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Journal Articles

Inverted-parabolic and weak strain dependencies on the critical current in practical $$<$$110$$>$$ and $$<$$100$$>$$ oriented REBCO tapes

Osamura, Kozo*; Machiya, Shutaro*; Kajiwara, Kentaro*; Kawasaki, Takuro; Harjo, S.; Zhang, Y.*; Fujita, Shinji*; Iijima, Yasuhiro*; Hampshire, D. P.*

AIP Advances (Internet), 9(7), p.075216_1 - 075216_11, 2019/07

 Times Cited Count:2 Percentile:22.92(Nanoscience & Nanotechnology)

Journal Articles

Design and burn-up analyses of new type holder for silicon neutron transmutation doping

Komeda, Masao; Arai, Masaji; Tamai, Kazuo*; Kawasaki, Kozo*

Applied Radiation and Isotopes, 113, p.60 - 65, 2016/07

 Times Cited Count:2 Percentile:25.63(Chemistry, Inorganic & Nuclear)

We designed and fabricated a new type holder that achieved uniform doping under long-term use at JRR-3. The new type holder uses an aluminum alloy and B$$_{4}$$C particles as filter materials to ensure uniform vertical flux distribution. Although the amount of filter material decreases with long-term use, it was found that the doping distribution did not change by much until 800 h. The lifetime of the new type holder (of the order of hundreds of hours) depends mainly on the amount of trapped radioactive isotopes. This indicates that the decrease in filtering ability over the filter's lifetime is not significant. The filtering ability remains stable for a long time, and the difference in the vertical doping distribution is 1.08 at 1600 h and 1.18 at 4000 h. The irradiation efficiency is expected to increase by 1.7 times when using the new type holder.

Journal Articles

Producing semiconductor by neutron irradiation

Komeda, Masao; Kawasaki, Kozo*

Hamon, 24(特別号), 2 Pages, 2014/11

no abstracts in English

Journal Articles

A New irradiation method with a neutron filter for silicon neutron transmutation doping at the Japan research reactor No. 3 (JRR-3)

Komeda, Masao; Kawasaki, Kozo*; Obara, Toru*

Applied Radiation and Isotopes, 74, p.70 - 77, 2013/04

 Times Cited Count:7 Percentile:54.8(Chemistry, Inorganic & Nuclear)

A new silicon irradiation holder with a neutron filter designed to make the vertical neutron flux profile uniform was studied. Irradiation methods to achieve uniform flux with a filter were discussed using Monte-Carlo calculation code MVP. Validation of the use of the MVP code for the holder's analyses was also discussed via characteristic experiments. It was found that a uniform profile of the vertical flux could be achieved by using the new type holder designed in this study. The vertical uniformity was $$pm$$3% when using the new type holder, while it was $$pm$$19.5% when using the normal holder. By using the new type holder, NTD-Si can be increased to 7 tons per year from 4 tons per year.

JAEA Reports

Investigation of neutron filter method using the research reactor JRR-3 for uniformity irradiation system; Technological examination to expand productivity of Neutron Transmutation Doping Silicon (NTD-Si) (Joint research)

Takeuchi, Masaki; Magome, Hirokatsu; Komeda, Masao; Kawasaki, Kozo*

JAEA-Technology 2009-037, 28 Pages, 2010/03

JAEA-Technology-2009-037.pdf:5.71MB

Japan Research Reactor No.3 (JRR-3) has been providing Neutron Transmutation Doping Silicon (NTD-Si). Though the inverse method is employed for producing NTD-Si in JRR-3, it is possible to increase the production rate of NTD-Si by using the neutron filter method. As the result, the prospect that the neutron filter method was able to develop without changing a geometrical size of NTD-Si facility in JRR3 was obtained.

