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Tsuchiya, Kunihiko; Nagao, Yoshiharu
Kinzoku, 86(10), p.893 - 899, 2016/10
no abstracts in English
Nagata, Hiroshi; Inoue, Shuichi; Yamaura, Takayuki; Tsuchiya, Kunihiko; Nagao, Yoshiharu
JAEA-Technology 2013-008, 30 Pages, 2013/06
JAEA-Technology-2013-008.pdf:2.24MB
Refurbishment of JMTR was completed in FY2010. For damage caused by the 2011 off the Pacific coast of Tohoku Earthquake, the repair of facilities was completed in October 2012. Currently, the JMTR is in preparation for restart. Irradiation tests for LWRs safety research, science and technologies, etc. are expected after the JMTR restart. On the other hand, aiming at the attractive irradiation testing reactor, the usability improvement has been discussed. As a part of the usability improvement, shortening of turnaround time was discussed focusing on the fabrication process of irradiation capsules, where the fabrication process was analyzed and reviewed by referring a trial fabrication of the mockup capsule. As a result, it was found that the turnaround time can be shortened 2 months from fabrication period of 6 months with communize of irradiation capsule parts, application of ready-made instrumentation including the sheath heater, reconsideration of inspection process, etc.
Imaizumi, Tomomi; Ide, Hiroshi; Naka, Michihiro; Komukai, Bunsaku; Nagao, Yoshiharu
UTNL-R-0483, p.10_2_1 - 10_2_8, 2013/03
no abstracts in English
Nagata, Hiroshi; Yamaura, Takayuki; Nagao, Yoshiharu
UTNL-R-0483, p.10_3_1 - 10_3_9, 2013/03
no abstracts in English
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.
Takemoto, Noriyuki; Tsuchiya, Kunihiko; Nagao, Yoshiharu; Kitagishi, Shigeru; Naka, Michihiro; Kimura, Akihiro; Sano, Tadafumi*; Unesaki, Hironobu*; Yoshimoto, Takaaki*; Nakajima, Ken*; et al.
KURRI Progress Report 2010, P. 204, 2011/10
no abstracts in English
Ishitsuka, Etsuo; Kitagishi, Shigeru; Aoyama, Masashi; Kawamata, Kazuo; Nagao, Yoshiharu; Ishihara, Masahiro; Kawamura, Hiroshi
Proceedings of 1st Asian Symposium on Material Testing Reactors (ASMTR 2011), p.111 - 115, 2011/02
Tsuchiya, Kunihiko; Kitagishi, Shigeru; Nagao, Yoshiharu; Takemoto, Noriyuki; Naka, Michihiro; Kimura, Akihiro; Sano, Tadafumi*; Unesaki, Hironobu*; Yoshimoto, Takaaki*; Nakajima, Ken*; et al.
KURRI Progress Report 2009, P. 196, 2010/10
no abstracts in English
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.
Imaizumi, Tomomi; Takemoto, Noriyuki; Nagao, Yoshiharu; Kawamura, Hiroshi
JAEA-Review 2009-074, 20 Pages, 2010/03
JAEA-Review-2009-074.pdf:4.11MB
For the neutronic calculation in JMTR, an error of only thermal-neutron-flux tends to extend in specific region, i.e. an irradiation region in beryllium reflectors surrounding the fuel region. From our former investigation, the reason is thought to be the neutron scattering and absorption in the thermal energy region. Therefore, the effect on the thermal neutron scattering law S(
,
) to hydrogen in light water and to beryllium metal was investigated. As a result, it was confirmed that the error could be caused by the treatment in inelastic scattering within coherent scattering in the beryllium metal, whereas no error factor was found to the hydrogen in light water.
Ide, Hiroshi; Kimura, Akihiro; Miura, Hiroshi; Hori, Naohiko; Nagao, Yoshiharu
JAEA-Technology 2009-067, 39 Pages, 2010/02
JAEA-Technology-2009-067.pdf:13.1MB
Visual inspection of inner side of a reactor pressure vessel was carried out using a underwater camera before the JMTR refurbishment work from the view point of its long term utilization because the reactor pressure vessel of the JMTR will be used continuously after restart of the JMTR. As a result, adhesion materials which can be easily removed using the gauze were observed around nozzles in a top head of the reactor pressure vessel. 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 reactor pressure vessel was observed, and thus the integrity of the reactor pressure vessel was confirmed. As for the view point of the aged effect, it became clear that the reactor pressure vessel of the JMTR can be used for more than 20 years. The visual inspection by the underwater camera is to be carried out periodically to confirm the integrity of the reactor pressure vessel.
