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Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.
JAEA-Technology 2011-031, 123 Pages, 2012/01
JAEA-Technology-2011-031.pdf:16.08MB
The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.
Ide, Hiroshi; Kimura, Akihiro; Miura, Hiroshi; Nagao, Yoshiharu; Hori, Naohiko; Kaminaga, Masanori
Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 10 Pages, 2010/05
Visual observation of inner side of a reactor pressure vessel (RPV) of JMTR was carried out using an underwater camera before the JMTR refurbishment work, because the RPV of the JMTR will be used continuously after restart of the JMTR. As a result of the visual observation, the harmful wound was not confirmed. Moreover, there was no loosening of the bolts and the screws. On the other hand, adhesion materials which can be easily removed were observed in a top closure. A major component of the adhesion materials is an iron as a result of the componential analysis. However, no significant problem affecting the integrity of the RPV was observed, and then the integrity of the RPV was confirmed. From view points of the stress corrosion cracking, fast neutron fluence and fatigue, it became clear that the RPV of the JMTR can be used for more than 20 years. The visual observation by the underwater camera is to be carried out periodically to confirm the integrity of the RPV in future.
Kaminaga, Masanori; Niimi, Motoji; Hori, Naohiko; Takahashi, Kunihiro; Kanno, Masaru; Nakagawa, Tetsuya; Nagao, Yoshiharu; Ishihara, Masahiro; Kawamura, Hiroshi
JAEA-Review 2009-056, 20 Pages, 2010/02
JAEA-Review-2009-056.pdf:8.35MB
The JMTR is a light water moderated and cooled, beryllium reflected tank- type reactor using LUE silicide plate-type fuels. Its thermal power is 50 MW, maximum thermal and fast neutron flux is 4 
10
m
s
. First criticality was achieved in March 1968, and its operation was stopped from August, 2006 for the refurbishment. The refurbishment is scheduled from the beginning of FY2007 to the end of FY2010. The renewed and upgraded JMTR will be re-started from FY2011. An investigation on aged components (aged-investigation) was carried out for concrete structures of the JMTR reactor building, exhaust stack, etc., and for tanks in the primary cooling system, heat exchangers, pipes in the secondary cooling system, cooling tower, emergency generators and so on, in order to identify their integrity. The aged-investigation was carried out at the beginning of FY2007. As a result, some components were decided to replace from viewpoints of future maintenance and improvement of reliability, and some components or structures were decided to repair. A visual inspection of inner side of the pressure vessel was carried out using an underwater camera in FY2008, and no serious damage was observed. Up to now, refurbishment works are in progress according to the planned schedule. In this paper, current status of JMTR refurbishment project is presented.
Ishihara, Masahiro; Kawamura, Hiroshi; Niimi, Motoji; Kaminaga, Masanori; Hori, Naohiko; Nagao, Yoshiharu
Proceedings of 12th International Group on Research Reactors (12th IGORR) (USB Flash Drive), 10 Pages, 2009/10
The JMTR is a light water cooling tank typed reactor with first criticality in March 1968. The JMTR has been applied to fuel/material irradiation tests for LWRs, HTGR, fusion reactor and RI production. However, the JMTR operation was once stopped at August 2006, and the refurbishment works are now conducting. The reactor facilities will be renewed taking four years from the beginning of FY 2007, and necessary examination and works are carrying out on schedule. The renewed JMTR will be started from FY 2011, and be operated for a period of about 20 years until around FY 2030. The usability improvement of the JMTR, e.g. higher reactor availability-factor, shortening turnaround time to get irradiation results, attractive irradiation cost, business confidence, is also discussing with users as the preparations for re-operation. In the paper, status of the refurbishment of reactor facilities are introduced, moreover the future program using the JMTR will be prescribed.
Hoesch, M.*; Fukuda, Tatsuo; Mizuki, Junichiro; Takenouchi, Tomohiro*; Kawarada, Hiroshi*; Sutter, J. P.*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Nagao, Masanori*; Takano, Yoshihiko*
Physical Review B, 75(14), p.140508_1 - 140508_4, 2007/04
Times Cited Count：35 Percentile：77.49(Materials Science, Multidisciplinary)We observed phonon dispersions using inelastic X-ray scattering from CVD-grown high quality superconducting (
=4.2 K) boron-doped and non-doped diamonds. By comparing these two, we found almost no change in the acoustic branch along both [111] and [001] directions. On the other hand, strong softening were observed in the optical branch of the boron-doped diamond in both directions: about 2 meV at Brillouin zone boundary and 8 meV at zone center (
point). From this result we estimated the electron-phonon coupling factor 
=0.33, and this supports theoretical models suggesting a phonon-mediated pairing mechanism via coupling of optical phonon modes to Fermi surfaces around the point.
Fukuda, Tatsuo; Hoesch, M.*; Takenouchi, Tomohiro*; Sutter, J. P.*; Tsutsui, Satoshi*; Baron, A.*; Nagao, Masanori*; Takano, Yoshihiko*; Kawarada, Hiroshi*; Mizuki, Junichiro
no journal, ,
Diamond is well known for its maximum hardness, large energy gap, high thermal conductivity, and so on. In addition to these, the superconductivity was discovered recently in boron doped (B-doped) diamond, and this was soon confirmed by other groups. We performed inelastic X-ray scattering experiments at BL35XU of SPring-8 to measure phonons in a highly B-doped CVD grown diamond having superconducting transition at 
4.2 K. By comparing the experimental results with those from nitrogen doped CVD grown diamond and/or pure diamond, we found that the optical modes are softened especially at around the Brillouin zone center along with a strong broadening, while the acoustic modes do not show both softening and broadening. This confirms the strong electron-phonon coupling in superconducting diamond.
Nagao, Yoshiharu; Ishihara, Masahiro; Kaminaga, Masanori; Niimi, Motoji; Kawamura, Hiroshi
no journal, ,
no abstracts in English
Imaizumi, Tomomi; Nagao, Yoshiharu; Kaminaga, Masanori; Ishihara, Masahiro
no journal, ,
no abstracts in English
Nagata, Hiroshi; Yamaura, Takayuki; Naka, Michihiro; Kawamata, Kazuo; Izumo, Hironobu; Hori, Naohiko; Nagao, Yoshiharu; Kusunoki, Tsuyoshi; Kaminaga, Masanori; Komori, Yoshihiro; et al.
no journal, ,
Conceptual design of the high-performance and low-cost next generation materials testing reactor which will be assumed to introduce to the nuclear power plant introduction country started from 2010 in the JAEA. Japanese atomic energy-related companies participate in this project, and this activity role as the environmental management and nuclear human resource development for the new research reactor designs. 10 MW thermal power by plate type fuel elements and swimming pool type was assumed as a design base. High safety, high cost performance, high reactor operation rate, high technology irradiation are targets of this conceptual design.
