MeV/u by developing a pre-booster and using existing super-conducting tandem-booster. The plan of this project, acceleration divices and present status will be outlined in the RIB session of the CAARI.
Ezato, Koichiro; Dairaku, Masayuki; Taniguchi, Masaki; Sato, Kazuyoshi; Akiba, Masato
Journal of Nuclear Materials, 307-311(Part1), p.144 - 148, 2002/12
no abstracts in English
Suzuki, Takayuki*; Usami, Saburo*; Kimura, Takae*; Koizumi, Koichi; Nakahira, Masataka; Takahashi, Hiroyuki*
Proceedings of 55th Annual Assembly of International Institute of Welding (IIW2002), 16 Pages, 2002/06
A new type of welded joint for the outer wall and rib of a double-walled vacuum vessel of a fusion reactor has been developed. The joint is manufactured by through-wall electron-beam welding (TW-EBW), in which the beam is injected from the outside of the outer wall. Static and fatigue tests are carried out on one-bead-specimens under an axial load and two-bead-specimens under a bending load. The experimental results are analytically investigated by FEM. Although this joint is partially penetrated, the net yield strength of the bead is increased by the plastic constraint due to triaxial tensile stress in the weldment. This phenomenon reduces the mean equivalent stress on the bead cross section, and the gross strength of the joint is close to that of a full thickness welded joint. The fatigue-strength reduction factor for low-cycle fatigue life is a little larger than four. The calculated fatigue-crack growth rate in the joint is conservatively calculated by using the maximum stress intensity factor of the crack and the fatigue-crack growth rate given in ASME Code Section XI.
Nakahira, Masataka; Takeda, Nobukazu; Hada, Kazuhiko; Tada, Eisuke; Miya, Kenzo*; Asada, Yasuhide*
Proceedings of 10th International Conference on Nuclear Engineering (ICONE 10) (CD-ROM), 7 Pages, 2002/04
The special features of Vacuum Vessel (VV) of International Thermonuclear Experimental Reactor (ITER) are complicated structure and electromagnetic load. The VV is torus shaped, double-walled structure with ribs. The electromagnetic force is not uniform. Thus the rules for axisymmetric structures and loading are not effective for ITER VV. The double ミwalled structure requires one-sided welding joints with no possibility of access from the other side. Every joints between outer wall and rib and field joints are this type. The joint between outer wall and rib is special T-joint with partial penetration. To cover these special issues on ITER VV, a new code is under development. Supporting R&Ds are planned to be material tests to obtain joint efficiency and fatigue reduction factor, UT sensitivity tests, sensitivity tests on crevice corrosion and examination-free welding for application to field joints. This paper describes the special features of ITER VV from code stand point, concept of new code and R&Ds to apply the new code to ITER VV.
Zhang, F.; Watanabe, Yasuhiro; Koseki, Shoichiro*; Tani, Norio; Adachi, Toshikazu*; Someya, Hirohiko*
JAERI-Tech 2002-039, 21 Pages, 2002/03
The 3 GeV Proton RCS of the JAERI-KEK Joint Project is a 25 Hz separate-function rapid cycling synchrotron under design. Bending magnets (BM) and quadrupole magnets (QM) are excited separately. The 3 GeV RCS requests above 10 families of magnets excited independently, far beyond 3 families in practical RCS's. Difficulty of field tracking between BM and QM is significantly increased Magnet strings are grouped into resonant networks and excited resonantly by power supplies driven by a waveform pattern, typically a DC-biased sinusoidal signal. To achieve a close tracking between many families, the driving signal of each power supply should be adjusted in phase and amplitude flexibly and dynamically.This report proposes a signal generator based on VXIbus. The VXIbus, an extension of VMEbus (VME eXtension for Instrument), provides an open architecture with shared process bus and timing. The VXIbus-based signal generator facilitates the timing synchronization and extension to many channels needed by the 3 GeV RCS. Experimental results of the signal generator are reported.
Takahashi, Yoshikazu; Kato, Takashi; Nunoya, Yoshihiko; Ando, Toshinari; Nishijima, Gen; Nakajima, Hideo; Hiyama, Tadao; Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; et al.
Fusion Engineering and Design, 58-59, p.93 - 97, 2001/11
no abstracts in English
JAERI-Conf 2001-012, 116 Pages, 2001/09
The third symposium on Science of Hadrons under Extreme Conditions, organized by the Research Group for Hadron Science, Advanced Science Research Center, was held at Tokai Research Establishment of JAERI on January 29 to 31, 2001. The symposium was devoted for discussions and presentations of research results in wide variety of hadron physics such as nuclear matter, high-energy nuclear reactions, quantum chromodynamics, neutron stars,supernovae, nucleosynthesis as well as finite nuclei to understand various aspects of hadrons under extreme conditions. Twenty two papers on these topics, including a special talk on the present status of JAERI-KEK joint project on high-intentisy proton accelerator, presented at the symposium aroused lively discussions among approximately 40 participants.
Nippon Genshiryoku Gakkai Monte Karuro Ho Ni Yoru Ryushi Shimyureshon No Genjo To Kadai, p.183 - 191, 2001/01
no abstracts in English
Takada, Hiroshi; Meigo, Shinichiro; Niita, Koji*
Advanced Monte Carlo for Radiation Physics, Particle Transport Simulation and Applications, p.949 - 954, 2001/00
no abstracts in English