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.
Takemoto, Noriyuki; Nagao, Yoshiharu; Ishihara, Masahiro
JAEA-Review 2009-037, 37 Pages, 2009/12
JAEA-Review-2009-037.pdf:7.71MB
The JMTR, one of the most high flux test reactors in the world, has been used for the irradiation experiments of fuels and materials related to LWRs, fundamental research and radioisotope productions. The JMTR was stopped at the beginning of August 2006 to conduct refurbishment works, and the reoperation will be planned from FY 2011. After reoperation, the JMTR will contribute to many fields, such as the lifetime extension of LWRs, expansion of industrial use, progress of science and technology. This report summarizes the activities on refurbishment works, development of new irradiation techniques, enhancement of reactor availability, etc.
Takemoto, Noriyuki; Naka, Michihiro; Nagao, Yoshiharu
Proceedings of 12th International Group on Research Reactors (12th IGORR) (USB Flash Drive), 11 Pages, 2009/10
no abstracts in English
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.
Ide, Hiroshi; Sakuta, Yoshiyuki; Hanawa, Yoshio; Tsuji, Tomoyuki; Tsuboi, Kazuaki; Nagao, Yoshiharu; Miyazawa, Masataka
JAEA-Technology 2009-019, 28 Pages, 2009/06
JAEA-Technology-2009-019.pdf:41.1MB
The main body of the JMTR is composed of reactor pressure vessel, core and reactor pool. At the bottom of the reactor pool, the Diaphragm-seal (2.6m outer diameter, 2m inner diameter, thickness 1.5mm) of the JMTR made of stainless steel is installed to prevent the water leak of the reactor pool and to absorb the expansion of the reactor pressure vessel due to pressure and temperature changes. Prior to the refurbishment of the JMTR, the inspection device which is a deposition-collection apparatus with underwater-camera was developed, and the visual inspection was carried out to confirm the soundness of the diaphragm-seal. As a result, harmful flaws and/or corrosions were not inspected in the visual inspection, and the soundness of the diaphragm seal was confirmed. In future, the long-term integrity of the diaphragm-seal will could be achieved by conducting the periodic inspection.
Kimura, Tadashi; Oto, Tsutomu; Izumo, Hironobu; Nagao, Yoshiharu; Kawamura, Hiroshi
JAEA-Review 2008-080, 16 Pages, 2009/03
JAEA-Review-2008-080.pdf:3.11MB
The ion exchange resin is used for the purification system of the primary cooling water and the pool canal water in the JMTR. The spent ion exchange resin is stored in the liquid waste tank. The amount of the spent ion exchange resin in the liquid waste tank increases with reactor operation. The possibility of the spent ion exchange resin processing for oversea processing facilities was examined as a procedure for processing of the spent ion exchange resin. As the results, technical, regulations, and social issues were extracted from the procedure of spent ion exchange resin processing at oversea processing facilities. Furthermore, the conditions of oversea processing were indicated.
Takemoto, Noriyuki; Nagao, Yoshiharu; Ishihara, Masahiro; Niimi, Motoji; Kawamura, Hiroshi
UTNL-R-0471, p.5_1_1 - 5_1_8, 2009/03
no abstracts in English
Kimura, Tadashi; Izumo, Hironobu; Nagao, Yoshiharu; Kawamura, Hiroshi
UTNL-R-0471, p.5_3_1 - 5_3_10, 2009/03
no abstracts in English
Takemoto, Noriyuki; Okumura, Keisuke; Katakura, Junichi; Nagao, Yoshiharu; Kawamura, Hiroshi
JAEA-Data/Code 2008-029, 24 Pages, 2009/02
JAEA-Data-Code-2008-029.pdf:2.73MB
The continuous energy cross section library for the Monte Carlo transport code MCNP, JAC08T1, has been generated from the latest version of Japanese evaluated nuclear data library JENDL/AC released in March, 2008. The latest version of NJOY (NJOY99.259), the evaluated nuclear data processing system, has been employed to produce the library after necessary modifications in order to process JENDL/AC.
