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

https://doi.org/10.1063/1.5092248

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

https://doi.org/10.1016/j.apradiso.2016.04.014

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 BC 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.

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

https://doi.org/10.1016/j.apradiso.2013.01.005

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 3% when using the new type holder, while it was 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.

Quantitative analyses of impurity silicon-carbide (SiC) and high-purity-titanium by neutron activation analyses based on k 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 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.

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

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.

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

Achievement of reactor-outlet coolant temperature of 950C 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

https://doi.org/10.3327/jnst.41.1245

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 950C 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 950C 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 950C 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.

High Temperature Engineering Test Reactor (HTTR) of JAERI achieved the reactor outlet helium gas temperature of 950C 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

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.