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Journal Articles

Evaluation of mechanical properties of oxide layers of fuel cladding material Zircaloy-4 and M5 oxidized under PWR condition using Nano indentation with spherical indenter

Shibata, Akira; Wakui, Takashi; Nakamura, Natsuki; Futakawa, Masatoshi; Maekawa, Katsuhiro*; Naka, Michihiro

Zairyo Shiken Gijutsu, 62(1), p.41 - 47, 2017/01

Nuclear reactor fuel cladding material has been gradually replaced from Zircaloy-4 to Zr-Nb alloys such as M5. To reveal the origin of good corrosion resistance of Zr-Nb alloys, evaluation on oxide layer of fuel cladding tube Zircaloy-4 and M5 was performed. Nano-indentation with spherical indenter was performed on oxide layer of those materials. Test results of the indentation were evaluated by the inverse analysis using Kalman filter and Finite Element Method. The results analysis shows that the oxide layer of M5 has more ductility compare from that of Zircaloy 4. Thus, oxide layer of Zircaloy4 could be injured by smaller strain compare from that of M5.

Journal Articles

Damage on the JMTR hot laboratory by the 2011 Great East Japan Earthquake

Shibata, Akira; Nakamura, Natsuki; Naka, Michihiro

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 11 Pages, 2017/00

An earthquake with magnitude 9.0 hit eastern Japan on 11th March 2011. It is known as "The 2011 Great East Japan Earthquake". The JMTR hot laboratory was damaged by the earthquake. This paper describes various damages on the JMTR hot laboratory caused by the earthquake. In the concrete cell, an electric lock of the shielding door of a hot cell was broken by the earth quake. Cracks were found in the walls of hot laboratory building. The exhaust stack of JMTR Hot laboratory is a part of gaseous waste treatment system. Thinning was found at anchor bolts on base of the stack in 2015. When thinning of anchor bolts were investigated, gaps between anchor bolt nuts and flange plate were found. It was concluded that the thinning was caused by water infiltration over a long period of time and the gaps were caused by elongation of thinning part of anchor bolts by series of earthquakes start from the 2011 Great East Japan Earthquake.

Journal Articles

Management of JMTR hot laboratory without operation of system of air supply and exhaust

Nakamura, Natsuki; Shibata, Akira; Naka, Michihiro

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 4 Pages, 2017/00

no abstracts in English

Journal Articles

Cause investigation for thinning of anchor bolts and gaps between anchor bolt nuts and a flange plate at the JMTR hot laboratory exhaust stack

Shibata, Akira; Kitagishi, Shigeru; Watashi, Katsumi; Matsui, Yoshinori; Omi, Masao; Sozawa, Shizuo; Naka, Michihiro

Nippon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.290 - 297, 2016/07

The exhaust stack of Japan Materials Testing Reactor Hot laboratory is a part of gaseous waste treatment system. It was built in 1970 and is 40 m in height. In 2015, thinning was found at some anchor bolts on base of the stack. When thinning of anchor bolts were investigated, gaps between anchor bolt nuts and flange plate was found. JAEA removed steel cylinder of stack which is 33 m in height for safety. In the end of investigation, thinning was found in all anchor bolts of the stack. Cause investigation for the thinning and the gaps were performed. It is concluded that the thinning was caused by water infiltration over a long period of time and the gaps were caused by elongation of thinning part of anchor bolts by the 2011 earthquake off the Pacific coast of Tohoku.

JAEA Reports

On-site training using JMTR and related facilities in FY2015

Eguchi, Shohei; Takemoto, Noriyuki; Shibata, Hiroshi; Naka, Michihiro; Nakamura, Jinichi; Tanimoto, Masataka; Ito, Haruhiko*

JAEA-Review 2016-001, 31 Pages, 2016/05

JAEA-Review-2016-001.pdf:9.05MB

Since fiscal 2011, a practical training course using the JMTR and other research infrastructures has been provided by Neutron Irradiation Testing Reactor Center for foreign young researchers and engineers in Asian and other countries which are planning to introduce power reactors. The aim of this course is to contribute to the human resource development in nuclear research field and to increase the future use the JMTR. On the other hand, a training course for Japanese young researchers and engineers has been conducted since fiscal 2010. These two separate courses were integrated. In fiscal 2015, this training course was conducted for 2 weeks and 17 young researchers and engineers from 7 countries were participated. They studied about the general outline of nuclear research, current status and R&D about nuclear energy, safety management of nuclear reactor, irradiation behavior of materials and fuels, facilities and technologies for irradiation and post irradiation, and nuclear characteristics of the reactor through lectures and practical trainings. At the end of the course, we had a discussion about the current status and future of energy mix and renewable energies of each country was discussed. The content of this training course in fiscal 2015 is reported in this paper.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 4

Kimura, Nobuaki; Takeuchi, Tomoaki; Shibata, Akira; Takemoto, Noriyuki; Kimura, Akihiro; Naka, Michihiro; Nishikata, Kaori; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; et al.