JAEA Reports

Quantitative analyses of impurity silicon-carbide (SiC) and high-purity-titanium by neutron activation analyses based on k$$_{0}$$ standardization method; Development of irradiation silicon technology in productivity using research reactor (Joint research)

Motohashi, Jun; Takahashi, Hiroyuki; Magome, Hirokatsu; Sasajima, Fumio; Tokunaga, Okihiro*; Kawasaki, Kozo*; Onizawa, Koji*; Isshiki, Masahiko*

JAEA-Technology 2009-036, 50 Pages, 2009/07

JAEA-Technology-2009-036.pdf:32.66MB

JRR-3 and JRR-4 have been providing neutron-transmutation-doped silicon (NTD-Si) by using the silicon NTD process. We have been considering to introduce the neutron filter, which is made of high-purity-titanium, into uniform doping. Silicon carbide (SiC) semiconductors doped with NTD technology are considered suitable for high power devices with superior performances to conventional Si-based devices. The impurity contents in the high-purity-titanium and SiC were analyzed by neutron activation analyses (NAA) using k$$_{0}$$ standardization method. Analyses showed that the number of impurity elements detected from the high-purity-titanium and SiC were 6 and 9, respectively. Among these impurity elements, Sc detected from the high-purity-titanium and Fe detected from SiC were comparatively long half life nuclides. From the viewpoint of exposure in handling them, we need to examine the impurity control of materials.

JAEA Reports

Research for the life-extension of the wide-range monitoring neutron detectors of HTTR (Joint research)

Saito, Kenji; Sekita, Kenji; Kawasaki, Kozo; Yamamoto, Kazuhiko*; Matsuura, Makoto*

JAEA-Technology 2007-059, 36 Pages, 2007/11

JAEA-Technology-2007-059.pdf:26.24MB

The Wide-Range Monitoring neutron detectors of HTTR are used under 450 $$^{circ}$$C in normal operation and 550 $$^{circ}$$C in the accidents. When the WRM detectors are used under the high temperature for a long time, characteristics of the detector might be degraded, because of the decrease of the nitrogen concentration in the ionization gas caused by adsorbtion of nitrogen into the electrode material. Consequently, the nitrogen gas adsorption test was carried out to clarify the quantity of absorbed nitrogen gas in electrode material under the high temperature. Then, the performance evaluation test of the prototype detector was carried out, and it was confirmed that degradation of the prototype detector characteristics didn't arise under the high temperature anvironment. This report describes the results of consideration about the life-extension of WRM detectors. As a result, it was confirmed that the WRM detectors are usable for 5 years under 450 $$^{circ}$$C in normal operation and 550 $$^{circ}$$C in the accidents.

Journal Articles

A Methodology of structural analysis for nuclear power plant size of assembly

Tani, Masayuki; Nakajima, Norihiro; Nishida, Akemi; Suzuki, Yoshio; Matsubara, Hitoshi; Araya, Fumimasa; Kushida, Noriyuki; Hazama, Osamu; Kondo, Makoto; Kawasaki, Kozo

Proceedings of Joint International Topical Meeting on Mathematics & Computations and Supercomputing in Nuclear Applications (M&C+SNA 2007) (CD-ROM), 12 Pages, 2007/04

JAEA Reports

Operating experiences since rise-to-power test in High Temperature Engineering Test Reactor (HTTR)

Tochio, Daisuke; Watanabe, Shuji; Motegi, Toshihiro; Kawano, Shuichi; Kameyama, Yasuhiko; Sekita, Kenji; Kawasaki, Kozo

JAEA-Technology 2007-014, 62 Pages, 2007/03

JAEA-Technology-2007-014.pdf:9.74MB

The rise-to-power test of the High Temperature Engineering Test Reactor (HTTR) was begun in April 2000. The reactor thermal power of 30 MW, which is the maximum thermal power of the HTTR, and the reactor outlet coolant temperature of 850$$^{circ}$$C in normal operation was achieved in middle of December 2001. After that reactor thermal power of 30 MW a reactor outlet coolant temperature of 950$$^{circ}$$C was achieved in the final rise-to-power test at April 2004. After receiving the operation permit, the safety demonstration tests were conducted to demonstrate inherent safety features of the HTGRs. This paper summarizes the HTTR operating experiences for five years since rise-to-power test that were catalogued into three categories, (1) Operating experience pertaining to new gas cooled reactor design, (2) Operating experience for improvement of the performance, (3) Operating experience due to fail of system and components.

JAEA Reports

The Approaches of safety design and safety evaluation at HTTR (High Temperature Engineering Test Reactor)

Iigaki, Kazuhiko; Saikusa, Akio; Sawahata, Hiroaki; Shinozaki, Masayuki; Tochio, Daisuke; Homma, Fumitaka; Tachibana, Yukio; Iyoku, Tatsuo; Kawasaki, Kozo; Baba, Osamu*

JAEA-Review 2006-010, 90 Pages, 2006/07

JAEA-Review-2006-010.pdf:5.65MB

Gas Cooled Reactor has long history of nuclear development, and High Temperature Gas Cooled Reactor (HTGR) has been expected that it can be supply high temperature energy to chemical industry and to power generation from the points of view of the safety, the efficiency, the environment and the economy. The HTGR design is tried to installed passive safety equipment. The current licensing review guideline was made for a Low Water Reactor (LWR) on safety evaluation therefore if it would be directly utilized in the HTGR it needs the special consideration for the HTGR. This paper describes that investigation result of the safety design and the safety evaluation traditions for the HTGR, comparison the safety design and safety evaluation feature for the HTGT with it's the LWR, and reflection for next HTGR based on HTTR operational experiment.

JAEA Reports

Test results of HTTR control system

Motegi, Toshihiro; Iigaki, Kazuhiko; Saito, Kenji; Sawahata, Hiroaki; Hirato, Yoji; Kondo, Makoto; Shibutani, Hideki; Ogawa, Satoru; Shinozaki, Masayuki; Mizushima, Toshihiko; et al.

JAEA-Technology 2006-029, 67 Pages, 2006/06

JAEA-Technology-2006-029.pdf:3.07MB

The plant control performance of the IHX helium flow rate control system, the PPWC helium flow rate control system, the secondary helium flow rate control system, the inlet temperature control system, the reactor power control system and the outlet temperature control system of the HTTR are obtained through function tests and power-up tests. As the test results, the control systems show stable control response under transient condition. Both of inlet temperature control system and reactor power control system shows stable operation from 30% to 100%, respectively. This report describes the outline of control systems and test results.

Journal Articles

HTTR test programme towards coupling with the IS process

Iyoku, Tatsuo; Sakaba, Nariaki; Nakagawa, Shigeaki; Tachibana, Yukio; Kasahara, Seiji; Kawasaki, Kozo

Nuclear Production of Hydrogen, p.167 - 176, 2006/00

no abstracts in English

Journal Articles

Achievement of coolant temperature of 950$$^{circ}$$C in HTTR

Kawasaki, Kozo; Iyoku, Tatsuo; Tachibana, Yukio; Nakazawa, Toshio; Goto, Minoru

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 8 Pages, 2005/05

High Temperature Engineering Test Reactor (HTTR) achieved a coolant temperature of 950$$^{circ}$$C at reactor outlet with its rated thermal power of 30MW on April 19, 2004. Achievement of the reactor outlet coolant temperature of 950$$^{circ}$$C makes it possible to extend use of high-temperature gas-cooled reactors beyond the field of electric power generation. Not only highly effective power generation with a high-temperature gas turbine system but also hydrogen production from water without emission of carbon dioxide will be possible utilizing the high temperature heat. This report describes the results of the high-temperature test operation of the HTTR.

Journal Articles

Achievement of reactor-outlet coolant temperature of 950$$^{circ}$$C in HTTR

Fujikawa, Seigo; Hayashi, Hideyuki; Nakazawa, Toshio; Kawasaki, Kozo; Iyoku, Tatsuo; Nakagawa, Shigeaki; Sakaba, Nariaki

Journal of Nuclear Science and Technology, 41(12), p.1245 - 1254, 2004/12

 Times Cited Count:75 Percentile:97.45(Nuclear Science & Technology)

A High Temperature Gas-cooled Reactor (HTGR) is particularly attractive due to its capability of producing high-temperature helium gas and to its inherent safety characteristics. The High Temperature Engineering Test Reactor (HTTR), which is the first HTGR in Japan, achieved its rated thermal power of 30MW and reactor-outlet coolant temperature of 950$$^{circ}$$C on 19 April 2004. During the high-temperature test operation which is the final phase of the rise-to-power tests, reactor characteristics and reactor performance were confirmed, and reactor operations were monitored to demonstrate the safety and stability of operation. The reactor-outlet coolant temperature of 950$$^{circ}$$C makes it possible to extend high-temperature gas-cooled reactor use beyond the field of electric power. Also, highly effective power generation with a high-temperature gas turbine becomes possible, as does hydrogen production from water. The achievement of 950$$^{circ}$$C will be a major contribution to the actualization of producing hydrogen from water using the high-temperature gas-cooled reactors. This report describes the results of the high-temperature test operation of the HTTR.