KURRI Progress Report 2012, P. 209, 2013/10

In research reactors, CCD cameras are used to observe reactor core for reactor operation management, e.g. to prevent debris from falling. In order to measure the reactor power and fuel burnup exactly by means of observation of Cherenkov light, the development of the on-line measurement device started in 2009. In this study, the wavelength and the absolute irradiance of the Cherenkov light were measured by a spectrometer, and the Cherenkov light was observed by the CCD camera. As a result, the measurement value is good agreement with the nominal value. On the other hand, the value by the visible imaging system was obtained the same tendency of nominal transmittance value of ND-filters.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2011

Watahiki, Shunsuke; Hanakawa, Hiroki; Imaizumi, Tomomi; Nagata, Hiroshi; Ide, Hiroshi; Komukai, Bunsaku; Kimura, Nobuaki; Miyauchi, Masaru; Ito, Masayasu; Nishikata, Kaori; et al.

JAEA-Technology 2013-021, 43 Pages, 2013/07

JAEA-Technology-2013-021.pdf:5.12MB

The number of research reactors in the world is decreasing because of their aging. On the other hand, the necessity of research reactor, which is used for human resources development, progress of the science and technology, industrial use and safety research is increasing for the countries which are planning to introduce the nuclear power plants. From above background, the Neutron Irradiation and Testing Reactor Center began to discuss a basic concept of Multipurpose Compact Research Reactor (MCRR) for education and training, etc., on 2010 to 2012. This activity is also expected to contribute to design tool improvement and human resource development in the center. In 2011, design study of reactor core, irradiation facilities with high versatility and practicality, and hot laboratory equipment for the production of Mo-99 was carried out. As the result of design study of reactor core, subcriticality and operation time of the reactor in consideration of an irradiation capsule, and about the transient response of the reactor to the reactivity disturbance during automatic control operation, it was possible to do automatic operation of MCRR, was confirmed. As the result of design study of irradiation facilities, it was confirmed that the implementation of an efficient mass production radioisotope Mo-99 can be expected. As the result of design study with hot laboratory facilities, Mo-99 production, RI export devised considered cell and facilities for exporting the specimens quickly was designed.

Journal Articles

Installation of JMTR core management system

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

Journal Articles

Ground-state configuration of the $$N=157$$ nucleus $$^{259}$$No

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; et al.

Physical Review C, 87(1), p.014332_1 - 014332_6, 2013/01

 Times Cited Count:4 Percentile:61.9(Physics, Nuclear)

The spin-parity and neutron configuration of the ground state of $$^{259}$$No have been identified through $$alpha$$-decay spectroscopy. The $$^{259}$$No is the nucleus with the largest neutron number whose spin-parities and single-particle configurations have ever been identified. The neutron 9/2$$^{+}$$[615] configuration was assigned to the ground state of $$^{259}$$No as well as to the 231.4 keV level in $$^{255}$$Fm. This allowed us to establish energy spacings and order of the neutron single-particle orbitals in such heaviest nuclear region. The appearance of the 9/2$$^{+}$$[615] ground state at $$N$$=157 implies that the order of the neutron orbitals between the $$N$$=152 and 162 deformed shell gaps should change considerably with increasing neutron number.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 3

Kimura, Nobuaki; Takemoto, Noriyuki; Nagata, Hiroshi; Kimura, Akihiro; Naka, Michihiro; Nishikata, Kaori; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.

KURRI Progress Report 2011, P. 219, 2012/10

In research reactors, a CCD camera is used to observe reactor core for reactor operation management, e.g. to prevent debris falling. In order to measure the reactor power and fuel burnup exactly by means of observation of Cherenkov light and $$gamma$$ ray information, the development of the on-line measurement device has been started since 2009. In this study, as a part of development of in-reactor surveillance, wavelength and absolute irradiance of Cherenkov light were measured by spectroscopy, and Cherenkov light was observed by the CCD camera. The neutral density filters (ND-filters) were used to investigate the transmittance of Cherenkov light in these measurements.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

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.

Journal Articles

Development on in-reactor observation system using cherenkov light, 2

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

Journal Articles

Development on in-reactor observation system using cherenkov light

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

Journal Articles

Investigation of optimization on in-core fuel management with high reactor-availability-factor of JMTR

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

JAEA Reports

Review on conformance of JMTR reactor facility to safety design examination guides for water-cooled reactors for test and research in JMTR reactor facility

Ide, Hiroshi; Naka, Michihiro; Sakuta, Yoshiyuki; Hori, Naohiko; Matsui, Yoshinori; Miyazawa, Masataka

JAEA-Review 2008-076, 442 Pages, 2009/03

JAEA-Review-2008-076.pdf:8.3MB

The safety design examination guides for water-cooled reactors for test and research was gathered in safe examination of the licensing as the purpose of showing the basics when the validity of the design is judged about from the viewpoint of keeping safety. For the confirmation of the JMTR reactor facility conforming the current guides, the check of the items mentioned in the licensing documents, annexes of licensing documents and related documents were carried out. As the result of check, there was the mention about conformity in licensing and so on. And the constructs, systems and devices which have safety functions have been produced under authorization of regulating authority. Therefore it was confirmed that the licensing were conformed to guides and the JMTR has enough performance.

JAEA Reports

Investigation on high availability-factor achievement of JMTR; How to achieve 60% availability-factor

Takemoto, Noriyuki; Izumo, Hironobu; Inoue, Shuichi; Abe, Shinichi; Naka, Michihiro; Akashi, Kazutomo; Omi, Masao; Miyazawa, Masataka; Baba, Osamu*; Nagao, Yoshiharu

JAEA-Review 2008-051, 36 Pages, 2008/10

JAEA-Review-2008-051.pdf:3.14MB

The JMTR has been refurbished to restart operation in FY2011. The restarted JMTR plays roles of (1) measures for long-term operation of light water reactors, (2) improvement in scientific technique, (3) increase of industrial use, (4) training of human resources, etc. It is needed to operate the restarted JMTR safety and stably and maintain high available factor (50$$sim$$70%) because of increasing of irradiation utilization demand. In this report, measures for training of reactor operators, organization for operating, etc were proposed to operate reactor safety and smoothly. And also reactor operation procedure was examined to improve available factor up to world level for materials testing reactor. As a result, it was turned out to be possible to realize stably 210 days operation per year (available factor: 60%).

JAEA Reports

Improvement of JMTR core management system; Applicability of SRAC2006 code system to JMTR core management system

Gorai, Shigeru; Naka, Michihiro; Izumo, Hironobu; Nagao, Yoshiharu; Kawamura, Hiroshi

JAEA-Technology 2008-040, 17 Pages, 2008/06

JAEA-Technology-2008-040.pdf:1.82MB

Various projects for improvement of JMTR are being carried out with the aim to re-start in FY2011. In the projects, it is planned to improve the JMTR core management system to execute neutronic calculations. The JMTR core management system is based on SRAC code system on mainframe, it is expected to improve the JMTR core management system by means of conversion from SRAC code system to the newest SRAC2006 code system on UNIX. Therefore neutronic calculations for JMTR using SRAC2006 code system were executed in order to estimate applicability and effectiveness of SARC2006 code system to the JMTR core management system.

Journal Articles

$$Q_{beta}$$ measurements of $$^{158,159}$$Pm, $$^{159,161}$$Sm, $$^{160-165}$$Eu, $$^{163}$$Gd and $$^{166}$$Tb using a total absorption BGO detector

Hayashi, Hiroaki*; Akita, Yukinori*; Suematsu, Osamu*; Shibata, Michihiro*; Asai, Masato; Sato, Tetsuya; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Osa, Akihiko; et al.

European Physical Journal A, 34(4), p.363 - 370, 2007/12

 Times Cited Count:15 Percentile:27.75(Physics, Nuclear)

$$Q_{beta}$$ values of $$^{160-165}$$Eu and $$^{163}$$Gd were measured for the first time using a total absorption BGO detector, and the data of $$^{158,159}$$Pm, $$^{159,161}$$Sm, and $$^{166}$$Tb obtained previously were reanalyzed. These nuclei were produced by the proton-induced fission of $$^{238}$$U at the JAEA-Tokai tandem accelerator facility, and separated from the reaction products using an on-line isotope separator. The deduced mass excesses and two-neutron separation energies were compared with those of atomic mass evaluations and theoretical predictions.

Journal Articles

$$alpha$$ decay of $$^{238}$$Cm and the new isotope $$^{237}$$Cm

Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.

Physical Review C, 73(6), p.067301_1 - 067301_4, 2006/06

 Times Cited Count:19 Percentile:25.03(Physics, Nuclear)

no abstracts in English

Journal Articles

Experimental identification of spin-parities and single-particle configurations in $$^{257}$$No and its $$alpha$$-decay daughter $$^{253}$$Fm

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ichikawa, Shinichi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Akiyama, Kazuhiko; Osa, Akihiko; Oura, Yasuji*; et al.

Physical Review Letters, 95(10), p.102502_1 - 102502_4, 2005/09

 Times Cited Count:60 Percentile:11.52(Physics, Multidisciplinary)

Excited states in $$^{253}$$Fm fed by the $$alpha$$ decay of $$^{257}$$No have been established through $$alpha$$-$$gamma$$ and $$alpha$$-electron coincidence spectroscopy using a gas-jet transport system and an on-line isotope separator. The spin-parity of the 124.1 keV level in $$^{253}$$Fm has been identified on the basis of the measured internal conversion coefficients. The $$nu 3/2^{+}[622]$$ configuration has been assigned to the ground state of $$^{257}$$No as well as to the 124.1 keV level. It was found that the ground state configuration of $$^{257}$$No is different from that of lighter $$N=155$$ isotones.

51 (Records 1-20 displayed on this page)