Journal Articles

JAERI completed performance tests of the High Temperature Engineering Test Reactor (HTTR) at 950$$^{circ}$$C

Kawasaki, Kozo; Iyoku, Tatsuo; Nakazawa, Toshio; Hayashi, Hideyuki; Fujikawa, Seigo

Nihon Genshiryoku Gakkai-Shi, 46(8), P. 510, 2004/08

no abstracts in English

Journal Articles

High Temperature Engineering Test Reactor (HTTR) of JAERI achieved the reactor outlet helium gas temperature of 950$$^{circ}$$C for the first time in the world

Kawasaki, Kozo; Iyoku, Tatsuo; Nakazawa, Toshio; Hayashi, Hideyuki; Fujikawa, Seigo

Nihon Genshiryoku Gakkai-Shi, 46(5), P. 301, 2004/05

no abstracts in English

Journal Articles

Present status of high temperature gas-cooled reactors development; Fuel inspection

Sawa, Kazuhiro; Kawasaki, Kozo

Kensa Gijutsu, 8(6), p.17 - 22, 2003/06

This report describes outline of High Temperature Gas-cooled Reactors (HTGR), present status of HTTR Project, which is proceeded by JAERI. Fabrication technique and inspection methods of the HTGR fuel, which is are one of the special features of the HTGR, are also introduced.

JAEA Reports

Test plans of the high temperature test operation at HTTR

Sakaba, Nariaki; Nakagawa, Shigeaki; Takada, Eiji*; Nojiri, Naoki; Shimakawa, Satoshi; Ueta, Shohei; Sawa, Kazuhiro; Fujimoto, Nozomu; Nakazawa, Toshio; Ashikagaya, Yoshinobu; et al.

JAERI-Tech 2003-043, 59 Pages, 2003/03

JAERI-Tech-2003-043.pdf:2.54MB

HTTR plans a high temperature test operation as the fifth step of the rise-to-power tests to achieve a reactor outlet coolant temperature of 950 degrees centigrade in the 2003 fiscal year. Since HTTR is the first HTGR in Japan which uses coated particle fuel as its fuel and helium gas as its coolant, it is necessary that the plan of the high temperature test operation is based on the previous rise-to-power tests with a thermal power of 30 MW and a reactor outlet coolant temperature at 850 degrees centigrade. During the high temperature test operation, reactor characteristics, reactor performances and reactor operations are confirmed for the safety and stability of operations. This report describes the evaluation result of the safety confirmations of the fuel, the control rods and the intermediate heat exchanger for the high temperature test operation. Also, problems which were identified during the previous operations are shown with their solution methods. Additionally, there is a discussion on the contents of the high temperature test operation. As a result of this study, it is shown that the HTTR can safely achieve a thermal power of 30MW with the reactor outlet coolant temperature at 950 degrees centigrade.

JAEA Reports

Research and development for the high-temperature helium-leak detection system, 2; Development of temperature sensors using optical fibre for the HTTR (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Tech 2003-041, 106 Pages, 2003/03

JAERI-Tech-2003-041.pdf:6.58MB

In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature inclease surrounded opitical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm$$^{3}$$/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm$$^{3}$$/s.

JAEA Reports

Research and development of a high-temperature helium-leak detection system, 1; Survey on leakage events and current leak detection technology (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Review 2002-041, 86 Pages, 2003/03

JAERI-Review-2002-041.pdf:3.21MB

In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R&D is to develop a helium-leak detection system for the high temperature environment appropriate to the HTTR. This system can shorten the time of detection to several hours from about one week in the current detection time. In addition, it can also identify easily the leak location using the optical fibre network. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical fibre detection technology to HTGRs.

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